CD Actual 3/CD ACTUAL 3.iso/linux/docs/linux-do/install-/install-.002

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Author's Note:

This is version 2.2.2 of the book, "Linux Installation and Getting
Started", formatted in plain ASCII for those readers without access
to PostScript printers. This document was generated by a set of tools
from LaTeX source, so there may be a number of formatting problems.
This is not the "official" version of the book! Please see
    sunsite.unc.edu:/pub/Linux/docs/LDP/install-guide
for PostScript, DVI, HTML, and other (nicely formatted) versions.
If you have the ability to print the guide or view it on-line,
I suggest you do so. This ASCII version is meant only for previewing
purposes.

This book may be freely distributed under certain conditions, and
you can order a printed and bound copy from a number of publishers.
The README file at the FTP site given above gives all the details.

                    -- M. Welsh













Linux Installation and Getting Started
_______________________________________________________________________
                                  Copyright (c) 1992--1994  Matt Welsh






Version 2.2.2, 11 February 1995.

This  book   is   an  installation   and   new-user  guide   for   the
Linux system,  meant for  UNIX novices  and  gurus alike.    Contained
herein is  information on  how to  obtain Linux,  installation of  the
software, a beginning tutorial for new UNIX users, and an introduction
to system administration.    It is meant  to be  general enough to  be
applicable to any distribution of the Linux software.

  This book is freely distributable; you may copy  and redistribute it
under certain conditions.   Please see the copyright and  distribution
statement on page x.









Contents




Preface                                                             vi
  Audience  . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
  Organization  . . . . . . . . . . . . . . . . . . . . . . . . . . vii
  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . vii
  Credits and Legalese  . . . . . . . . . . . . . . . . . . . . . . viii
  Documentation Conventions . . . . . . . . . . . . . . . . . . . . xi
1 Introduction to Linux                                              1
  1.1 About This Book . . . . . . . . . . . . . . . . . . . . . . .  1
  1.2 A Brief History of Linux  . . . . . . . . . . . . . . . . . .  3
  1.3 System Features . . . . . . . . . . . . . . . . . . . . . . .  5
  1.4 Software Features . . . . . . . . . . . . . . . . . . . . . .  6
    1.4.1 Basic commands and utilities  . . . . . . . . . . . . . .  7
    1.4.2 Text processing and word processing . . . . . . . . . . .  8
    1.4.3 Programming languages and utilities . . . . . . . . . . . 11
    1.4.4 The X Window System . . . . . . . . . . . . . . . . . . . 12
    1.4.5 Networking  . . . . . . . . . . . . . . . . . . . . . . . 14
    1.4.6 Telecommunications and BBS software . . . . . . . . . . . 15
    1.4.7 Interfacing with MS-DOS . . . . . . . . . . . . . . . . . 16
    1.4.8 Other applications  . . . . . . . . . . . . . . . . . . . 16
  1.5 About Linux's Copyright . . . . . . . . . . . . . . . . . . . 18
  1.6 The Design and Philosophy of Linux  . . . . . . . . . . . . . 19
    1.6.1 Hints for UNIX novices  . . . . . . . . . . . . . . . . . 22
    1.6.2 Hints for UNIX gurus  . . . . . . . . . . . . . . . . . . 22
  1.7 Differences Between Linux and Other Operating Systems . . . . 23
    1.7.1 Why use Linux?  . . . . . . . . . . . . . . . . . . . . . 23
    1.7.2 Linux vs.  MS-DOS . . . . . . . . . . . . . . . . . . . . 24
    1.7.3 Linux vs.  The Other Guys . . . . . . . . . . . . . . . . 25
    1.7.4 Other implementations of UNIX . . . . . . . . . . . . . . 25
  1.8 Hardware Requirements . . . . . . . . . . . . . . . . . . . . 27
    1.8.1 Motherboard and CPU requirements  . . . . . . . . . . . . 28
    1.8.2 Memory requirements . . . . . . . . . . . . . . . . . . . 28
    1.8.3 Hard drive controller requirements  . . . . . . . . . . . 29
    1.8.4 Hard drive space requirements . . . . . . . . . . . . . . 29
    1.8.5 Monitor and video adapator requirements . . . . . . . . . 30
    1.8.6 Miscellaneous hardware  . . . . . . . . . . . . . . . . . 30
    1.8.7 Ethernet cards  . . . . . . . . . . . . . . . . . . . . . 31
  1.9 Sources of Linux Information  . . . . . . . . . . . . . . . . 32
    1.9.1 Online documents  . . . . . . . . . . . . . . . . . . . . 32


                                  i


    1.9.2 Linux on the World Wide Web . . . . . . . . . . . . . . . 33
    1.9.3 Books and other published works . . . . . . . . . . . . . 33
    1.9.4 USENET newsgroups . . . . . . . . . . . . . . . . . . . . 34
    1.9.5 Internet mailing lists  . . . . . . . . . . . . . . . . . 36
  1.10 Getting Help . . . . . . . . . . . . . . . . . . . . . . . . 37

2 Obtaining and Installing Linux                                    40
  2.1 Distributions of Linux  . . . . . . . . . . . . . . . . . . . 40
    2.1.1 Getting Linux from the Internet . . . . . . . . . . . . . 41
    2.1.2 Getting Linux from other online sources . . . . . . . . . 42
    2.1.3 Getting Linux via mail order  . . . . . . . . . . . . . . 42
    2.1.4 Getting Slackware . . . . . . . . . . . . . . . . . . . . 43
  2.2 Preparing to Install Linux  . . . . . . . . . . . . . . . . . 50
    2.2.1 Installation overview . . . . . . . . . . . . . . . . . . 50
    2.2.2 Repartitioning concepts . . . . . . . . . . . . . . . . . 52
    2.2.3 Linux partition requirements  . . . . . . . . . . . . . . 52
    2.2.4 Repartitioning your drives  . . . . . . . . . . . . . . . 54
  2.3 Installing the Linux software . . . . . . . . . . . . . . . . 56
    2.3.1 Booting Linux . . . . . . . . . . . . . . . . . . . . . . 56
    2.3.2 Drives and partitions under Linux . . . . . . . . . . . . 58
    2.3.3 Creating Linux partitions . . . . . . . . . . . . . . . . 60
    2.3.4 Creating the swap space . . . . . . . . . . . . . . . . . 63
    2.3.5 Creating the filesystems  . . . . . . . . . . . . . . . . 64
    2.3.6 Installing the software . . . . . . . . . . . . . . . . . 65
    2.3.7 Creating the boot floppy or installing LILO . . . . . . . 69
    2.3.8 Additional installation procedures  . . . . . . . . . . . 70
  2.4 Postinstallation procedures . . . . . . . . . . . . . . . . . 70
  2.5 Running Into Trouble  . . . . . . . . . . . . . . . . . . . . 71
    2.5.1 Problems with booting the installation media  . . . . . . 72
    2.5.2 Hardware problems . . . . . . . . . . . . . . . . . . . . 74
    2.5.3 Problems installing the software  . . . . . . . . . . . . 79
    2.5.4 Problems after installing Linux . . . . . . . . . . . . . 81
3 Linux Tutorial                                                    85
  3.1 Introduction  . . . . . . . . . . . . . . . . . . . . . . . . 85
  3.2 Basic UNIX Concepts . . . . . . . . . . . . . . . . . . . . . 86
    3.2.1 Creating an account . . . . . . . . . . . . . . . . . . . 86
    3.2.2 Logging in  . . . . . . . . . . . . . . . . . . . . . . . 86
    3.2.3 Virtual consoles  . . . . . . . . . . . . . . . . . . . . 87
    3.2.4 Shells and commands . . . . . . . . . . . . . . . . . . . 87
    3.2.5 Logging out . . . . . . . . . . . . . . . . . . . . . . . 89
    3.2.6 Changing your password  . . . . . . . . . . . . . . . . . 89
    3.2.7 Files and directories . . . . . . . . . . . . . . . . . . 89
    3.2.8 The directory tree  . . . . . . . . . . . . . . . . . . . 90
    3.2.9 The current working directory . . . . . . . . . . . . . . 90
    3.2.1 0Referring to home directories  . . . . . . . . . . . . . 92
  3.3 First Steps into UNIX . . . . . . . . . . . . . . . . . . . . 92
    3.3.1 Moving around . . . . . . . . . . . . . . . . . . . . . . 92
    3.3.2 Looking at the contents of directories  . . . . . . . . . 93
    3.3.3 Creating new directories  . . . . . . . . . . . . . . . . 95
    3.3.4 Copying files . . . . . . . . . . . . . . . . . . . . . . 96


    3.3.5 Moving files  . . . . . . . . . . . . . . . . . . . . . . 96
    3.3.6 Deleting files and directories  . . . . . . . . . . . . . 96
    3.3.7 Looking at files  . . . . . . . . . . . . . . . . . . . . 97
    3.3.8 Getting online help . . . . . . . . . . . . . . . . . . . 97
  3.4 Summary of Basic Commands . . . . . . . . . . . . . . . . . . 98
  3.5 Exploring the File System  . . . . . . . . . . . . . . . . . 100
  3.6 Types of shells  . . . . . . . . . . . . . . . . . . . . . . 105
  3.7 Wildcards  . . . . . . . . . . . . . . . . . . . . . . . . . 106
  3.8 UNIX Plumbing  . . . . . . . . . . . . . . . . . . . . . . . 108
    3.8.1 Standard input and output  . . . . . . . . . . . . . . . 108
    3.8.2 Redirecting input and output . . . . . . . . . . . . . . 109
    3.8.3 Using pipes  . . . . . . . . . . . . . . . . . . . . . . 110
    3.8.4 Non-destructive redirection  . . . . . . . . . . . . . . 112
  3.9 File Permissions . . . . . . . . . . . . . . . . . . . . . . 112
    3.9.1 Concepts of file permissions . . . . . . . . . . . . . . 112
    3.9.2 Interpreting file permissions  . . . . . . . . . . . . . 113
    3.9.3 Dependencies . . . . . . . . . . . . . . . . . . . . . . 114
    3.9.4 Changing permissions . . . . . . . . . . . . . . . . . . 115
  3.10 Managing file links . . . . . . . . . . . . . . . . . . . . 115
    3.10.1 Hard links  . . . . . . . . . . . . . . . . . . . . . . 115
    3.10.2 Symbolic links  . . . . . . . . . . . . . . . . . . . . 117
  3.11 Job Control . . . . . . . . . . . . . . . . . . . . . . . . 117
    3.11.1 Jobs and processes  . . . . . . . . . . . . . . . . . . 117
    3.11.2 Foreground and background . . . . . . . . . . . . . . . 118
    3.11.3 Backgrounding and killing jobs  . . . . . . . . . . . . 119
    3.11.4 Stopping and restarting jobs  . . . . . . . . . . . . . 121
  3.12 Using the vi Editor . . . . . . . . . . . . . . . . . . . . 123
    3.12.1 Concepts  . . . . . . . . . . . . . . . . . . . . . . . 124
    3.12.2 Starting vi . . . . . . . . . . . . . . . . . . . . . . 124
    3.12.3 Inserting text  . . . . . . . . . . . . . . . . . . . . 125
    3.12.4 Deleting text . . . . . . . . . . . . . . . . . . . . . 126
    3.12.5 Changing text . . . . . . . . . . . . . . . . . . . . . 127
    3.12.6 Moving commands . . . . . . . . . . . . . . . . . . . . 128
    3.12.7 Saving files and quitting vi  . . . . . . . . . . . . . 128
    3.12.8 Editing another file  . . . . . . . . . . . . . . . . . 129
    3.12.9 Including other files . . . . . . . . . . . . . . . . . 129
    3.12.10 Running shell commands . . . . . . . . . . . . . . . . 130
    3.12.11 Getting help . . . . . . . . . . . . . . . . . . . . . 130
  3.13Customizing your Environment . . . . . . . . . . . . . . . . 130
    3.13.1 Shell scripts . . . . . . . . . . . . . . . . . . . . . 131
    3.13.2 Shell variables and the environment . . . . . . . . . . 132
    3.13.3 Shell initialization scripts  . . . . . . . . . . . . . 135
  3.14 So You Want to Strike Out on Your Own?  . . . . . . . . . . 135

4 System Administration                                            137
  4.1  About Root, Hats, and the Feeling of Power  . . . . . . . . 137
    4.1.1 The root account . . . . . . . . . . . . . . . . . . . . 137
    4.1.2 Abusing the system . . . . . . . . . . . . . . . . . . . 139
    4.1.3 Dealing with users . . . . . . . . . . . . . . . . . . . 139
    4.1.4 Setting the rules  . . . . . . . . . . . . . . . . . . . 140
    4.1.5 What it all means  . . . . . . . . . . . . . . . . . . . 140


  4.2  Booting the System  . . . . . . . . . . . . . . . . . . . . 141
    4.2.1 Using a boot floppy  . . . . . . . . . . . . . . . . . . 141
    4.2.2 Using LILO . . . . . . . . . . . . . . . . . . . . . . . 142
  4.3 Shutting Down  . . . . . . . . . . . . . . . . . . . . . . . 143
  4.4 Managing Users . . . . . . . . . . . . . . . . . . . . . . . 144
    4.4.1 User management concepts . . . . . . . . . . . . . . . . 144
    4.4.2 Adding users . . . . . . . . . . . . . . . . . . . . . . 146
    4.4.3 Deleting users . . . . . . . . . . . . . . . . . . . . . 146
    4.4.4 Setting user attributes  . . . . . . . . . . . . . . . . 146
    4.4.5 Groups . . . . . . . . . . . . . . . . . . . . . . . . . 147
  4.5 Archiving and Compressing Files  . . . . . . . . . . . . . . 147
    4.5.1 Using tar  . . . . . . . . . . . . . . . . . . . . . . . 148
    4.5.2 gzip and compress  . . . . . . . . . . . . . . . . . . . 149
    4.5.3 Putting them together  . . . . . . . . . . . . . . . . . 149
  4.6 Using Floppies and Making Backups  . . . . . . . . . . . . . 151
    4.6.1 Using floppies for backups . . . . . . . . . . . . . . . 151
    4.6.2 Using floppies as filesystems  . . . . . . . . . . . . . 151
  4.7 Upgrading and Installing New Software  . . . . . . . . . . . 152
    4.7.1 Upgrading the kernel . . . . . . . . . . . . . . . . . . 153
    4.7.2 Upgrading the libraries  . . . . . . . . . . . . . . . . 154
    4.7.3 Upgrading gcc  . . . . . . . . . . . . . . . . . . . . . 155
    4.7.4 Upgrading other software . . . . . . . . . . . . . . . . 156
  4.8 Managing Filesystems . . . . . . . . . . . . . . . . . . . . 156
    4.8.1 Mounting filesystems . . . . . . . . . . . . . . . . . . 156
    4.8.2 Checking filesystems . . . . . . . . . . . . . . . . . . 158
  4.9 Using a swap file  . . . . . . . . . . . . . . . . . . . . . 159
  4.10 Miscellaneous Tasks . . . . . . . . . . . . . . . . . . . . 160
    4.10.1 System startup files  . . . . . . . . . . . . . . . . . 160
    4.10.2 Setting the hostname  . . . . . . . . . . . . . . . . . 161
  4.11 What To Do In An Emergency  . . . . . . . . . . . . . . . . 162
    4.11.1 Recovering using a maintenance diskette . . . . . . . . 162
    4.11.2 Fixing the root password  . . . . . . . . . . . . . . . 163
    4.11.3 Fixing trashed filesystems  . . . . . . . . . . . . . . 163
    4.11.4 Recovering lost files . . . . . . . . . . . . . . . . . 164
    4.11.5 Fixing trashed libraries  . . . . . . . . . . . . . . . 164

5 Advanced Features                                                165
  5.1 The X Window System  . . . . . . . . . . . . . . . . . . . . 165
    5.1.1 Hardware requirements  . . . . . . . . . . . . . . . . . 166
    5.1.2 Installing XFree86 . . . . . . . . . . . . . . . . . . . 168
    5.1.3 Configuring XFree86  . . . . . . . . . . . . . . . . . . 170
    5.1.4 Filling in video card information  . . . . . . . . . . . 178
    5.1.5 Running XFree86  . . . . . . . . . . . . . . . . . . . . 182
    5.1.6 Running into trouble . . . . . . . . . . . . . . . . . . 183
  5.2 Accessing MS-DOS Files . . . . . . . . . . . . . . . . . . . 184
  5.3 Networking with TCP/IP . . . . . . . . . . . . . . . . . . . 185
    5.3.1 Hardware Requirements  . . . . . . . . . . . . . . . . . 186
    5.3.2 Configuring TCP/IP on your system  . . . . . . . . . . . 186
    5.3.3 SLIP Configuration . . . . . . . . . . . . . . . . . . . 194
    5.3.4 Using dip  . . . . . . . . . . . . . . . . . . . . . . . 197
  5.4 Networking with UUCP . . . . . . . . . . . . . . . . . . . . 199
                                                                     v
_______________________________________________________________________

  5.5 Electronic Mail  . . . . . . . . . . . . . . . . . . . . . . 200
  5.6 News and USENET  . . . . . . . . . . . . . . . . . . . . . . 200

A Sources of Linux Information                                     203
  A.1 Online Documents . . . . . . . . . . . . . . . . . . . . . . 203
  A.2 Linux Documentation Project Manuals  . . . . . . . . . . . . 205
  A.3 Books and Other Published Works  . . . . . . . . . . . . . . 206
    A.3.1 Using UNIX . . . . . . . . . . . . . . . . . . . . . . . 207
    A.3.2 Systems Administration . . . . . . . . . . . . . . . . . 207
    A.3.3 The X Window System  . . . . . . . . . . . . . . . . . . 208
    A.3.4 Programming  . . . . . . . . . . . . . . . . . . . . . . 208
    A.3.5 Kernel Hacking . . . . . . . . . . . . . . . . . . . . . 209
B Linux Vendor List                                                211

C FTP Tutorial and Site List                                       214
  C.1 Starting ftp . . . . . . . . . . . . . . . . . . . . . . . . 214
  C.2 Logging In . . . . . . . . . . . . . . . . . . . . . . . . . 215
  C.3 Poking Around  . . . . . . . . . . . . . . . . . . . . . . . 215
  C.4 Downloading files  . . . . . . . . . . . . . . . . . . . . . 217
  C.5 Quitting FTP   . . . . . . . . . . . . . . . . . . . . . . . 219
  C.6 Using ftpmail  . . . . . . . . . . . . . . . . . . . . . . . 220
  C.7 Linux FTP Site List  . . . . . . . . . . . . . . . . . . . . 220
D Linux BBS List                                                   222
  D.1 United States  . . . . . . . . . . . . . . . . . . . . . . . 222
  D.2 Outside of the United States . . . . . . . . . . . . . . . . 224

E The GNU General Public License                                   227
  E.1 Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . 227
  E.2 Terms  and  Conditions  for  Copying,   Distribution,  and
    Modification  . . . . . . . . . . . . . . . . . . . . . . . .  228
  E.3 Appendix:  How to Apply These Terms to Your New Programs . . 233









Preface



``You are in a maze of twisty little passages, all alike.''
  Before you looms  one of the  most complex and utterly  intimidating
systems ever written.   Linux,  the free UNIX  clone for the  personal
computer, produced by a mishmash team of UNIX gurus, hackers,  and the
occasional loon.   The system itself  reflects this complex  heritage,
and although the development of Linux may appear to be  a disorganized
volunteer effort, the system  is powerful, fast,  and free.   It is  a
true 32-bit operating system solution.
  My  own experiences  with  Linux began  several  years ago,  when  I
sat down  to  figure out  how  to  install the  only  ``distribution''
available at the time---a couple  of diskettes made available by  H.J.
Lu.   I  downloaded a  slew  of files  and read  pages  upon pages  of
loosely-organized installation notes.   Somehow, I managed to  install
this basic  system and  get everything  working together.    This  was
long before you could buy the Linux software on CD-ROM  from worldwide
distributors; before, in fact, Linux even knew how to  access a CD-ROM
drive.   This  was before  XFree86,  before Emacs,  before  commercial
software support,  and before  Linux became  a true  rival to  MS-DOS,
Microsoft Windows, and OS/2 in the personal computer market.
  You hold in  your very hands the map  and guidebook to the  world of
Linux.  It is my hope that this book will help you to get rolling with
what I consider to be the fastest, most powerful  operating system for
the personal computer.    Setting up your  own Linux  system can be  a
great deal of fun---so grab a cup of coffee, sit back, and read on.
  Grab a cup for  me, too, while you're at  it.  I've been  up hacking
Linux for days.


Audience

This book is for any personal  computer user who wants to  install and
use Linux on their system.   We assume  that you have basic  knowledge
about personal  computers and  operating systems  such  as MS-DOS.  No
previous knowledge about Linux or UNIX is assumed.
  Despite this,  we strongly suggest that  UNIX novices invest in  one
of the many good UNIX books out there.  Several of them  are listed in
Appendix A.




                                  vi
                                                                   vii
_______________________________________________________________________

Organization

This book contains the following chapters.
  Chapter 1,  Introduction to Linux,  gives a general introduction  to
what Linux is, what it can do for you, and what is required  to run it
on your system.  It  also provides helpful hints for getting  help and
reducing overall stress.
  Chapter 2,  Obtaining and Installing Linux,  explains how to  obtain
the Linux software, as well as how to install it---from repartitioning
your drive,  creating filesystems,  and  loading the  software on  the
system.    It  contains  instructions  meant to  be  general  for  any
distribution of Linux,  and relies on  the documentation provided  for
your particular release to fill in any gaps.
  Chapter 3, Linux Tutorial,  is a complete introduction to  using the
Linux system for UNIX novices.  If you have  previous UNIX experience,
most of this material should be familiar.
  Chapter 4, System  Administration, introduces many of  the important
concepts of system  administration under  Linux.   This  will also  be
of interest to UNIX system  administrators who want to know  about the
Linux-specific issues of running a system.
  Chapter 5, Advanced Features,  introduces the reader to a  number of
advanced features supported by Linux, such as the X  Window System and
TCP/IP networking.   A  complete guide to  configuring XFree86-3.1  is
included.
  Appendix A,  Sources of  Linux Information,  is a  listing of  other
sources of  information  about Linux,  including  newsgroups,  mailing
lists, online documents, and books.
  Appendix B,  Linux Vendor List,  provides a  short list of  software
vendors offering Linux software and services.
  Appendix  C,  FTP  Tutorial  and  Site  List,   is  a  tutorial  for
downloading files  from  the Internet  with  FTP. This  appendix  also
includes a listing of FTP archive sites which carry Linux software.
  Appendix D, Linux BBS  List, is a listing of bulletin  board systems
worldwide which carry Linux software.  Because most Linux users are do
not have access to the Internet,  it is important that  information on
BBS systems becomes available.
  Appendix E,  The  GNU General  Public License,  contains  a copy  of
the GNU GPL, the license  agreement under which Linux is  distributed.
It is  very  important  that  Linux users  understand  the  GPL;  many
disagreements over the  terms of the  GPL have  been raised in  recent
months.


Acknowledgments

This book has been long in the making, and many people are responsible
for the  outcome.     In  particular,  I would  like  to  thank  Larry
Greenfield and  Karl Fogel  for their  work on  the  first version  of
Chapter 3, and to Lars  Wirzenius for his work  on Chapter 4.   Thanks
to Michael K. Johnson  for his assistance with  the LDP and the  LaTeX
                                                                  viii
_______________________________________________________________________

conventions used in this manual, and to Ed Chi, who sent  me a printed
copy of the book for edition.
  Thanks to Melinda A. McBride at SSC, Inc., who  did an excellent job
completing the index for Chapters 3, 4,  and 5.  I would also  like to
thank Andy Oram, Lar Kaufman, and Bill Hahn at O'Reilly and Associates
for their assistance with the Linux Documentation Project.
  Thanks to  Linux Systems Labs,  Morse Telecommunications,  Yggdrasil
Computing, and  others for their  support of  the Linux  Documentation
Project through sales of this book and other works.
  Much  thanks to  the many  activists,  including (in  no  particular
order) Linus Torvalds, Donald Becker,  Alan Cox, Remy Card,  Ted T'so,
H.J. Lu, Ross Biro, Drew Eckhardt,  Ed Carp, Eric Youngdale,  Fred van
Kempen, Steven Tweedie, and  a score of  others, for devoting so  much
time and energy to  this project, and  without whom there wouldn't  be
anything to write a book about.
  Special thanks to the myriad of readers who  have sent their helpful
comments and corrections.  There are  far too many to list here.   Who
needs a spell checker, when you have an audience?

                                                            Matt Welsh
                                                       13 January 1994


Credits and Legalese

The  Linux  Documentation  Project  is   a  loose  team  of   writers,
proofreaders, and editors who are working on a set of definitive Linux
manuals.  The overall coordinator of the project is Matt  Welsh, aided
by Lars Wirzenius and Michael K. Johnson.
  This  manual is  but  one in  a  set  of several  being  distributed
by the Linux  Documentation Project, including  a Linux User's  Guide,
System Administrator's  Guide,  and  Kernel  Hacker's Guide.     These
manuals are  all  available  in  LaTeX source  format  and  Postscript
output for  anonymous  FTP  from  sunsite.unc.edu,  in  the  directory
/pub/Linux/docs/LDP.
  We encourage anyone with  a penchant for writing or editing  to join
us in improving  Linux documentation.    If you  have Internet  e-mail
access, you can  join the DOC channel  of the Linux-Activists  mailing
list by sending mail to

    [e-mail]

with the line

    X-Mn-Admin:  join DOC

as the first line of the message body.
  Feel free to  get in touch with  the author and coordinator of  this
manual if you have questions, postcards, money, or ideas.   Matt Welsh
can be reached via Internet e-mail at [e-mail], and in real
                                                                    ix
_______________________________________________________________________

life at

    205 Gray Street
    Wilson, N.C. 27896
    U.S.A.
                                                                     x
_______________________________________________________________________

UNIX is a trademark of X/Open.
Linux is not a trademark, and has no connection to UNIXTM or X/Open.
The X Window System is  a trademark of the Massachusetts  Institute of
Technology.
MS-DOS and Microsoft Windows are trademarks of Microsoft, Inc.














Copyright cO1992--1994  Matt Welsh
205 Gray Street NE, Wilson NC, 27893 USA
[e-mail]

Linux  Installation  and  Getting   Started  may  be  reproduced   and
distributed, in whole or in part, subject to the following conditions:

0.  The copyright  notice above  and this  permission  notice must  be
    preserved complete on all complete or partial copies.

1.  Any translation  or  derivative  work of  Linux  Installation  and
    Getting Started must be approved  by the author in  writing before
    distribution.

2.  If you distribute Linux Installation and Getting Started  in part,
    instructions for  obtaining the  complete version  of this  manual
    must be included,  and a  means for  obtaining a complete  version
    provided.

3.  Small portions may be  reproduced as illustrations for reviews  or
    quotes in other  works without  this permission  notice if  proper
    citation is given.

4.  The GNU General Public License referenced below may  be reproduced
    under the conditions given within it.

5.  Several  sections  of  this  document  are  held   under  separate
    copyright.    When  these  sections are  covered  by  a  different
    copyright, the separate  copyright is  noted.   If you  distribute
    Linux Installation  and Getting  Started in  part,  and that  part
    is, in  whole,  covered under  a  separate, noted  copyright,  the
    conditions of that copyright apply.
                                                                    xi
_______________________________________________________________________

  Exceptions   to   these  rules   may   be   granted   for   academic
purposes:   Write  to Matt  Welsh,  at  the above  address,  or  email
[e-mail], and ask.  These restrictions are here  to protect
us as authors, not to restrict you as educators and learners.
  The author encourages  distributors of Linux software in  any medium
to use the  book as an  installation and new  user guide.   Given  the
copyright above, you are free  to print and distribute copies  of this
book with your software.  You may either distribute this  book free of
charge, or for profit.  If  doing so, you may wish to include  a short
``installation supplement'' for your release.
  The  author  would  like  to  know  of  any  plans  to  publish  and
distribute this book commercially.   In this  way, we can ensure  that
you are kept up-to-date with new revisions.  And, should a new version
be right around the corner,  you might wish to delay  your publication
of the book until it is available.
  If  you   are  distributing  this   book  commercially,   donations,
royalties,  and/or printed  copies  are  greatly  appreciated  by  the
author.  Contributing in this way shows your support for free software
and the Linux Documentation Project.

All source code in  Linux Installation and  Getting Started is  placed
under the GNU General Public  License.  See  Appendix E for a copy  of
the GNU ``GPL.''


Documentation Conventions

These conventions should be obvious,  but we'll include them  here for
the pedantic.

Bold       Used  to mark  new concepts,  WARNINGS, and  keywords in  a
           language.

italics    Used for  emphasis in text, and occasionally for  quotes or
           introductions at the beginning of a section.   Also used to
           indicate commands for the user to  type when showing screen
           interaction (see below).
<slanted>  Used  to mark  meta-variables in  the text,  especially  in
           representations of the command line.  For example,


               ls -l <foo>

           where  <foo>  would  ``stand  for''  a  filename,  such  as
           /bin/cp.

Typewriter Used to represent screen interaction, as in


               $ ls --l /bin/cp
               -rwxr-xr-
                                                                   xii
_______________________________________________________________________

               x  1 root    wheel    12104 Sep 25 15:53 /bin/cp


           Also used for code examples, whether it  is C code, a shell
           script,  or something else,  and to display general  files,
           such as configuration files.   When necessary for clarity's
           sake,  these examples or figures  will be enclosed in  thin
           boxes.
[Key]      Represents a key  to press.  You will often see it  in this
           form:


               Press [return] to continue.

!          A  diamond in the  margin, like  a black  diamond on a  ski
           hill,  marks ``danger''  or ``caution.''   Read  paragraphs
           marked this way carefully.








Chapter 1




Introduction to Linux



Linux is  quite  possibly  the  most  important  achievement  of  free
software since the original Space War,  or, more recently, Emacs.   It
has developed into the operating system for businesses, education, and
personal productivity.  Linux is  no longer just for UNIX  wizards who
sit for hours in front of the glowing console (although  we assure you
that quite a number of users fall into this category).  This book will
help you get the most out of it.
  Linux  (pronounced with  a short  i,  as in  LIH-nucks)  is a  clone
of the  UNIX operating  system  that runs  on  Intel 80386  and  80486
computers.    It  supports a  wide  range  of software,  from  TeX  to
X Windows to the GNU C/C++ compiler to TCP/IP.  It's a versatile, bona
fide implementation of UNIX,  freely distributed by  the terms of  the
GNU General Public License (see Appendix E).
  Linux can  turn any  386 or  486 PC  into a  workstation.   It  will
give you the full power  of UNIX at your  fingertips.  Businesses  are
installing Linux on entire networks  of machines, using the  operating
system to manage  financial and hospital  records, a distributed  user
computing environment,  telecommunications, and  more.    Universities
worldwide are using  Linux for teaching  courses on operating  systems
programming and  design.     And,  of  course,  computing  enthusiasts
everywhere are using Linux at home, for programming, productivity, and
all-around hacking.
  What makes Linux  so different is that  it is a free  implementation
of UNIX.  It was  and still  is developed  by a  group of  volunteers,
primarily on the Internet, exchanging code, reporting bugs, and fixing
problems in an open-ended environment.   Anyone is welcome to  join in
the Linux development effort:  all  it takes is interest in  hacking a
free UNIX clone and some kind of programming know-how.   The book that
you hold in your hands is your tour guide.

1.1 About This Book

This book  is  an installation  and  entry-level  guide to  the  Linux
system.   The purpose  is to  get new users  up and  running with  the
system by consolodating  as much important  material as possible  into


                                  1
1.1.   About This Book                                               2
_______________________________________________________________________

one book.  Instead of covering many of the volatile technical details,
those things which tend to change with rapid development,  we give you
enough background to find out more on your own.
  Linux is  not difficult to install  and use.   However, as with  any
implementation of UNIX, there  is often some  black magic involved  to
get everything working correctly.  We hope that this book will get you
on the Linux tourbus and show you how groovy this operating system can
be.
  In this book, we cover the following topics.

 o  What is Linux?  The design and philosophy of this unique operating
    system, and what it can do for you.

 o  All of  the details  of what  is needed  to run  Linux,  including
    suggestions on what kind of hardware configuration  is recommended
    for a complete system.

 o  How to obtain  and install Linux.    There are many  distributions
    of  the  Linux  software.     We  present  a   general  discussion
    of  Linux  software  distributions,   how  to  obtain  them,   and
    generic instructions for installing the software (which  should be
    applicable to any distribution).

    This edition also contains specific instructions for the Slackware
    distribution of Linux.

 o  A brief introductory UNIX tutorial, for those users who have never
    had experience with UNIX before.  This tutorial should, hopefully,
    provide enough material for complete novices to have  enough basic
    know-how to find their way around the system.

 o  An introduction to systems administration with Linux.  This covers
    the most important tasks  that new Linux administrators will  need
    to be familiar with, such as creating users, managing filesystems,
    and so forth.

 o  Information on configuring  more advanced aspects  of Linux,  such
    as the X Window System,  networking with TCP/IP and SLIP,  and the
    setup of electronic mail and news systems.

  This book is for  the personal computer user wishing to  get started
with Linux.  We don't  assume previous UNIX experience, but  do expect
novices to  refer  to  other materials  along  the  way.    For  those
unfamiliar with UNIX, a list of useful sources of information is given
in Appendix A.  In general,  this book is meant to be read  along with
another book on basic UNIX concepts.
1.2.   A Brief History of Linux                                      3
_______________________________________________________________________

1.2 A Brief History of Linux

UNIX is one of the most popular operating systems worldwide because of
its large support base and distribution.  It was  originally developed
as a  multitasking  system for  minicomputers  and mainframes  in  the
mid-1970's, but has since grown to become one of the  most widely used
operating systems anywhere, despite its sometimes  confusing interface
and lack of central standardization.
  The real  reason  for UNIX's  popularity?   Many  hackers feel  that
UNIX is the Right Thing---the One  True Operating System.  Hence,  the
development of Linux by an expanding group of UNIX hackers who want to
get their hands dirty with their own system.
  Versions  of UNIX  exist for  many  systems---ranging from  personal
computers to supercomputers such as the  Cray Y-MP.  Most  versions of
UNIX for personal computers  are quite expensive  and cumbersome.   At
the time of this writing, a one-machine version of AT&T's System V for
the 386 runs at about US$1500.
  Linux is a freely distributable version of  UNIX developed primarily
by Linus Torvalds (1) at the University of Helsinki in Finland.  Linux
was developed  with the  help  of many  UNIX programmers  and  wizards
across the Internet, allowing anyone with enough know-how and gumption
the ability  to develop  and  change the  system.    The Linux  kernel
uses no code from  AT&T or any other  proprietary source, and much  of
the software available for  Linux is developed  by the GNU project  at
the Free Software  Foundation in Cambridge,  Massachusetts.   However,
programmers all over the world have contributed to the growing pool of
Linux software.
  Linux  was  originally  developed  as  a  hobby   project  by  Linus
Torvalds.   It was inspired  by Minix, a  small UNIX system  developed
by Andy Tanenbaum,  and   the first  discussions about  Linux were  on
the USENET newsgroup comp.os.minix.  These discussions  were concerned
mostly with the development of a small, academic UNIX system for Minix
users who wanted more.
  The very  early development  of Linux  was mostly  dealing with  the
task-switching features  of the  80386 protected-mode  interface,  all
written in assembly code.  Linus writes,

     ``After that it  was plain sailing:  hairy coding still,  but
    I had some devices, and debugging was easier.  I started using
    C at  this stage,  and it  certainly  speeds up  developement.
    This is also when I start to get serious about my megalomaniac
    ideas to make `a better Minix  than Minix'.  I was  hoping I'd
    be able to recompile gcc under Linux some day...
     ``Two months for  basic setup, but then only slightly  longer
    until I had  a disk-driver (seriously  buggy, but it  happened
    to work  on my  machine) and  a small  filesystem.   That  was
    about when I made 0.01 available [around late August of 1991]:

----------------------------
 1. [e-mail].
1.2.   A Brief History of Linux                                      4
_______________________________________________________________________

    it wasn't pretty,  it had  no floppy driver,  and it  couldn't
    do much anything.   I don't  think anybody ever compiled  that
    version.  But by  then I was hooked,  and didn't want to  stop
    until I could chuck out Minix.''

  No  announcement  was  ever made  for  Linux  version  0.01.     The
0.01 sources weren't even  executable:  they  contained only the  bare
rudiments of the kernel source, and  assumed that you had access  to a
Minix machine to compile and play with them.
  On 5  October 1991, Linus  announced the first ``official''  version
of Linux, version 0.02.   At  this point, Linus  was able to run  bash
(the GNU Bourne  Again Shell) and  gcc (the GNU  C compiler), but  not
very much else was working.   Again,  this was intended as a  hacker's
system.  The primary focus was kernel development---none of the issues
of user support, documentation, distribution, and so on had  even been
addressed.   Today, the  Linux community  still seems  to treat  these
ergonomic issues  as secondary  to  the ``real  programming''---kernel
development.
  Linus wrote in comp.os.minix,

     ``Do you pine for  the nice days of Minix-1.1, when  men were
    men and wrote  their own device  drivers?   Are you without  a
    nice project and just dying to cut your teeth on a  OS you can
    try to modify for your needs?  Are you finding  it frustrating
    when everything works on Minix?  No more all-nighters to get a
    nifty program working?  Then this post might be just for you.
     ``As  I  mentioned  a  month  ago,  I'm  working  on  a  free
    version of a  Minix-lookalike for  AT-386 computers.   It  has
    finally reached the stage where  it's even usable (though  may
    not be  depending on  what  you want),  and  I am  willing  to
    put out  the sources  for  wider distribution.    It  is  just
    version 0.02...but I've successfully  run bash, gcc, gnu-make,
    gnu-sed, compress, etc.  under it.''

  After version 0.03, Linus  bumped the version number up to  0.10, as
more people started  to work  on the  system.   After several  further
revisions, Linus increased the version number to 0.95, to  reflect his
expectation that  the system  was ready  for  an ``official''  release
very soon.   (Generally, software is  not assigned the version  number
1.0 until it  is theoretically  complete or  bug-free.)   This was  in
March of 1992.   Almost a year and a  half later, in late  December of
1993, the Linux kernel was still at version 0.99.pl14---asymptotically
approaching 1.0.  As of  the time of this writing, the  current kernel
version is 1.1 patchlevel 52, and 1.2 is right around the corner.
  Today,  Linux  is   a  complete  UNIX  clone,  capable   of  running
X Windows,  TCP/IP, Emacs,  UUCP,  mail and  news software,  you  name
it.  Almost all of  the major free software packages have  been ported
to Linux, and commercial  software is becoming  available.  Much  more
hardware is supported than in original  versions of the kernel.   Many
people have  executed  benchmarks on  80486  Linux systems  and  found
1.3.   System Features                                               5
_______________________________________________________________________

them comparable with mid-range workstations from Sun  Microsystems and
Digital Equipment Corporation.  Who would have ever guessed  that this
``little'' UNIX clone would have grown up to take on  the entire world
of personal computing?


1.3 System Features

Linux supports most of the features found in other  implementations of
UNIX, plus quite a few that aren't found elsewhere.  This section is a
nickel tour of the Linux kernel features.
  Linux is a  complete multitasking, multiuser operating  system (just
like all  other versions  of UNIX).  This means  that  many users  can
be logged into  the same  machine at once,  running multiple  programs
simultaneously.
  The  Linux  system  is mostly  compatible  with  a  number  of  UNIX
standards (inasmuch  as  UNIX  has  standards) on  the  source  level,
including IEEE  POSIX.1,  System V,  and  BSD features.        It  was
developed with source portability  in mind:   therefore, you are  most
likely to find commonly-used  features in the  Linux system which  are
shared across multiple  implementations.   A great  deal of free  UNIX
software available on  the Internet  and elsewhere  compiles on  Linux
out of the box.   In addition, all  source code for the Linux  system,
including the kernel,  device drivers, libraries,  user programs,  and
development tools, is freely distributable.
  Other  specific  internal  features  of  Linux   include  POSIX  job
control (used by shells  such as csh  and bash), pseudoterminals  (pty
devices), and  support  for  national or  customized  keyboards  using
dynamically-loadable keyboard drivers.    Linux also supports  virtual
consoles, which allow  you to switch  between multiple login  sessions
from the system console in text mode.  Users of the ``screen'' program
will find the Linux virtual console implementation familiar.
  The kernel is able  to emulate 387-FPU instructions itself,  so that
systems without  a  math coprocessor  can  run programs  that  require
floating-point math instructions.
  Linux supports various filesystem  types for storing data.   Various
filesystems,  such as  the  ext2fs  filesystem,  have  been  developed
specifically for Linux.  Other  filesystem types, such as  the Minix-1
and Xenix filesystems, are also supported.  The  MS-DOS filesystem has
been implemented as well, allowing you to access MS-DOS  files on hard
drive or floppy directly.  The ISO 9660 CD-ROM filesystem  type, which
reads all standard formats of CD-ROMs, is also supported.   We'll talk
more about filesystems in Chapters 2 and 4.
  Linux  provides  a complete  implementation  of  TCP/IP  networking.
This includes device  drivers for  many popular  Ethernet cards,  SLIP
(Serial Line  Internet  Protocol,  allowing  you to  access  a  TCP/IP
network via  a  serial  connection),   PLIP  (Parallel  Line  Internet
Protocol), PPP (Point-to-Point Protocol),  NFS (Network File  System),
and so on.    The complete  range of  TCP/IP clients  and services  is
supported, such as FTP, telnet, NNTP, and SMTP. We'll  talk more about
networking in Chapter 5.
1.4.   Software Features                                             6
_______________________________________________________________________

  The Linux  kernel  is developed  to use  the special  protected-mode
features of the  Intel 80386  and 80486  processors.   In  particular,
Linux  makes  use  of   the  protected-mode  descriptor-based   memory
management paradigm and many of  the other advanced features of  these
processors.   Anyone  familiar with  80386 protected-mode  programming
knows that this chip  was designed for  a multitasking system such  as
UNIX (or, actually, Multics).  Linux exploits this functionality.
  The Linux  kernel supports  demand-paged loaded executables.    That
is, only  those segments  of a  program  which are  actually used  are
read into memory  from disk.    Also, copy-on-write  pages are  shared
among executables, meaning that if several instances of a  program are
running at once, they  will share pages  in physical memory,  reducing
overall memory usage.
  In order  to increase  the amount  of available  memory, Linux  also
implements disk  paging:   that  is,  up to  256 megabytes  of  ``swap
space''(2) can  be  allocated on  disk.    When  the  system  requires
more physical memory, it  will swap out  inactive pages to disk,  thus
allowing you  to run  larger applications  and support  more users  at
once.  However,  swap is no substitute  for physical RAM---it is  much
slower due to drive access latency times.
  The kernel also implements  a unified memory pool for  user programs
and disk cache.  In this way, all free memory is used for caching, and
the cache is reduced when running large programs.
  Executables use  dynamically linked shared  libraries, meaning  that
executables share common library code  in a single library file  found
on disk, not unlike the SunOS  shared library mechanism.   This allows
executable files to occupy much  less space on disk,  especially those
that use many  library functions.   There  are also  statically-linked
libraries for  those who  wish  to use  object debugging  or  maintain
``complete'' executables without the need  for shared libraries to  be
in place.  Linux shared libraries are dynamically linked  at run-time,
allowing the programmer to replace modules of the libraries with their
own routines.
  To  facilitate debugging,  the  Linux  kernel  does core  dumps  for
post-mortem analysis.  Using a core dump and an executable linked with
debugging support, it is possible  to determine what caused  a program
to crash.


1.4 Software Features

In this  section,   we'll  introduce  you  to  many  of  the  software
applications available for Linux,  and talk about  a number of  common
computing tasks.  After all, the most important part of  the system is
----------------------------
 2. Swap space  is inappropriately  named:  entire  processes are  not
swapped, but rather individual pages.  Of course, in many cases entire
processes will be swapped out, but this is not neccessarily always the
case.
1.4.   Software Features                                             7
_______________________________________________________________________

the wide range of software  available for it.   The fact that most  of
this software is freely distributable is even more impressive.

1.4.1 Basic commands and utilities

Virtually every  utility that  you would  expect to  find on  standard
implementations of UNIX has been ported to Linux.  This includes basic
commands such as ls,  awk, tr,  sed, bc, more,  and so on.   You  name
it, Linux has  it.   Therefore, you can  expect your familiar  working
environment on other  UNIX systems  to be  duplicated on Linux.    All
of the  standard commands  and utilities  are there.    (Novice  Linux
users should see  Chapter 3 for  an introduction  to these basic  UNIX
commands.)
  Many text editors  are available, including vi,  ex, pico, jove,  as
well as GNU Emacs and variants such as Lucid Emacs (which incorporates
extensions for use  under X Windows)  and joe.   Whatever text  editor
you're accustomed to using has more than likely been ported  to Linux.

  The choice of a text editor is an interesting one.   Many UNIX users
still use ``simple''  editors such as  vi (in  fact, the author  wrote
this book using vi  under Linux).   However, vi has many  limitations,
due to  its  age,  and  more  modern (and  complex)  editors  such  as
Emacs are gaining popularity.   Emacs  supports a complete  LISP-based
macro language and interpreter, a  powerful command syntax, and  other
fun-filled extensions.   Emacs macro  packages exist  to allow you  to
read electronic  mail  and news,  edit  the contents  of  directories,
and even engage in  an artificially intelligent psychotherapy  session
(indispensible for stressed-out Linux hackers).
  One  interesting note  is that  most of  the  basic Linux  utilities
are GNU software.   These GNU utilities support advanced  features not
found in the standard  versions from BSD  or AT&T. For example,  GNU's
version of the vi editor, elvis, includes a structured  macro language
which differs from  the original  AT&T implementation.   However,  the
GNU utilities strive to remain compatible with their BSD and  System V
counterparts.  Many people consider the GNU versions of these programs
superior to the originals.
  The  most important  utility  to  many users  is  the  shell.    The
shell is  a  program  which  reads  and  executes  commands  from  the
user.  In addition, many  shells provide features such as  job control
(allowing the user to manage  several running processes at  once---not
as Orwellian  as  it sounds),  input  and output  redirection,  and  a
command language for writing shell scripts.  A shell script  is a file
containing a program  in the  shell command language,  analogous to  a
``batch file'' under MS-DOS.
  There are  many  types of  shells available  for Linux.    The  most
important difference  between shells  is the  command language.    For
example, the C Shell (csh)  uses a command language somewhat  like the
C programming language.   The  classic Bourne  Shell uses a  different
command language.   One's  choice of  a shell  is often  based on  the
command language that it provides.  The shell that you use defines, to
1.4.   Software Features                                             8
_______________________________________________________________________

some extent, your working environment under Linux.
  No matter what  shell you're accustomed to,  some version of it  has
probably been ported  to Linux.   The  most popular  shell is the  GNU
Bourne Again Shell (bash), a Bourne shell variant which  includes many
advanced features, such as job  control, command history, command  and
filename completion, an Emacs-like  interface for editing the  command
line, and powerful extensions  to the standard Bourne shell  language.
Another popular shell is tcsh, a version of the C  Shell with advanced
functionality similar to  that found in  bash.   Other shells  include
zsh, a small Bourne-like shell;  the Korn shell (ksh); BSD's ash;  and
rc, the Plan 9 shell.
  What's so important  about these basic utilities?   Linux gives  you
the unique opportunity to tailor a  custom system to your needs.   For
example, if  you're the  only person  who uses  your  system, and  you
prefer to  exclusively use  the vi  editor,  and bash  as your  shell,
there's no reason to  install other editors  or shells.   The ``do  it
yourself'' attitude is prevalent among Linux hackers and users.

1.4.2 Text processing and word processing

Almost every  computer user  has  a need  for  some kind  of  document
preparation system.   (How many computer  enthusiasts do you know  who
still use pen and paper?   Not many, we'll  wager.)  In the  PC world,
word processing is  the norm:   it involves  editing and  manipulating
text (often  in  a ``What-You-See-Is-What-You-Get''  environment)  and
producing printed copies of the  text, complete with figures,  tables,
and other garnishes.
  In  the UNIX  world,  text processing  is  much more  common,  which
is quite  different than  the classical  concept  of word  processing.
With a text  processing system, text  is entered  by the author  using
a ``typesetting language'',  which describes  how the  text should  be
formatted.    Instead of  entering  the  text within  a  special  word
processing environment,  the  source may  be  modified with  any  text
editor such as vi or Emacs.  Once the source text  (in the typesetting
language) is  complete, the  user  formats the  text  with a  separate
program, which converts the source to a format suitable  for printing.
This is somewhat analogous to programming in a language such as C, and
``compiling'' the document into a printable form.
  There are many text processing systems available for Linux.   One is
groff, the GNU version of the classic nroff text  formatter originally
developed by Bell Labs and still used on many UNIX  systems worldwide.
Another modern  text processing  system is  TeX,  developed by  Donald
Knuth of computer science fame.   Dialects of TeX, such as  LaTeX, are
also available.
  Text processors such  as TeX and groff  differ mostly in the  syntax
of their formatting languages.   The  choice of one formatting  system
over another  is  also based  upon  what  utilities are  available  to
satisfy your needs, as well as personal taste.
  For example, some  people consider the groff formatting  language to
be a bit obscure, so they  use TeX, which is more readable  by humans.
1.4.  Software Features                                              9
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However, groff is capable of producing plain ASCII output, viewable on
a terminal, while TeX is  intended primarily for output to  a printing
device.  However, various  programs exist to produce plain  ASCII from
TeX-formatted documents, or to convert TeX to groff, for example.
  Another text processing system is texinfo, an extension  to TeX used
for software documentation by the  Free Software Foundation.   texinfo
is capable of  producing a  printed document,  or an  online-browsable
hypertext ``Info'' document from a single source file.  Info files are
the main format of documentation used by GNU software such as Emacs.
  Text  processors are  used  widely in  the computing  community  for
producing papers, theses, magazine articles, and books (in  fact, this
book was  produced using  LaTeX). The  ability to  process the  source
language as  a plain  text  file opens  the  door to  many  extensions
to the  text processor  itself.    Because  source documents  are  not
stored in  an  obscure format,  readable  only  by a  particular  word
processor, programmers are able  to write parsers and translators  for
the formatting language, extending the system.
  What  does such  a  formatting language  look  like?    In  general,
the formatting language  source consists  mostly of  the text  itself,
along with ``control codes'' to  produce a particular effect,  such as
changing fonts, setting margins, creating lists, and so on.
  As an example, take the following text:

    Mr.  Torvalds:

    We are  very  upset  with  your  current  plans  to  implement
    post-hypnotic suggestion in  the Linux  terminal driver  code.
    We feel this way for three reasons:


    1.  Planting subliminal messages in the terminal driver is not
        only immoral, it is a waste of time;

    2.  It has been proven that ``post-hypnotic  suggestions'' are
        ineffective when used upon unsuspecting UNIX hackers;

    3.  We have already implemented high-voltage electric  shocks,
        as a security measure, in the code for login.


    We hope you will reconsider.

  This  text would  appear in  the LaTeX  formatting  language as  the
following:

    \begin{quote}
    Mr. Torvalds:

    We are very upset with your current plans to  implement {\em post-
    hypnotic
1.4.   Software Features                                            10
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    suggestion\/}      in      the       {\bf      Linux}       termi-
    nal driver code. We feel this
    way for three reasons:
    \begin{enumerate}
    \item    Planting    subliminal     messages    in    the     ker-
    nel driver is not only
          immoral, it is a waste of time;
    \item  It   has   been   proven   that   ``post-hypnotic   sugges-
    tions'' are ineffective
          when used upon unsuspecting UNIX hackers;
    \item   We   have    already   implemented   high-voltage    elec-
    tric shocks, as a
          security measure, in the code for {\tt login}.
    \end{enumerate}
    We hope you will reconsider.
    \end{quote}

  The author enters the  above ``source'' text using any  text editor,
and generates  the  formatted output  by  processing the  source  with
LaTeX. At  first glance,  the typesetting  language may  appear to  be
obscure, but  it's  actually  quite easy  to  learn.    Using  a  text
processing system enforces typographical standards when writing.   For
example, all enumerated  lists within a document  will look the  same,
unless the  author  modifies the  definition  of the  enumerated  list
``environment''.    The  primary  goal  is  to  allow  the  author  to
concentrate on  writing the  actual text,  instead  of worrying  about
typesetting conventions.
  WYSIWYG  word  processors are  attractive  for  many  reasons;  they
provide a  powerful  (and  sometimes  complex)  visual  interface  for
editing the document.   However, this interface is  inherently limited
to those aspects of text layout which are accessible to the user.  For
example, many word  processors provide  a special ``format  language''
for producing complicated expressions  such as mathematical  formulae.
This is identical text processing, albeit on a much smaller scale.
  The subtle benefit of text processing is that  the system allows you
to specify exactly what you mean.  Also, text processing systems allow
you to edit the source  text with any text  editor, and the source  is
easily converted to other formats.  The tradeoff for  this flexibility
and power is the lack of a WYSIWYG interface.
  Many  users of  word processors  are used  to  seeing the  formatted
text as they edit  it.  On  the other hand,  when writing with a  text
processor, one generally does not worry about how the text will appear
when formatted.  The writer learns to expect how the  text should look
from the formatting commands used in the source.
  There are programs  which allow you  to view the formatted  document
on a graphics display before printing.  For example,  the xdvi program
displays a ``device  independent'' file  generated by  the TeX  system
under the X Windows  environment.   Other software applications,  such
as xfig,  provide a  WYSIWYG graphics  interface  for drawing  figures
and diagrams, which are subsequently converted to the  text processing
1.4.   Software Features                                            11
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language for inclusion in your document.
  Admittedly, text  processors such as  nroff were around long  before
word processing was available.   However, many people still  prefer to
use text processing, because it  is more versatile and  independent of
a graphics environment.   In either case,  the idoc word processor  is
also available for Linux, and before long we expect  to see commercial
word processors becoming available as  well.  If you  absolutely don't
want to give up  word processing for  text processing, you can  always
run MS-DOS, or some other operating system, in addition to Linux.
  There are  many other  text-processing-related utilities  available.
The powerful METAFONT  system, used  for designing fonts  for TeX,  is
included with the Linux  port of TeX.  Other programs include  ispell,
an interactive  spell  checker  and  corrector;  makeindex,  used  for
generating indicies in  LaTeX documents;  as  well as  many groff  and
TeX-based macro packages  for formatting many  types of documents  and
mathematical texts.  Conversion  programs to translate between TeX  or
groff source to a myriad of other formats are available.

1.4.3 Programming languages and utilities

Linux provides a complete UNIX programming environment,  including all
of the standard libraries, programming tools, compilers, and debuggers
that you would expect to find on other UNIX systems.   Within the UNIX
software development world,  applications and  systems programming  is
usually done in C or C++.   The standard C and C++ compiler  for Linux
is GNU's gcc, which  is an advanced,  modern compiler supporting  many
options.   It is  also capable  of compiling C++  (including AT&T  3.0
features) as well as  Objective-C, another object-oriented dialect  of
C.
  Besides C and  C++, many other compiled and  interpreted programming
languages have  been ported  to  Linux,  such as  Smalltalk,  FORTRAN,
Pascal,  LISP, Scheme,   and Ada  (if  you're  masochistic  enough  to
program in Ada---we're not going to  stop you).  In addition,  various
assemblers for writing protected-mode 80386 code are available, as are
UNIX hacking favorites such  as Perl (the  script language to end  all
script languages) and Tcl/Tk  (a shell-like command processing  system
including support for developing simple X Windows applications).
  The advanced  gdb  debugger has  been ported,  which  allows you  to
 step through  a program  to find  bugs, or  examine the  cause for  a
crash using  a core  dump.    gprof, a  profiling utility,  will  give
you performance statistics  for your program,  letting you know  where
your program is spending most of  its time executing.  The  Emacs text
editor provides an interactive editing and compilation environment for
various programming  languages.    Other tools  include GNU  make  and
imake, used to manage  compilation of large  applications; and RCS,  a
system for source locking and revision control.
  Linux implements  dynamically-linked shared  libraries, which  allow
binaries to  be much  smaller  as the  subroutine  code is  linked  at
run-time.  These DLL libraries also allow the  applications programmer
to override  function definitions with  their own code.   For example,
1.4.   Software Features                                            12
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if a  programmer wished  to  write her  own  version of  the  malloc()
library routine,  the linker would  use the  programmer's new  routine
instead of the one found in the libraries.
  Linux is  ideal for  developing UNIX  applications.   It provides  a
modern programming environment  with all  of the  bells and  whistles.
Various standards  such as  POSIX.1 are  supported, allowing  software
written for Linux to be easily ported to other systems.   Professional
UNIX programmers and  system administrators can  use Linux to  develop
software at home, and  then transfer the  software to UNIX systems  at
work.   This not only  can save a  great deal of  time and money,  but
will also let you work in the  comfort of your own home.(3)   Computer
Science students  can  use Linux  to  learn  UNIX programming  and  to
explore other aspects of the system, such as kernel architecture.
  With Linux,  not only  do you  have access  to the  complete set  of
libraries and programming  utilities, but you  also have the  complete
kernel and library source code at your fingertips.

1.4.4 The X Window System

The X  Window  System is  the  standard  graphics interface  for  UNIX
machines.  It is a powerful environment supporting  many applications.
Using X Windows, the  user can have  multiple terminal windows on  the
screen at once,  each one  containing a  different login session.    A
pointing device such as  a mouse is often  used with the X  interface,
although it isn't required.
  Many  X-specific applications  have  been written,  such  as  games,
graphics utilities, programming  and documentation tools,  and so  on.
With Linux and X,  your system is  a bona fide  workstation.   Coupled
with TCP/IP networking,  you can even  display X applications  running
on other machines  on your Linux  display, as  is possible with  other
systems running X.
  The X Window System  was originally developed at MIT, and  is freely
distributable.    However,  may commercial  vendors  have  distributed
proprietary enhancements  to the  original X  Windows software.    The
version of X Windows available for  Linux is known as XFree86,  a port
of X11R5 made freely distributable  for 80386-based UNIX systems  such
as Linux.  XFree86 supports a wide range of video  hardware, including
VGA, Super VGA, and a number  of accelerated video adaptors.   This is
a complete distribution of  the X Windows  software, containing the  X
server itself, many applications and utilities, programming libraries,
and documentation.
  Standard X applications include xterm (a terminal  emulator used for
most text-based applications within an  X window); xdm (the  X Session
Manager, which handles logins); xclock (a simple clock  display); xman
(an X-based  man page  reader), and  more.   The  many X  applications

----------------------------
 3. The author  uses his Linux  system to develop  and test X  Windows
applications at home, which  can be directly compiled on  workstations
elsewhere.
1.4.   Software Features                                            13
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available for Linux  are too numerous  to mention  here, but the  base
XFree86 distribution includes the  ``standard'' applications found  in
the original MIT release.   Many others are available separately,  and
theoretically any  application written  for X  Windows should  compile
cleanly under Linux.
  The look  and feel  of the X  Windows interface  is controlled to  a
large extent  by the  window manager.    This friendly  program is  in
charge of the placement of  windows, the user interface  for resizing,
iconifying, and moving windows,  the appearance of window frames,  and
so on.   The standard XFree86  distribution includes twm, the  classic
MIT window manager, although more advanced window managers such as the
Open Look Virtual Window Manager (olvwm)  are available as well.   One
window manager that is  popular among Linux  users is fvwm.   This  is
a small window manager,  requiring less than  half of the memory  used
by twm.  It provides a  3-D appearance for windows, as well  a virtual
desktop---if the user moves the mouse  to the edge of the screen,  the
entire desktop is shifted as if  the display were much larger  than it
actually is.  fvwm is  greatly customizable, and allows  all functions
to be accessed from  the keyboard as  well as the  mouse.  Many  Linux
distributions use fvwm as the standard window manager.
  The XFree86 distribution contains programming libraries  and include
files for those wily programmers  who wish to develop X  applications.
Various widget  sets,  such  as  Athena,  Open  Look,  and  Xaw3D  are
supported.    All of  the  standard fonts,  bitmaps,  man  pages,  and
documentation are  included.   PEX  (a programming  interface for  3-D
graphics) is also supported.
  Many X  applications programmers  use the  proprietary Motif  widget
set for development.   Several vendors  sell single and  multiple-user
licenses  for  a  binary  version  of  Motif  for  Linux.      Because
Motif itself is  relatively expensive,  not many Linux  users own  it.
However, binaries statically linked with Motif routines may  be freely
distributed.  Therefore, if you  write a program using Motif  and wish
to distribute  it freely,  you  may  provide a  binary so  that  users
without Motif can use the program.
  The only major  caveats with X Windows  are the hardware and  memory
requirements.  A  386 with 4  megabytes of RAM  is capable of  running
X, but  8 megabytes  or more  of physical  RAM are  needed  to use  it
comfortably.  A faster processor  is nice to have as well,  but having
enough physical RAM is much more  important.  In addition,  to achieve
really slick video  performance, an  accelerated video  card (such  as
a local bus  S3-chipset card)  is strongly recommended.    Performance
ratings in excess  of 140,000  xstones have been  acheived with  Linux
and XFree86.    With  sufficient hardware,  you'll  find that  running
X and  Linux is  as fast,  or faster,  than  running X  on other  UNIX
workstations.
  In Chapter 5 we'll discuss how to install and use X on your system.
1.4.   Software Features                                            14
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1.4.5 Networking

Interested in  communicating with  the world?    Yes?    No?    Maybe?
Linux supports the two primary networking protocols for  UNIX systems:
TCP/IP  and  UUCP.  TCP/IP  (Transmission   Control  Protocol/Internet
Protocol, for acronym aficionados) is the set of  networking paradigms
that allow  systems all  over the  world to  communicate  on a  single
network known as the Internet.   With Linux, TCP/IP, and  a connection
to the network, you can communicate with users and machines across the
Internet via electronic  mail, USENET news,  file transfers with  FTP,
and more.  There are many Linux systems currently on the Internet.
  Most  TCP/IP   networks  use  Ethernet   as  the  physical   network
transport.  Linux supports many popular Ethernet cards  and interfaces
for personal computers, including  the D-Link pocket Ethernet  adaptor
for laptops.
  However, because  not everyone has an  Ethernet drop at home,  Linux
also supports SLIP (Serial Line Internet Protocol), which allows   you
to connect to the Internet  via modem.   In order to use SLIP,  you'll
need to  have access  to a  SLIP server,  a machine  connected to  the
network which allows dial-in access.  Many businesses and universities
provide such SLIP  servers.   In  fact, if  your Linux  system has  an
Ethernet connection as well as a modem, you can configure it as a SLIP
server for other hosts.
  NFS (Network  File System)  allows your system  to seamlessly  share
files with  other  machines  on  the  network.    FTP  (File  Transfer
Protocol) allows you to transfer files between other machines.   Other
applications include  sendmail,  a system  for sending  and  receiving
electronic mail using  the SMTP protocol;  NNTP-based electronic  news
systems such as C-News and INN;  telnet, rlogin, and rsh,  which allow
you to login and  execute commands on  other machines on the  network;
and finger,  which allows  you to  get information  on other  Internet
users.   There  are literally  tons of  TCP/IP-based applications  and
protocols out there.
  The full  range of mail  and news readers  are available for  Linux,
such as elm, pine, rn, nn, and tin.  Whatever your preference, you can
configure your Linux system  to send and  receive electronic mail  and
news from all over the world.
  If  you have  experience  with  TCP/IP applications  on  other  UNIX
systems, Linux will be  very familiar to you.   The system provides  a
standard socket programming interface, so virtually any  program which
uses TCP/IP can be ported to Linux.  The Linux X  server also supports
TCP/IP, allowing you to display applications running on  other systems
on your Linux display.
  In  Chapter 5  we'll  discuss  configuration and  setup  of  TCP/IP,
including SLIP, for Linux.
  UUCP (UNIX-to-UNIX  Copy)  is an  older mechanism  used to  transfer
files, electronic  mail, and  electronic news  between UNIX  machines.
Classically, UUCP  machines connected  to each  other  over the  phone
lines via modem, but UUCP is  able to transport over a  TCP/IP network
as well.   If you do  not have access  to a TCP/IP  network or a  SLIP
1.4.   Software Features                                            15
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server, you can configure  your system to  send and receive files  and
electronic mail using UUCP. See Chapter 5 for more information.

1.4.6 Telecommunications and BBS software

If you  have a  modem,  you will  be able  to  communicate with  other
machines using one  of the  telecommunications packages available  for
Linux.  Many people use telecommunications software to access bulletin
board systems (BBSs),  as well as commercial  online services such  as
Prodigy, CompuServe,  and America  On-Line.   Other  people use  their
modems to  connect to  a UNIX  system  at work  or school.    You  can
even use your modem and  Linux system to send and  receive facsimiles.
Telecommunications software under Linux is very similar to  that found
under MS-DOS or other operating systems.   Anyone who has ever  used a
telecommunications package will find the Linux equivalent familiar.
  One  of  the  most popular  communications  packages  for  Linux  is
Seyon, an X application providing a customizable, ergonomic interface,
with built-in  support for  various file  transfer  protocols such  as
Kermit, ZModem, and so on.  Other telecommunications  programs include
C-Kermit, pcomm,  and minicom.   These  are similar to  communications
programs found on other operating systems, and are quite easy to use.
  If  you do  not  have access  to a  SLIP  server (see  the  previous
section), you can use term to  multiplex your serial line.   term will
allow you to open  multiple login sessions  over the modem  connection
to a remote machine.   term will also  allow you to redirect X  client
connections to your local X server, through the serial  line, allowing
you to display remote  X applications on your  Linux system.   Another
software package, KA9Q, implements a similar SLIP-like interface.
  Running  a bulletin  board system  (BBS) is  a  favorite hobby  (and
means of income) for many people.  Linux supports a wide  range of BBS
software, most of which  is more powerful  than what is available  for
other operating systems.  With a  phone line, a modem, and  Linux, you
can turn your  system into  a BBS,  providing dial-in  access to  your
system to users worldwide.   BBS software for Linux includes  XBBS and
the UniBoard BBS packages.
  Most BBS  software locks  the user  into a  menu-based system  where
only certain functions and applications are available.  An alternative
to BBS access  is full UNIX  access, which would  allow users to  dial
into your  system and  login as  a regular  user.    While this  would
require a  fair  amount of  maintenance  on  the part  of  the  system
administrator, it can be done,  and providing public UNIX  access from
your Linux  system is  not  difficult to  do.    Along with  a  TCP/IP
network, you can provide electronic  mail and news access to  users on
your system.
  If you do  not have access to a  TCP/IP network or UUCP feed,  Linux
will also allow  you to  communicate with  a number  of BBS  networks,
such as FidoNet, with which you can exchange electronic  news and mail
via the phone line.   More  information on telecommunications and  BBS
software under Linux can be found in Chapter 5.
1.4.   Software Features                                            16
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1.4.7 Interfacing with MS-DOS

Various utilities exist  to interface  with the world  of MS-DOS.  The
most well-known application is the Linux MS-DOS Emulator, which allows
you to run  many MS-DOS applications  directly from  Linux.   Although
Linux and MS-DOS are completely different operating systems, the 80386
protected-mode environment allows certain tasks  to behave as if  they
were running in 8086-emulation mode, as MS-DOS applications do.
  The MS-DOS  emulator is  still under development,  yet many  popular
applications  run  under  it.      Understandably,   however,   MS-DOS
applications which use bizarre or esoteric features of the  system may
never be supported,  because it  is only  an emulator.   For  example,
you wouldn't expect  to be able  to run any  programs which use  80386
protected-mode features, such  as Microsoft  Windows (in 386  enhanced
mode, that is).
  Applications which run successfully under the  Linux MS-DOS Emulator
include 4DOS (a  command interpreter), Foxpro  2.0, Harvard  Graphics,
MathCad, Stacker  3.1,  Turbo Assembler,  Turbo C/C++,  Turbo  Pascal,
Microsoft Windows 3.0 (in real mode),  and WordPerfect 5.1.   Standard
MS-DOS commands and utilities (such as PKZIP, and so on) work with the
emulator as well.
  The MS-DOS Emulator is meant mostly as an ad  hoc solution for those
people who need MS-DOS only for a few applications, but  use Linux for
everything else.   It's not meant to  be a complete implementation  of
MS-DOS. Of course, if the Emulator doesn't satisfy your needs, you can
always run MS-DOS as well as Linux on the same system.  Using the LILO
boot loader, you can  specify at boot  time which operating system  to
start.  Linux can coexist with other operating systems,  such as OS/2,
as well.
  Linux provides a  seamless interface for transferring files  between
Linux and MS-DOS. You  can mount an  MS-DOS partition or floppy  under
Linux, and directly access MS-DOS files as you would any other.
  Currently  under  development   is  a  project  known  as   WINE---a
Microsoft Windows emulator for the X Window System under Linux.   Once
WINE is complete,  users will be able  to run MS-Windows  applications
directly from Linux.  This is similar to the  proprietary WABI Windows
emulator from Sun Microsystems.  At the time of this  writing, WINE is
still in the early stages of development, but the outlook is good.
  In  Chapter 5  we'll  talk  about  the MS-DOS  tools  available  for
Linux.

1.4.8 Other applications

A host  of miscellany  is available  for Linux,  as  one would  expect
from such  a  hodgepodge operating  system.    Linux's  primary  focus
is currently  for  personal  UNIX  computing,   but  this  is  rapidly
changing.    Business  and  scientific  software  is  expanding,   and
commercial software vendors are beginning to contribute to the growing
pool of applications.
  Several  relational databases  are  available for  Linux,  including
1.4.   Software Features                                            17
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Postgres, Ingres, and  Mbase.   These are full-featured,  professional
client/server database applications  similar to  those found on  other
UNIX platforms.  /rdb,  a commercial database system, is  available as
well.
  Scientific computing  applications  include FELT  (a finite  element
analysis tool); gnuplot  (a plotting  and data analysis  application);
Octave (a symbolic mathematics package, similar to MATLAB); xspread (a
spreadsheet calculator);  xfractint, an  X-based port  of the  popular
Fractint fractal  generator;  xlispstat  (a statistics  package),  and
more.  Other applications include Spice (a circuit design and analysis
tool) and Khoros (an image/digital signal processing and visualization
system).
  Of course,  there are many more  such applications which have  been,
and can be,  ported to  run on Linux.   Whatever  your field,  porting
UNIX-based applications  to  Linux should  be  quite  straightforward.
Linux provides a  complete UNIX programming  interface, sufficient  to
serve as the base for any scientific application.
  As with any operating system,  Linux has its share of games.   These
include classic text-based  dungeon games such  as Nethack and  Moria;
MUDs (multi-user dungeons,  which allow  many users to  interact in  a
text-based adventure) such as DikuMUD  and TinyMUD; as well as  a slew
of X games  such as xtetris,  netrek, and Xboard  (the X11 version  of
gnuchess).  The  popular shoot-em-up arcade-style  Doom has also  been
ported to Linux.
  For  audiophiles, Linux  has  support for  various sound  cards  and
related software,  such as  CDplayer (a  program which  can control  a
CD-ROM drive as a conventional  CD player, surprisingly enough),  MIDI
sequencers and editors  (allowing you  to compose  music for  playback
through a synthesizer or other MIDI-controlled instrument),  and sound
editors for digitized sounds.
  Can't find the application  you're looking for?  The  Linux Software
Map, described  in  Appendix  A,  contains  a list  of  many  software
packages which have been written and ported to Linux.  While this list
is far from complete, it contains  a great deal of software.   Another
way to find Linux applications is to look at the INDEX  files found on
Linux FTP sites, if you have  Internet access.  Just by  poking around
you'll find a great deal of software just waiting to be played with.
  If you absolutely can't  find what you need, you can  always attempt
to port the application from another  platform to Linux.   Most freely
distributable UNIX-based  software  will  compile on  Linux  with  few
problems.   Or,  if  all else  fails, you  can  write the  application
yourself.    If it's  a  commercial  application you're  looking  for,
there may  be a  free ``clone''  available.    Or,  you can  encourage
the software company  to consider  releasing a  Linux binary  version.
Several individuals have contacted software companies, asking  them to
port their applications to Linux, and have met with various degrees of
success.
1.5.   About Linux's Copyright                                      18
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1.5 About Linux's Copyright

Linux is covered by what is  known as the GNU General  Public License,
or GPL. The GPL was developed for the GNU project by the Free Software
Foundataion.   It makes a  number of  provisions for the  distribution
and modification of ``free software''.  ``Free'' in this  sense refers
to freedom,  not  just cost.    The  GPL has  always been  subject  to
misinterpretation, and  we hope  that this  summary will  help you  to
understand the extent and goals of the GPL and its effect on Linux.  A
complete copy of the GPL is included in Appendix E.
  Originally,  Linus  Torvalds released  Linux  under a  license  more
restrictive than  the GPL,  which allowed  the software  to be  freely
distributed and modified, but  prevented any money changing hands  for
its distribution and use.  On the other hand, the GPL allows people to
sell and make profit  from free software, but  does not allow them  to
restrict the right for others to distribute the software in any way.
  First, it should be explained that ``free software''  covered by the
GPL is not in the public  domain.  Public domain software  is software
which is  not  copyrighted, and  is  literally  owned by  the  public.
Software covered by  the GPL,  on the  other hand,  is copyrighted  to
the author or  authors.   This  means that the  software is  protected
by standard international copyright laws,  and that the author  of the
software is legally defined.  Just because the software  may be freely
distributed does not mean that it is in the public domain.
  GPL-licensed  software  is  also  not  ``shareware''.     Generally,
``shareware'' software is owned and copyrighted by the author, but the
author requires users to send in money for its use after distribution.
On the other hand, software covered by the GPL may  be distributed and
used free of charge.
  The GPL  also allows people  to take and  modify free software,  and
distribute their own versions of the  software.  However,  any derived
works from GPL  software must  also be  covered by the  GPL. In  other
words, a company could  not take Linux, modify  it, and sell it  under
a restrictive license.   If any software  is derived from Linux,  that
software must be covered by the GPL as well.
  The  GPL allows  free  software  to  be distributed  and  used  free
of charge.    However,  it also  allows a  person  or organization  to
distribute GPL software  for a  fee, and  even to make  a profit  from
its sale and  distribution.   However,  in selling  GPL software,  the
distributor cannot take those rights away from the purchaser; that is,
if you purchase GPL software from some source, you  may distribute the
software for free, or sell it yourself as well.
  This might sound like  a contradiction at first.  Why  sell software
for profit when  the GPL  allows anyone  to obtain it  for free?    As
an example,  let's say that  some company  decided to  bundle a  large
amount of free software on a  CD-ROM and distribute it.   That company
would need to charge  for the overhead  of producing and  distributing
the CD-ROM, and the  company may even decide  to make profit from  the
sales of software.  This is allowed by the GPL.
  Organizations  which   sell  free   software  must  follow   certain
1.6.   The Design and Philosophy of Linux                           19
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restrictions set forth  in the  GPL. First, they  cannot restrict  the
rights of users who  purchase the software.   This  means that if  you
buy a CD-ROM of GPL software, you can copy and  distribute that CD-ROM
free of charge, or  resell it yourself.   Secondly, distributors  must
make it  obvious to  users  that the  software  is indeed  covered  by
the GPL.  Thirdly,  distributors must  provide,  free of  charge,  the
complete source code for  the software being  distributed.  This  will
allow anyone who purchases GPL software to make modifications  of that
software.
  Allowing a company  to distribute and sell  free software is a  very
good thing.    Not everyone  has access  to the  Internet to  download
software, such  as Linux,  for  free.   The  GPL  allows companies  to
sell and distribute  software to  those people  who do  not have  free
(cost-wise) access to the software.   For example,  many organizations
sell Linux  on diskette,  tape, or  CD-ROM via  mail  order, and  make
profit from these sales.   The developers of  Linux may never see  any
of this profit; that is the understanding that is  reached between the
developer and the distributor  when software is  licensed by the  GPL.
In other words, Linus knew that companies may wish to  sell Linux, and
that he may not see a penny of the profits from those sales.
  In the free software world,  the important issue is not money.   The
goal of free software  is always to  develop and distribute  fantastic
software and  to allow  anyone to  obtain and  use it.    In the  next
section, we'll discuss how this applies to the development of Linux.


1.6 The Design and Philosophy of Linux

When new users encounter Linux,  they often have a  few misconceptions
and false expectations  of the system.   Linux  is a unique  operating
system, and it is important to understand its philosophy and design in
order to use it effectively.  Time enough for a soapbox.   Even if you
are an aged UNIX guru, what follows is probably of interest to you.
  In  commercial  UNIX  development  houses,   the  entire  system  is
developed with  a rigorous  policy of  quality assurance,  source  and
revision  control  systems,  documentation,  and   bug  reporting  and
resolution.  Developers are not  allowed to add features or  to change
key sections of code on  a whim:  they  must validate the change as  a
response to a bug report and consequently ``check in'' all  changes to
the source control system,  so that the changes  can be backed out  if
necessary.  Each developer is assigned one or more parts of the system
code, and only  that developer may  alter those  sections of the  code
while it is ``checked out''.
  Internally,   the  quality   assurance   department  runs   rigorous
regression test suites on each new  pass of the operating system,  and
reports any bugs.  It  is the responsibility of the developers  to fix
these bugs as reported.  A complicated system of  statistical analysis
is employed to  ensure that  a certain  percentage of  bugs are  fixed
before the next  release, and  that the  operating system  as a  whole
passes certain release criteria.
  In all, the process  used by commercial UNIX developers  to maintain
1.6.   The Design and Philosophy of Linux                           20
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and support their code is  very complicated, and quite  reasonably so.
The company must  have quantitative  proof that the  next revision  of
the operating system  is ready  to be  shipped;  hence, the  gathering
and analysis of statistics  about the operating system's  performance.
It is  a big  job to  develop a  commercial UNIX  system, often  large
enough to employ hundreds (if not thousands) of  programmers, testers,
documentors,  and  administrative  personel.     Of  course,   no  two
commercial UNIX vendors are alike, but you get the general picture.
  With  Linux, you  can  throw out  the  entire concept  of  organized
development, source  control  systems,  structured bug  reporting,  or
statistical analysis.  Linux is, and more than likely  always will be,
a hacker's operating system.(4)
  Linux is primarily developed as a group effort  by volunteers on the
Internet from all  over the world.   Across  the Internet and  beyond,
anyone with enough know-how has  the opportunity to aid in  developing
and debugging the kernel, porting new software, writing documentation,
or helping new  users.   There is  no single organization  responsible
for developing the  system.   For the most  part, the Linux  community
communicates via  various mailing  lists  and USENET  newsgroups.    A
number of conventions  have sprung up  around the development  effort:
for example,  anyone  wishing  to  have  their code  included  in  the
``official'' kernel should mail  it to Linus  Torvalds, which he  will
test and include in the kernel (as long as it doesn't  break things or
go against the overall design of the system, he will  more than likely
include it).
  The  system itself  is designed  with  a very  open-ended,  feature-
minded approach.    While  recently the  number  of new  features  and
critical changes to the  system have diminished,  the general rule  is
that a new  version of  the kernel  will be released  about every  few
months (sometimes even more frequently than this).  Of course, this is
a very rough figure:   it depends on  a several factors including  the
number of bugs to be fixed, the amount of feedback  from users testing
pre-release versions of the code,  and the amount of sleep  that Linus
has had this week.
  Let it  suffice to  say that not  every single  bug has been  fixed,
and not every problem  ironed out between  releases.   As long as  the
system appears to be free of  critical or oft-manifesting bugs,  it is
considered ``stable'' and new revisions will be released.   The thrust
behind Linux development is not an effort to release perfect, bug-free
code:  it is to  develop a free implementation  of UNIX. Linux is  for
the developers, more than anyone else.
  Anyone who has a  new feature or software application to add  to the
system generally makes it available in an ``alpha''   stage---that is,
a stage for testing by  those brave or unwary  users who want to  bash

----------------------------
 4. What I mean by ``hacker'' is a feverishly dedicated  programmer, a
person who enjoys exploiting computers and generally doing interesting
things with them.   This is  in contrast to  the common denotation  of
``hacker'' as a computer wrongdoer or outlaw.
1.6.   The Design and Philosophy of Linux                           21
_______________________________________________________________________

out problems with the  initial code.   Because the Linux community  is
largely based on the Internet,  alpha software is usually  uploaded to
one or more  of the  various Linux FTP  sites (see  Appendix C) and  a
message posted to one of the Linux USENET newsgroups about  how to get
and test the code.   Users  who download and  test alpha software  can
then mail results, bug fixes, or questions to the author.
  After the initial  problems in the alpha  code have been fixed,  the
code enters  a ``beta''  stage,   in  which it  is usually  considered
stable but  not complete  (that  is,  it works,  but  not all  of  the
features may  be  present).    Otherwise,  it  may go  directly  to  a
``final'' stage  in  which the  software  is considered  complete  and
usable.  For kernel  code, once it  is complete the developer may  ask
Linus to include it in the  standard kernel, or as an  optional add-on
feature to the kernel.
  Keep in  mind that  these are  only conventions---not rules.    Some
people feel so confident with  their software that they don't  need to
release an alpha or test version.  It is always up to the developer to
make these decisions.
  You might be amazed that such a nonstructured  system of volunteers,
programming and debugging a complete  UNIX system, could get  anything
done at all.   As it turns  out, it is one  of the most efficient  and
motivated development efforts ever employed.  The entire  Linux kernel
was written from scratch, without employing any code  from proprietary
sources.  A great deal of work was put forth by volunteers to port all
of the free software  under the sun  to the Linux  system.   Libraries
were written and ported,  filesystems developed, and hardware  drivers
written for many popular devices.
  The Linux software is  generally released as a distribution,   which
is a set  of pre-packaged  software making up  an entire  system.   It
would be quite  difficult for most  users to  build a complete  system
from the ground up,  starting with the  kernel, adding utilities,  and
installing all of  the necessary  software by  hand.   Instead,  there
are a number of software  distributions including everything that  you
need to  install and  run  a complete  system.    Again, there  is  no
standard distribution---there are many, each with their own advantages
and disadvantages.  We'll talk more about the various  available Linux
distributions in Section 2.1.
  Despite the completeness of the Linux software, you  will still need
a bit of  UNIX know-how  to install  and run a  complete system.    No
distribution of Linux is completely  bug-free, so you may  be required
to fix small  problems by  hand after  installation.   Running a  UNIX
system is not an easy task, not even for commercial  versions of UNIX.
If you're  serious about  Linux,  bear in  mind that  it  will take  a
considerable amount of effort and  attention on your part to  keep the
system running and  take care  of things:   this is  true of any  UNIX
system, and Linux is  no exception.   Because of the diversity of  the
Linux community and the many needs which the software is attempting to
meet, not eveything can be taken care of for you all of the time.
1.6.   The Design and Philosophy of Linux                           22
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1.6.1 Hints for UNIX novices

Installing and using your  own Linux system  does not require a  great
deal of background in  UNIX. In fact,  many UNIX novices  successfully
install Linux  on  their systems.     This is  a  worthwhile  learning
experience, but keep in mind that it can be very  frustrating to some.
If you're lucky,  you will  be able  to install and  start using  your
Linux system without any UNIX background.  However, once you are ready
to delve into  the more  complex tasks  of running  Linux---installing
new software, recompiling the kernel, and so forth---having background
knowledge in UNIX is going to be a necessity.
  Fortunately,  by   running  your  own  Linux  system  you   will  be
able to  learn  the essentials  of  UNIX  necessary for  these  tasks.
This book  contains  a  good  deal  of information  to  help  you  get
started---Chapter 3 is a tutorial covering UNIX basics, and  Chapter 4
contains information on Linux system administration.  You may  wish to
read these chapters before you  attempt to install Linux at  all---the
information contained therein will prove  to be invaluable should  you
run into problems.
  Nobody can expect  to go from being a  UNIX novice to a  UNIX system
administrator overnight.  No implementation of UNIX is expected to run
trouble- and maintenance-free.   You  must be  aptly prepared for  the
journey which lies ahead.   Otherwise, if you're new to UNIX,  you may
very well become overly frustrated with the system.

1.6.2 Hints for UNIX gurus

Even  those  people  with  years  of  UNIX  programming   and  systems
administration experience may need assistance before they are  able to
pick up and install Linux.  There are still aspects of the system that
UNIX wizards will need to be familiar with before diving in.   For one
thing, Linux is not a commercial UNIX system.  It does  not attempt to
uphold the same standards as other UNIX systems you have may have come
across.  To be more  specific, while stability is an  important factor
in the development of Linux, it is not the only factor.
  More important, perhaps, is functionality.  In  many cases, new code
will make it into  the standard kernel even  though it is still  buggy
and not functionally  complete.   The  assumption is that  it is  more
important to release code  which users can test  and use than delay  a
release until it is ``complete''.  As an example,  WINE (the Microsoft
Windows Emulator for Linux) had  an ``official'' alpha release  before
it was completely tested.   In this way, the Linux community  at large
had a chance  to work with  the code,  test it,  and help develop  it,
while those who found the  alpha code ``good enough'' for  their needs
could use  it.    Commercial UNIX  vendors  rarely, if  ever,  release
software in this manner.
  If  you have  been a  UNIX  systems administrator  for more  than  a
decade, and have used every  commercial UNIX system under the  Sun (no
pun intended), Linux  may take some getting  used to.   The system  is
very modern and dynamic.   A new kernel release is  made approximately
1.7.   Differences Between Linux and Other Operating Systems        23
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every few months.  New software is constantly being released.  One day
your system may be completely  up-to-date with the current trend,  and
the next day the same system is considered to be in the Stone Age.
  With all of this  dynamic activity, how can you be expected  to keep
up with the ever-changing Linux world?  For the most part,  it is best
to upgrade incrementally;  that is,  upgrade only  those parts of  the
system that need upgrading,  and then only  when you think an  upgrade
is necessary.  For  example, if you never  use Emacs, there is  little
reason to  continuously install  every new  release of  Emacs on  your
system.  Furthermore,  even if you  are an avid  Emacs user, there  is
usually no reason to upgrade it  unless you find that some  feature is
missing that is in the next release.  There is little or  no reason to
always be on top of the newest version of software.
  We  hope that  Linux will  meet  or exceed  your expectations  of  a
homebrew UNIX system.  At the very core of Linux is the spirit of free
software, of constant  development and  growth.   The Linux  community
favors expansion over stability,  and that is  a difficult concept  to
swallow for many people, especially  those so steeped in the  world of
commercial UNIX. You cannot expect  Linux to be perfect;  nothing ever
is in the free software world.  However, we believe  that Linux really
is as complete and useful as any other implementation of UNIX.


1.7 Differences Between Linux and Other Operating Systems

It is important to understand the differences between Linux  and other
operating systems, such as MS-DOS, OS/2, and other  implementations of
UNIX for the personal computer.  First of all, it should be made clear
that Linux will coexist  happily with other  operating systems on  the
same machine:  that is, you  can run MS-DOS and OS/2 along  with Linux
on the same system without problems.  There are even  ways to interact
between the various operating systems, as we'll see.

1.7.1 Why use Linux?

Why use  Linux  instead  of  a  well-known,   well-tested,  and  well-
documented commercial operating system?  We could give you  a thousand
reasons.   One of the  most important,  however, is  that Linux is  an
excellent choice  for personal  UNIX  computing.    If you're  a  UNIX
software developer, why  use MS-DOS  at home?   Linux  will allow  you
to develop and test UNIX  software on your PC, including  database and
X Windows applications.   If you're a  student, chances are that  your
university computing systems run  UNIX. With Linux,  you can run  your
own UNIX system  and tailor  it to  your own  needs.   Installing  and
running Linux is also an excellent way to learn UNIX if you don't have
access to other UNIX machines.
  But let's  not  lose sight.    Linux isn't  just  for personal  UNIX
users.  It  is robust and  complete enough to  handle large tasks,  as
well as  distributed computing  needs.   Many  businesses---especially
small  ones---are  moving  to  Linux  in  lieu  of   other  UNIX-based
1.7.   Differences Between Linux and Other Operating Systems        24
_______________________________________________________________________

workstation environments.     Universities  are finding  Linux  to  be
perfect for  teaching courses  in operating  systems design.    Larger
commercial software vendors are starting to realize  the opportunities
that a free operating system can provide.
  The  following  sections   should  point  out  the  most   important
differences between Linux and other  operating systems.  We  hope that
you'll find that Linux  can meet your  computing needs, or (at  least)
enhance your current computing  environment.   Keep in mind that  they
best way to get a taste for Linux is just to try  it out---you needn't
even install a complete system  to get a feel for  it.  In  Chapter 2,
we'll show you how.

1.7.2 Linux vs.  MS-DOS

It's not uncommon  to run both  Linux and MS-DOS  on the same  system.
Many Linux  users  rely  on  MS-DOS  for  applications  such  as  word
processing.    While  Linux  provides  its  own  analogues  for  these
applications (for  example,  TeX), there  are  various reasons  why  a
particular user would want to  run MS-DOS as well  as Linux.  If  your
entire dissertation is written using  WordPerfect for MS-DOS, you  may
not be able to easily convert it  to TeX or some other format.   There
are many commercial applications for MS-DOS which aren't available for
Linux, and there's no reason why you can't use both.
  As you might know,  MS-DOS does not fully utilize  the functionality
of the 80386  and 80486 processors.    On the other  hand, Linux  runs
completely in  the processor's  protected mode,  and  exploits all  of
the features of the processor.   You can  directly access all of  your
available memory (and  beyond, using  virtual RAM).  Linux provides  a
complete UNIX interface  not available  under MS-DOS---developing  and
porting UNIX  applications under  Linux is  easily done,  while  under
MS-DOS you  are limited  to a  small subset  of  the UNIX  programming
functionality.  Because Linux is  a true UNIX system, you do  not have
these limitations.
  We could  debate the  pros and cons  of MS-DOS  and Linux for  pages
on end.   However, let  it suffice  to say that  Linux and MS-DOS  are
completely different entities.    MS-DOS is  inexpensive (compared  to
other commercial operating systems), and has a strong foothold  in the
PC computing world.  No other operating system for the  PC has reached
the level of popularity of MS-DOS---largely because the cost  of these
other operating systems  is unapproachable  to most personal  computer
users.  Very few  PC users can imagine  spending $1000 or more on  the
operating system alone.  Linux, however, is free, and you finally have
the chance to decide.
  We will  allow you to  make your own judgments  of Linux and  MS-DOS
based on your expectations and needs.  Linux is not for everybody.  If
you have always wanted to run a complete UNIX system at  home, without
the high cost of other UNIX  implementations for the PC, Linux  may be
what you're looking for.
  There are  tools available to  allow you  to interact between  Linux
and MS-DOS. For example, it is easy to access MS-DOS files from Linux.
1.7.   Differences Between Linux and Other Operating Systems        25
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There is also an  MS-DOS emulator available,  which allows you to  run
many popular MS-DOS  applications.   A Microsoft  Windows emulator  is
currently under development.

1.7.3 Linux vs.  The Other Guys

A number of other  advanced operating systems are  on the rise in  the
PC world.   Specifically, IBM's  OS/2 and  Microsoft's Windows NT  are
becoming very popular as more users move away from MS-DOS.
  Both OS/2  and Windows NT are  full multitasking operating  systems,
much like Linux.  Technically,  OS/2, Windows NT, and Linux  are quite
similar:  they  support roughly  the same  features in  terms of  user
interface, networking,  security, and  so forth.    However, the  real
difference between Linux and The Other Guys is the fact  that Linux is
a version of UNIX,  and hence benefits  from the contributions of  the
UNIX community at large.
  What makes  UNIX so  important?   Not only  is it  the most  popular
operating system for multiuser machines, it is also the foundation for
the majority of the free  software world.   If you have access to  the
Internet, nearly all of the  free software available there  is written
specifically for  UNIX  systems.    (The  Internet itself  is  largely
UNIX-based.)
  There are many  implementations of UNIX,  from many vendors, and  no
single organization is responsible for distribution.  There is a large
push in the  UNIX community for  standardization in  the form of  open
systems, but no single corporation  controls this design.  Hence,  any
vendor (or, as it turns out, any hacker) may implement these standards
in an implementation of UNIX.
  OS/2 and  Windows NT, on  the other  hand, are proprietary  systems.
The interface and design are  controlled by a single corporation,  and
only that corporation may implement that design.  (Don't expect to see
a free version of  OS/2 anytime in  the near future.)   In one  sense,
this kind of organization  is beneficial:   it sets a strict  standard
for the programming and user  interface unlike that found even  in the
open systems community.  OS/2 is OS/2 wherever you go---the same holds
for Windows NT.
  However, the UNIX  interface is constantly developing  and changing.
Several organizations are  attempting to  standardize the  programming
model, but  the task  is very  difficult.   Linux,  in particular,  is
mostly compliant with  the POSIX.1 standard  for the UNIX  programming
interface.   As time  goes on,  it is  expected that  the system  will
adhere to other such standards, but standardization is not the primary
issue in the Linux development community.

1.7.4 Other implementations of UNIX

There are  several other  implementations of  UNIX for  the 80386  and
80486.  The 80386 architecture lends itself to the UNIX  design, and a
number of vendors have taken advantage of this.
  Feature-wise, other  implementations of  UNIX for the  PC are  quite
1.7.   Differences Between Linux and Other Operating Systems        26
_______________________________________________________________________

similar to Linux.   You will see  that almost all commercial  versions
of UNIX support  roughly the same  software, programming  environment,
and networking features.   However, there are some  strong differences
between Linux and commercial versions of UNIX.
  First  of  all,  Linux  supports  a   different  range  of  hardware
from commercial  implementations.    In  general, Linux  supports  the
most well-known  hardware devices,  but support  is  still limited  to
that hardware  which developers  actually have  access to.    However,
commercial UNIX vendors generally have a wider support base,  and tend
to support more  hardware, although Linux  is not far  behind.   We'll
cover the hardware requirements for Linux in Section 1.8.
  Secondly, commercial  implementations of  UNIX usually come  bundled
with a complete set of documentation as well as user  support from the
vendor.  In contrast, most  of the documentation for Linux  is limited
to documents available on the  Internet---and books such as this  one.
In Section 1.9  we'll list  sources of Linux  documentation and  other
information.
  As far as  stability and robustness  are concerned, many users  have
reported that Linux is at least as stable as commercial  UNIX systems.
Linux is still  under development, and  certain features (such  TCP/IP
networking) are less stable but improve as time goes by.
  The most important factor to consider for many users is  price.  The
Linux software is free, if you have access to the Internet (or another
computer network) and  can download  it.   If you  do not have  access
to such a  network, you  may need  to purchase  it via  mail order  on
diskette, tape, or  CD-ROM (see Appendix  B).      Of course, you  may
copy Linux from a friend who  may already have the software,  or share
the cost of purchasing it with someone  else.  If you are  planning to
install Linux on a large number of machines, you need  only purchase a
single copy of the software---Linux  is not distributed on a  ``single
machine'' license.
  The  value  of   commercial  UNIX  implementations  should  not   be
demeaned:  along with  the price of  the software itself, one  usually
pays for documentation,  support,  and assurance  of quality.    These
are very  important  factors  for  large  institutions,  but  personal
computer users may  not require  these benefits.   In  any case,  many
businesses and universities are finding that running Linux on a lab of
inexpensive personal computers is preferrable to running  a commercial
version of UNIX  in a  lab of  workstations.   Linux  can provide  the
functionality of a  workstation on PC  hardware at  a fraction of  the
cost.
  As a  ``real-world''  example of  Linux's use  within the  computing
community,  Linux  systems  have  travelled  the  high   seas  of  the
North Pacific, managing  telecommunications and  data analysis for  an
oceanographic research  vessel.    Linux  systems  are being  used  at
research stations in Antarctica.  As a more mundane  example, perhaps,
several hospitals are using Linux to maintain patient records.   It is
proving to be as reliable and useful as other implementations of UNIX.
  There are other free or inexpensive implementations of  UNIX for the
386 and 486.  One of the most well-known is  386BSD, an implementation
1.8.   Hardware Requirements                                        27
_______________________________________________________________________

and port of BSD UNIX  for the 386.   386BSD is comparable to  Linux in
many ways, but which  one is ``better''  depends on your own  personal
needs and expectations.  The only strong distinction that  we can make
is that Linux is developed openly (where any volunteer can  aid in the
development process), while 386BSD  is developed within a closed  team
of programmers who  maintain the  system.   Because  of this,  serious
philosophical and design differences  exist between the two  projects.
The goals of  the two projects  are entirely different:   the goal  of
Linux is to develop  a complete UNIX system  from scratch (and have  a
lot of fun  in the  process), and  the goal  of 386BSD is  in part  to
modify the existing BSD code for use on the 386.
  NetBSD is  another port of  the BSD NET/2  distribution to a  number
of machines,  including the  386.   NetBSD  has a  slightly more  open
development structure, and is comparable to 386BSD in many respects.
  Another project  of note  is HURD,  an effort by  the Free  Software
Foundation to develop and distribute  a free version of UNIX  for many
platforms.  Contact the Free Software Foundation (the address is given
in Appendix E) for more information  about this project.  At  the time
of this writing, HURD is still in early stages of development.
  Other inexpensive versions of  UNIX exist as well, such  as Coherent
(available for about $99) and Minix (an academic but useful UNIX clone
upon which  early development  of Linux  was based).    Some of  these
implementations are  of mostly  academic  interest, while  others  are
full-fledged systems for real productivity.  Needless to say, however,
many personal UNIX users are moving to Linux.


1.8 Hardware Requirements

Now you must be convinced  of how wonderful Linux  is, and all of  the
great things  that it  can  do for  you.    However, before  you  rush
out and install  the software, you  need to be  aware of the  hardware
requirements and limitations that Linux has.
  Keep in  mind that Linux was  developed by its  users.  This  means,
for the most part,  that the hardware which  is supported by Linux  is
only the hardware which the users and developers actually  have access
to.  As  it turns out,  most of the  popular hardware and  peripherals
for 80386/80486 systems  are supported (in  fact, Linux supports  more
hardware than some commercial implementations of UNIX).  However, some
of the more  obscure and esoteric  devices aren't supported  yet.   As
time goes on,  a  wider range  of hardware  is supported,  so if  your
favorite devices aren't listed here, chances are that support for them
is forthcoming.
  Another  drawback for  hardware  support under  Linux is  that  many
companies have  decided to  keep the  hardware interface  proprietary.
The upshot of  this is  that volunteer Linux  developers simply  can't
write drivers for those  devices (if they  could, those drivers  would
be owned by the company that owned the interface,  which would violate
the GPL).  The companies  that maintain  proprietary interfaces  write
their own drivers for operating  systems such as MS-DOS and  Microsoft
Windows; the  end user  (that's you)  never  needs to  know about  the
1.8.   Hardware Requirements                                        28
_______________________________________________________________________

interface.   Unfortunately, this  does not allow  Linux developers  to
write drivers for those devices.
  There is very little that can be done about the situation.   In some
cases, programmers have  attempted to write  hackish drivers based  on
assumptions about the interface.  In other cases, developers will work
with the company in question  and attempt to obtain information  about
the device interface, with varying degrees of success.
  In the following  sections, we'll attempt to summarize  the hardware
requirements for Linux.   The Linux  Hardware HOWTO (see Section  1.9)
contains a more complete listing of hardware supported by Linux.
  Disclaimer:  a good deal of hardware support  for Linux is currently
in the development stage.   Some distributions may or may  not support
these experimental features.   This  section primarily lists  hardware
which has been  supported for  some time  and is known  to be  stable.
When in  doubt,  consult the  documentation  for the  distribution  of
Linux you are  using (see Section  2.1 for  more information on  Linux
distributions).

1.8.1 Motherboard and CPU requirements

Linux currently  supports  systems  with an  Intel  80386,  80486,  or
Pentium CPU. This includes  all variations on  this CPU type, such  as
the 386SX, 486SX, 486DX,  and 486DX2.   Non-Intel ``clones'', such  as
AMD and Cyrix processors, work with Linux as well.
  If you  have a 80386  or 80486SX, you  may also wish  to use a  math
coprocessor, although  one isn't  required (the  Linux  kernel can  do
FPU emulation if you do  not have a math  coprocessor).  All  standard
FPU couplings are  supported, such  as IIT, Cyrix  FasMath, and  Intel
coprocessors.
  The  system motherboard  must  use  ISA or  EISA  bus  architecture.
These terms  define how  the system  interfaces  with peripherals  and
other components on the main bus.  Most systems sold  today are either
ISA or EISA bus.  IBM's MicroChannel (MCA) bus, found on machines such
as the IBM PS/2, is not currently supported.
  Systems which  use a local  bus architecture  (for faster video  and
disk access) are supported as well.   It is suggested that you  have a
standard local bus architecture such as the VESA Local Bus (``VLB'').

1.8.2 Memory requirements

Linux requires very little  memory to run  compared to other  advanced
operating systems.  You should  have at the very least 2  megabytes of
RAM; however, it is strongly suggested that you have 4 megabytes.  The
more memory you have, the faster the system will run.
  Linux can support the  full 32-bit address range of the 386/486;  in
other words, it will utilize all of your RAM automatically.
  Linux  will run  happily with  only 4  megabytes  of RAM,  including
all of the bells  and whistles such  as X Windows,  Emacs, and so  on.
However, having more memory is almost as important as  having a faster
processor.   8 megabytes  is more  than enough  for personal  use;  16
1.8.   Hardware Requirements                                        29
_______________________________________________________________________

megabytes or more may be needed if you are expecting a heavy user load
on the system.
  Most Linux  users allocate  a portion  of their hard  drive as  swap
space, which is  used as virtual RAM.  Even if you  have a great  deal
of physical  RAM in  your machine,  you may  wish to  use swap  space.
While swap space  is no replacement  for actual  physical RAM, it  can
allow your system to run larger applications by swapping  out inactive
portions of code to disk.   The amount  of swap space that you  should
allocate depends on several factors; we'll come back to  this question
in Section 2.2.3.

1.8.3 Hard drive controller requirements

You do not  need to  have a hard  drive to  run Linux;  you can run  a
minimal system completely  from floppy.    However, this  is slow  and
very limited, and many users have access to hard drive storage anyway.
You must have an  AT-standard (16-bit) controller.   There is  support
in the  kernel for  XT-standard  (8 bit)  controllers;  however,  most
controllers used today are AT-standard.  Linux should support all MFM,
RLL, and IDE  controllers.   Most, but not  all, ESDI controllers  are
supported---only those which do ST506 hardware emulation.
  The general rule for  non-SCSI hard drive and floppy  controllers is
that if you  can access  the drive  from MS-DOS  or another  operating
system, you should be able to access it from Linux.
  Linux also  supports  a number  of popular  SCSI drive  controllers,
although support for SCSI  is more limited  because of the wide  range
of controller interface standards.  Supported SCSI controllers include
the Adaptec AHA1542B, AHA1542C, AHA1742A (BIOS version 1.34), AHA1522,
AHA1740, AHA1740  (SCSI-2 controller,  BIOS  1.34 in  Enhanced  mode);
Future Domain 1680, TMC-850,  TMC-950; Seagate ST-02; UltraStor  SCSI;
Western Digital WD7000FASST.  Clones which  are based  on these  cards
should work as well.

1.8.4 Hard drive space requirements

Of course, to install Linux, you'll  need to have some amount  of free
space on your hard drive.  Linux will support multiple  hard drives in
the same machine;  you can  allocate space  for Linux across  multiple
drives if necessary.
  The  amount of  hard  drive  space  that you  will  require  depends
greatly  on  your  needs  and  the  amount  of  software  that  you're
installing.  Linux is relatively small as UNIX implementations go; you
could run a complete  system in 10  to 20 megabytes  of space on  your
drive.   However, if  you want  to have  room for  expansion, and  for
larger packages such as X Windows, you  will need more space.   If you
plan to allow  multiple users  to use the  machine, you  will need  to
allocate storage for their files.
  Also, unless you have  a large amount of physical RAM  (16 megabytes
or more), you will more than likely want to allocate swap space, to be
used as virtual RAM. We will discuss all of the  details of installing
1.8.   Hardware Requirements                                        30
_______________________________________________________________________

and using swap space in Section 2.2.3.
  Each distribution of  Linux usually comes with some  literature that
should help  you  to gauge  the  precise  amount of  required  storage
depending on the  amount of  software you plan  to install.   You  can
run a minimal system  with less than 20  megabytes; a complete  system
with all  of the  bells and  whistles  in 80  megabytes or  less;  and
a very large  system with  room for  many users and  space for  future
expansion in the  range of 100-150  megabytes.   Again, these  figures
are meant only as a ballpark  approximation; you will have to  look at
your own needs and goals  in order to determine your  specific storage
requirements.

1.8.5 Monitor and video adapator requirements

Linux supports all standard Hercules,  CGA, EGA, VGA, IBM  monochrome,
and Super  VGA video  cards and  monitors for  the default  text-based
interface.  In general, if  the video card and monitor  coupling works
under another operating  system such  as MS-DOS, it  should work  fine
with Linux.  Original IBM CGA cards suffer from  ``snow'' under Linux,
which is not pleasant to use.
  Graphical  environments such  as  the  X Window  System  have  video
hardware requirements  of  their  own.     Instead  of  listing  these
requirements here, we relegate  the discussion to  Section 5.1.1.   In
short, to run the X Window System on your Linux machine, you will need
one of the video cards listed in that section.

1.8.6 Miscellaneous hardware

The above sections  described the  hardware which is  required to  run
a Linux system.   However,  most users have  a number of  ``optional''
devices such as tape and CD-ROM storage, sound boards, and  so on, and
are interested in whether or not this hardware is supported  by Linux.
Read on.

1.8.6.1 Mice and other pointing devices

For the most part,  you will only be  using a mouse under a  graphical
environment such  as the  X Window  System.   However,  several  Linux
applications not associated with a graphics environment do make use of
the mouse.
  Linux supports  all  standard serial  mice, including  Logitech,  MM
series, Mouseman, Microsoft  (2-button) and Mouse Systems  (3-button).
Linux also supports Microsoft, Logitech, and ATIXL busmice.   The PS/2
mouse interface is supported as well.
  All other  pointing devices, such as  trackballs, which emulate  the
above mice, should work as well.
1.8.   Hardware Requirements                                        31
_______________________________________________________________________

1.8.6.2 CD-ROM storage

Almost all CD-ROM drives use the SCSI interface.  As long  as you have
a SCSI adaptor supported by Linux, then your CD-ROM drive should work.
A number of  CD-ROM drives  have been  verified to  work under  Linux,
including the NEC CDR-74, Sony CDU-541,  and Texel DM-3024.   The Sony
internal CDU-31a and the Mistsumi CD-ROM drives are supported by Linux
as well.
  Linux supports the standard ISO-9660 filesystem for CD-ROMs.

1.8.6.3 Tape drives

There are several types of tape drives available on the market.   Most
of them use the  SCSI interface, all of  which should be supported  by
Linux.  Among  the verified SCSI tape  drives are the Sankyo  CP150SE;
Tandberg 3600;  Wangtek  5525ES,  5150ES,  and 5099EN  with  the  PC36
adaptor.  Other QIC-02 drives should be supported as well.
  Drivers  are currently  under  development  for various  other  tape
devices,  such  as Colorado  drives  which  hang  off  of  the  floppy
controller.

1.8.6.4 Printers

Linux supports the complete  range of parallel printers.   If you  are
able to  access your  printer via  the parallel  port  from MS-DOS  or
another operating system, you should  be able to access it  from Linux
as well.  The Linux printing software consists of the UNIX standard lp
and lpr software.  This software also allows you to print remotely via
the network, if you have one available.

1.8.6.5 Modems

As with  printer support,  Linux  supports the  full  range of  serial
modems, both  internal  and  external.    There  is a  great  deal  of
telecommunications software  available  for Linux,  including  Kermit,
pcomm, minicom, and Seyon.   If your modem is accessible  from another
operating system on the same machine, you should be able  to access it
from Linux with no difficulty.

1.8.7 Ethernet cards

Many popular Ethernet cards and  LAN adaptors are supported by  Linux.
These include:

 o  3com 3c503, 3c503/16

 o  Novell NE1000, NE2000

 o  Western Digital WD8003, WD8013
1.9.   Sources of Linux Information                                 32
_______________________________________________________________________

 o  Hewlett Packard HP27245, HP27247, HP27250

 o  D-Link DE-600

The following clones are reported to work:

 o  LANNET LEC-45

 o  Alta Combo

 o  Artisoft LANtastic AE-2

 o  Asante Etherpak 2001/2003,

 o  D-Link Ethernet II

 o  LTC E-NET/16 P/N 8300-200-002

 o  Network Solutions HE-203,

 o  SVEC 4 Dimension Ethernet

 o  4-Dimension FD0490 EtherBoard 16

Clones which are compatible with any of the above cards should work as
well.


1.9 Sources of Linux Information

As you have probably  guessed, there are  many sources of  information
about Linux available  apart from  this book.    In particular,  there
are a number  of books, not  specific to Linux  but rather about  UNIX
in general, that will  be of importance,  especially to those  readers
without previous UNIX experience.   If you are new to the  UNIX world,
we seriously suggest  that you take  the time to  peruse one of  these
books before you attempt to brave the jungles of Linux.  Specifically,
the book Learning the UNIX Operating System, by Grace  Todino and John
Strang, is a good place to start.
  Many of  the following sources of  information are available  online
in some electronic form.  That  is, you must have access to  an online
network, such as the Internet, USENET, or Fidonet, in  order to access
the information contained therein.   If you do not have  online access
to any of this material, you might be able to find someone kind enough
to give you hardcopies of the documents in question.  Read on.

1.9.1 Online documents

If you have  access to the  Internet, there  are many Linux  documents
available via anonymous FTP from archive sites all over the world.  If
1.9.   Sources of Linux Information                                 33
_______________________________________________________________________

you do not have direct Internet  access, these documents may  still be
available to you:  many  Linux distributions on CD-ROM contain  all of
the documents mentioned  here.   Also,  they are  distributed on  many
other networks, such as  Fidonet and CompuServe.   If you are able  to
send mail to Internet sites, you  may be able to retrieve  these files
using one of the  ftpmail servers which  will electronically mail  you
the documents or files  from FTP archive  sites.   See Appendix C  for
more information on using ftpmail.
  There is  a  great number  of FTP  archive sites  which carry  Linux
software and related documents.   A  list of well-known Linux  archive
sites is given in Appendix C.  In order to reduce network traffic, you
should always use the FTP site which is  geographically (network-wise)
closest to you.
  Appendix A contains a  listing of some of the Linux  documents which
are available via anonymous FTP.  The filenames will differ  depending
on the  archive  site  in  question;  most  sites  keep  Linux-related
documents in the docs subdirectory of their Linux archive space.   For
example, on the FTP  site sunsite.unc.edu, Linux  files are stored  in
the directory /pub/Linux, with Linux-related documentation being found
in /pub/Linux/docs.
  Examples  of  available  online  documents  are  the  Linux  FAQ,  a
collection of frequently asked questions about Linux; the  Linux HOWTO
documents, each describing a specific aspect of the system---including
the Installation HOWTO,  the Printing HOWTO,  and the Ethernet  HOWTO;
and, the Linux META-FAQ, a list of other sources  of Linux information
on the Internet.
  Most of  these documents are  also regularly posted  to one or  more
Linux-related USENET newsgroups; see Section 1.9.4 below.

1.9.2 Linux on the World Wide Web

The Linux  Documentation Home  Page is  available for  World Wide  Web
users at the URL

    http://sunsite.unc.edu/mdw/linux.html

This page contains many HOWTOs and other documents in HTML  format, as
well as pointers to other sites of interest to Linux users.

1.9.3 Books and other published works

At this time, there are few published works specifically  about Linux.
Most noteworthy are  the books from  the Linux Documentation  Project,
a project carried  out over  the Internet  to write  and distribute  a
bona fide set of ``manuals'' for  Linux.  These manuals  are analogues
to the documentation sets available with commercial versions  of UNIX:
they cover everything from installing Linux, to using and  running the
system, programming, networking, kernel development, and more.
  The Linux Documentation Project manuals are  available via anonymous
FTP from the Internet, as well as via mail order from several sources.
1.9.   Sources of Linux Information                                 34
_______________________________________________________________________

Appendix A lists the manuals  which are available and covers  means of
obtaining them in detail.
  There  are  not  many  books  specifically   about  Linux  currently
available.  However, there are  a large number of books about  UNIX in
general which are certainly applicable to Linux---as far as  using and
programming the system  is concerned,  Linux does  not differ  greatly
from other implementations  of UNIX. In  short, almost everything  you
want to know about using and programming Linux can be found in sources
meant for a general UNIX audience.  In fact, this book is  meant to be
complemented by the large library  of UNIX books currently  available;
here, we present  the most important  Linux-specific details and  hope
that you will look to other sources for more in-depth information.
  Armed with  a number  of good  books about  using UNIX,  as well  as
the book you hold  in your hands,  you should be  able to tackle  just
about anything.  Appendix A includes a list of highly-recommended UNIX
books, both for UNIX newcomers and UNIX wizards alike.
  There is  also  a monthly  magazine about  Linux,  called the  Linux
Journal.  It is distributed worldwide, and is an excellent way to keep
in touch with the many  goings-on in the Linux  community---especially
if you do not have access to USENET news (see below).   See Appendix A
for information on subscribing to the Linux Journal.

1.9.4 USENET newsgroups

USENET is  a  worldwide  electronic  news and  discussion  forum  with
a heavy  contingent  of  so-called  ``newsgroups''---discussion  areas
devoted to  a particular  topic.   Much  of the  development of  Linux
has been  done over  the waves  of the  Internet and  USENET, and  not
suprisingly there  are a  number of  USENET  newsgroups available  for
discussions about Linux.
  The original  Linux newsgroup was alt.os.linux,  and was created  to
move some of the discussions about Linux out of comp.os.minix  and the
various mailing lists.  Soon,  the traffic on alt.os.linux grew  to be
large enough that a newsgroup in  the comp hierarchy was warranted;  a
vote was taken in February of 1992, and comp.os.linux was created.
  comp.os.linux quickly became  one of the most popular  (and loudest)
USENET groups; more popular than any other comp.os group.  In December
of 1992, a vote  was taken to split  the newsgroup in order to  reduce
traffic; only  comp.os.linux.announce passed this  vote.   In July  of
1993, the group was finally split into the new hierarchy.  Almost 2000
people voted in the comp.os.linux reorganization, making it one of the
largest USENET Call For Votes ever.
  If you  do  not have  direct USENET  access,  but are  able to  send
and receive electronic mail from the Internet, there  are mail-to-news
gateways available for each of the newsgroups below.

comp.os.linux.announce
           comp.os.linux.announce   is  a   moderated  newsgroup   for
           announcements  and  important  postings   about  the  Linux
           system   (such  as  bug  reports,   important  patches   to
1.9.   Sources of Linux Information                                 35
_______________________________________________________________________

           software,  and so on).   If you  read any Linux  newsgroups
           at all,  read this one.   Often, the important  postings in
           this  group are  not crossposted  to  other groups.    This
           group  also contains  many periodic  postings about  Linux,
           including  many of  the online documents  described in  the
           last section and listed in Appendix A.

           Postings  to  this  newsgroup  must   be  approved  by  the
           moderators,  Matt Welsh and  Lars Wirzenius.   If you  wish
           to  submit  and  article  to  this  group,  in  most  cases
           you  can simply  post  the article  as you  normally  would
           (using  Pnews or  whatever posting software  that you  have
           available);  the news  software will automatically  forward
           the article  to the moderators for  approval.  However,  if
           your  news system  is not set  up correctly,  you may  need
           to  mail the article  directly; the  submission address  is
           [e-mail].
           The  rest   of  the  Linux  newsgroups  listed   below  are
           unmoderated.

comp.os.linux.help
           This  is  the  most  popular  Linux   newsgroup.     It  is
           for  questions  and answers  about using,  setting  up,  or
           otherwise  running  a Linux  system.    If you  are  having
           problems with  Linux, you may  post to this newsgroup,  and
           hopefully receive  a reply from  someone who might be  able
           to help.   However, it is strongly suggested that  you read
           all  of the  available Linux  documentation before  posting
           questions to this newsgroup.

comp.os.linux.admin
           This  newsgroup  is  for  questions  and  discussion  about
           running a Linux system, most commonly  in an active, multi-
           user  environment.    Any discussion  about  administrative
           issues  of  Linux  (such  as  packaging  software,   making
           backups, handling users, and so on) is welcome here.

comp.os.linux.development
           This  is a newsgroup for  discussions about development  of
           the  Linux  system.    All  issues related  to  kernel  and
           system software development should be discussed  here.  For
           example, if  you are writing a kernel driver and  need help
           with certain aspects of the programming,  this would be the
           place  to ask.    This  newsgroup is  also for  discussions
           about the direction and goals  behind the Linux development
           effort, as described (somewhat) in Section 1.6.
           It   should   be  noted   that   this  newsgroup   is   not
           (technically)   for   discussions  about   development   of
           software   for  Linux,  but   rather  for  discussions   of
           development  of  Linux.    That  is,  issues  dealing  with
1.9.   Sources of Linux Information                                 36
_______________________________________________________________________

           applications  programming under Linux  should be  discussed
           in  another Linux  newsgroup; comp.os.linux.development  is
           about  developing the  Linux system  itself, including  the
           kernel, system libraries, and so on.

comp.os.linux.misc
           This  newsgroup is for all  discussion which doesn't  quite
           fit into the other available Linux  groups.  In particular,
           advocacy  wars (the incessant  ``Linux versus Windows  NT''
           thread,  for example),  should  be waged  here, as  opposed
           to  in the  technical Linux groups.    Any nontechnical  or
           metadiscourse  about  the  Linux system  should  remain  in
           comp.os.linux.misc.

  It  should be  noted that  the  newsgroup comp.os.linux,  which  was
originally the  only  Linux group,  has  been  superseded by  the  new
hierarchy of groups.  If you have access to comp.os.linux,  but not to
the newer Linux groups listed above, encourage your news administrator
to create the new groups on your system.

1.9.5 Internet mailing lists

If you have access  to Internet electronic  mail, you can  participate
in a number of mailing  lists even if you  do not have USENET  access.
Note that if you are  not directly on the  Internet, you can join  one
of these mailing lists as long as you are able  to exchange electronic
mail with the  Internet (for example,  UUCP, FidoNET, CompuServe,  and
other networks all have access to Internet mail).
  The  ``Linux  Activists''  mailing  list  is   primarily  for  Linux
developers and people  interested in  aiding the development  process.
This is a  ``multi-channel'' mailing list,  in which  you join one  or
more ``channels'' based  on your particular  interests.   Some of  the
available channels include:  NORMAL, for general Linux-related issues;
KERNEL, for kernel development;  GCC, for discussions relating to  the
gcc compiler and library development;  NET, for discussions about  the
TCP/IP networking  code;  DOC,  for  issues relating  to  writing  and
distributing Linux documentation; and more.
  For more  information about the Linux  Activists mailing list,  send
mail to

    [e-mail]

You will receive  a list  of currently  available channels,  including
information on how to subscribe and unsubscribe to particular channels
on the list.
  Quite a few special-purpose mailing lists about and  for Linux exist
as well.  The best way to  find out about these is to watch  the Linux
USENET newsgroups for announcements,  as well as  to read the list  of
publicly-available mailing lists,  periodically posted  to the  USENET
group news.answers.
1.10.   Getting Help                                                37
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1.10 Getting Help

You will undoubtedly  require some  degree of  assistance during  your
adventures in the Linux world.  Even the most wizardly of UNIX wizards
occasionally is stumped by  some quirk or  feature of Linux, and  it's
important to know how and where to find help when you need it.
  The  primary means  of  getting help  in  the  Linux world  are  via
Internet  mailing  lists  and  USENET  newsgroups,  as   discussed  in
Section 1.9.  If  you don't have online  access to these sources,  you
might be  able to  find comparable  Linux discussion  forums on  other
online services, such as on local BBS's, CompuServe, and so on.
  A number of  businesses are providing commercial support  for Linux.
This will allow you to pay a ``subscription fee'' which will allow you
to call the consultants for help with your Linux problems.  Appendix B
contains a list  of Linux  vendors, some of  which provide  commercial
support.  However, if you have access to USENET and Internet mail, you
may find the free support found there to be just as useful.
  Keeping the following suggestions in mind will  greatly improve your
experiences with Linux and will guarantee you more success  in finding
help to your problems.
  Consult all available  documentation...first!   The first  thing you
should do when encountering a  problem is consult the various  sources
of information listed in Section 1.9 and Appendix A.   These documents
were laboriously written  for people like  you---people who need  help
with the Linux system.   Even  books written for  UNIX in general  are
applicable to Linux, and you should take advantage of them.  More than
likely, you will find  the answer to  your problems somewhere in  this
documentation, as impossible as it may seem.
  If  you have  access to  USENET  news or  any of  the  Linux-related
mailing lists, be sure to  actually read the information  there before
posting for help with your problem.   Many times, solutions  to common
problems are  not  easy to  find  in documentation,  and  instead  are
well-covered in the newsgroups and mailing lists devoted to Linux.  If
you only post to these groups,  and don't actually read them,  you are
asking for trouble.
  Learn  to  appreciate  self-maintenance.    In  most  cases,  it  is
preferable to do as much  independent research and investigation  into
the problem as possible before seeking  outside help.  After all,  you
asked for it,  by running  Linux in the  first place!   Remember  that
Linux is all about hacking  and fixing problems yourself.   It is  not
a commercial  operating system,  nor does  it  try to  look like  one.
Hacking won't kill you.  In fact, it will teach you a great deal about
the system  to investigate  and solve  problems yourself---maybe  even
enough to one day call yourself a Linux guru.  Learn to appreciate the
value of hacking the system,  and how to  fix problems yourself.   You
can't expect to  run a  complete, homebrew Linux  system without  some
degree of handiwork.
  Remain calm.   It is vital  to refrain from getting frustrated  with
the system, at  all costs.   Nothing is earned  by taking an  axe---or
worse, a powerful  electromagnet---to your  Linux system in  a fit  of
1.10.   Getting Help                                                38
_______________________________________________________________________

anger.  The authors  have found that a  large punching bag or  similar
inanimate object is a wonderful  way to relieve the occasional  stress
attack.  As Linux matures  and distributions become more reliable,  we
hope that this problem  will go away.   However, even commercial  UNIX
implementations can be  tricky at  times.   When all  else fails,  sit
back, take a few deep breaths, and go after the problem again when you
feel relaxed.  Your mind and conscience will be clearer.
  Refrain  from posting  spuriously.   Many  people  make the  mistake
of posting or mailing  messages pleading for  help prematurely.   When
encountering a problem, do not---we repeat, do  not---rush immediately
to your  nearest terminal  and  post a  message to  one  of the  Linux
USENET newsgroups.    Often,  you  will catch  your own  mistake  five
minutes later and find yourself in the curious situation  of defending
your own sanity in  a public forum.   Before  posting anything any  of
the Linux mailing lists  or newsgroups, first  attempt to resolve  the
problem yourself and be absolutely certain what the problem is.   Does
your system not  respond when  switched on?   Perhaps  the machine  is
unplugged.
  If you do  post for help,  make it worthwhile.   If all else  fails,
you may  wish to  post a  message for  help in  any of  the number  of
electronic forums dedicated  to Linux, such  as USENET newsgroups  and
mailing lists.   When posting, remember  that the people reading  your
post are not  there to help  you.   The network  is not your  personal
consulting service.  Therefore,  it is important to remain  as polite,
terse, and informative as possible.
  How can  one accomplish this?    First, you  should include as  much
(relevant) information about your system and your problem as possible.
Posting the simple request,  ``I cannot seem  to get e-mail to  work''
will probably get you nowhere  unless you include information on  your
system, what software you are using, what you have attempted  to do so
far and what the results were.  When including  technical information,
it is  usually a  good  idea to  include  general information  on  the
version(s) of your  software (Linux kernel  version, for example),  as
well as a  brief summary  of your  hardware configuration.    However,
don't overdo  it---including  information on  the  brand and  type  of
monitor that  you have  probably  is irrelevant  if you're  trying  to
configure networking software.
  Secondly,  remember that  you need  to  make some  attempt---however
feeble---at solving your problem  before you go  to the Net.   If  you
have never attempted  to set  up electronic  mail,  for instance,  and
first decide to ask folks on the Net how to go about doing it, you are
making a big mistake.  There are a number of  documents available (see
the Section 1.9) on  how to get started  with many common tasks  under
Linux.  The idea  is to get as far  along as possible on your  own and
then ask for help if and when you get stuck.
  Also  remember  that  the  people  reading  your  message,   however
helpful, may occasionally  get frustrated by  seeing the same  problem
over and over again.   Be sure to  actually read the Linux  newsgroups
and mailing  lists before  posting your  problems.   Many  times,  the
solution to your problem has been discussed repeatedly, and all that's
1.10.   Getting Help                                                39
_______________________________________________________________________

required to find it is to browse the current messages.
  Lastly,  when posting to  electronic newsgroups  and mailing  lists,
try to  be  as  polite  as  possible.    It  is  much  more  effective
and worthwhile to  be polite,  direct,  and informative---more  people
will be willing  to help  you if  you master  a humble  tone.   To  be
sure, the flame  war is an  art form across  many forms of  electronic
communication, but  don't  allow  that  to preoccupy  your  and  other
people's time.    Save  the network  undue wear  and  tear by  keeping
bandwidth as low as possible, and by paying as much attention to other
sources of information  which are available  to you.   The network  is
an excellent way  to get  help with  your Linux  problems---but it  is
important to know how to use the network effectively.








Chapter 2




Obtaining and Installing Linux



In this chapter, we'll describe  how to obtain the Linux software,  in
the form of one of the various pre-packaged distributions,  and how to
install the distribution that you choose.
  As we have  mentioned, there is no single  ``official'' distribution
of the Linux software;  there are, in  fact, many distributions,  each
of which  serves  a  particular purpose  and  set  of goals.     These
distributions are available  via anonymous FTP  from the Internet,  on
BBS systems worldwide, and via mail on diskette, tape, and CD-ROM.
  Here, we  present a  general overview of  the installation  process.
Each distribution has its own specific installation  instructions, but
armed with the concepts presented here you should be able to feel your
way through any installation.  Appendix A lists sources of information
for installation instructions  and other  help, if you're  at a  total
loss.
  This  book  contains additional  sections  detailing  the  Slackware
distribution of Linux.

2.1 Distributions of Linux

Because Linux is free  software, no single  organization or entity  is
responsible for releasing and distributing  the software.   Therefore,
anyone is free to put together  and distribute the Linux software,  as
long as the restrictions in the GPL are observed.  The  upshot of this
is that there are many distributions of Linux, available via anonymous
FTP or via mail order.
  You  are now  faced with  the  task of  deciding upon  a  particular
distribution of Linux which suits  your needs.  Not  all distributions
are alike.   Many of  them come with  just about  all of the  software
you'd need to  run a  complete system---and  then some.   Other  Linux
distributions are ``small'' distributions  intended for users  without
copious amounts of  diskspace.   Many distributions  contain only  the
core Linux software, and you  are expected to install  larger software
packages, such as the X Window System, yourself.  (In  Chapter 4 we'll
show you how.)
  The  Linux Distribution  HOWTO  (see  Appendix A)  contains  a  list


                                  40
2.1.   Distributions of Linux                                       41
_______________________________________________________________________

of Linux  distributions available  via the  Internet as  well as  mail
order.   Appendix  B  also lists  contact addresses  for  a number  of
Linux mail-order vendors.  If  you purchased this book in  printed the
form, the publisher should  also be able to  provide you with a  Linux
distribution or tell you who can.
  How  can you  decide  among all  of these  distributions?    If  you
have access to USENET news,  or another computer conferencing  system,
you might want  to ask  there for  personal opinions  from people  who
have installed  Linux.   Even  better,  if you  know  someone who  has
installed Linux,  ask  them for  help  and advice.    There  are  many
factors to consider when choosing a distribution,  however, everyone's
needs and opinions are different.   In actuality, most of  the popular
Linux distributions contain roughly the  same set of software,  so the
distribution that you select is more or less arbitrary.
  This book contains  information on installing the popular  Slackware
and Slackware Pro distributions of Linux.

2.1.1 Getting Linux from the Internet

If you have access to the Internet, the easiest way to obtain Linux is
via anonymous FTP.(1) Appendix C  lists a number of FTP  archive sites
which carry Linux software.  One of these is sunsite.unc.edu,  and the
various Linux distributions can be found in the directory

    /pub/Linux/distributions

there.
  Many  distributions are  released  via anonymous  FTP  as a  set  of
disk images.     That  is,  the  distribution consists  of  a  set  of
files, and  each file  contains the  binary image  of  a floppy.    In
order to copy  the contents  of the image  file onto  the floppy,  you
can use the  RAWRITE.EXE program  under MS-DOS.  This program  copies,
block-for-block, the contents of  a file to  a floppy, without  regard
for disk format.(2)
  RAWRITE.EXE is available  on the various Linux FTP sites,  including
sunsite.unc.edu in the directory

    /pub/Linux/system/Install/rawwrite

----------------------------
 1. If you do  not have direct Internet  access, you can obtain  Linux
via the  ftpmail  service,  provided  that  you have  the  ability  to
exchange e-mail with the Internet.  See Appendix C for details.
 2. If you have access to a UNIX workstation with a  floppy drive, you
can also use the  dd command to  copy the file  image directly to  the
floppy.   A command  such as  ``dd of=/dev/rfd0  if=foo bs=18k''  will
``raw write'' the contents of the  file foo to the floppy device  on a
Sun workstation.  Consult  your local UNIX gurus for  more information
on your system's floppy devices and the use of dd.
2.1.   Distributions of Linux                                       42
_______________________________________________________________________

  Therefore, in  many cases, you simply  download the set of  diskette
images, and use RAWRITE.EXE  with each image in  turn to create a  set
of diskettes.    You boot  from the  so-called  ``boot diskette''  and
you're ready to roll.  The software is usually installed directly from
the floppies, although  some distributions allow  you to install  from
an MS-DOS partition  on your  hard drive.    Some distributions  allow
you to install  over a  TCP/IP network.   The  documentation for  each
distribution should describe  these installation  methods if they  are
available.
  Other Linux distributions are installed from a set  of MS-DOS format
floppies.  For example,  the Slackware distribution of  Linux requires
only the boot and root diskettes to be created using  RAWRITE.EXE. The
rest of the diskettes are copied to MS-DOS format diskettes  using the
MS-DOS COPY command.   The system installs the software  directly from
the MS-DOS floppies.    This saves you  the trouble  of having to  use
RAWRITE.EXE for many  image files,  although it requires  you to  have
access to an MS-DOS system to create the diskettes.
  Each  distribution  of Linux  available  via  anonymous  FTP  should
include a  README file  describing  how to  download and  prepare  the
diskettes for installation.    Be sure  to read all  of the  available
documentation for the release that you are using.
  When downloading  the Linux  software, be  sure to  use binary  mode
for all file transfers (with most FTP clients, the  command ``binary''
enables this mode).
  See  Section  2.1.4,   below,  for  information  on   obtaining  the
Slackware distribution from the Internet.

2.1.2 Getting Linux from other online sources

If you  have access  to another  computer network  such as  CompuServe
or Prodigy,  there  may be  a  means to  download the  Linux  software
from these sources.   In addition,  many bulletin board (BBS)  systems
carry Linux  software.    A  list  of  Linux  BBS sites  is  given  in
Appendix D.   Not  all Linux  distributions are  available from  these
computer networks,  however---many  of them,  especially  the  various
CD-ROM distributions, are only available via mail order.

2.1.3 Getting Linux via mail order

If you don't have Internet or BBS access, many Linux distributions are
available via mail  order on  diskette,  tape, or  CD-ROM. Appendix  B
lists a number  of these  distributors.   Many of  them accept  credit
cards as well as international orders, so if you're not  in the United
States or Canada you still should be able to obtain Linux in this way.
  Linux is  free software,  although distributors are  allowed by  the
GPL to  charge a  fee for  it.   Therefore,  ordering  Linux via  mail
order might  cost  you between  US$30  and US$150,  depending  on  the
distribution.  However, if you know someone who  has already purchased
or downloaded a release of Linux, you are free to borrow or copy their
software for your  own use.    Linux distributors are  not allowed  to
2.1.   Distributions of Linux                                       43
_______________________________________________________________________

restrict the license  or redistribution  of the software  in any  way.
If you are thinking  about installing an  entire lab of machines  with
Linux, for example, you only need to purchase a single copy  of one of
the distributions, which can be used to install all of the machines.

2.1.4 Getting Slackware

Slackware is a  popular distribution  of Linux  maintained by  Patrick
Volkerding.(3)  It is easy to install and fairly complete,  and may be
obtained both from the Internet as well as on CD-ROM from  a number of
vendors (see Appendix B).
  The Slackware  distribution consists of a  number of ``disk  sets'',
each one containing a particular type of software (for example,  the d
disk set contains development tools such as the gcc compiler,  and the
x disk set contains the X Window  System software).  You can  elect to
install whatever disk sets you like, and can install new ones later.
  The version of Slackware  described here is 2.0.0, of 25  June 1994.
Installation of later versions of Slackware should be very  similar to
the information given here.

2.1.4.1 Slackware disk sets

Unfortunately,  Slackware  does  not  maintain  a  complete   list  of
diskspace requirements  for  each disk  set.    You  need at  least  7
megabytes to install  just the  ``A'' series  of disks;  a very  rough
estimate of the  required diskspace would  be 2  or 2.5 megabytes  per
disk.
  The following disk sets are available:

A          The base  system.   Enough to get  up and running and  have
           elvis and comm programs available.   Based around the 1.0.9
           Linux kernel, and the new filesystem standard (FSSTND).
           These disks  are known to fit  on 1.2M disks, although  the
           rest of Slackware  won't.  If you have only a  1.2M floppy,
           you  can  still install  the  base system,  download  other
           disks you want and install them from your hard drive.

AP         Various  applications  and  add ons,  such  as  the  manual
           pages,  groff,  ispell  (GNU and  international  versions),
           term,  joe,  jove,  ghostscript,  sc,  bc,  and  the  quota
           patches.

D          Program  development.    GCC/G++/Objective  C  2.5.8,  make
           (GNU  and BSD), byacc  and GNU  bison, flex,  the 4.5.26  C
           libraries, gdb, kernel source for  1.0.9, SVGAlib, ncurses,
           clisp, f2c, p2c, m4, perl, rcs.

----------------------------
 3.  Patrick   Volkerding  can   be  reached   on   the  Internet   at
[e-mail].
2.1.   Distributions of Linux                                       44
_______________________________________________________________________

E          GNU Emacs 19.25.

F          A collection of FAQs and other documentation.

I          Info  pages for GNU  software.   Documentation for  various
           programs readable by info or Emacs.

N          Networking.  TCP/IP, UUCP, mailx,  dip, deliver, elm, pine,
           smail, cnews, nn, tin, trn.

OOP        Object Oriented Programming.  GNU  Smalltalk 1.1.1, and the
           Smalltalk Interface to X (STIX).
Q          Alpha  kernel source and  images (currently contains  Linux
           1.1.18).

TCL        Tcl, Tk, TclX, blt, itcl.

Y          Games.      The  BSD  games  collection,  and   Tetris  for
           terminals.

X          The base XFree86 2.1.1 system, with  libXpm, fvwm 1.20, and
           xlock added.

XAP        X applications:  X11 ghostscript,  libgr13, seyon, workman,
           xfilemanager,  xv  3.01, GNU  chess  and xboard,  xfm  1.2,
           ghostview, and various X games.

XD         X11  program development.   X11 libraries, server  linkkit,
           PEX support.

XV         Xview 3.2  release 5.   XView libraries, and the Open  Look
           virtual and non-virtual window managers.
IV         Interviews libraries, include files, and  the doc and idraw
           apps.

OI         ParcPlace's  Object   Builder  2.0  and  Object   Interface
           Library   4.0,   generously   made  available   for   Linux
           developers according  to the terms in the  "copying" notice
           found  in these  directories.   Note that  these only  work
           with  libc-4.4.4, but a  new version  may be released  once
           gcc 2.5.9 is available.

T          The TeX and LaTeX text formatting systems.

  You must get the ``A'' disk set; the rest are  optional.  We suggest
installing the A, AP, and D sets, as well as the X set if  you plan to
run the X Window System.
2.1.   Distributions of Linux                                       45
_______________________________________________________________________

2.1.4.2 Getting Slackware from the Internet

The Slackware release of Linux may be found on any number of FTP sites
worldwide.   Appendix  C lists  several  of the  Linux FTP  sites;  we
suggest that you try to find the software on the FTP site nearest you,
to reduce net traffic.   However, two of the major Linux  FTP archives
are sunsite.unc.edu and tsx-11.mit.edu.
  The Slackware release may be found at least on the following sites:

 o  sunsite.unc.edu:/pub/Linux/distributions/slackware

 o  tsx-11.mit.edu:/pub/linux/packages/slackware

 o  ftp.cdrom.com:/pub/linux/slackware

  ftp.cdrom.com is Slackware's home site.

2.1.4.2.1 Downloading the  files You  should  download  the  following
files using  FTP.  Be  sure  to use  binary  mode  when  transferring.
Appendix C contains a complete tutorial on using FTP.

 o  The various README  files,  as well as  SLACKWARE_FAQ.  Be sure  to
    read these files before attempting to install the software, to get
    any updates or changes to this document.

 o  A bootdisk image.  This is a file that you will write  to a floppy
    to create the Slackware  boot disk.   If you have a 1.44  megabyte
    boot floppy (3.5"), look  in the directory  bootdsks.144.  If  you
    have a 1.2  megabyte boot  floppy (5.25"),  look in the  directory
    bootdsks.12.

    You need one of the following bootdisk files.


    --  bare.gz.  This is a  boot floppy that has only IDE  hard drive
        drivers.  (No SCSI, CD-ROM, or networking support.)   Use this
        if you only have an IDE hard drive controller and aren't going
        to be installing over the network or from CD-ROM.

    --  cdu31a.gz.    Contains  IDE,  SCSI, and  the  Sony  CDU31A/33A
        driver.

    --  mitsumi.gz.    Contains  IDE,  SCSI, and  the  Mitsumi  CD-ROM
        driver.

    --  modern.gz.  An experimental boot disk with a newer kernel, and
        all drivers except  those for network cards  and the Sony  535
        CD-ROM.

    --  net.gz.  Contains IDE and network drivers.
2.1.   Distributions of Linux                                       46
_______________________________________________________________________

    --  sbpcd.gz.  Contains IDE, SCSI, and  SoundBlaster Pro/Panasonic
        CD-ROM drivers.

    --  scsi.gz.  Contains IDE, SCSI, and SCSI CD-ROM drivers.

    --  scsinet.gz.   Contains  IDE, SCSI,  SCSI  CD-ROM, and  network
        drivers.

    --  sony535.gz.    Contains IDE,  SCSI,  and Sony  535/531  CD-ROM
        drivers.

    --  xt.gz.  Contains IDE and XT hard drive drivers.


    You need only one of  the above bootdisk images, depending  on the
    hardware that you have in your system.

    The issue here  is that some hardware  drivers conflict with  each
    other in strange ways, and instead of attempting to debug hardware
    problems on your  system it's easier  to use  a boot floppy  image
    with only certain drivers enabled.  Most users  should try scsi.gz
    or bare.gz.

 o  A rootdisk image.  This is a file that you will write  to a floppy
    to create the Slackware installation  disk.  As with  the bootdisk
    image, look in rootdsks.144  or rootdsks.12 depending on the  type
    of boot floppy drive that you have.

    You need one of the following files:


    --  color144.gz.  The menu-based color installation disk  for 1.44
        megabyte drives.  Most users should use this rootdisk.

    --  umsds144.gz.   A version of the  color144 disk for  installing
        with the UMSDOS filesystem, which allows you to  install Linux
        onto a directory of an  MS-DOS filesystem.   This installation
        method is not  discussed in detail here,  but it will  prevent
        you from  having to  repartition your  drive.    More on  this
        later.

    --  tty144.gz.    The terminal-based  installation disk  for  1.44
        megabyte drives.   If  color144.gz doesn't work  for you,  try
        tty144.gz instead.

    --  colrlite.gz.  The  menu-based color installation disk for  1.2
        megabyte drives.

    --  umsds12.gz.   A version  of the colrlite  disk for  installing
        with  the  UMSDOS  filesystem.      See  the  description   of
2.1.   Distributions of Linux                                       47
_______________________________________________________________________

        umsds144.gz, above.

    --  tty12.gz.    The  terminal-based  installation  disk  for  1.2
        megabyte drives.  Use this rootdisk if you have a 1.2 megabyte
        boot floppy and colrlite.gz doesn't work for you.


    Again, you need only one  of the above rootdisk images,  depending
    on the type of boot floppy drive that you have.

 o  GZIP.EXE. This is  an MS-DOS  executable of  the gzip  compression
    program used  to compress  the boot  and rootdisk  files (the  .gz
    extension on the filenames indicates this).  This can  be found in
    the install directory.

 o  RAWRITE.EXE. This  is  an  MS-DOS  program  that  will  write  the
    contents of a file (such as the boot and rootdisk images) directly
    to a floppy, without regard to  format.  You will  use RAWRITE.EXE
    to create the boot and  root floppies.   This can be found in  the
    install directory as well.

    You only need RAWRITE.EXE and  GZIP.EXE if you plan to  create the
    boot and root floppies from an MS-DOS system.  If  you have access
    to a UNIX workstation with a floppy drive instead,  you can create
    the floppies from there, using the  dd command.  See the  man page
    for dd and ask your local UNIX administrators for assistance.

 o  The  files  in  the  directories  slakware/a1,  slakware/a2,   and
    slakware/a3.   These  files  make up  the ``A''  disk  set of  the
    Slackware distribution.    They are  required.   Later,  you  will
    copy these files to MS-DOS floppies for installation (or,  you can
    install from your hard drive).  Therefore, when you download these
    files, keep them in separate  directories; don't mix the  a1 files
    with the a2 files, and so on.

    Be sure that you get the files without periods in the filenames as
    well.  That is, within FTP, use the command ``mget  *'' instead of
    ``mget *.*''.

 o  The files in  the directories ap1,  ap2, etc.,  depending on  what
    disk sets you are installing.  For example, if  you are installing
    the ``X'' disk series, get the files in the directories x1 through
    x5.  As with the ``A'' disk set, above, be sure to  keep the files
    in separate directories when you download them.

2.1.4.3 Getting Slackware on CD-ROM

Slackware is also available on  CD-ROM. Most Slackware CD-ROMs  simply
contain a copy of the files  as they appear on the FTP  archive sites,
as described above.   Therefore, if you  have a Slackware CD-ROM,  you
2.1.   Distributions of Linux                                       48
_______________________________________________________________________

have all of the files that you need.
  You will  have to create a  boot and root  floppy from the files  on
the CD-ROM. See  Section 2.1.4.2.1,  above,  for a  discussion on  the
available boot and root disk images.
  First, decide which  boot and root disk images  you will use.   They
should all be  on the CD-ROM.  Below, we will  describe how to  create
these floppies.

2.1.4.4 Installation methods

Slackware provides several different means of installing the software.
The most popular is installing  from an MS-DOS partition on  your hard
drive; another is  to install  from a set  of MS-DOS floppies  created
from the disk sets that you downloaded.
  If  you have  Slackware  on a  CD-ROM,  you  can install  the  files
directly from  there.    The Slackware  Pro distribution,  from  Morse
Telecommunications, allows you to install Slackware so that many files
are accessed  directly on  the  CD-ROM. This  can  save a  great  deal
of space on your  hard drive, with  the tradeoff that running  certain
applications will be slower.

2.1.4.4.1 Creating the boot and root floppies You must create floppies
from the bootdisk and rootdisk images that you downloaded (or  have on
CD-ROM), no matter what type of installation you will be doing.
  On an MS-DOS system,  you must uncompress the bootdisk  and rootdisk
images using  GZIP.EXE.  For  example,  if you're  using  the  bare.gz
bootdisk image, issue the MS-DOS command:

    C:\> GZIP -D BARE.GZ

which will uncompress bare.gz and  leave you with the  file bare.   If
you are installing from CD-ROM, you can copy the bootdisk  image (such
as bare.gz) to  you hard drive,  and run GZIP.EXE  from the CD-ROM  to
uncompress it.
  You must similarly uncompress  the rootdisk image.  For  example, if
you are using the rootdisk color144.gz, issue the command:

    C:\> GZIP -D COLOR144.GZ

which will uncompress the file and leave you with color144.
  Next,  you must  have two  high-density  MS-DOS formatted  floppies.
(They must be of  the same type;  that is, if  your boot floppy  drive
is a 3.5" drive, both floppies must be high-density 3.5" disks.)   You
will use RAWRITE.EXE  to write  the boot  and rootdisk  images to  the
floppies.
  Issue the command:

    C:\> RAWRITE

  Answer the prompts for the name of the file to  write (such as bare,
2.1.   Distributions of Linux                                       49
_______________________________________________________________________

or color144) and  the floppy to  write it to  (such as  A:).   RAWRITE
will copy the file, block-by-block, directly to the floppy.   Also use
RAWRITE for the root disk  image.  When  you're done, you'll have  two
floppies:  one containing the boot disk, the other containing the root
disk.   Note that  these two floppies  will no  longer be readable  by
MS-DOS (they are ``Linux format'' floppies, in some sense).
  Be sure  that  you're using  brand-new, error-free  floppies.    The
floppies must have no bad blocks on them.
  Note that you do not  need to be running MS-DOS in order  to install
Slackware.  However, running MS-DOS makes it easier to create the boot
and root floppies, and it makes it easier to install  the software (as
you can install directly from an MS-DOS partition on your system).  If
you are not running MS-DOS on your system, you can  use someone else's
MS-DOS system just to create the floppies, and install from there.
  It is not necessary to use GZIP.EXE and  RAWRITE.EXE under MS-DOS to
create the boot and root floppies, either.   You can use the  gzip and
dd commands on a UNIX system to do the same job.  (For  this, you will
need a UNIX workstation with a floppy drive, of course.)  For example,
on a Sun workstation  with the floppy  drive on device /dev/rfd0,  you
can use the commands:

    $ gunzip bare.gz
    $ dd if=bare of=/dev/rfd0 obs=18k

  You  must provide  the  appropriate  block size  argument  (the  obs
argument) on some workstations (e.g., Suns) or this will fail.  If you
have problems the man page for dd will be instructive.

2.1.4.4.2 Preparing  for  installation   from  hard  drive If   you're
planning on  installing  the  Slackware  software  directly  from  the
hard drive (which  is often  faster and  more reliable  than a  floppy
installation), you will  need an MS-DOS partition  on the system  that
you're installing Slackware to.
  Note:  If  you plan to install  Slackware from an MS-DOS  partition,
that partition  must  NOT  be compressed  with  DoubleSpace,  Stacker,
or any  other  MS-DOS drive  compression  utility.    Linux  currently
cannot read DoubleSpace/Stacker MS-DOS partitions directly.   (You can
access them via the  MS-DOS Emulator, but that  is not an option  when
installing the Linux software.)
  To prepare  for hard drive installation,  simply create a  directory
on the hard drive to store the Slackware files.  For example,

    C:\> MKDIR SLACKWAR

  will create the  directory C:\SLACKWAR to hold the  Slackware files.
Under this directory, you should create subdirectories A1, A2,  and so
on, for each disk  set that you  downloaded, using the MKDIR  command.
All of  the  files from  the  A1 disk  should  go into  the  directory
SLACKWAR\A1, and so forth.
2.2.   Preparing to Install Linux                                   50
_______________________________________________________________________

2.1.4.4.3 Preparing for  floppy installation If  you  wish to  install
Slackware from floppies instead of the hard drive, you'll need to have
one blank, MS-DOS  formatted floppy for each  Slackware disk that  you
downloaded.  These disks must be high-density format.
  The A  disk set (disks A1  through A3) may  be either 3.5" or  5.25"
floppies.   However, the  rest of the  disk sets  must be 3.5"  disks.
Therefore, if  you only  have a  5.25" floppy  drive,  you'll need  to
borrow a 3.5" drive from someone  in order to install disk  sets other
than A. (Or, you can install from the hard drive, as  explained in the
previous section.)
  To  make the  disks,  simply  copy  the files  from  each  Slackware
directory onto  an  MS-DOS formatted  floppy,  using the  MS-DOS  COPY
command.  As so:

    C:\> COPY A1\*.* A:

will copy the contents of the A1 disk to the floppy in drive A:.   You
should repeat this for each disk that you downloaded.
  You do  not need  to modify  or uncompress  the files  on the  disks
in any way;  you merely need  to copy  them to MS-DOS  floppies.   The
Slackware installation procedure takes care of uncompressing the files
for you.

2.1.4.4.4 Preparing for CD-ROM installation If you have Slackware on a
CD-ROM, you are ready  to install the  software once you have  created
the boot and root floppies.   The software will be  installed directly
from CD.


2.2 Preparing to Install Linux

After you  have obtained  a  distribution of  Linux,  you're ready  to
prepare your system  for installation.   This  takes a certain  degree
of planning,  especially  if you're  already running  other  operating
systems.  In the following sections we'll describe how to plan for the
Linux installation.

2.2.1 Installation overview

While each release of Linux is  different, in general the  method used
to install the software is as follows:

1.  Repartition your  hard drive(s).    If  you have  other  operating
    systems already installed, you will need to repartition the drives
    in order  to allocate  space  for Linux.    This  is discussed  in
    Section 2.2.4, below.

2.  Boot  the  Linux  installation  media.     Each   distribution  of
    Linux has  some  kind  of installation  media---usually  a  ``boot
    floppy''---which is used  to install the software.   Booting  this
2.2.   Preparing to Install Linux                                   51
_______________________________________________________________________

    media will  either  present you  with  some kind  of  installation
    program, which will  step you through  the Linux installation,  or
    allow you to install the software by hand.

3.  Create Linux partitions.   After repartitioning to allocate  space
    for Linux,  you  create  Linux  partitions on  that  empty  space.
    This is  accomplished with  the Linux  fdisk program,  covered  in
    Section 2.3.3.

4.  Create filesystems and swap space.  At this point, you will create
    one or more filesystems, used to store files, on the newly-created
    partitions.  In addition, if you plan to use swap  space, you will
    create the swap space  on one of your  Linux partitions.  This  is
    covered in Sections 2.3.4 and 2.3.5.

5.  Install the software on  the new filesystems.   Finally, you  will
    install the  Linux  software  on your  newly-created  filesystems.
    After this,  it's smooth  sailing---if all  goes  well.   This  is
    covered in Section 2.3.6.  Later, in Section 2.5, we describe what
    to do if anything goes wrong.

  Many distributions  of Linux provide  an installation program  which
will step you through  the installation process,  and automate one  or
more of the above steps for you.  Keep in mind throughout this chapter
that any number of the above steps may be automated for you, depending
on the distribution.
  The Slackware  distribution of  Linux,  covered in  this book,  only
requires you to repartition your drive, using fdisk, and use the setup
program to accomplish the other steps.
  Important hint:  While  preparing to install Linux, the  best advice
that we can give is to take notes during the entire procedure.   Write
down everything that you do, everything that you type,  and everything
that you see  that might be  out of the  ordinary.   The idea here  is
simple:  if  (or when!)   you run  into trouble, you  want to be  able
to retrace your steps and find out what went wrong.   Installing Linux
isn't difficult, but  there are many  details to remember.   You  want
to have a record of  all of these details  so that you can  experiment
with other methods if something goes wrong.  Also,  keeping a notebook
of your Linux installation experience  is useful when you want  to ask
other people for help, for example,  when posting a message to  one of
the Linux-related USENET groups.  Your notebook is also something that
you'll want to show to your grandchildren someday.(4)

----------------------------
 4. The author shamefully admits that he kept a notebook of all of his
tribulations with Linux for the  first few months of working  with the
system.  It is now gathering dust on his bookshelf.
2.2.   Preparing to Install Linux                                   52
_______________________________________________________________________

2.2.2 Repartitioning concepts

In general, hard drives  are divided into  partitions, where a  single
partition is devoted to  a single operating system.   For example,  on
one hard drive, you may have several separate partitions---one devoted
to, say, MS-DOS, another to OS/2, and another to Linux.
  If you  already have other  software installed  on your system,  you
may need to  resize those  partitions in  order to free  up space  for
Linux.   You will  then create  one or  more Linux  partitions on  the
resulting free space for  storing the Linux  software and swap  space.
We call this process repartitioning.
  Many  MS-DOS  systems utilize  a  single  partition  inhabiting  the
entire drive.  To MS-DOS, this partition is known as C:.   If you have
more than one partition, MS-DOS  names them D:, E:, and  so on.   In a
way, each partition acts like a separate hard drive.
  On the first sector of  the disk is a master boot record  along with
a partition table.  The boot  record (as the name implies) is  used to
boot the system.   The partition table contains information  about the
locations and sizes of your partitions.
  There  are  three kinds  of  partitions:    primary,  extended,  and
logical.  Of these, primary partitions are used most often.   However,
because of a limit in  the size of the  partition table, you can  only
have four primary partitions on any given drive.
  The  way around  this four-partition  limit is  to  use an  extended
partition.     An  extended   partition  doesn't  hold  any  data   by
itself; instead, it  acts as a  ``container'' for logical  partitions.
Therefore, you  could  create  one extended  partition,  covering  the
entire drive, and within it create many logical partitions.   However,
you may have only one extended partition per drive.

2.2.3 Linux partition requirements

Before we explain how to repartition your drives, you need  to have an
idea of how much space you will  be allocating for Linux.  We  will be
discussing how to create these partitions later, in Section 2.3.3.
  On  UNIX  systems,  files are  stored  on  a  filesystem,  which  is
essentially a section  of the  hard drive  (or other  medium, such  as
CD-ROM or  diskette) formatted  to hold  files.    Each filesystem  is
associated with a specific  part of the  directory tree; for  example,
on many systems,  there is a filesystem  for all of  the files in  the
directory /usr, another for /tmp, and  so on.  The root  filesystem is
the primary filesystem, which corresponds to the topmost directory, /.

  Under Linux,  each filesystem lives on  a separate partition on  the
hard drive.  For instance, if you have a filesystem for  / and another
for /usr, you will need two partitions to hold the two filesystems.
  Before you install Linux,  you will need to prepare  filesystems for
storing the Linux  software.   You must have  at least one  filesystem
(the root  filesystem),  and  therefore one  partition,  allocated  to
Linux.   Many  Linux users  opt to  store all  of their  files on  the
2.2.   Preparing to Install Linux                                   53
_______________________________________________________________________

root filesystem, which is in most cases easier to  manage than several
filesystems and partitions.
  However,  you  may create  multiple  filesystems  for Linux  if  you
wish---for example, you may want to use separate filesystems  for /usr
and /home.  Those  readers with UNIX system administration  experience
will know how to use multiple filesystems creatively.  In Chapter 4 we
discuss the use of multiple partitions and filesystems.
  Why use more than  one filesystem?  The most commonly  stated reason
is safety; if,  for some reason, one  of your filesystems is  damaged,
the others will  (usually) be unharmed.    On the other  hand, if  you
store all of your  files on the root  filesystem, and for some  reason
the filesystem is damaged, then you may lose all of your  files in one
fell swoop.   This  is, however,  rather uncommon;  if you backup  the
system regularly you should be quite safe.(5)
  Another reason to  use multiple filesystems  is to divvy up  storage
between multiple hard  drives.   If you have,  say, 40 megabytes  free
on one hard drive,  and 50 megabytes free  on another, you might  want
to create  a 40-megabyte  root filesystem  on the  first  drive and  a
50-megabyte /usr  filesystem  on the  other.    Currently  it  is  not
possible for a single filesystem to span multiple drives; if your free
hard drive storage is fragmented  between drives you will need  to use
multiple filesystems to utilize it all.
  In summary,  Linux requires  at least  one partition,  for the  root
filesystem.   If you  wish to  create multiple  filesystems, you  will
need a  separate  partition for  each  additional  filesystem.    Some
distributions of Linux automatically create partitions and filesystems
for you, so you may not need to worry about these issues at all.
  Another issue  to  consider when  planning your  partitions is  swap
space.   If  you wish  to  use swap  space with  Linux,  you have  two
options.  The first is to use a swap file which exists on  one of your
Linux filesystems.  You will  create the swap file for use  as virtual
RAM after you install the software.  The second option is  to create a
swap partition, an individual partition to be used only as swap space.
Most people use a swap partition instead of a swap file.
  A single swap file or  partition may be up to 16 megabytes  in size.
If you wish  to use more  than 16  megabytes of swap,  you can  create
multiple swap partitions or files---up to eight in all.   For example,
if you need 32 megabytes of swap, you can create  two 16-megabyte swap
partitions.
  Setting  up a  swap  partition  is covered  in  Section  2.3.4,  and
setting up a swap file in Chapter 4.
  Therefore, in general,  you will create at least two  partitions for
Linux:  one for use as the  root filesystem, and the other for  use as
swap space.  There are,  of course, many variations on the  above, but
this is the minimal  setup.   You are not  required to use swap  space
with Linux, but if you have less than 16 megabytes of  physical RAM it

----------------------------
 5. The author uses  a single 200-megabyte  filesystem for all of  his
Linux files, and hasn't had any problems (so far).
2.2.   Preparing to Install Linux                                   54
_______________________________________________________________________

is strongly suggested that you do.
  Of course, you need  to be aware of how much space  these partitions
will require.     The  size  of  your  Linux  filesystems  (containing
the software  itself)  depends greatly  on  how much  software  you're
installing and what distribution of  Linux you are using.   Hopefully,
the documentation that came  with your distribution  will give you  an
approximation of the  space requirements.   A  small Linux system  can
use 20 megabytes  or less;  a larger  system anywhere from  80 to  100
megabytes, or  more.   Keep  in mind  that  in addition  to the  space
required by the software itself, you need to allocate  extra space for
user directories, room for future expansion, and so forth.
  The  size of  your swap  partition  (should you  elect to  use  one)
depends on how much virtual  RAM you require.   A rule of thumb  is to
use a swap partition that is twice the space of your physical RAM; for
example, if you have 4  megabytes of physical RAM, an  8-megabyte swap
partition should suffice.   Of course, this is  mere speculation---the
actual amount of swap space  that you require depends on  the software
which you will be running.   If you have a great deal of  physical RAM
(say, sixteen megabytes or more), you  may not wish to use  swap space
at all.
  Important note:   Because  of BIOS  limitations, it  is usually  not
possible to boot from partitions  using cylinders numbered over  1023.
Therefore, when setting aside space  for Linux, keep in mind  that you
may not want to use a  partition in the >1023-cylinder range  for your
Linux root filesystem.  Linux can still use partitions  with cylinders
numbered over 1023, however,  you may not be  able to boot Linux  from
such a partition.  This advice may seem premature, but it is important
to know while planning your drive layout.
  If you absolutely must use a partition with  cylinders numbered over
1023 for your Linux  root filesystem, you  can always boot Linux  from
floppy.  This is  not so bad,  actually---it only takes a few  seconds
longer to boot than from the hard drive.  At any rate,  it's always an
option.

2.2.4 Repartitioning your drives

In this section, we'll describe how to resize your  current partitions
(if any) to  make space for  Linux.   If you  are installing Linux  on
a ``clean''  hard drive,  you can  skip  this section  and proceed  to
Section 2.3, below.
  The usual way to resize an existing partition is  to delete it (thus
destroying all of the data on that partition) and recreate it.  Before
repartitioning your drives,  backup your system.   After resizing  the
partitions, you can reinstall your original software from  the backup.
However, there  are several programs  available for  MS-DOS which  are
able to resize partitions nondestructively.  One of these  is known as
``FIPS'', and can be found on many Linux FTP sites.
  Also, keep  in mind that because  you'll be shrinking your  original
partitions, you may not have space  to reinstall everything.   In this
case, you need to delete enough unwanted software to allow the rest to
2.2.   Preparing to Install Linux                                   55
_______________________________________________________________________

fit on the smaller partitions.
  The program used to  repartition is known as fdisk.   Each operating
system has  its  own analogue  of  this program;  for  example,  under
MS-DOS, it is  invoked with  the FDISK  command.   You should  consult
your documentation for  whatever operating  systems you are  currently
running for information on repartitioning.  Here, we'll discuss how to
resize partitions for MS-DOS using FDISK, but this  information should
be easily extrapolated to other operating systems.
  Please consult the documentation for your  current operating systems
before repartitioning  your drive.    This section  is meant  to be  a
general overview of the process; there are many subtleties  that we do
not cover here.   You can lose all of  the software on your  system if
you do not repartition the drive correctly.
  A  warning:   Do  not modify  or  create  partitions for  any  other
operating systems  (including Linux)  using  FDISK under  MS-DOS.  You
should only modify partitions for  a particular operating system  with
the version of fdisk included with that operating system; for example,
you will create Linux partitions  using a version of fdisk  for Linux.
Later, in Section 2.3.3, we  describe how to create  Linux partitions,
but for now we are concerned with resizing your current ones.
  Let's  say  that you  have  a  single  hard drive  on  your  system,
currently devoted  entirely  to  MS-DOS. Hence,  your  drive  consists
of a  single MS-DOS  partition, commonly  known  as ``C:''.    Because
this repartitioning method  will destroy the  data on that  partition,
you need to create  a bootable MS-DOS  ``system disk'' which  contains
everything necessary to run FDISK and restore the software from backup
after the repartitioning is complete.
  In many cases,  you can use the  MS-DOS installation disks for  this
purpose.  However, if you need to create your own  system disk, format
a floppy with the command

    FORMAT /s A:

Copy onto this floppy all  of the necessary MS-DOS utilities  (usually
most of the software in the directory \DOS on your drive),  as well as
the programs FORMAT.COM and FDISK.EXE. You should now be able  to boot
this floppy, and run the command

    FDISK C:

to start up FDISK.
  Use of  FDISK should  be  self-explanatory, but  consult the  MS-DOS
documentation for  details.    When  you  start FDISK,  use  the  menu
option to display the partition table, and write down  the information
displayed there.  It  is important to keep  a record of your  original
setup in case you want to back out of the Linux installation.
  To  delete an  existing  partition,  choose  the FDISK  menu  option
``Delete an MS-DOS Partition or Logical DOS Drive''.  Specify the type
of partition that you wish  to delete (primary, extended,  or logical)
and the number of the partition.  Verify all of the warnings.  Poof!
2.3.   Installing the Linux software                                56
_______________________________________________________________________

  To create  a new  (smaller) partition  for MS-DOS,  just choose  the
FDISK option  ``Create an  MS-DOS Partition  or  Logical DOS  Drive''.
Specify the type  of partition  (primary, extended,  or logical),  and
the size of the partition to  create (specified in megabytes).   FDISK
should create the partition and you're ready to roll.
  After  you're done  using FDISK,  you should  exit  the program  and
reformat any new partitions.   For example,  if you resized the  first
DOS partition on your drive (C:) you should run the command

    FORMAT /s C:

You may now reinstall your original software from backup.


2.3 Installing the Linux software

After you  have resized  your existing  partitions to  make space  for
Linux, you  are  ready to  install the  software.    Here is  a  brief
overview of the procedure:

 o  Boot the Linux installation media;

 o  Run fdisk under Linux to create Linux partitions;

 o  Run mke2fs and mkswap to create Linux filesystems and swap space;

 o  Install the Linux software;

 o  Finally, either install the LILO  boot loader on your  hard drive,
    or create a boot floppy in order to boot your new Linux system.

  As we have said,  one (or more) of these steps may be  automated for
you by the  installation procedure, depending  on the distribution  of
Linux which you are using.  Please consult the  documentation for your
distribution for specific instructions.

2.3.1 Booting Linux

The first step  is to  boot the  Linux installation  media.   In  most
cases, this is a ``boot floppy'' which contains a  small Linux system.
Upon booting the floppy,  you will be  presented with an  installation
menu of some kind which will lead you through the  steps of installing
the software.   On other distributions, you  will be presented with  a
login prompt when  booting this floppy.   Here,  you usually login  as
root or install to begin the installation process.
  The documentation which came with your  particular distribution will
explain what is necessary to boot Linux from the installation media.
  If you are installing the Slackware distribution of  Linux, all that
is required  is to  boot  the boot  floppy which  you  created in  the
previous section.
2.3.   Installing the Linux software                                57
_______________________________________________________________________

  Most  distributions of  Linux use  a boot  floppy  which allows  you
to enter  hardware parameters  at  a boot  prompt,  to force  hardware
detection of various devices.   For  example, if your SCSI  controller
is not detected when booting the  floppy, you will need to  reboot and
specify the hardware parameters (such  as I/O address and IRQ)  at the
boot prompt.
  Likewise, IBM PS/1,  ThinkPad, and ValuePoint machines do  not store
drive geometry in the CMOS, and you must specify it at boot time.
  The boot  prompt is often displayed  automatically when booting  the
boot floppy.  This is the case for the Slackware distribution.   Other
distributions require you to hold down [shift] or [ctrl] while booting
the floppy.  If successful, you should see the prompt

    boot:

and possibly other messages.
  To try booting without  any special parameters, just press  enter at
the boot prompt.
  Watch  the messages  as  the system  boots.    If  you have  a  SCSI
controller, you should see a listing  of the SCSI hosts detected.   If
you see the message

    SCSI: 0 hosts

then your SCSI controller was not  detected, and you will have  to use
the following procedure.
  Also, the  system will display  information on the drive  partitions
and devices detected.    If any  of this information  is incorrect  or
missing, you will have to force hardware detection.
  On the  other hand, if all  goes well and  you hardware seems to  be
detected, you can skip to the following section, Section 2.3.2.
  To  force  hardware  detection,  you   must  enter  the  appropriate
parameters at the boot prompt, using the following syntax:

    ramdisk <parameters...>

  There are a  number of such parameters  available; here are some  of
the most common.

hd=<cylinders>,<heads>,<sectors>
           Specify the harddrive geometry.   Required for systems such
           as the  IBM PS/1, ValuePoint,  and ThinkPad.  For  example,
           if your drive  has 683 cylinders, 16 heads, and  32 sectors
           per track, enter

               ramdisk hd=683,16,32


tmc8xx=<memaddr>,<irq>
           Specify  address  and  IRQ  for   BIOS-less  Future  Domain
           TMC-8xx SCSI controller.  For example,
2.3.   Installing the Linux software                                58
_______________________________________________________________________

               ramdisk tmc8xx=0xca000,5


           Note that the  0x prefix must be used for all  values given
           in  hexadecimal.   This is  true for all  of the  following
           options.
st0x=<memaddr>,<irq>
           Specify  address   and  IRQ  for  BIOS-less   Seagate  ST02
           controller.

t128=<memaddr>,<irq>
           Specify  address  and  IRQ  for   BIOS-less  Trantor  T128B
           controller.

           ncr5380=<port>,<irq>,<dma>   Specify  port,   IRQ,  and   DMA
           channel for generic NCR5380 controller.

aha152x=<port>,<irq>,<scsi_id>,1
           Specify  port,  IRQ, and  SCSI  ID for  BIOS-less  AIC-6260
           controllers.     This  includes  Adaptec  1510,  152x,  and
           Soundblaster-SCSI controllers.

  For each of these, you must enter ramdisk  followed by the parameter
that you wish to use.
  If you  have questions  about these boot-time  options, please  read
the Linux  SCSI HOWTO,  which should  be available  on  any Linux  FTP
archive site (or from wherever you obtained this book), as well as the
Linux CD-ROM HOWTO. These documents describe hardware compatibility in
much more detail.

2.3.2 Drives and partitions under Linux

Many distributions  require you  to create  Linux  partitions by  hand
using the fdisk program.   Others may automatically create  partitions
for you.  Either way, you should know the  following information about
Linux partitions and device names.
  Drives and  partitions under  Linux are given  different names  than
their counterparts  under  other operating  systems.    Under  MS-DOS,
floppy drives  are  referred  to  as  A:  and  B:,  while  hard  drive
partitions are named  C:, D:,  and so  on.   Under  Linux, the  naming
convention is quite different.
  Device  drivers,   found  in  the  directory   /dev,  are  used   to
communicate with devices on  your system (such  as hard drives,  mice,
and so on).   For  example, if you  have a mouse  on your system,  you
access it through the driver /dev/mouse.  Floppy drives,  hard drives,
and individual partitions are all  given individual device drivers  of
their own.  Don't worry about the device driver interface for  now; it
is important only to understand  how the various devices are  named in
order to use them.
  Table 2.1 lists the names of these various device drivers.
2.3.   Installing the Linux software                                59
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        Device                                       Name

        First floppy (A:)                            /dev/fd0
        Second floppy (B:)                           /dev/fd1
        First hard drive (entire drive)              /dev/hda
        First hard drive, primary partition 1        /dev/hda1
        First hard drive, primary partition 2        /dev/hda2
        First hard drive, primary partition 3        /dev/hda3
        First hard drive, primary partition 4        /dev/hda4
        First hard drive, logical partition 1        /dev/hda5
        First.hard drive, logical partition 2        /dev/hda6
        ..

        Second hard drive (entire drive)             /dev/hdb
        Second.hard drive, primary partition 1       /dev/hdb1
        ..
        First SCSI hard drive (entire drive)         /dev/sda
        First.SCSI hard drive, primary partition 1   /dev/sda1

        ..
        Second SCSI hard drive (entire drive)        /dev/sdb
        Second.SCSI hard drive, primary partition 1  /dev/sdb1
        ..

                  Table 2.1:  Linux partition names



  A few  notes about this  table.  Note  that /dev/fd0 corresponds  to
the first floppy drive (A:  under MS-DOS) and /dev/fd1 corresponds  to
the second floppy (B:).
  Also,  SCSI hard  drives are  named differently  than other  drives.
IDE, MFM, and RLL  drives are accessed  through the devices  /dev/hda,
/dev/hdb, and so on.  The individual partitions on  the drive /dev/hda
are /dev/hda1, /dev/hda2, and so on.   However, SCSI drives  are named
/dev/sda, /dev/sdb, etc., with  partition names such as /dev/sda1  and
/dev/sda2.
  Here's an  example.    Let's say  that you  have a  single IDE  hard
drive, with 3  primary partitions.   The first two  are set aside  for
MS-DOS, and  the third  is an  extended partition  which contains  two
logical partitions, both for use by  Linux.  The devices  referring to
these partitions would be:
   First MS-DOS partition (C:)     /dev/hda1
   Second MS-DOS partition (D:)    /dev/hda2
   Extended partition              /dev/hda3
   First Linux logical partition   /dev/hda5
   Second Linux logical partition  /dev/hda6

  Note  that  /dev/hda4 is  skipped;  it  corresponds  to  the  fourth
primary partition,  which we  don't have  in  this example.    Logical
2.3.   Installing the Linux software                                60
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partitions are named consecutively starting with /dev/hda5.

2.3.3 Creating Linux partitions

Now you are ready to  create Linux partitions with the  fdisk command.
As described in  Section 2.2.3,  in general  you will  need to  create
at least  one partition  for the  Linux software  itself, and  another
partition for swap space.
  After booting the installation media, run fdisk by typing

    fdisk <drive>

where <drive> is the  Linux device name  of the drive  you plan to add
partitions to (see Table 2.1).  For instance, if you want to run fdisk
on the first SCSI disk in your system, use the command fdisk /dev/sda.
/dev/hda (the first  IDE drive) is  the default  if you don't  specify
one.
  If you  are creating Linux  partitions on more  than one drive,  run
fdisk once for each drive.

    # fdisk /dev/hda

    Command (m for help):


Here fdisk is waiting for a command;  you can type m to get a  list of
options.

    Command (m for help):  m
    Command action
    a toggle a bootable flag
    d delete a partition
    l list known partition types
    m print this menu
    n add a new partition
    p print the partition table
    q quit without saving changes
    t change a partition's system id
    u change display/entry units
    v verify the partition table
    w write table to disk and exit
    x extra functionality (experts only)

    Command (m for help):

The n command is used  to create a new partition.   Most of  the other
options you won't need to worry  about.  To quit fdisk  without saving
any changes, use the q command.   To quit fdisk and write  the changes
to the partition table to disk, use the w command.
  The first  thing you  should do  is display  your current  partition
table and write the information down, for later reference.   Use the p
2.3.   Installing the Linux software                                61
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command.

    Command (m for help):  p
    Disk /dev/hda:  16 heads, 38 sectors, 683 cylinders
    Units = cylinders of 608 * 512 bytes


       Device Boot  Begin   Start     End  Blocks   Id  System
    /dev/hda1   *         1        1      203    61693     6  DOS  16-
    bit >=32M



    Command (m for help):

In this  example, we  have  a single  MS-DOS  partition on  /dev/hda1,
which is 61693 blocks  (about 60 megs).(6)   This partition starts  at
cylinder number 1, and ends on cylinder  203.  We have a total  of 683
cylinders in this  disk;  so there are  480 cylinders  left to  create
Linux partitions on.
  To create  a new partition,  use the  n command.   In this  example,
we'll create  two primary  partitions  (/dev/hda2 and  /dev/hda3)  for
Linux.

    Command (m for help):  n
    Command action
    e extended
    p primary partition (1-4)
    p

Here, fdisk is asking the type  of the partition to create:   extended
or primary.  In our  example, we're creating only  primary partitions,
so we choose p.

    Partition number (1-4):

fdisk will then ask for the  number of the partition to create;  since
partition 1 is already used, our first Linux partition  will be number
2.

    Partition number (1-4):  2
    First cylinder (204-683):

Now enter  the starting  cylinder  number of  the  partition.    Since
cylinders 204 through 683  are unused, we'll  use the first  available
one (numbered 204).   There's no reason  to leave empty space  between
partitions.

----------------------------
 6. A block, under Linux, is 1024 bytes.
2.3.   Installing the Linux software                                62
_______________________________________________________________________

    First cylinder (204-683):  204
    Last cylinder or +size or +sizeM or +sizeK (204-683):

fdisk is  asking  for  the size  of  the  partition  to create.     We
can either specify  an ending  cylinder number,  or a  size in  bytes,
kilobytes, or megabytes.  Since we want our partition to be 80 megs in
size, we specify +80M. When  specifying a partition size in  this way,
fdisk will round the  actual partition size  to the nearest number  of
cylinders.

    Last cylinder or +size or +sizeM or +sizeK (204-683):  +80M

    Warning:  Linux  cannot currently  use 33090  sectors of  this
    partition

If you see a warning message such  as this, it can be ignored.   fdisk
prints the warning  because it's  an older program,  and dates  before
the time  that Linux  partitions were  allowed to  be  larger than  64
megabytes.
  Now we're ready to create  our second Linux partition.  For  sake of
demonstration, we'll create it with a size of 10 megabytes.

    Command (m for help):  n
    Command action
    e extended
    p primary partition (1-4)
    p
    Partition number (1-4):  3
    First cylinder (474-683):  474
    Last cylinder or +size or +sizeM or +sizeK (474-683):  +10M

  At last,  we'll  display the  partition table.    Again, write  down
all of  this  information---especially the  block  sizes of  your  new
partitions.    You'll  need  to  know  the  sizes  of  the  partitions
when creating filesystems,  later.   Also,  verify that  none of  your
partitions overlap.

    Command (m for help):  p

    Disk /dev/hda:  16 heads, 38 sectors, 683 cylinders
    Units = cylinders of 608 * 512 bytes


       Device Boot  Begin   Start     End  Blocks   Id  System
    /dev/hda1   *         1        1      203    61693     6  DOS  16-
    bit >=32M
    /dev/hda2         204     204     473   82080   81  Linux/MINIX
    /dev/hda3         474     474     507   10336   81  Linux/MINIX
2.3.   Installing the Linux software                                63
_______________________________________________________________________

As you can  see, /dev/hda2  is now  a partition of  size 82080  blocks
(which corresponds  to about  80 megabytes),  and  /dev/hda3 is  10336
blocks (about 10 megs).
  Note that many distributions (such as Slackware) require  you to use
the t command in  fdisk to change  the type of  the swap partition  to
``Linux swap'',  which is usually  numbered 82.    You can  use the  L
command to print a  list of known partition  type codes, and then  use
t to set the type of  the swap partition to that which  corresponds to
``Linux swap''.
  In  this   way,   the  installation   software  will   be  able   to
automatically find  your  swap partitions  based  on  type.    If  the
installation software doesn't seem  to recognize your swap  partition,
you might want to re-run fdisk and use the t command  on the partition
in question.
  In the example above, the remaining cylinders on  the disk (numbered
508 to 683) are  unused.  You  may wish to  leave unused space on  the
disk, in case you wish to create additional partitions later.
  Finally, we use the w command to write the changes  to disk and exit
fdisk.

    Command (m for help):  w

    #

  Keep in mind that  none of the changes you make while  running fdisk
will take effect until  you give the  w command, so  you can toy  with
different configurations and save them when you're done.  Also, if you
want to quit fdisk at any  time without saving the changes, use  the q
command.  Remember that you shouldn't modify partitions  for operating
systems other than Linux with the Linux fdisk program.
  Remember that  you may not  be able to boot  Linux from a  partition
using cylinders numbered  over 1023.    Therefore, you  should try  to
create your Linux root partition  within the sub-1024 cylinder  range.
Again, if this is impossible, you can simply boot Linux from floppy.
  Some Linux  distributions  require you  to reboot  the system  after
running fdisk.  This  is to allow the  changes to the partition  table
to take effect  before installing  the software.    Newer versions  of
fdisk automatically update the partition information in the kernel, so
rebooting isn't necessary.    To be on  the safe  side, after  running
fdisk you  should reboot  the installation  media, as  before,  before
proceeding.

2.3.4 Creating the swap space

If you are planning  to use a swap  partition for virtual RAM,  you're
ready to prepare  it for use.(7)   In  Chapter 4  we will discuss  the

----------------------------
 7. Again, some  distributions of  Linux will prepare  the swap  space
automatically for you, or via an installation menu option.
2.3.   Installing the Linux software                                64
_______________________________________________________________________

preparation of a swap file in case you don't want to use an individual
partition.
  Many distributions  require you  to create and  activate swap  space
before installing  the  software.    If you  have  a small  amount  of
physical RAM, the installation procedure may not be  successful unless
you have some amount of swap space enabled.
  The  Slackware  distribution requires  you  to  create  swap  space,
before installation, if you have 4 megabytes of RAM or less.   If this
is not the case, the  Slackware installation procedure can be  used to
prepare swap space automatically.   If in  doubt, go ahead and  follow
the procedure described here; it can't hurt.
  The command  used to  prepare  a swap  partition is  mkswap, and  it
takes the form

    mkswap -c <partition> <size>

where <partition> is the name of the swap  partition, and <size> is the
size of  the partition,  in  blocks.(8)   For  example,  if your  swap
partition is /dev/hda3 and is 10336 blocks in size, use the command

    # mkswap --c /dev/hda3 10336

The -c option tells  mkswap to check for  bad blocks on the  partition
when creating the swap space.
  If you are using multiple swap partitions, you  will need to execute
the appropriate mkswap command for each partition.
  After formatting the  swap space, you need  to enable it for use  by
the system.  Usually,  the system automatically enables swap  space at
boot time.   However,  because you  have not yet  installed the  Linux
software, you need to enable it by hand.
  The command to enable swap space is swapon, and it takes the form

    swapon <partition>

In the example above,  to enable the swap  space on /dev/hda3, we  use
the command

    # swapon /dev/hda3


2.3.5 Creating the filesystems

Before you can  use your  Linux partitions  to store  files, you  must
create filesystems on  them.   Creating a  filesystem is analogous  to
formatting a partition under  MS-DOS or other  operating systems.   We
discussed filesystems briefly in Section 2.2.3.

----------------------------
 8. This is the size as reported by fdisk, using the p menu option.  A
block under Linux is 1024 bytes.
2.3.   Installing the Linux software                                65
_______________________________________________________________________

  There are several  types of filesystems available  for Linux.   Each
filesystem type has its  own format and  set of characteristics  (such
as filename  length,  maximum file  size,  and so  on).    Linux  also
supports several ``third-party'' filesystem  types such as the  MS-DOS
filesystem.
  The  most commonly  used  filesystem  type is  the  Second  Extended
Filesystem, or ext2fs.   The ext2fs is  one of the most efficient  and
flexible filesystems;  it allows filenames  up to  256 characters  and
filesystem sizes of up to  4 terabytes.   In Chapter 4, we'll  discuss
the various filesystem types available for Linux.  Initially, however,
we suggest that you use the ext2fs filesystem.
  If you  are installing the  Slackware distribution, filesystems  are
created automatically for you by the installation  procedure described
in the next section.  If you wish to create your  filesystems by hand,
however, follow the procedure described here.
  To create an ext2fs filesystem, use the command

    mke2fs -c <partition> <size>

where <partition> is the name of the partition,  and <size> is the size
of the partition  in blocks.   For  example, to  create a  82080-block
filesystem on /dev/hda2, use the command

    # mke2fs --c /dev/hda2 82080

  If you're using multiple  filesystems for Linux, you'll need  to use
the appropriate mke2fs command for each filesystem.
  If you have encountered any problems at this point,  see Section 2.5
at the end of this chapter.

2.3.6 Installing the software

Finally,  you are  ready  to  install  the software  on  your  system.
Every distribution has  a different mechanism  for doing  this.   Many
distributions have  a  self-contained  program  which  will  step  you
through the installation.   On other  distributions, you will have  to
mount your filesystems in  a certain subdirectory  (such as /mnt)  and
copy the software to them by  hand.  On CD-ROM distributions,  you may
be given the option to install a portion of the software  on your hard
drives, and leave most of the software on the CD-ROM.
  Some  distributions offer  several  different  ways to  install  the
software.   For  example,  you may  be able  to  install the  software
directly from an MS-DOS partition on your hard drive,  instead of from
floppies.  Or, you  may be able to  install over a TCP/IP network  via
FTP or NFS. See your distribution's documentation for details.
  For example, the Slackware distribution only requires  you to create
partitions with fdisk,  optionally create swap  space with mkswap  and
swapon (if you have  4 megs or  less of RAM),  and then run the  setup
program.  setup leads you through a very self-explanatory  menu system
to install the software.  Use of setup is described in detail below.
2.3.   Installing the Linux software                                66
_______________________________________________________________________

  The exact method used to install the Linux  software differs greatly
with each  distribution.    We're  hoping  that installing  the  Linux
software should be self-explanatory, as it is with most distributions.

2.3.6.1 Installing Slackware with setup

If you  are  installing  Slackware,  after  creating  partitions  (and
possibly swap space), use the command

    # setup

This will present you will a menu-based procedure to walk  you through
the remaining steps of installation.
  The  procedure described  here  corresponds  to that  found  on  the
color144 and  colrlite  root disks;  the  other  root disks  may  have
slightly different procedures.
  The setup menu consists of the following items.   Use the arrow keys
to move over the items, and  press [enter] or [spacebar] to  select an
item.

Help       View the setup help file.

Keymap     This option allows you to specify  the keyboard mapping for
           your  system if you  do not  have a  US keyboard.   A  list
           of keymaps  will be presented; select the  appropriate item
           from the list.
Quick      This   allows  you   to   select  between   ``quick''   and
           ``verbose''  installation  modes.      ``Verbose''  is  the
           default, and is recommended  for most installations (unless
           you've  installed Slackware a  dozen times,  in which  case
           you already know this).

Make tags  This  allows  Slackware  installation   experts  to  create
           customized ``tag  files'' for preselecting packages.   This
           is   only  necessary  for   customizing  the   installation
           procedure  in  some  way;  you shouldn't  have  to  concern
           yourself with this.

Addswap    This will be the first item that  most users will select to
           install  Slackware.   A list  of available swap  partitions
           will  be  displayed  (those partitions  with  type  ``Linux
           swap''  as set  in fdisk).   You  will be  able to  specify
           which  partitions you  wish to  use for  swap space.    You
           will  then be  asked if  you wish  to run  mkswap on  these
           partitions.

           If  you  have  already  executed   mkswap  and  swapon  (as
           described in  Section 2.3.4) on your swap partitions,  then
           you  should not  allow  setup to  execute mkswap  on  these
           partitions.
   2.3.   Installing the Linux software                                67
   _______________________________________________________________________

              Even if you have already executed  mkswap and swapon, it is
              necessary to use the Addswap menu  item:  This ensures that
              your swap  partitions will be  available once you have  the
              system installed.

!             Be  warned!    Creating  swap  space on  a  partition  will
              destroy data  on that partition.   Be sure that you're  not
              wiping out data that you want to keep.
              If  you select this  menu item,  you will be  automatically
              prompted if  you wish to proceed with the  following items.
              In general, you should do this.

   Target     This item  allows you to specify the partitions  upon which
              Linux is to  be installed.  A list of  available partitions
              (those with  type ``Linux native'', as specified  by fdisk)
              will be displayed, and you will be  asked to enter the name
              of  your Linux  root partition,  such  as /dev/hda2.    You
              will then  be prompted for the type of filesystem  that you
              wish  to create;  we  suggest using  the ext2fs  filesystem
              type  as described in Section  2.3.5.   This will create  a
              filesystem on  the named partition---somewhat analogous  to
              ``formatting'' the partition under MS-DOS.
              You  will also be  prompted for  any other partitions  that
              you  might wish  to use for  Linux.   For  example, if  you
              created a separate partition for  /usr (see Section 2.2.3),
              you will be  able to specify the name of the  partition and
              the  location where  it should be  mounted (as  in /usr  or
              /usr/bin).

!             Be  warned!   Creating  a  filesystem on  a partition  will
              destroy all  data on that partition.   Be sure that  you're
              not wiping out data that you want to keep.
              Even if  you already created your filesystems  using mke2fs
              (see Section 2.3.5),  you must use the Target menu  item to
              specify the partitions where Linux will be installed.

   Source     This  menu item  allows you to  specify where  you will  be
              installing Slackware  from, such as floppy, hard  drive, or
              CD-ROM.
              If you  are installing from hard  drive, you will be  asked
              what partition  the Slackware files  are found on, as  well
              as the  type of partition.   For  example, if you have  the
              Slackware files  on an MS-DOS partition, enter the  name of
              the  partition (such  as /dev/hda1) and  select MS-DOS  FAT
              as the  type.   You will then  be asked what directory  the
              files may be  found under on this partition.   For example,
              if you have the Slackware files  stored under the directory
              C:\SLACK on your MS-DOS partition, enter
2.3.   Installing the Linux software                                68
_______________________________________________________________________

               /slack


           as  the  location.    Note  that  you  should  use  forward
           slashes, not backslashes, in the pathname.
           If you  are installing from CD-ROM,  you will be asked  the
           type  of CD-ROM  device  that you  are  using, as  well  as
           what  directory on the  CD-ROM the files  may be found  in.
           Many CD-ROMs have the files  contained within the directory
           /slakware, but this depends on the release.
           If  you  are  installing  Slackware  Professional,(9)   two
           directories are  used on the  CD-ROM. slakware is used  for
           the standard  system which will install the  files directly
           to your hard drive.  slackpro  is used for the CD-ROM-based
           system  where many  files are  accessed  directly from  the
           CD-ROM. This  can save diskspace, but accessing  many files
           is  also  noticeably  slower.     Several  other  Slackware
           vendors provide  the ability to  run the software from  the
           CD-ROM  as well.   However,  if you  have the diskspace  to
           spare, we  recommend not running Slackware from  the CD-ROM
           itself.  Performance is generally slower.

           If  you are  attempting  a hard  drive or  CD-ROM  install,
           Slackware  may  report  that  there is  a  mount  error  at
           this  point.   This  is  usually an  indication that  there
           was  a problem  accessing  the hard  drive or  CD-ROM.  See
           Section  2.5.3 for  more  information if  you see  such  an
           error message.

Disk sets  This menu  option allows you to  select the disk sets  that
           you wish to install.  You must  install at least the A disk
           set.   Simply  use the  arrow keys and  spacebar to  select
           which disk sets you wish to install.
           Note  that selecting a  particular disk  set does not  mean
           that all  packages on the disk  set will be installed;  you
           will  be prompted  before installing packages  on the  disk
           set marked as ``optional'' or ``recommended.''

Install    At  long last,  this menu  item will  install the  software
           on  your system.   You will be  prompted for the  prompting
           method;  most users  should select  ``normal.''   For  each
           disk set that you selected,  the ``required'' packages will
           be installed, and you will be  prompted when installing the
           ``optional''  and ``recommended''  packages.    If you  are
           installing  from floppy you  will be  asked to insert  each
           floppy in succession.

----------------------------
 9. Slackware Professional  is a version  of Slackware available  from
Morse Telecommunications.
2.3.   Installing the Linux software                                69
_______________________________________________________________________

           As each  package is installed  a short description will  be
           printed.    Unless you have  background in  UNIX or  Linux,
           many  of these  descriptions  will not  mean much  to  you.
           Take  note of which  packages are being  installed, so  you
           know  what's there,  but don't  worry about  trying to  jot
           down everything that's printed on the display.

           The  most common  error  encountered here  is that  a  file
           cannot  be  found  on  a  floppy,  or  an  I/O  error  when
           attempting  to  read  the  floppy.      The  former  is  an
           indication  that   the  files  on  your  floppy   might  be
           corrupted  or  incomplete;   the  latter  that  the  floppy
           itself  is  bad.   Any  floppies  which give  these  errors
           should  be replaced,  and  you should  re-install the  disk
           set  containing those  floppies.    See Section  2.5.3  for
           suggestions.
           You  may also have  read errors  when attempting to  access
           a  CD-ROM;  be  sure  that the  CD-ROM  is  clean,  has  no
           fingerprints, etc.

Configure  This menu  item performs some post-installation  configura-
           tion  of your system.    This is covered  in the  following
           section.


2.3.7 Creating the boot floppy or installing LILO

Every distribution  provides  some means  of  booting your  new  Linux
system after you  have installed  the software.   In  many cases,  the
installation procedure will create a ``boot floppy'' which  contains a
Linux kernel configured to use your newly-created root filesystem.  In
order to boot  Linux, you  would boot  from this  floppy, and  control
would be  transferred to  your hard  drive after  booting.   On  other
distributions, this ``boot floppy'' is the installation floppy itself.
  Many distributions give  you the option  of installing LILO on  your
hard drive.   LILO  is a  program that  is installed  on your  drive's
master boot record.  It is able to boot a number of operating systems,
including MS-DOS and Linux, and  allows you to select at  startup time
which to boot.
  For the  Slackware distribution,  the  Configure item  in the  setup
menu will allow you to create  a boot floppy as well as  install LILO.
These options should be fairly  self-explanatory.  The Configure  menu
item also  allows  you to  specify  your modem,  mouse,  and  timezone
information.
  In  order  for  LILO to  be  installed  successfully,  it  needs  to
know a good deal of  information about your drive  configuration---for
example, which  partitions contain  which  operating systems,  how  to
boot each  operating system,  and so  on.    Many distributions,  when
installing LILO, attempt  to ``guess''  at the appropriate  parameters
for your configuration.  Although  it's not often, the  automated LILO
installation provided by some distributions  can fail, and leave  your
2.4.   Postinstallation procedures                                  70
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master boot record in shambles  (although it's very doubtful that  any
damage to the actual  data on your  hard drive will  take place).   In
particular, if you  use OS/2's  Boot Manager,  you should not  install
LILO using the  automated procedure---there  are special  instructions
for using LILO with the Boot Manager, which will be covered later.
  In many  cases, it  is best  to use a  boot floppy,  until you  have
a chance  to configure  LILO yourself,  by hand.    If you're  feeling
exceptionally trustworthy, though, you can go ahead with the automated
LILO installation if it is provided with your distribution.
  In Chapter  4, we'll cover  in detail how  to configure and  install
LILO for your particular setup.
  If  everything goes  well,  then congratulations!    You  have  just
installed  Linux  on  your   system.     Go   have  a  Diet  Coke   or
something---you deserve it.
  In  case you  did  run  into  any trouble,  the  next  section  will
describe the most common sticking points for Linux  installations, and
how to get around them.

2.3.8 Additional installation procedures

Some  distributions   of  Linux   provide  a   number  of   additional
installation procedures, allowing  you to  configure various  software
packages such  as  TCP/IP networking,  the  X Window  System,  and  so
on.   If  you are  provided with  these  configuration options  during
installation, you  may  wish  to read  ahead  in  this book  for  more
information on how to configure this software.  Otherwise,  you should
put off  these  installation  procedures  until you  have  a  complete
understanding of how to configure the software.
  It's up  to  you; if  all  else fails,  just go  with  the flow  and
see what  happens.    It's very  doubtful that  anything  that you  do
incorrectly now cannot be undone in the future.  (Knock on wood.)


2.4 Postinstallation procedures

After you have completed installing  the Linux software, there  should
be very little left to do before you can begin to use the system.   In
most cases, you should  be able to reboot  the system, login as  root,
and begin exploring  the system.   (Each  distribution has a  slightly
different method for doing this.)
  At  this point  it's  a  good idea  to  explain  how to  reboot  and
shutdown the  system as  you're using  it.   You  should never  reboot
or shutdown your  Linux system by  pressing the  reset switch or  with
the old ``Vulcan Nerve  Pinch''---that is, by pressing  [ctrl-alt-del]
in unison.(10)   You shouldn't  simply switch  off the power,  either.

----------------------------
10. On  most Linux  systems, however,  [ctrl-alt-del]  will cause  the
system to  shutdown  gracefully,  as  if  you had  used  the  shutdown
command.
2.5.   Running Into Trouble                                         71
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As with  most  UNIX  systems,  Linux  caches disk  writes  in  memory.
Therefore, if  you suddenly reboot  the system  without shutting  down
``cleanly'', you can corrupt the  data on your drives,  causing untold
damage.
  The  easiest way  to  shut down  the  system  is with  the  shutdown
command.     As  an  example,  to  shutdown  and   reboot  the  system
immediately, use the following command as root:

    # shutdown --r now

This will  cleanly reboot  your system.    The man  page for  shutdown
describes the other command-line arguments that are available.(11)
  Note,  however, that  many Linux  distributions do  not provide  the
shutdown command on the installation media.  This means that the first
time you reboot your  system after installation,  you may need to  use
the [ctrl-alt-del]  combination after  all.   Thereafter,  you  should
always use the shutdown command.
  After you  have a chance to  explore and use  the system, there  are
several configuration chores that you should undertake.  The  first is
to create a user account for yourself (and, optionally,  for any other
users that might have access to  the system).  Creating  user accounts
is described in  Section 4.4.   Usually,  all that you  have to do  is
login as root, and run the adduser (sometimes useradd) program.   This
will lead you through several prompts to create a new user account.
  If you  created more  than one filesystem  for Linux,  or if  you're
using a  swap partition,  you may  need  to edit  the file  /etc/fstab
in order for  those filesystems  to be  available automatically  after
rebooting.  (For  example, if you're  using a separate filesystem  for
/usr, and  none of  the files  that should  be  in /usr  appear to  be
present, you may simply need to  mount that filesystem.)   Section 4.8
describes this procedure.    Note that the  Slackware distribution  of
Linux automatically  configures your  filesystems  and swap  space  at
installation time, so this usually isn't necessary.


2.5 Running Into Trouble

Almost everyone runs into some kind of snag or hangup  when attempting
to install Linux the  first time.   Most of the  time, the problem  is
caused by a simple  misunderstanding.  Sometimes,  however, it can  be
something more serious, such as an oversight by one of the developers,
or a bug.
  This section  will  describe some  of the  most common  installation
problems, and how  to solve  them.   If your  installation appears  to
be successful, but you  received unexpected error messages during  the
installation, these are described here as well.
----------------------------
11. Use the command man shutdown to see the manual page for shutdown.
2.5.   Running Into Trouble                                         72
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2.5.1 Problems with booting the installation media

When attempting to  boot the  installation media for  the first  time,
you may  encounter a  number of  problems.   These  are listed  below.
Note that  the following  problems  are not  related to  booting  your
newly-installed Linux system.   See Section  2.5.4 for information  on
these kinds of pitfalls.

 o  Floppy or media error when attempting to boot.

    The most popular cause for this kind of problem is  a corrupt boot
    floppy.  Either  the floppy is  physically damaged, in which  case
    you should re-create the disk with a brand new floppy, or the data
    on the floppy  is bad, in  which case you  should verify that  you
    downloaded and transferred the data  to the floppy correctly.   In
    many cases,  simply re-creating the  boot floppy  will solve  your
    problems.  Retrace your steps and try again.

    If you  received  your  boot  floppy  from  a  mail  order  vendor
    or some  other distributor,  instead of  downloading and  creating
    it yourself,  contact  the  distributor and  ask  for a  new  boot
    floppy---but only after verifying that this is indeed the problem.

 o  System ``hangs'' during boot or after booting.

    After the  installation media  boots,  you will  see  a number  of
    messages from  the kernel  itself, indicating  which devices  were
    detected and  configured.     After  this,  you  will  usually  be
    presented with  a  login  prompt,  allowing you  to  proceed  with
    installation (some distributions  instead drop  you right into  an
    installation program of  some kind).    The system  may appear  to
    ``hang'' during  several of  these steps.    During  all of  these
    steps, be patient; loading software from floppy is very slow.   In
    many cases, the system has not hung at all, but is merely taking a
    long time.  Verify that  there is no drive or system  activity for
    at least several minutes before assuming that the system is hung.


    1.  After booting from the LILO  prompt, the system must  load the
        kernel image from floppy.  This may take several  seconds; you
        will know that things are going well if the floppy drive light
        is still on.

    2.  While the kernel boots, SCSI  devices must be probed for.   If
        you do not  have any SCSI devices  installed, the system  will
        ``hang'' for up to 15 seconds while the SCSI  probe continues;
        this usually occurs after the line


            lp_init:  lp1 exists (0), using polling driver
2.5.   Running Into Trouble                                         73
_______________________________________________________________________

        appears on your screen.

    3.  After the kernel is  finished booting, control is  transferred
        to the  system bootup  files  on the  floppy.    Finally,  you
        will be  presented with  a login  prompt, or  be dropped  into
        an installation program.   If you  are presented with a  login
        prompt such as


            Linux login:


        you should  then  login  (usually as  root  or  install---this
        varies with each distribution).  After entering  the username,
        the  system may  pause  for  20  seconds  or  more  while  the
        installation program  or shell  is being  loaded from  floppy.
        Again, the floppy drive light should be on.  Don't assume that
        the system is hung.


    Any of  the  above  items  may  be the  source  of  your  problem.
    However, it  is possible  that the  system  actually may  ``hang''
    while booting, which can be due to several causes.   First of all,
    you may not  have enough  available RAM to  boot the  installation
    media.  (See the  following item for information on  disabling the
    ramdisk to free up memory.)

    The cause  of  many  system  hangs  is  hardware  incompatibility.
    Section 1.8 in the last chapter presented an overview of supported
    hardware under Linux.  Even if your hardware is supported, you may
    run into problems with incompatible hardware  configurations which
    are causing the system to hang.   See Section 2.5.2, below,  for a
    discussion of hardware incompatibilities.

 o  System reports out  of memory errors while  attempting to boot  or
    install the software.

    This item deals with  the amount of  RAM that you have  available.
    On systems  with 4  megabytes of  RAM or  less, you  may run  into
    trouble booting the installation media or installing  the software
    itself.   This is  because many distributions  use a  ``ramdisk'',
    which is a  filesystem loaded  directly into  RAM, for  operations
    while using  the installation  media.   The  entire  image of  the
    installation boot  floppy,  for  example,  may be  loaded  into  a
    ramdisk, which may require more than a megabyte of RAM.

    The solution  to this  problem is  to disable  the ramdisk  option
    when booting the  install media.    Each release  has a  different
    procedure for doing  this; on  the SLS release,  for example,  you
    type ``floppy'' at the LILO prompt when booting the a1 disk.   See
2.5.   Running Into Trouble                                         74
_______________________________________________________________________

    your distribution's documentation for details.

    You may not  see an  ``out of  memory'' error  when attempting  to
    boot or install the software; instead, the system may unexpectedly
    hang, or fail  to boot.   If your  system hangs,  and none of  the
    explanations in the  previous section  seem to be  the cause,  try
    disabling the ramdisk.

    Keep in mind that  Linux itself requires  at least 2 megabytes  of
    RAM to run at all; some distributions of Linux require 4 megabytes
    or more.

 o  The system  reports  an error  such  as ``permission  denied''  or
    ``file not found'' while booting.

    This is  an  indication that  your  installation bootup  media  is
    corrupt.  If you attempt to boot from the  installation media (and
    you're sure that  you're doing everything  correctly), you  should
    not see any errors such as this.  Contact the  distributor of your
    Linux software and find out about the problem, and  perhaps obtain
    another copy of the  boot media if necessary.   If you  downloaded
    the bootup disk yourself, try re-creating the bootup disk, and see
    if this solves your problem.

 o  The system reports  the error ``VFS: Unable  to mount root''  when
    booting.

    This error message  means that the root  filesystem (found on  the
    boot media itself), could  not be found.   This means that  either
    your boot  media is  corrupt in  some  way, or  that  you are  not
    booting the system correctly.

    For example, many CD-ROM  distributions require that you have  the
    CD-ROM in the drive  when booting.   Also be sure that the  CD-ROM
    drive is on, and check for any activity.  It's  also possible that
    the system is  not locating your  CD-ROM drive at  boot time;  see
    Section 2.5.2 for more information.

    If you're sure  that you  are booting the  system correctly,  then
    your bootup media may indeed be corrupt.  This is  a very uncommon
    problem, so try other  solutions before attempting to use  another
    boot floppy or tape.


2.5.2 Hardware problems

The most  common  form  of  problem  when  attempting  to  install  or
use Linux  is  an incompatibility  with  hardware.    Even if  all  of
your hardware is  supported by Linux,  a misconfiguration or  hardware
conflict can sometimes cause strange results---your devices may not be
2.5.   Running Into Trouble                                         75
_______________________________________________________________________

detected at boot time, or the system may hang.
  It is important  to isolate these  hardware problems if you  suspect
that they  may be  the  source of  your  trouble.   In  the  following
sections we will  describe some  common hardware problems  and how  to
resolve them.

2.5.2.1 Isolating hardware problems

If you experience a problem  that you believe to be  hardware-related,
the first  thing that  you  should to  do is  attempt  to isolate  the
problem.  This means eliminating all possible variables  and (usually)
taking the system apart, piece-by-piece, until the offending  piece of
hardware is isolated.
  This is not as frightening  as it may sound.  Basically,  you should
remove all nonessential hardware from your system, and  then determine
which device is actually causing the trouble---possibly by reinserting
each device, one at  a time.   This means  that you should remove  all
hardware other than the  floppy and video  controllers, and of  course
the keyboard.  Even innocent-looking devices such as mouse controllers
can wreak unknown havoc on your peace of mind unless you consider them
nonessential.
  For example,  let's say  that the system  hangs during the  Ethernet
board detection sequence  at boot time.    You might hypothesize  that
there is  a  conflict or  problem  with  the Ethernet  board  in  your
machine.  The quick and easy  way to find out is to pull  the Ethernet
board, and  try booting  again.   If  everything goes  well, then  you
know that either  (a) the  Ethernet board  is not  supported by  Linux
(see Section 1.8 for a list of compatible boards), or (b)  there is an
address or IRQ conflict with the board.
  ``Address or IRQ  conflict?''   What on earth does  that mean?   All
devices in your machine use an IRQ, or interrupt request line, to tell
the system that they  need something done  on their behalf.   You  can
think of the  IRQ as a  cord that the  device tugs  when it needs  the
system to take care of some pending request.  If more  than one device
is tugging on  the same  cord, the  kernel won't be  able to  detemine
which device it needs to service.  Instant mayhem.
  Therefore,  be sure that  all of  your installed  devices are  using
unique IRQ lines.    In general the  IRQ for  a device can  be set  by
jumpers on the card; see  the documentation for the  particular device
for details.  Some  devices do not require the  use of an IRQ  at all,
but it is  suggested that you  configure them to  use one if  possible
(the Seagate ST01 and ST02 SCSI controllers being good examples).
  In some  cases, the  kernel provided on  your installation media  is
configured to use  a certain IRQ  for certain devices.   For  example,
on some distributions  of Linux,  the kernel is  preconfigured to  use
IRQ 5 for the TMC-950 SCSI controller, the Mitsumi  CD-ROM controller,
and the bus mouse  driver.  If  you want to use  two or more of  these
devices, you'll need  to first install  Linux with  only one of  these
devices enabled,  then recompile  the kernel  in order  to change  the
default IRQ  for one  of them.    (See Chapter  4  for information  on
2.5.   Running Into Trouble                                         76
_______________________________________________________________________

recompiling the kernel.)
  Another area where hardware conflicts can arise is  with DMA (direct
memory access) channels, I/O  addresses, and shared memory  addresses.
All of  these  terms  describe  mechanisms through  which  the  system
interfaces with hardware devices.  Some Ethernet boards,  for example,
use a shared memory address  as well as an  IRQ to interface with  the
system.  If any of these are in conflict with other  devices, then the
system may behave  unexpectedly.   You  should be able  to change  the
DMA channel, I/O or shared  memory addresses for your  various devices
with jumper settings.  (Unfortunately, some devices don't allow you to
change these settings.)
  The documentation for  your various hardware devices should  specify
the IRQ, DMA channel, I/O  address, or shared memory address  that the
devices use, and how to configure them.  Again, the simple  way to get
around these problems is just  to temporarily disable the  conflicting
devices until you have time to determine the cause of the problem.
  Table  2.2 is  a  list  of IRQ  and  DMA  channels used  by  various
``standard'' devices found on most  systems.  Almost all  systems will
have some of these devices, so you should avoid setting the IRQ or DMA
of other devices in conflict with these values.

          Device                    I/Oaddress     IRQ   DMA

          ttyS0 (COM1)                 3f8          4    n/a
          ttyS1 (COM2)                 2f8          3    n/a
          ttyS2 (COM3)                 3e8          4    n/a
          ttyS3 (COM4)                 2e8          3    n/a
          lp0 (LPT1)                   378 - 37f    7    n/a
          lp1 (LPT2)                   278 - 27f    5    n/a
          fd0, fd1 (floppies 1 and 2)  3f0 - 3f7    6    2
          fd2, fd3 (floppies 3 and 4)  370 - 377    10   3

                  Table 2.2:  Common device settings



2.5.2.2 Problems recognizing hard drive or controller

When Linux boots, you should see  a series of messages on  your screen
such as:

    Console:  colour EGA+ 80x25, 8 virtual consoles
    Serial driver version 3.96 with no serial options enabled
    tty00 at 0x03f8 (irq = 4) is a 16450
    tty03 at 0x02e8 (irq = 3) is a 16550A
    lp_init:  lp1 exists (0), using polling driver
    ...

Here, the kernel is detecting the various hardware devices  present on
your system.  At some point, you should see the line
2.5.   Running Into Trouble                                         77
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    Partition check:

followed by a list of recognized partitions, for example:

    Partition check:
    hda:  hda1 hda2
    hdb:  hdb1 hdb2 hdb3

If, for some  reason, your  drives or  partitions are not  recognized,
then you will not be able to access them in any way.
  There are several things that can cause this to happen:

 o  Hard drive or controller not supported.   If you are using  a hard
    drive controller (IDE, SCSI,  or otherwise) that is not  supported
    by Linux, the  kernel will not recognize  your partitions at  boot
    time.

 o  Drive  or  controller  improperly  configured.     Even   if  your
    controller is  supported  by  Linux,  it  may  not  be  configured
    correctly.  (This is particularly a problem for  SCSI controllers;
    most non-SCSI controllers should work fine without  any additional
    configuration).

    Refer to the documentation  for your hard drive and/or  controller
    for  information  on  solving  these  kinds  of  problems.      In
    particular, many hard  drives will need  to have  a jumper set  if
    they are to  be used  as a  ``slave'' drive (for  example, as  the
    second hard drive).  The  acid test for this kind of  condition is
    to boot up MS-DOS, or  some other operating system, known  to work
    with your drive and controller.   If you can access the  drive and
    controller from another operating system, then it is not a problem
    with your hardware configuration.

    See Section 2.5.2.1, above, for information on  resolving possible
    device conflicts, and Section  2.5.2.3, below, for information  on
    configuring SCSI devices.

 o  Controller properly configured, but not detected.   Some BIOS-less
    SCSI controllers require the user to specify information about the
    controller at boot time.  Section 2.5.2.3, below, describes how to
    force hardware detection for these controllers.

 o  Hard drive geometry not recognized.  Some systems, such as the IBM
    PS/ValuePoint, do not store hard drive geometry information in the
    CMOS memory, where Linux expects to  find it.  Also,  certain SCSI
    controllers need to be told where to find drive  geometry in order
    for Linux to recognize the layout of your drive.

    Most distributions provide  a bootup option  to specify the  drive
    geometry.  In  general, when booting  the installation media,  you
2.5.   Running Into Trouble                                         78
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    can specify the  drive geometry  at the  LILO boot  prompt with  a
    command such as:


        boot:  linux hd=<cylinders>,<heads>,<sectors>


    where <cylinders>, <heads>,  and <sectors> correspond to  the number
    of cylinders, heads, and sectors per track for your hard drive.

    After installing the Linux software,  you will be able  to install
    LILO, allowing you to boot from the hard drive.  At that time, you
    can specify the drive geometry to the LILO installation procedure,
    making it unnecessary  to enter the drive  geometry each time  you
    boot.  See Chapter 4 for more about LILO.


2.5.2.3 Problems with SCSI controllers and devices

Presented here  are  some  of  the  most  common  problems  with  SCSI
controllers and devices such as CD-ROMs, hard drives, and tape drives.
If you are having  problems getting Linux  to recognize your drive  or
controller, read on.
  The  Linux  SCSI  HOWTO  (see  Appendix  A)   contains  much  useful
information on SCSI devices in addition to that listed here.  SCSI can
be particularly tricky to configure at times.

 o  A SCSI device is  detected at all possible  ID's.  This is  caused
    by strapping the  device to  the same address  as the  controller.
    You need to change  the jumper settings so  that the drive uses  a
    different address from the controller itself.

 o  Linux reports  sense errors,  even  if the  devices  are known  to
    be error-free.    This can  be caused  by bad  cables,  or by  bad
    termination.  If your SCSI bus is not terminated at both ends, you
    may have errors  accessing SCSI devices.    When in doubt,  always
    check your cables.

 o  SCSI devices report timeout errors.   This is usually caused  by a
    conflict with IRQ,  DMA, or  device addresses.    Also check  that
    interrupts are enabled correctly on your controller.

 o  SCSI controllers  using  BIOS are  not  detected.    Detection  of
    controllers using BIOS will  fail if the  BIOS is disabled, or  if
    your controller's ``signature'' is  not recognized by the  kernel.
    See the Linux SCSI HOWTO for more information about this.

 o  Controllers using  memory  mapped  I/O  do  not work.     This  is
    caused when the  memory-mapped I/O  ports are incorrectly  cached.
    Either mark the board's address space as uncacheable in  the XCMOS
2.5.   Running Into Trouble                                         79
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    settings, or disable cache altogether.

 o  When partitioning, you get a warning that ``cylinders > 1024'', or
    you are unable to boot  from a partition using  cylinders numbered
    above 1023.  BIOS limits the number of cylinders to  1024, and any
    partition using cylinders numbered above this won't  be accessible
    from the BIOS.  As far as  Linux is  concerned, this affects  only
    booting; once the system has  booted you should be able  to access
    the partition.    Your options  are to  either boot  Linux from  a
    boot floppy,  or boot from  a partition  using cylinders  numbered
    below 1024.  See Section 2.3.7 for information on  creating a boot
    diskette or installing LILO.

 o  CD-ROM drive or other removeable media devices are  not recognized
    at boot time.  Try booting  with a CD-ROM (or disk) in  the drive.
    This is necessary for some devices.

  If your  SCSI controller is  not recognized, you  may need to  force
hardware detection  at boot  time.    This is  particularly  important
for BIOS-less  SCSI controllers.    Most  distributions allow  you  to
specify the  controller IRQ  and shared  memory  address when  booting
the installation  media.   For  example, if  you are  using a  TMC-8xx
controller, you may be able to enter

    boot:  linux tmx8xx=<interrupt>,<memory-address>

at the LILO boot  prompt, where <interrupt> is  the IRQ of controller,
and <memory-address> is the shared memory address.  Whether or not you
will be able to do this  depends on the distribution of Linux  you are
using; consult your documentation for details.

2.5.3 Problems installing the software

Actually installing the Linux  software should be quite  trouble-free,
if you're lucky.  The only problems that you might experience would be
related to corrupt installation media  or lack of space on  your Linux
filesystems.  Here is a list of these common problems.


 o  System reports ``Read error'', ``file not found'', or other errors
    while attempting to install the software.  This is indicative of a
    problem with your installation media.  If you  are installing from
    floppy, keep in mind that floppies are quite succeptible  to media
    errors of this type.   Be  sure to use brand-new,  newly-formatted
    floppies.   If you have  an MS-DOS partition  on your drive,  many
    Linux distributions allow  you to  install the  software from  the
    hard drive.    This may  be faster  and more  reliable than  using
    floppies.

    If you  are  using  a  CD-ROM,  be sure  to  check  the  disc  for
    scratches, dust, or other problems which might cause media errors.
2.5.   Running Into Trouble                                         80
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    The cause of the problem may be that the media is in the incorrect
    format.  For example, if using floppies, many  Linux distributions
    require that  the floppies  be  formatted in  high-density  MS-DOS
    format.  (The boot  floppy is the exception;  it is not in  MS-DOS
    format in most cases.)  If all else fails, either obtain a new set
    of floppies, or recreate the floppies (using new diskettes) if you
    downloaded the software yourself.

 o  System reports errors such as ``tar:  read error'' or ``gzip:  not
    in gzip  format''.   This  problem is  usually  caused by  corrupt
    files on the  installation media  itself.   In  other words,  your
    floppy may be error-free,  but the data on  the floppy is in  some
    way corrupted.  For example, if you downloaded  the Linux software
    using text mode, rather than binary mode, then your  files will be
    corrupt, and unreadable by the installation software.

 o  System reports errors  such as  ``device full'' while  installing.
    This is  a clear-cut  sign that  you have  run out  of space  when
    installing the software.  Not all Linux distributions will be able
    to cleanly pick up  the mess; you shouldn't  be able to abort  the
    installation and expect the system to work.

    The solution  is  usually  to  re-create  your  filesystems  (with
    the mke2fs  command)  which  will delete  the  partially-installed
    software.  You can  then attempt to re-install the software,  this
    time selecting a smaller amount of software to install.   In other
    cases, you may need to start completely from scratch,  and rethink
    your partition and filesystem sizes.

 o  System reports errors such as ``read_intr:   0x10'' while accessing
    the hard drive.   This is usually  an indication of bad blocks  on
    your drive.   However,  if you  receive these  errors while  using
    mkswap or mke2fs, the system may be having trouble  accessing your
    drive.  This can either be a hardware problem (see Section 2.5.2),
    or it might be a case of  poorly specified geometry.  If  you used
    the


        hd=<cylinders>,<heads>,<sectors>


    option at boot  time to  force detection of  your drive  geometry,
    and incorrectly  specified the  geometry, you  could  be prone  to
    this problem.   This  can also  happen if your  drive geometry  is
    incorrectly specified in the system CMOS.

 o  System reports errors such  as ``file not found'' or  ``permission
    denied''.   This problem  can occur  if not all  of the  necessary
    files  are  present  on  the  installation  media  (see  the  next
    paragraph)  or  if  there  is  a  permissions  problem   with  the
2.5.   Running Into Trouble                                         81
_______________________________________________________________________

    installation software.  For  example, some distributions of  Linux
    have been known to have bugs in the installation  software itself.
    These are usually  fixed very rapidly,  and are quite  infrequent.
    If you suspect that the  distribution software contains bugs,  and
    you're sure that  you have  not done anything  wrong, contact  the
    maintainer of the distribution to report the bug.

  If you have  other strange errors when installing  Linux (especially
if you downloaded the  software yourself), be  sure that you  actually
obtained all of the  necessary files when  downloading.  For  example,
some people use the FTP command

    mget *.*

when downloading the Linux software  via FTP. This will download  only
those files that contain a ``.''  in their filenames; if there are any
files without the ``.'', you will  miss them.  The correct  command to
use in this case is

    mget *

  The best advice is to retrace your steps  when something goes wrong.
You may think that  you have done  everything correctly, when in  fact
you forgot a small  but important step  somewhere along the  way.   In
many cases,  just attempting to  re-download or  re-install the  Linux
software can solve the problem.  Don't beat your head against the wall
any longer than you have to!
  Also, if Linux unexpectedly hangs during installation,  there may be
a hardware problem of some kind.  See Section 2.5.2 for hints.

2.5.4 Problems after installing Linux

You've spent an entire afternoon installing  Linux.  In order  to make
space for it, you wiped your MS-DOS and OS/2 partitions, and tearfully
deleted your copies  of SimCity and  Wing Commander.   You reboot  the
system, and nothing happens.   Or, even worse, something happens,  but
it's not what should happen.  What do you do?
  In Section 2.5.1, we  covered some of the most common  problems that
can occur when  booting the Linux  installation media---many of  those
problems may apply here.  In addition, you may be victim to one of the
following maladies.

2.5.4.1 Problems booting Linux from floppy

If you are  using a  floppy to  boot Linux,  you may  need to  specify
the location of  your Linux  root partition  at boot  time.   This  is
especially true  if you  are using  the  original installation  floppy
itself, and not a custom boot floppy created during installation.
  While booting the floppy, hold down [shift] or [ctrl].   This should
present you with a boot menu;  press [tab] to see a list  of available
2.5.   Running Into Trouble                                         82
_______________________________________________________________________

options.  For example, many distributions allow you to type

    boot:  linux hd=<partition>

at the boot  menu,  where <partition>  is the  name of the  Linux root
partition, such  as /dev/hda2.    Consult the  documentation for  your
distribution for details.

2.5.4.2 Problems booting Linux from the hard drive

If you opted to install LILO, instead of creating a boot  floppy, then
you should be able to  boot Linux from the  hard drive.  However,  the
automated LILO installation  procedure used  by many distributions  is
not always perfect.    It may  make incorrect  assumptions about  your
partition layout, in which  case you will  need to re-install LILO  to
get everything right.  Installing LILO is covered in Chapter 4.

 o  System reports ``Drive not bootable---Please insert system disk.''
    You will get this  error message if  the hard drive's master  boot
    record is corrupt in some way.  In most cases,  it's harmless, and
    everything else on your drive is still intact.   There are several
    ways around this:


    1.  While partitioning  your  drive  using  fdisk,  you  may  have
        deleted the partition that was  marked as ``active''.   MS-DOS
        and other  operating systems  attempt to  boot the  ``active''
        partition at boot time (Linux pays no attention to whether the
        partition is ``active''  or not).    You may be  able to  boot
        MS-DOS from floppy  and run FDISK  to set  the active flag  on
        your MS-DOS paritition, and all will be well.

        Another command to try (with MS-DOS 5.0 and higher) is


            FDISK /MBR


        This command  will attempt to  rebuild the  hard drive  master
        boot record for  booting MS-DOS, overwriting  LILO. If you  no
        longer have MS-DOS  on your  hard drive,  you'll need to  boot
        Linux from floppy and attempt to install LILO later.

    2.  If you created  an MS-DOS partition  using Linux's version  of
        fdisk, or  vice versa, you  may get  this error.   You  should
        create MS-DOS partitions  only using  MS-DOS's version  FDISK.
        (The same  applies to  operating systems  other than  MS-DOS.)
        The best solution  here is  either to start  from scratch  and
        repartition the  drive  correctly,  or to  merely  delete  and
        re-create the offending  partitions using the correct  version
2.5.   Running Into Trouble                                         83
_______________________________________________________________________

        of fdisk.

    3.  The LILO  installation procedure  may have  failed.   In  this
        case, you  should  either boot  from  your Linux  boot  floppy
        (if you have  one), or from  the original installation  media.
        Either of  these  should provide  options for  specifying  the
        Linux root partition to use  when booting.  Hold  down [shift]
        or [ctrl] at boot time, and press [tab] from the boot menu for
        a list of options.


 o  When booting the system  from the hard  drive, MS-DOS (or  another
    operating system)  starts instead  of Linux.    First of  all,  be
    sure that you  actually installed LILO  when installing the  Linux
    software.   If not,  then the  system will still  boot MS-DOS  (or
    whatever other operating system you may have) when you  attempt to
    boot from the hard drive.   In order  to boot Linux from the  hard
    drive, you will need to install LILO (see Chapter 4).

    On the other hand, if you did install LILO,  and another operating
    system boots instead of  Linux, then you  have LILO configured  to
    boot that other  operating system by  default.   While the  system
    is booting, hold down  [shift] or [ctrl],  and press [tab] at  the
    boot prompt.   This  should present  you with a  list of  possible
    operating systems to boot; select the appropriate  option (usually
    just ``linux'') to boot Linux.

    If you wish  to select Linux  as the  default operating system  to
    boot, you will need to re-install LILO. See Chapter 4.

    It also may be  possible that you  attempted to install LILO,  but
    the installation procedure failed in  some way.  See  the previous
    item.

2.5.4.3 Problems logging in

After booting Linux, you should be presented with a login prompt, like
so:

    linux login:

At this point, either  the distribution's documentation or the  system
itself will tell you what to  do.  For many distributions,  you simply
login as root, with no password.  Other possible usernames  to try are
guest or test.
  Most newly-installed  Linux systems  should not  require a  password
for the initial login.  However, if you are asked to enter a password,
there may be a problem.  First, try using a password equivalent to the
username; that is, if you are logging in as root, use  ``root'' as the
password.
2.5.   Running Into Trouble                                         84
_______________________________________________________________________

  If you simply can't login,  there may be a problem.   First, consult
your distribution's documentation;  the username  and password to  use
may be buried in there somewhere.  The username and  password may have
been given to you  during the installation  procedure, or they may  be
printed on the login banner.
  One  cause of  this  may be  a  problem  with installing  the  Linux
login and  initialization  files.    If  this  is the  case,  you  may
need to reinstall  (at least  parts of)  the Linux  software, or  boot
your installation media and attempt  to fix the problem by  hand---see
Chapter 4 for hints.

2.5.4.4 Problems using the system

If login is successful,  you should be  presented with a shell  prompt
(such as ``#''  or ``$'')  and can  happily roam  around your  system.
However, there are  some initial problems with  using the system  that
sometimes creep up.
  The most common  initial configuration problem is incorrect  file or
directory permissions.  This can cause the error message

    Shell-init:  permission denied

to be printed after logging in (in fact, any time you  see the message
``permission denied'' you can be  fairly certain that it is  a problem
with file permissions).
  In many cases,  it's a simple matter  of using the chmod command  to
fix the permissions  of the  appropriate files  or directories.    For
example, some distributions  of Linux once  used the (incorrect)  file
mode 0644  for the  root directory  (/).   The  fix was  to issue  the
command

    # chmod 755 /

as root.  However, in order to issue this command, you  needed to boot
from the installation media  and mount your  Linux root filesystem  by
hand---a hairy task for most newcomers.
  As you  use  the system,  you may  run  into places  where file  and
directory permissions  are incorrect,  or software  does  not work  as
configured.  Welcome to the world of Linux!   While most distributions
are quite trouble-free, very few of  them are perfect.  We  don't want
to cover all of those problems here.  Instead, throughout  the book we
help you to solve many of these configuration problems by teaching you
how to find them  and fix them  yourself.   In Chapter 1 we  discussed
this philosophy in  some detail.    In Chapter  4, we  give hints  for
fixing many of these common configuration problems.








Chapter 3




Linux Tutorial



3.1 Introduction

New users of UNIX and Linux may  be a bit intimidated by the  size and
apparent complexity of the  system before them.   There are many  good
books on using UNIX out there, for all levels of expertise from novice
to expert.   However,  none of  these books  covers, specifically,  an
introduction to using Linux.  While 95% of using Linux is exactly like
using other UNIX systems, the most straightforward way to get going on
your new system is with a tutorial tailored for Linux.  Herein is such
a tutorial.
  This chapter  does not  go into a  large amount  of detail or  cover
many advanced topics.   Instead, it is  intended to get the new  Linux
user running, on both  feet, so that  he or she  may then read a  more
general book about UNIX and  understand the basic differences  between
other UNIX systems and Linux.
  Very little  is assumed here,  except perhaps some familiarity  with
personal computer systems, and MS-DOS. However, even if you're  not an
MS-DOS user, you  should be able  to understand everything  here.   At
first glance, UNIX looks a lot like MS-DOS (after all, parts of MS-DOS
were modeled on the CP/M operating  system, which in turn  was modeled
on UNIX). However, only the very superficial features of UNIX resemble
MS-DOS in any way.   Even  if you're completely  new to the PC  world,
this tutorial should be of help.
  And, before we  begin:  Don't be afraid  to experiment.   The system
won't bite you.  You can't destroy anything by working  on the system.
UNIX has some amount of security built in, to prevent ``normal'' users
(the role which  you will now  assume) from  damaging files which  are
essential to the system.   Even so, the absolute worst thing  that can
happen is that you'll delete all of your files---and you'll have to go
back and re-install the system.   So, at this point, you  have nothing
to lose.






                                  85
3.2.   Basic UNIX Concepts                                          86
_______________________________________________________________________

3.2 Basic UNIX Concepts

UNIX is a multitasking, multiuser  operating system.  This  means that
there can be many people using one computer at the same  time, running
many different applications.   (This differs  from MS-DOS, where  only
one person can use the system at any one time.)  Under UNIX, for users
to identify themselves to the system, they must log in,  which entails
two steps:   Entering  your  login name  (the  name which  the  system
identifies you as), and entering your password, which is your personal
secret key to logging into your  account.  Because only you  know your
password, no one else can login to the system under your username.
  On traditional  UNIX systems, the  system administrator will  assign
you a username and an initial  password when you are given  an account
on the system.  However, because you are the system administrator, you
must set up your own account before you can login---see Section 3.2.1,
below.    For  the  following discussions,  we'll  use  the  imaginary
username ``larry''.
  In addition,  each UNIX system has  a hostname assigned  to it.   It
is this hostname that  gives your machine  a name, gives it  character
and charm.    The hostname  is used  to  identify individual  machines
on a network,  but even  if your  machine isn't  networked, it  should
have a  hostname.     In  Section  4.10.2  we'll  cover  setting  your
system's hostname.  For our examples, below, the  system's hostname is
``mousehouse''.

3.2.1 Creating an account

Before you can  use the system,  you must  set up  a user account  for
yourself.  This  is because it's  usually not a  good idea to use  the
root account for  normal use.    The root account  should be  reserved
for running privileged  commands and  for maintaining  the system,  as
discussed in Section 4.1.
  In order  to create an account  for yourself, you  need to login  as
root and use  the useradd  or adduser command.    See Section 4.4  for
information on this procedure.

3.2.2 Logging in

At login time, you'll  see a prompt  resembling the following on  your
screen:


    mousehouse login:

  Here, enter your  username, and press the  [Return] key.  Our  hero,
larry, would type the following:

    mousehouse login:  larry
    Password:
3.2.   Basic UNIX Concepts                                          87
_______________________________________________________________________

  Now, enter  your password.   It won't be  echoed to the screen  when
you login, so type  carefully.  If  you mistype your password,  you'll
see the message

    Login incorrect

and you'll have to try again.
  Once you have correctly  entered the username and password,  you are
officially logged into the system, and are free to roam.

3.2.3 Virtual consoles

The system's console is the monitor and keyboard connected directly to
the system.   (Because UNIX is a  multiuser operating system, you  may
have other terminals  connected to  serial ports on  your system,  but
these would not be the console.)   Linux, like some other  versions of
UNIX, provides access to virtual  consoles (or VC's), which  allow you
to have more than one login session from your console at a time.
  To demonstrate this,  login to your system (as  demonstrated above).
Now, press [alt-F2].  You should see the login:  prompt again.  You're
looking at the second virtual console---you logged into the first.  To
switch back to the first VC, press  [alt-F1].  Voila!  You're  back to
your first login session.
  A newly-installed  Linux system  probably allows you  to access  the
first four VC's,  using [alt-F1]  through [alt-F4].    However, it  is
possible to enable up to 12  VC's---one for each function key  on your
keyboard.  As you can see, use of VC's can be  very powerful---you can
be working on several different VC's at once.
  While the use of VC's is somewhat limiting (after  all, you can only
be looking at one VC at a time), it should give you a  feel for UNIX's
multiuser capabilities.  While you're working on VC #1, you can switch
over to VC #2 and start working on something else.

3.2.4 Shells and commands

For most of your explorations in the world of UNIX,  you'll be talking
to the  system  through the  use  of a  shell.    A  shell is  just  a
program which takes  user input  (e.g., commands which  you type)  and
translates them  into instructions.    This  can  be compared  to  the
COMMAND.COM program  under MS-DOS,  which  does essentially  the  same
thing.   The  shell is  just one  interface to  UNIX.  There are  many
possible interfaces---such as the X Window System, which lets  you run
commands by using the mouse and keyboard in conjunction.
  As soon as you login, the system starts the shell,  and you can type
commands to it.  Here's a quick example.  Here, Larry logs  in, and is
left sitting at the shell prompt.

    mousehouse login:  larry
    Password:  larry's password
    Welcome to Mousehouse!
3.2.   Basic UNIX Concepts                                          88
_______________________________________________________________________


    /home/larry#

``/home/larry#'' is the shell's prompt, indicating that it's  ready to
take commands.  (More on what  the prompt itself means later.)   Let's
try telling the system to do something interesting:

    /home/larry# make love
    make:  *** No way to make target `love'.  Stop.
    /home/larry#

  Well, as it turns out make was the name of an  actual program on the
system, and the  shell executed this program  when given the  command.
(Unfortunately, the system was being unfriendly.)
  This brings us  to one burning question:   What are commands?   What
happens when you type ``make  love''?  The  first word on the  command
line, ``make'', is the name of the command to be executed.  Everything
else on  the command  line  is taken  as  arguments to  this  command.
Examples:

    /home/larry# cp foo bar

Here, the name of the command is ``cp'', and the arguments are ``foo''
and ``bar''.
  When you type  a command, the shell does  several things.   First of
all, it  looks at  the command  name, and  checks to  see if  it is  a
command which is internal  to the shell.   (That  is, a command  which
the shell knows how to  execute itself.   There are a number of  these
commands, and we'll go into them later.)  The shell also checks to see
if the command is an alias,  or substitute name, for  another command.
If neither of these conditions apply,  the shell looks for  a program,
on the disk, with  the command's name.   If  it finds such a  program,
the shell runs it, giving  the program the arguments specified  on the
command line.
  In our  example, the shell  looks for the  program called make,  and
runs it with  the argument  love.   Make is  a program  often used  to
compile large  programs,  and it  takes  as arguments  the name  of  a
``target'' to compile.   In the case  of ``make love'', we  instructed
make to compile the target love.  Because make can't find  a target by
this name, it fails with a humorous error message, and we are returned
to the shell prompt.
  What happens if  we type a command to  a shell, and the  shell can't
find a program with the command name to run?  Well, we can try it:

    /home/larry# eat dirt
    eat:  command not found
    /home/larry#

Quite simply, if the  shell can't find a  program with the name  given
on the command line (here, ``eat''), it prints an  error message which
3.2.   Basic UNIX Concepts                                          89
_______________________________________________________________________

should be self-explanatory.   You'll often  see this error message  if
you mistype a  command (for example,  if you  had typed ``mkae  love''
instead of ``make love'').

3.2.5 Logging out

Before we delve much further, we should tell you how to log out of the
system.  At the shell prompt, use the command

    /home/larry# exit

to logout.  There are other  ways of logging out as well, but  this is
the most foolproof one.

3.2.6 Changing your password

You should also be aware of how to change your password.   The command
passwd will prompt you for your  old password, and your  new password.
It will  ask you  to reenter  the new  password for  validation.    Be
careful not to forget your password---if you do, you will  have to ask
the system administrator to reset it  for you.  (If you're  the system
administrator, see Section 4.4.)


3.2.7 Files and directories

Under most operating systems (UNIX included), there is the  concept of
a file, which is  just a bundle of  information which is given a  name
(called a filename).   Examples  of files would  be your history  term
paper, an e-mail message, or an actual program which  can be executed.
Essentially, anything which is saved on disk is saved in an individual
file.
  Files are  identified by  their filenames.   For  example, the  file
containing your  history  paper  might  be  saved  with  the  filename
history-paper.  These names usually identify the file and its contents
in some form which is meaningful to you.  There is  no standard format
for filenames as there  is under MS-DOS  and other operating  systems;
in general, filenames  may contain any  character (except /---see  the
discussion of pathnames, below), and are limited to 256  characters in
length.
  With the  concept of  files comes  the concept  of directories.    A
directory is  just a  collection  of files.    It  can be  thought  of
as a  ``folder'' which  contains many  different files.    Directories
themselves are  given  names,   with  which  you  can  identify  them.
Furthermore, directories are maintained in a tree-like structure; that
is, directories may contain other directories.
  A file  may be  referred to  by its pathname,  which is  made up  of
the filename, preceded  by the  name of the  directory which  contains
the file.  For  example, let's say  that Larry has a directory  called
papers, which contains three  files:  history-final, english-lit,  and
masters-thesis.  (Each of  these three files contains information  for
3.2.   Basic UNIX Concepts                                          90
_______________________________________________________________________

three of Larry's ongoing projects.)  To refer to the file english-lit,
Larry can specify the file's pathname:

    papers/english-lit

  As  you can  see, the  directory  and file  names  are separated  by
a single slash  (/).   For  this reason,  filenames themselves  cannot
contain the  / character.    MS-DOS users  will  find this  convention
familiar, although  in the  MS-DOS world,  the backslash  (\) is  used
instead.
  As mentioned, directories can  be nested within each other  as well.
For example,  let's  say  that Larry  has  another  directory,  within
papers, called notes.   This directory  contains the files  math-notes
and cheat-sheet.  The pathname of the file cheat-sheet would be

    papers/notes/cheat-sheet

  Therefore,  the pathname  really is  a ``path''  which  you take  to
locate a certain file.   The directory  above a given subdirectory  is
known as the  parent directory.   Here,  the directory  papers is  the
parent of the notes directory.

3.2.8 The directory tree

Most UNIX systems  have a standard  layout for  files, so that  system
resources and  programs can  be easily  located.    This layout  forms
a directory tree,  which  starts at  the ``/''  directory, also  known
as ``the root directory''.   Directly underneath / are  some important
subdirectories:  /bin,  /etc, /dev,  and /usr,  among others.    These
directories in  turn contain  other directories  which contain  system
configuration files, programs, and so on.
  In  particular,  each  user has  a  home  directory,  which  is  the
directory set aside  for that  user to  store his or  her files.    In
the examples  above, all  of Larry's  files (such  as cheat-sheet  and
history-final) were contained  in Larry's  home directory.    Usually,
user home directories are contained under /home, and are named for the
user who owns that  directory.   Therefore, Larry's home directory  is
/home/larry.
  In Figure 3.2.8 a  sample directory tree is represented.   It should
give you  some  idea of  how  the directory  tree  on your  system  is
organized.

3.2.9 The current working directory

At any  given time,  commands that  you type  to the  shell are  given
in terms  of  your  current working  directory.    You  can  think  of
your working directory  as the  directory in which  you are  currently
``located''.  When you first  login, your working directory is  set to
your home directory---/home/larry in our case.  Whenever you reference
a file, you may  refer to it in  relationship to your current  working
3.2.   Basic UNIX Concepts                                          91
_______________________________________________________________________



/___|_bin
    |_dev
    |_etc
    |_home_____larry
    |        |_sam
    |_lib
    |_proc
    |_tmp
    |_usr__|X386
           |_bin
           |_emacs
           |_etc
           |_g++-include
           |_include
           |_lib
           |_local_____bin
           |         |_emacs
           |         |_etc
           |         |_lib
           |_man
           |_spool
           |_src_____linux
           |_tmp



        Figure 3.1:  A typical (abridged) Unix directory tree.



directory, instead of specifying the full pathname of the file.
  Here's an  example.    Larry has  the directory  papers, and  papers
contains the file history-final.  If Larry wants to look at this file,
he can use the command

    /home/larry# more /home/larry/papers/history-final

The more  command  simply displays  a  file,  one  screen at  a  time.
However, because Larry's current working directory is  /home/larry, he
can instead refer to the file  relative to his current location.   The
command would be

    /home/larry# more papers/history-final

Therefore, if  you begin  a  filename (such  as  papers/final) with  a
character other than ``/'',  the system assumes that you're  referring
3.3.   First Steps into UNIX                                        92
_______________________________________________________________________

to the file in terms relative to your current working directory.  This
is known as a relative pathname.
  On the other hand, if you begin a filename with  a ``/'', the system
interprets this as a full pathname---that is, a pathname including the
entire path to the file, starting from the root directory, /.  This is
known as an absolute pathname.

3.2.10 Referring to home directories

Under both tcsh and  bash,(1) your home  directory can be referred  to
using the tilde character (``~'').  For example, the command

    /home/larry# more ~/papers/history-final

is equivalent to

    /home/larry# more /home/larry/papers/history-final

The ``~'' character  is simply  replaced with  the name  of your  home
directory by the shell.
  In addition,  you  can specify  other user's  home directories  with
the tilde  as well.    The  pathname ``~karl/letters''  translates  to
``/home/karl/letters'' by  the shell  (if  /home/karl is  karl's  home
directory).   The use  of the  tilde is  simply a  shortcut; there  is
no directory named ``~''---it's just  syntactic sugar provided by  the
shell.


3.3 First Steps into UNIX

Before we begin,  it is important  to note that  all file and  command
names on a  UNIX system are  case-sensitive (unlike operating  systems
such as MS-DOS). For example, the command make is  very different than
Make or MAKE. The same hold for file and directory names.

3.3.1 Moving around

Now that we can login, and know how to refer to files using pathnames,
how can we change our current working directory, to make life easier?
  The command  for moving  around in  the directory  structure is  cd,
short for ``change directory''.   You'll  notice that many  often-used
Unix commands are two or three letters.   The usage of the  cd command
is:

    cd <directory>

----------------------------
 1. tcsh and bash are  two shells running under  Linux.  The shell  is
the program which reads  user commands and  executes them; most  Linux
systems enable either tcsh or bash for new user accounts.
3.3.   First Steps into UNIX                                        93
_______________________________________________________________________

where <directory>  is the  name  of the  directory  which you  wish to
change to.
  As we said,  when you login, you begin  in your home directory.   If
Larry wanted to move down into  the papers subdirectory, he'd  use the
command

    /home/larry# cd papers
    /home/larry/papers#

As you can see, Larry's prompt changes to reflect  his current working
directory (so he  knows where he  is).   Now that  he's in the  papers
directory, he can look at his history final with the command

    /home/larry/papers# more history-final

  Now, Larry is stuck in the papers subdirectory.  To  move back up to
the parent directory, use the command

    /home/larry/papers# cd ..
    /home/larry#

(Note the space between the ``cd''  and the ``..''.)   Every directory
has an  entry named  ``..''   which  refers to  the parent  directory.
Similarly, every directory has an entry  named ``.''  which  refers to
itself.  Therefore, the command

    /home/larry/papers# cd .

gets us nowhere.
  You can also use absolute  pathnames in the cd command.  To  cd into
Karl's home directory, we can use the command

    /home/larry/papers# cd /home/karl
    /home/karl#

  Also, using  cd with no  argument will return you  to your own  home
directory.

    /home/karl# cd
    /home/larry#


3.3.2 Looking at the contents of directories

Now that you know how  to move around directories you  probably think,
``So what?''  The basic  skill of moving around directories  is fairly
useless, so let's introduce a new command, ls.  ls prints a listing of
files and directories, by  default from your  current directory.   For
example:
3.3.  First Steps into UNIX                                         94
_______________________________________________________________________

    /home/larry# ls
    Mail
    letters
    papers
    /home/larry#

  Here  we  can see  that  Larry  has  three entries  in  his  current
directory:   Mail,  letters,  and  papers.     This  doesn't  tell  us
much---are these directories or files?   We can  use the -F option  on
the ls command to tell us more.

    /home/larry# ls --F
    Mail/
    letters/
    papers/
    /home/larry#


From the / appended to each filename, we know that these three entries
are in fact subdirectories.
  Using ls -F may  also append ``*'' to the  end of a filename.   This
indicates that the file  is an executable, or  a program which can  be
run.  If  nothing is appended  to the filename  using ls -F, the  file
is a ``plain  old file'',  that is,  it's neither a  directory, or  an
executable.
  In  general, each  UNIX command  may  take a  number  of options  in
addition to  other arguments.    These options  usually  begin with  a
``-'', as demonstrated  above with ls  -F. The -F  option tells ls  to
give more information about the  type of the files involved---in  this
case, printing a / after each directory name.
  If you give ls a directory name, it will print  the contents of that
directory.

    /home/larry# ls --F papers
    english-lit
    history-final
    masters-thesis
    notes/
    /home/larry#

  Or,  for  a  more interesting  listing,  let's  see  what's  in  the
system's /etc directory.


    /home/larry# ls /etc


    Images       ftpusers     lpc          rc.new       shells
    adm          getty        magic        rc0.d        startcons
    bcheckrc     gettydefs    motd         rc1.d        swapoff

3.3.   First Steps into UNIX                                        95
_______________________________________________________________________

    brc          group        mount        rc2.d        swapon
    brc~         inet         mtab         rc3.d        syslog.conf
    csh.cshrc    init         mtools       rc4.d        syslog.pid
    csh.login    init.d       pac          rc5.d        syslogd.reload
    default      initrunlvl   passwd       rmt          termcap
    disktab      inittab      printcap     rpc          umount
    fdprm        inittab.old  profile      rpcinfo      update
    fstab        issue        psdatabase   securetty    utmp
    ftpaccess    lilo         rc           services     wtmp
    /home/larry#



  (For those MS-DOS users  out there, notice how the filenames  can be
longer than 8 characters, and can contain periods in any position.  It
is even possible to have more than one period in a filename.)
  Let's cd up to the  top of the directory tree, using ``cd  ..'', and
then down to another directory:  /usr/bin.

    /home/larry# cd ..
    /home# cd ..
    /# cd usr
    /usr# cd bin
    /usr/bin#

You can  also  move into  directories  in  multiple steps,  as  in  cd
/usr/bin.
  Try moving  around various directories,  using ls and cd.   In  some
cases, you  may  run into  a  foreboding ``Permission  denied''  error
message.  This is simply the concept of UNIX security kicking  in:  in
order to ls or to cd into a directory, you must have  permission to do
so.  We'll talk more about this in   Section 3.9.


3.3.3 Creating new directories

It's time to learn how to  create directories.  This involves  the use
of the mkdir command.  Try the following:

    /home/larry# mkdir foo
    /home/larry# ls -F
    Mail/
    foo/
    letters/
    papers/
    /home/larry# cd foo
    /home/larry/foo# ls
   3.3.   First Steps into UNIX                                        96
   _______________________________________________________________________

       /home/larry/foo#

     Congrats!   You've  just made  a new  directory and  moved into  it.
   Since there aren't any files in this new directory, let's learn how to
   copy files from one place to another.

   3.3.4 Copying files

   Copying files is done with the command cp:


       /home/larry/foo# cp /etc/termcap  .
       /home/larry/foo# cp /etc/shells  .
       /home/larry/foo# ls --F
       shells     termcap
       /home/larry/foo# cp shells bells
       /home/larry/foo# ls --F
       bells     shells     termcap
       /home/larry/foo#

     The cp command  copies the files listed  on the command line to  the
   file or directory given as the last  argument.  Notice how we  use the
   directory ``.''  to refer to the current directory.

   3.3.5 Moving files

   A new command  named mv moves  files, instead  of copying  them.   The
   syntax is very straightforward.

       /home/larry/foo# mv termcap sells
       /home/larry/foo# ls -F
       bells     sells     shells
       /home/larry/foo#

     Notice how termcap  no longer exists, but  in its place is the  file
   sells.  This can  be used to rename files,  as we have just done,  but
   also to move a file to a completely new directory.
!    Note:  mv and cp will overwrite the destination  file (if it already
   exists) without asking  you.   Be careful  when you  move a file  into
   another directory:  there may already be a file with the  same name in
   that directory, which you'll overwrite!

   3.3.6 Deleting files and directories

   You now have an ugly rhyme developing with the use of  the ls command.
   To delete a file, use the rm command.  (``rm'' stands for ``remove'').


       /home/larry/foo# rm bells sells
       /home/larry/foo# ls -F
3.3.   First Steps into UNIX                                        97
_______________________________________________________________________

    shells
    /home/larry/foo#

  We're left  with nothing but shells,  but we won't  complain.   Note
that rm by  default won't prompt  you before  deleting a file---so  be
careful.
  A  related  command  to  rm is  rmdir.     This  command  deletes  a
directory, but  only if  the directory  is empty.    If the  directory
contains any files or subdirectories, rmdir will complain.

3.3.7 Looking at files

The commands more and cat are used for viewing the  contents of files.
more displays a file, one screenful at a time, while  cat displays the
whole file at once.
  To look at the file shells, we can use the command

    /home/larry/foo# more shells

  In case  you're  interested what  shells contains,  it's  a list  of
valid shell programs on your system.   On most systems,  this includes
/bin/sh, /bin/bash, and  /bin/csh.  We'll  talk about these  different
types of shells later.
  While using more,  press [Space] to display  the next page of  text,
and [b]  to display  the  previous page.    There  are other  commands
available in more as well,  these are just  the basics.  Pressing  [q]
will quit more.
  Quit more and try cat  /etc/termcap.  The text will probably  fly by
much too quickly for you to read it.  The name ``cat'' actually stands
for ``concatenate'', which is  the real use of  the program.  The  cat
command can be used to  concatenate the contents of several  files and
save the result to another file.  This will be discussed later.


3.3.8 Getting online help

Almost every UNIX  system, Linux included,  provides a facility  known
as ``manual pages'',  or ``man  pages'' for  short.   These man  pages
contain online documentation for all  of the various system  commands,
resources, configuration files, and so on.
  The command  used to  access man  pages  is man.    For example,  if
you're interested in  finding out about  the other  options of the  ls
command, you can type

    /home/larry# man ls

and the man page for ls will be displayed.
  Unfortunately,  most of  the man  pages out  there  are written  for
those who already have some idea of what the command or resource does.
For this reason, man pages usually only contain the hardcore technical
details of the command, without a lot of tutorial.  However, man pages
3.4.   Summary of Basic Commands                                    98
_______________________________________________________________________

can be an invaluable  resource for jogging  your memory if you  forget
the syntax of a command.  Man pages will also tell you a lot about the
commands which we won't tell you in this book.
  I suggest  that  you try  man for  the commands  we've already  gone
over, and whenever  I introduce  a new  command.   You'll notice  some
of these commands won't  have man pages.   This  could be for  several
reasons.  For one, the  man pages haven't been written yet  (the Linux
Documentation Project  is responsible  for man  pages  under Linux  as
well.  We are gradually  accumulating most of the man  pages available
for the system).  Secondly, the the command might be an internal shell
command, or an alias (as discussed in Section 3.2.4), in which case it
would not have a man page of its  own.  One example is cd, which  is a
shell internal command.   The shell actually processes the  cd---there
is no separate program which contains this command.


3.4 Summary of Basic Commands

This section introduces some  of the most  useful basic commands on  a
UNIX system, including those covered in the last section.
  Note that  options usually  begin with a  ``-'', and  in most  cases
multiple one-letter options may be combined using a single ``-''.  For
example, instead of using the command ls -l -F, it is  adequate to use
ls -lF.
  Instead of listing  all of the options  available for each of  these
commands, we'll only  talk about those which  are useful or  important
at this time.   In fact,  most of these  commands have a large  number
of options (most of which you'll never  use).  You can use man  to see
the manual pages  for each command,  which list  all of the  available
options.
  Also note  that  many of  these commands  take a  list  of files  or
directories as  arguments,  denoted by  ``<file1> ... <fileN>''.   For
example, the cp command  takes as arguments a  list of files to  copy,
followed by the destination file or directory.  When copying more than
one file, the destination must be a directory.
cd         Change the current working directory.
           Syntax:  cd <directory>
           <directory> is the  directory to change to.  (``.''  refers
           to the current directory, ``..''  the parent directory.)
           Example:  cd ../foo sets the current directory to ../foo.

ls         Displays  information about  the named  files and  directo-
           ries.
           Syntax:  ls <file1> <file2> ... <fileN>
           Where   <file1>  through  <fileN>   are  the   filenames  or
           directories  to list.   Options:   There  are more  options
           than you want  to think about.  The most commonly  used are
           -F (used to display some information  about the type of the
           file),  and -l  (gives  a ``long''  listing including  file
           size, owner, permissions, and so on.   This will be covered
3.4.   Summary of Basic Commands                                    99
_______________________________________________________________________

           in detail later.)
           Example:   ls -lF /home/larry will display the  contents of
           the directory /home/larry.

cp         Copies file(s) to another file or directory.
           Syntax:  cp <file1> <file2> ... <fileN> <destination>
           Where  <file1> through  <fileN> are the  files to  copy, and
           <destination> is the destination file or directory.
           Example:   cp ../frog  joe copies the  file ../frog to  the
           file or directory joe.

mv         Moves file(s)  to another file or directory.   This command
           does the  equivalent of a copy followed by the  deletion of
           the original.  This can be used  to rename files, as in the
           MS-DOS command RENAME.
           Syntax:  mv <file1> <file2> ... <fileN> <destination>
           Where  <file1> through  <fileN> are the  files to  move, and
           <destination> is the destination file or directory.
           Example:   mv  ../frog joe moves  the file  ../frog to  the
           file or directory joe.

rm         Deletes  files.   Note that  when files  are deleted  under
           UNIX, they are unrecoverable (unlike  MS-DOS, where you can
           usually ``undelete'' the file).
           Syntax:  rm <file1> <file2> ... <fileN>
           Where <file1> through <fileN> are the filenames to delete.
           Options:   -i will prompt for confirmation  before deleting
           the file.
           Example:   rm -i  /home/larry/joe /home/larry/frog  deletes
           the files joe and frog in /home/larry.

mkdir      Creates new directories.
           Syntax:  mkdir <dir1> <dir2> ... <dirN>
           Where <dir1> through <dirN> are the directories to create.
           Example:    mkdir /home/larry/test  creates  the  directory
           test under /home/larry.
rmdir      This command deletes empty directories.   When using rmdir,
           your  current  working directory  must  not be  within  the
           directory to be deleted.
           Syntax:  rmdir <dir1> <dir2> ... <dirN>
           Where <dir1> through <dirN> are the directories to delete.
           Example:   rmdir /home/larry/papers  deletes the  directory
           /home/larry/papers, if it is empty.

man        Displays the manual page for the  given command or resource
           (that is,  any system utility  which isn't a command,  such
           as a library function.)  Syntax:  man <command>
           Where <command>  is the name of  the command or resource to
           get help on.
           Example:  man ls gives help on the ls command.
3.5.   Exploring the File System                                   100
_______________________________________________________________________

more       Displays the contents of the named  files, one screenful at
           a time.
           Syntax:  more <file1> <file2> ... <fileN>
           Where <file1> through <fileN> are the files to display.
           Example:    more  papers/history-final  displays  the  file
           papers/history-final.

cat        Officially used  to concatenate files, cat is also  used to
           display the entire contents of a file at once.
           Syntax:  cat <file1> <file2> ... <fileN>
           Where <file1> through <fileN> are the files to display.
           Example:      cat  letters/from-mdw   displays   the   file
           letters/from-mdw.

echo       Simply echoes the given arguments.
           Syntax:  echo <arg1> <arg2> ... <argN>
           Where <arg1> through <argN> are the arguments to echo.
           Example:   echo "Hello world"  displays the string  ``Hello
           world''.

grep       Display all of the lines in  the named file(s) matching the
           given pattern.
           Syntax:  grep <pattern> <file1> <file2> ... <fileN>
           Where  <pattern>  is  a  regular  expression  pattern,  and
           <file1> through <fileN> are the files to search.
           Example:  grep loomer /etc/hosts will  display all lines in
           the file /etc/hosts which contain the pattern ``loomer''.


3.5 Exploring the File System

The file  system is  the  collection of  files  and the  hierarchy  of
directories on your system.   I promised  before to escort you  around
the filesystem and the time has come.
  You have the skills and the knowledge to make sense  out of what I'm
saying, and you have a roadmap.  (Refer to Figure 3.2.8 on page 91).
  First, change to the root directory (cd /), and do  an ls -F. You'll
probably see these directories(2):  bin, dev, etc, home, install, lib,
mnt, proc, root, tmp, user, usr, and var.
  Let's take a look at each of these directories.

/bin       /bin is  short for ``binaries'', or  executables.  This  is
           where  many essential  system  programs reside.    Use  the
           command  ``ls -F /bin''  to list the  files here.   If  you
           look  down the list  you may  see a few  commands that  you
           recognize, such  as cp, ls, and  mv.  These are  the actual

----------------------------
 2. You may  see others, and  you might not  see all of  them.   Don't
worry.  Every release of Linux differs in some respects.
3.5.   Exploring the File System                                   101
_______________________________________________________________________

           programs for these commands.  When  you use the cp command,
           you're running the program /bin/cp.

           Using  ls -F,  you'll see  that most  (if not  all) of  the
           files in  /bin have an  asterisk (``*'') appended to  their
           filenames.  This indicates that  the files are executables,
           as described in Section 3.3.2.
/dev       Next on our stop is /dev.  Take a look, again with ls -F.

           The  ``files'' in /dev are  known as device  drivers---they
           are used  to access system  devices and resources, such  as
           disk drives, modems, memory, and so on.   For example, just
           as you can  read data from a file, you can read  input from
           the mouse by accessing /dev/mouse.
           The  filenames beginning with fd  are floppy disk  devices.
           fd0 is the  first floppy disk drive, fd1 the second.   Now,
           the  astute  among you  will  notice  that there  are  more
           floppy disk  devices then just  the two I've listed  above:
           they  represent  specific  types  of floppy  disks.     For
           example, fd1H1440 will access  high-density, 3.5" diskettes
           in drive 1.

           Here  is a list of  some of the  most commonly used  device
           files.   Note  that even though  you may  not have some  of
           the devices listed below, the chances  are that you'll have
           entries in /dev for them anyway.

             o /dev/console refers to the  system's console---that is,
               the monitor connected directly to your system.

             o The  various /dev/ttyS  and /dev/cua  devices are  used
               for  accessing serial ports.   For example,  /dev/ttyS0
               refers to  ``COM1'' under MS-DOS. The  /dev/cua devices
               are ``callout'' devices, which  are used in conjunction
               with a modem.

             o The device names beginning with  hd access hard drives.
               /dev/hda  refers to  the whole first  hard disk,  while
               hda1 refers to the first partition on /dev/hda.

             o The  device names  beginning with sd  are SCSI  drives.
               If  you have a  SCSI hard  drive, instead of  accessing
               it through  /dev/hda, you would access /dev/sda.   SCSI
               tapes are accessed via st  devices, and SCSI CD-ROM via
               sr devices.

             o The  device  names beginning  with lp  access  parallel
               ports.    /dev/lp0  refers to  ``LPT1''  in the  MS-DOS
               world.
3.5.   Exploring the File System                                   102
_______________________________________________________________________

             o /dev/null is  used as a ``black hole''---any  data sent
               to this  device is gone forever.   Why is this  useful?
               Well,  if  you  wanted  to suppress  the  output  of  a
               command appearing  on your screen, you could  send that
               output  to  /dev/null.    We'll  talk more  about  this
               later.

             o The device  names beginning with /dev/tty refer  to the
               ``virtual  consoles'' on your  system (accessed via  by
               pressing  [alt-F1], [alt-F2],  and so on).    /dev/tty1
               refers  to  the  first  VC,  /dev/tty2  refers  to  the
               second, and so on.

             o The device names beginning  with /dev/pty are ``pseudo-
               terminals''.   They are used to provide  a ``terminal''
               to  remote  login  sessions.    For  example,  if  your
               machine is  on a network, incoming telnet  logins would
               use one of the /dev/pty devices.


/etc       /etc  contains a  number  of miscellaneous  system  config-
           uration  files.     These  include  /etc/passwd  (the  user
           database), /etc/rc (the system  initialization script), and
           so on.

/sbin      sbin is  used for storing essential system binaries,  to be
           used by the system administrator.

/home      /home  contains  user's home  directories.    For  example,
           /home/larry is  the home directory for the  user ``larry''.
           On a newly-installed system, there may  not be any users in
           this directory.

/lib       /lib contains  shared library images.  These  files contain
           code which many programs share in common.   Instead of each
           program containing  its own copy of these  shared routines,
           they are  all stored in  one common place,  in /lib.   This
           makes  executable files smaller,  and saves  space on  your
           system.

/proc      /proc is  a ``virtual filesystem'', the files in  which are
           stored  in memory, not  on the  drive.   They refer to  the
           various  processes running  on the  system,  and allow  you
           to  get information about what  programs and processes  are
           running at  any given time.   We'll go into more  detail in
           Section 3.11.1.
/tmp       Many programs have a need to  generate some information and
           store it in  a temporary file.  The canonical  location for
           these files is in /tmp.
3.5.   Exploring the File System                                   103
_______________________________________________________________________

/usr       /usr is a  very important directory.  It contains  a number
           of subdirectories  which in turn  contain some of the  most
           important and useful programs and  configuration files used
           on the system.

           The various  directories described above are  essential for
           the  system  to  operate,  but most  of  the  things  found
           in  /usr are  optional  for the  system.   However,  it  is
           those  optional things  which make  the  system useful  and
           interesting.    Without /usr,  you'd  more or  less have  a
           boring  system, only with  programs like cp and  ls.   /usr
           contains  most  of the  larger  software packages  and  the
           configuration files which accompany them.
/usr/X386  /usr/X386  contains The X Window  System, if you  installed
           it.   The X  Window System is  a large, powerful  graphical
           environment  which provides  a  large number  of  graphical
           utilities  and programs, displayed  in ``windows'' on  your
           screen.    If you're  at  all familiar  with the  Microsoft
           Windows  or Macintosh  environments,  X Windows  will  look
           very  familiar.    The  /usr/X386  directory  contains  all
           of  the X  Windows  executables, configuration  files,  and
           support  files.   This will  be covered in  more detail  in
           Section 5.1.

/usr/bin   /usr/bin  is the real  warehouse for  software on any  UNIX
           system.   It contains most of the executables  for programs
           not found in other places, such as /bin.

/usr/etc   Just  as /etc contained  miscellaneous system programs  and
           configuration files,  /usr/etc contains even more  of these
           utilities  and files.    In  general,  the files  found  in
           /usr/etc  are not  essential to  the system,  unlike  those
           found in /etc, which are.

/usr/include
           /usr/include  contains include  files for  the C  compiler.
           These  files (most  of  which end  in .h,  for  ``header'')
           declare  data structure names,  subroutines, and  constants
           used  when writing  programs  in C.  Those files  found  in
           /usr/include/sys  are generally  used  when programming  on
           the  UNIX system level.   If  you are  familiar with the  C
           programming  language, here you'll  find header files  such
           as stdio.h, which declares functions such as printf().

/usr/g++-include
           /usr/g++-include  contains   include  files  for  the   C++
           compiler (much like /usr/include).

/usr/lib   /usr/lib  contains  the  ``stub''  and  ``static''  library
           equivalents  to the files  found in /lib.   When  compiling
           a  program, the  program is ``linked''  with the  libraries
3.5.   Exploring the File System                                   104
_______________________________________________________________________

           found in  /usr/lib, which then directs the program  to look
           in /lib when  it needs the actual code in the library.   In
           addition, various other programs  store configuration files
           in /usr/lib.

/usr/local /usr/local  is  a  lot  like   /usr---it  contains  various
           programs and  files not essential to the system,  but which
           make  the system  fun  and exciting.    In  general,  those
           programs  found  in  /usr/local are  specialized  for  your
           system specifically---that  is, /usr/local differs  greatly
           between UNIX systems.
           Here,  you'll  find large  software  packages such  as  TeX
           (a  document  formatting system)  and  Emacs (a  large  and
           powerful editor), if you installed them.

/usr/man   This directory  contains the actual man  pages.  There  are
           two subdirectories for every man  page ``section'' (use the
           command man  man for details).  For  example, /usr/man/man1
           contains  the source  (that is,  the unformatted  original)
           for man pages in section 1,  and /usr/man/cat1 contains the
           formatted man pages for section 1.

/usr/src   /usr/src contains the source code  (the uncompiled program)
           for various  programs on your system.   The most  important
           thing  here is  /usr/src/linux, which  contains the  source
           code for the Linux kernel.

/var       /var holds  directories that often  change in size or  tend
           to  grow.   Many  of those  directories used  to reside  in
           /usr,  but  since  we  are trying  to  keep  it  relatively
           unchangeable, the  directories that change often  have been
           moved to /var.  Some of those directories are:

/var/adm   /var/adm contains  various files of interest to  the system
           administrator, specifically  system logs, which record  any
           errors  or problems with  the system.   Other files  record
           logins  to the system,  as well  as failed login  attempts.
           This will be covered in Chapter 4.

/var/spool /var/spool  contains  files  which are  to  be  ``spooled''
           to  another program.    For  example,  if your  machine  is
           connected  to a network,  incoming mail  will be stored  in
           /var/spool/mail, until you read it or  delete it.  Outgoing
           or incoming news articles may  be found in /var/spool/news,
           and so on.
3.6.   Types of shells                                             105
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3.6 Types of shells

As I have  mentioned too many  times before,  UNIX is a  multitasking,
multiuser operating system.  Multitasking is very useful, and once you
get used to it, you'll  use it all of the  time.  Before long,  you'll
be able to run programs in the ``background'', switch between multiple
tasks,  and ``pipeline''  programs  together  to  achieve  complicated
results with a single command.
  Many of the features we'll be covering in  this section are features
provided by  the  shell  itself.    Be  careful not  to  confuse  UNIX
(the actual operating system)  with the shell---the  shell is just  an
interface to the underlying system.   The shell provides a  great deal
of functionality on top of UNIX itself.
  The shell is not only an interpreter for  your interactive commands,
which you type  at the  prompt.   It  is also  a powerful  programming
language, which  allows  you  to write  shell  scripts,  to  ``batch''
several shell  commands  together  in  a  file.    MS-DOS  users  will
recognize the similarity to ``batch files''.  Use of  shell scripts is
a very powerful tool, which will allow you to automate and expand your
usage of UNIX. See Section 3.13.1 for more information.
  There are several types of shells in the UNIX world.   The two major
types are the ``Bourne shell'' and the ``C shell''.   The Bourne shell
uses a command syntax like  the original shell on early  UNIX systems,
such as System III. The name of the Bourne shell on  most UNIX systems
is /bin/sh (where sh stands  for ``shell'').   The C shell (not to  be
confused with sea shell)  uses a different  syntax, somewhat like  the
programming language C, and on most UNIX systems is named /bin/csh.
  Under  Linux,   there  are  several   variations  of  these   shells
available.  The two most commonly used are the Bourne  Again Shell, or
``Bash'' (/bin/bash), and  Tcsh (/bin/tcsh).   Bash is  a form of  the
Bourne shell with many of the advanced features found in  the C shell.
Because Bash supports a superset of the Bourne shell syntax, any shell
scripts written in the  standard Bourne shell  should work with  Bash.
For those who prefer to use  the C shell syntax, Linux  supports Tcsh,
which is an expanded version of the original C shell.
  The type  of shell  that you  decide to  use is  mostly a  religious
issue.  Some  folks prefer the Bourne  shell syntax with the  advanced
features of Bash, and some prefer the more structured  C shell syntax.
As far as normal commands, such as cp and ls, are  concerned, the type
of shell you're using doesn't matter---the  syntax is the same.   Only
when you start  to write  shell scripts  or use some  of the  advanced
features of the shell do the differences between shell types  begin to
matter.
  As we're discussing some of the features of the  shell, below, we'll
note those differences between Bourne and C shells.  However,  for the
purposes of this manual, most of  those differences are minimal.   (If
you're really curious at this point,  read the man pages for  bash and
tcsh).
3.7.   Wildcards                                                   106
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3.7 Wildcards

A key feature  of most Unix  shells is the  ability to reference  more
than one filename using special characters.  These so-called wildcards
allow you to refer to, say, all filenames which  contain the character
``n''.
  The wildcard ``*'' refers  to any character or string  of characters
in a filename.   For example,  when you use  the character ``*'' in  a
filename, the shell replaces  it with all possible substitutions  from
filenames in the directory which you're referencing.
  Here's a  quick example.   Let's  suppose that  Larry has the  files
frog, joe, and stuff in his current directory.

    /home/larry# ls
    frog     joe     stuff
    /home/larry#

  To access all  files with the letter  ``o'' in the filename, we  can
use the command

    /home/larry# ls *o*
    frog     joe
    /home/larry#

As you can see,  the use of the  ``*'' wildcard was replaced with  all
substitutions which matched the wildcard from filenames in the current
directory.
  The use  of ``*'' by  itself simply  matches all filenames,  because
all characters match the wildcard.

    /home/larry# ls *
    frog     joe     stuff
    /home/larry#

  Here are a few more examples.

    /home/larry# ls f*
    frog
    /home/larry# ls *ff
    stuff
    /home/larry# ls *f*
    frog     stuff
    /home/larry# ls s*f
    stuff
    /home/larry#

  The process of  changing a ``*''  into filenames is called  wildcard
expansion and  is  done  by the  shell.     This is  important:    the
individual commands, such as ls, never see the ``*'' in  their list of
parameters.   The shell  expands the  wildcard to include  all of  the
3.7.   Wildcards                                                   107
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filenames which match.  So, the command

    /home/larry# ls *o*

is expanded by the shell to actually be

    /home/larry# ls frog joe

  One important note  about the ``*'' wildcard.   Using this  wildcard
will not match  filenames which  begin with a  single period  (``.'').
These files  are  treated as  ``hidden''  files---while they  are  not
really hidden, they don't  show up on  normal ls listings, and  aren't
touched by the use of the ``*'' wildcard.
  Here's an  example.   We already mentioned  that each directory  has
two special entries in it:   ``.''   refers to the current  directory,
and ``..''  refers to the parent directory.  However, when you use ls,
these two entries don't show up.

    /home/larry# ls
    frog     joe     stuff
    /home/larry#

If you use the -a switch  with ls, however, you can  display filenames
which begin with ``.''.  Observe:

    /home/larry# ls -a
    .      ..      .bash_profile      .bashrc      frog        joe
    stuff
    /home/larry#

Now we can see  the two special  entries, ``.''   and ``..'', as  well
as two other ``hidden'' files---.bash_profile and .bashrc.   These two
files are startup files used by bash when larry logs in.  More on them
in Section 3.13.3.
  Note that  when we  use the ``*''  wildcard, none  of the  filenames
beginning with ``.''  are displayed.

    /home/larry# ls *
    frog     joe     stuff
    /home/larry#

This is a  safety feature:   if the  ``*'' wildcard matched  filenames
beginning with ``.'',  it would also match  the directory names  ``.''
and ``..''.  This can be dangerous when using certain commands.
  Another wildcard  is ``?''.   The ``?''   wildcard will only  expand
a single character.   Thus, ``ls ?''   will display all one  character
filenames, and  ``ls termca?''    would  display  ``termcap'' but  not
``termcap.backup''.  Here's another example:

    /home/larry# ls j?e
3.8.   UNIX Plumbing                                               108
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    joe
    /home/larry# ls f??g
    frog
    /home/larry# ls ????f
    stuff
    /home/larry#

  As you  can see, wildcards  allow you to specify  many files at  one
time.  In  the simple command  summary, in Section  3.4, we said  that
the cp and mv commands actually can copy or move multiple files at one
time.  For example,

    /home/larry# cp /etc/s* /home/larry

will copy all filenames in /etc beginning with ``s'' to  the directory
/home/larry.  Therefore, the format of the cp command is really

    cp <file1> <file2> <file3> ... <fileN> <destination>

where <file1>  through <fileN>  is a  list  of filenames  to copy,  and
<destination> is the  destination file or  directory to  copy them to.
mv has an identical syntax.
  Note that  if you  are copying  or moving  more than  one file,  the
<destination> must be a directory.  You can only copy or move a single
file to another file.


3.8 UNIX Plumbing

3.8.1 Standard input and output

Many UNIX commands get input from what is known as  standard input and
send their output to standard  output (often abbreviated as  ``stdin''
and ``stdout'').  Your shell sets things up so that  standard input is
your keyboard, and standard output is the screen.
  Here's an example using  the command cat.  Normally, cat  reads data
from all of  the filenames given  on the command  line and sends  this
data directly to stdout.  Therefore, using the command

    /home/larry/papers# cat history-final masters-thesis

will display  the  contents  of  the file  history-final  followed  by
masters-thesis.
  However, if no filenames are given to cat as  parameters, it instead
reads data  from stdin,  and  sends it  back  to stdout.    Here's  an
example.

    /home/larry/papers# cat
    Hello there.
    Hello there.
3.8.   UNIX Plumbing                                               109
_______________________________________________________________________

    Bye.
    Bye.
    [ctrl-D]
    /home/larry/papers#

As you can see, each line  that the user types (displayed  in italics)
is immediately echoed  back by  the cat  command.   When reading  from
standard input, commands know that the input is ``finished'' when they
receive an EOT (end-of-text) signal.  In general, this is generated by
pressing [ctrl-D].
  Here's another  example.   The command sort reads  in lines of  text
(again, from stdin, unless files  are given on the command line),  and
sends the sorted output to stdout.  Try the following.

    /home/larry/papers# sort
    bananas
    carrots
    apples
    [ctrl-D]
    apples
    bananas
    carrots
    /home/larry/papers#

Now we can alphabetize our shopping list...  isn't UNIX useful?

3.8.2 Redirecting input and output

Now, let's say that we  wanted to send the  output of sort to a  file,
to save our shopping list elsewhere.  The shell allows  us to redirect
standard output to a filename, using the ``>'' symbol.   Here's how it
works.

    /home/larry/papers# sort > shopping-list
    bananas
    carrots
    apples
    [ctrl-D]
    /home/larry/papers#

As you  can see,  the  result  of the  sort command  isn't  displayed,
instead it's saved  to the  file shopping-list.   Let's  look at  this
file.

    /home/larry/papers# cat shopping-list
    apples
    bananas
    carrots
    /home/larry/papers#
3.8.   UNIX Plumbing                                               110
_______________________________________________________________________

Now we can  sort our  shopping list,  and  save it,  too!   But  let's
suppose that we were storing  our unsorted, original shopping  list in
the file items.  One way of sorting the information and saving it to a
file would be to give  sort the name of the  file to read, in  lieu of
standard input, and redirect standard output as we did above.  As so:

    /home/larry/papers# sort items > shopping-list
    /home/larry/papers# cat shopping-list
    apples
    bananas
    carrots
    /home/larry/papers#

However, there's another way of doing this.  Not only  can we redirect
standard output, but we can redirect standard input as well, using the
``<'' symbol.

    /home/larry/papers# sort < items
    apples
    bananas
    carrots
    /home/larry/papers#

Technically, sort < items is equivalent to sort items,  but the former
allows us to demonstrate the  point:  sort <  items behaves as if  the
data in the file items was typed to standard input.  The shell handles
the redirection.  sort  wasn't given the name  of the file (items)  to
read; as far as sort is concerned, it was still  reading from standard
input as if you had typed the data from your keyboard.
  This introduces  the concept of  a filter.   A  filter is a  program
which reads data from  standard input, processes  it in some way,  and
sends the  processed data  to  standard output.    Using  redirection,
standard input and/or  standard output can  be referenced from  files.
sort is a simple  filter:  it  sorts the incoming  data and sends  the
result to  standard output.    cat is  even simpler:    it doesn't  do
anything with the incoming data, it simply outputs whatever  was given
to it.

3.8.3 Using pipes

We've already demonstrated  how to  use sort  as a filter.    However,
these examples assumed that you had data in a file somewhere,  or were
willing to type the data to standard input yourself.  What if the data
you wanted to sort  came from the output  of another command, such  as
ls?   For example, using  the -r  option with sort  sorts the data  in
reverse-alphabetical order.  If you  wanted to list the files  in your
current directory in reverse order, one way to do it would be:

    /home/larry/papers# ls
    english-list
3.8.   UNIX Plumbing                                               111
_______________________________________________________________________

    history-final
    masters-thesis
    notes
    /home/larry/papers# ls > file-list
    /home/larry/papers# sort -r file-list
    notes
    masters-thesis
    history-final
    english-list
    /home/larry/papers#

Here, we saved the  output of ls in  a file, and  then ran sort -r  on
that file.  But this is unwieldy and causes us to use a temporary file
to save the data from ls.
  The solution is  to use pipelining.   Pipelining is another  feature
of the shell which  allows you to  connect a string  of commands in  a
``pipe'', where the stdout  of the first  command is sent directly  to
the stdin of the second command, and so on.  Here, we wish to send the
stdout of ls to the stdin of sort.  The ``_'' symbol is used to create
a pipe:

    /home/larry/papers# ls | sort -r
    notes
    masters-thesis
    history-final
    english-list
    /home/larry/papers#

This command is much shorter, and obviously easier to type.
  Another useful example---using the command

    /home/larry/papers# ls /usr/bin

is going to display a long list  a files, most of which will  fly past
the screen too quickly for you to read them.  Instead,  let's use more
to display the list of files in /usr/bin.

    /home/larry/papers# ls /usr/bin | more

Now you can page down the list of files at your own leisure.
  But the fun doesn't stop  here!  We can pipe more than  two commands
together.   The  command head  is a  filter which  displays the  first
lines from an input stream  (here, input from a  pipe).  If we  wanted
to display  the last  filename in  alphabetical order  in the  current
directory, we can use:

    /home/larry/papers# ls | sort -r | head -1
    notes
    /home/larry/papers#
3.9.   File Permissions                                            112
_______________________________________________________________________

where head -1 simply displays the first line of input that it receives
(in this case, the stream of reverse-sorted data from ls).

3.8.4 Non-destructive redirection

Using ``>'' to  redirect output to  a file is  destructive:  in  other
words, the command

    /home/larry/papers# ls > file-list

overwrites the  contents of  the file  file-list.   If,  instead,  you
redirect with the symbol  ``>>'', the output  will be appended to  the
named file, instead of overwriting it.

    /home/larry/papers# ls >> file-list

will append the output of the ls command to file-list.
  Just keep  in mind  that redirection  and using  pipes are  features
provided by the  shell---the shell  provides this  handy syntax  using
``>'' and ``>>'' and ``_''.   It has  nothing to do with the  commands
themselves, but the shell.


3.9 File Permissions

3.9.1 Concepts of file permissions

Because there are multiple users on a UNIX system, in order to protect
individual user's files from tampering  by other users, UNIX  provides
a mechanism known as  file permissions.   This mechanism allows  files
and directories to be ``owned'' by a particular user.   As an example,
because Larry  created the  files in  his home  directory, Larry  owns
those files, and has access to them.
  UNIX also  allows files  to be  shared between users  and groups  of
users.  If  Larry so desired,  he could cut  off access to his  files,
such that no other user could  access them.  However, on  most systems
the default is to allow other users to read your files, but not modify
or delete them in any way.
  As  explained above,  every  file is  owned  by a  particular  user.
However, files  are  also owned  by a  particular  group, which  is  a
system-defined group of users.  Every user is placed into at least one
group when that user  is created.   However, the system  administrator
may also grant the user access to more than one group.
  Groups are  usually defined by  the type of  users which access  the
machine.   For example,  on  a university  UNIX system,  users may  be
placed into the groups  student, staff, faculty or  guest.  There  are
also a few  system-defined groups (such  as bin  and admin) which  are
used by the system itself to control access to resources---very rarely
do actual users belong to these system groups.
  Permissions  fall into  three  main  divisions:   read,  write,  and
3.9.   File Permissions                                            113
_______________________________________________________________________

execute.  These permissions may be granted to three  classes of users:
the owner of the file, the group to which the file belongs, and to all
users, regardless of group.
  Read permission allows a  user to read the contents of the  file, or
in the case  of directories,  to list  the contents  of the  directory
(using ls).  Write permission  allows the user to write to  and modify
the file.  For directories, write permission allows the user to create
new files or  delete files within  that directory.   Finally,  execute
permission allows  the user  to run  the file  as a  program or  shell
script (if the file happens to be a program or shell script, that is).
For directories, having execute permission allows the user to  cd into
the directory in question.

3.9.2 Interpreting file permissions

Let's look at an example to  demonstrate file permissions.   Using the
ls command with the -l option  will display a ``long'' listing  of the
file, including file permissions.

    /home/larry/foo# ls -l stuff


    -rw-r--r--   1 larry    users         505 Mar 13 19:05 stuff


    /home/larry/foo#

  The  first  field  printed  in  the  listing   represents  the  file
permissions.  The third  field is the owner  of the file (larry),  and
the fourth  field is  the group  to which  the  file belongs  (users).
Obviously, the last field is the  name of the file (stuff),  and we'll
cover the other fields later.
  This file is owned by larry, and belongs to the group  users.  Let's
look at the file permissions.  The string -rw-r--r-- lists,  in order,
the permissions granted  to the  file's owner, the  file's group,  and
everybody else.
  The first  character of  the permissions  string (``-'')  represents
the type  of  file.    A  ``-'' just  means  that  this is  a  regular
file (as opposed to  a directory or  device driver).   The next  three
letters (``rw-'')  represent the  permissions  granted to  the  file's
owner, larry.  The ``r'' stands for ``read'' and the  ``w'' stands for
``write''.   Thus, larry  has read  and write permission  to the  file
stuff.
  As we mentioned,  besides read and  write permission, there is  also
``execute'' permission---represented by an ``x''.   However, there  is
a ``-'' here  in place  of the ``x'',  so Larry  doesn't have  execute
permission on this file.  This is fine, the file stuff isn't a program
of any kind.   Of course,  because Larry owns the  file, he may  grant
himself execute permission for the file  if he so desires.   This will
be covered shortly.
3.9.   File Permissions                                            114
_______________________________________________________________________

  The next  three characters, r--,  represent the group's  permissions
on the file.  The group which  owns this file is users.   Because only
an ``r'' appears here, any user  which belongs to the group  users may
read this file.
  The  last three  characters,  also  r--, represent  the  permissions
granted to every other user on the system (other than the owner of the
file and those in the group users).   Again, because only an  ``r'' is
present, other users may read the file, but not write to it or execute
it.
  Here are some other examples of group permissions.

-rwxr-xr-x The  owner of the  file may  read, write,  and execute  the
           file.  Users in the file's group,  and all other users, may
           read and execute the file.

-rw------- The  owner of the  file may read  and write the  file.   No
           other user can access the file.
-rwxrwxrwx All users may read, write, and execute the file.


3.9.3 Dependencies

It is important to  note that the permissions  granted to a file  also
depend on  the permissions  of  the directory  in  which the  file  is
located.   For example,  even if a  file is set  to -rwxrwxrwx,  other
users cannot access the file unless they have read and  execute access
to the directory in which the file is located.  For  example, if Larry
wanted to restrict  access to all  of his files,  he could simply  set
the permissions on his home  directory /home/larry to -rwx------.   In
this way, no  other user has  access to his  directory, and all  files
and directories within  it.   Larry  doesn't need to  worry about  the
individual permissions on each of his files.
  In other  words, to  access a  file at  all, you  must have  execute
access to  all directories  along the  file's pathname,  and read  (or
execute) access to the file itself.
  Usually, users  on a  UNIX system  are very open  with their  files.
The usual set of permissions given to files is -rw-r--r--,  which will
allow other users to read the file, but not change it in any way.  The
usual set of  permissions given  to directories  is -rwxr-xr-x,  which
will allow  other users  to  look through  your directories,  but  not
create or delete files within them.
  However, many  users wish to  keep other users  out of their  files.
Setting the permissions  of a file  to -rw-------  will not allow  any
other user to access the file.  Likewise, setting the permissions of a
directory to -rwx------ will keep other users out of the  directory in
question.
3.10.   Managing file links                                        115
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3.9.4 Changing permissions

The command chmod is used to set the permissions on a file.   Only the
owner of a file may change the  permissions on that file.   The syntax
of chmod is:

    chmod {a,u,g,o}{+,-}{r,w,x} <filenames>

  Briefly,  you supply one  or more  of all,  user,  group, or  other.
Then you specify whether you are adding rights (+) or taking them away
(-).  Finally, you  specify one or more  of read, write, and  execute.
Some examples of legal commands are:

chmod a+r stuff
           Gives all users read access to the file.

chmod +r stuff
           Same as  above---if none of a, u,  g, or o is specified,  a
           is assumed.

chmod og-x stuff
           Remove execute permission from users other than the owner.

chmod u+rwx stuff
           Allow  the owner of  the file to  read, write, and  execute
           the file.
chmod o-rwx stuff
           Remove  read,  write,  and  execute permission  from  users
           other than the owner and users in the file's group.



3.10 Managing file links

Links allow you  to give  a single  file multiple  names.   Files  are
actually identified  to the  system by  their inode  number, which  is
just the unique filesystem  identifier for the  file(3).  A  directory
is actually  a  listing  of  inode numbers  with  their  corresponding
filenames.  Each  filename in a  directory is a  link to a  particular
inode.

3.10.1 Hard links

The ln command is  used to create  multiple links for  one file.   For
example, let's say that you have the  file foo in a directory.   Using
ls -i, we can look at the inode number for this file.

----------------------------
 3. The command ls -i will display file inode numbers.
3.10.   Managing file links                                        116
_______________________________________________________________________

    # ls -i foo
    22192 foo
    #

Here, the file foo has an inode number of 22192 in the filesystem.  We
can create another link to foo, named bar:

    # ln foo bar

With ls -i, we see that the two files have the same inode.

    # ls -i foo bar
    22192 bar   22192 foo
    #

Now, accessing either foo or  bar will access the  same file.  If  you
make changes to foo, those changes will  be made to bar as well.   For
all purposes, foo and bar are the same file.
  These links are known  as hard links because they directly  create a
link to an inode.  Note that you can only hard-link files  on the same
filesystem; symbolic links (see below) don't have this restriction.
  When you delete a  file with rm, you are actually only  deleting one
link to a file.  If you use the command

    # rm foo

then only the link named foo is deleted; bar will still exist.  A file
is only actually deleted  on the system  when it has  no links to  it.
Usually, files have only one link, so using the rm command deletes the
file.  However, if a file has multiple links to it, using rm will only
delete a single link; in order to delete the file, you must delete all
links to the file.
  The command ls -l will display the number of links  to a file (among
other information).

    # ls -l foo bar
    -rw-r--r--   2 root     root          12 Aug  5 16:51 bar
    -rw-r--r--   2 root     root          12 Aug  5 16:50 foo
    #

The second column in the listing, ``2'', specifies the number of links
to the file.
  As it  turns out,  a directory  is actually just  a file  containing
information about link-to-inode translations.   Also, every  directory
has at  least two  hard links  in it:   ``.''    (a  link pointing  to
itself), and ``..''  (a link  pointing to the parent directory).   The
root directory (/) ``..''  link just points back to /.
3.11.   Job Control                                                117
_______________________________________________________________________

3.10.2 Symbolic links

Symbolic links are another type of link, which are  somewhat different
than hard links.   A symbolic link allows  you to give a file  another
name, but it doesn't link the file by inode.
  The command  ln -s  will create  a symbolic  link to  a file.    For
example, if we use the command

    # ln -s foo bar

we will create the  symbolic link bar  pointing to the  file foo.   If
we use ls -i,  we will see that  the two files have different  inodes,
indeed.

    # ls -i foo bar
    22195 bar   22192 foo
    #

However, using ls -l, we see  that the file bar is a  symlink pointing
to foo.

    # ls -l foo bar
    lrwxrwxrwx   1 root     root           3 Aug  5 16:51  bar -> foo
    -rw-r--r--   1 root     root          12 Aug  5 16:50 foo
    #

  The permission  bits on a  symbolic link are  not used (they  always
appear as rwxrwxrwx).  Instead,  the permissions on the  symbolic link
are determined by the permissions  on the target of the  symbolic link
(in our example, the file foo).
  Functionally, hard links  and symbolic links are similar,  but there
are some differences.  For  one thing, you can create a  symbolic link
to a file which doesn't  exist; the same  is not true for hard  links.
Symbolic links are processed by the kernel differently than hard links
are, which is just a  technical difference but sometimes  an important
one.  Symbolic links are helpful because they identify  what file they
point to; with  hard links, there  is no easy  way to determine  which
files are linked to the same inode.
  Links are used in many  places on the Linux system.   Symbolic links
are especially important to  the shared library images  in /lib.   See
Section 4.7.2 for more information.


3.11 Job Control

3.11.1 Jobs and processes

Job control  is a  feature  provided by  many  shells (Bash  and  Tcsh
included) which allows  you to control  multiple running commands,  or
3.11.   Job Control                                                118
_______________________________________________________________________

jobs, at once.   Before  we can delve  much further,  we need to  talk
about processes.
  Every  time  you run  a  program,  you  start  what is  known  as  a
process---which is  just a  fancy name  for a  running program.    The
command ps displays a list of currently running processes.   Here's an
example:

    /home/larry# ps


      PID TT STAT  TIME COMMAND
       24  3 S     0:03 (bash)
      161  3 R     0:00 ps


    /home/larry#

The PID  listed  in the  first  column is  the  process ID,  a  unique
number given to  every running  process.   The  last column,  COMMAND,
is the name  of the  running command.    Here, we're  only looking  at
the processes which  Larry is currently  running(4).   These are  bash
(Larry's shell), and the ps command itself.   As you can see,  bash is
running concurrently with the ps command.  bash executed ps when Larry
typed the command.    After ps  is finished running  (after the  table
of processes is displayed), control  is returned to the  bash process,
which displays the prompt, ready for another command.
  A running  process  is known  as a  job to  the shell.    The  terms
process and job are  interchangeable.   However, a process is  usually
referred to as a ``job'' when used in conjunction with job control---a
feature of  the  shell which  allows  you  to switch  between  several
independent jobs.
  In most cases users  are only running a single job at  a time---that
being whatever command they last typed  to the shell.  However,  using
job control, you can run several jobs at once,  switching between them
as needed.  How might this be useful?  Let's say that you're editing a
text file and need to suddenly interrupt your editing and do something
else.  With job control,  you can temporarily suspend the editor,  and
back at the shell prompt start to work on something else.  When you're
done, you can start the editor back up, and be back where you started,
as if you never left the editor.  This is just one example.  There are
many practical uses for job control.

3.11.2 Foreground and background

Jobs can either be in the foreground or in the background.   There can
only be one job  in the foreground  at any one  time.  The  foreground

----------------------------
 4.  There  are  many  other  processes  running  on  the   system  as
well---``ps -aux'' lists them all.
3.11.   Job Control                                                119
_______________________________________________________________________

job is the job  which you interact  with---it receives input from  the
keyboard and sends  output to your  screen.   (Unless, of course,  you
have redirected input  or output, as  described in Section  3.8).   On
the other  hand, jobs  in the  background  do not  receive input  from
the terminal---in general,  they run  along quietly  without need  for
interaction.
  Some  jobs take  a  long  time  to finish,  and  don't  do  anything
interesting while they are  running.   Compiling programs is one  such
job, as is compressing a large file.  There's no reason why you should
sit around being bored while these jobs complete their tasks;  you can
just run them in the  background.  While  the jobs are running in  the
background, you are free to run other programs.
  Jobs may  also be  suspended.   A  suspended job  is a  job that  is
not currently running, but is temporarily stopped.   After you suspend
a job, you  can tell  the job to  continue, in  the foreground or  the
background as needed.   Resuming a suspended  job will not change  the
state of the job in  any way---the job will  continue to run where  it
left off.
  Note that  suspending  a job  is not  equal to  interrupting a  job.
When you interrupt a running  process (by hitting your interrupt  key,
which is usually [ctrl-C])(5), it kills  the process, for good.   Once
the job is  killed, there's  no hope of  resuming it;  you'll have  to
re-run the command.  Also note that some programs  trap the interrupt,
so that hitting [ctrl-C] won't immediately  kill the job.  This  is to
allow the program to perform  any necessary cleanup operations  before
exiting.  In fact, some  programs simply don't allow you to  kill them
with an interrupt at all.

3.11.3 Backgrounding and killing jobs

Let's begin with a  simple example.   The command  yes is a  seemingly
useless command  which sends  an  endless stream  of y's  to  standard
output.  (This  is actually useful.   If you  piped the output of  yes
to another command which asked a  series of yes and no questions,  the
stream of y's would confirm all of the questions.)
  Try it out.

    /home/larry# yes
    y
    y
    y
    y
    y


----------------------------
 5. The interrupt key can be set using the stty command.   The default
on most systems is [ctrl-C], but we can't guarantee the  same for your
system.
3.11.   Job Control                                                120
_______________________________________________________________________

The y's will  continue ad  infinitum.   You  can kill  the process  by
hitting your  interrupt key,  which is  usually [ctrl-C].  So that  we
don't have to put up with  the annoying stream of y's,  let's redirect
the standard  output  of yes  to  /dev/null.    As you  may  remember,
/dev/null acts as a ``black hole'' for data.  Any data sent to it will
disappear.  This is a  very effective method of quieting  an otherwise
verbose program.

    /home/larry# yes > /dev/null

Ah, much better.   Nothing  is printed, but  the shell prompt  doesn't
come back.  This is because yes is still running, and is sending those
inane y's to /dev/null.   Again,  to kill the  job, hit the  interrupt
key.
  Let's suppose  that we wanted  the yes command  to continue to  run,
but wanted to get our shell prompt  back to work on other things.   We
can put yes  into the  background,  which will  allow it  to run,  but
without need for interaction.
  One way  to put a process  in the background  is to append an  ``&''
character to the end of the command.

    /home/larry# yes > /dev/null &
    [1] 164
    /home/larry#

As you can  see, we  have our shell  prompt back.   But  what is  this
``[1] 164''?  And is the yes command really running?
  The ``[1]''  represents the  job number for  the yes  process.   The
shell assigns a job number to every  running job.  Because yes  is the
one and only  job that  we're currently  running, it  is assigned  job
number 1.  The ``164'' is the process ID, or PID, number  given by the
system to the job.  Either number may be used to refer to  the job, as
we'll see later.
  You  now   have  the   yes  process  running   in  the   background,
continuously sending a stream of  y's to /dev/null.   To check on  the
status of this process, use the shell internal command jobs.

    /home/larry# jobs
    [1]+  Running                 yes >/dev/null  &
    /home/larry#

Sure enough,  there it  is.   You  could also  use the  ps command  as
demonstrated above to check on the status of the job.
  To terminate  the job,  use the command  kill.   This command  takes
either a job number or a process  ID number as an argument.   This was
job number 1, so using the command

    /home/larry# kill %1

will kill the job.  When identifying the job with the  job number, you
3.11.   Job Control                                                121
_______________________________________________________________________

must prefix the number with a percent (``%'') character.
  Now that  we've killed the job,  we can use  jobs again to check  on
it:

    /home/larry# jobs


    [1]+  Terminated              yes >/dev/null


    /home/larry#

The job is in fact dead, and if we use the jobs  command again nothing
should be printed.
  You can also kill  the job using the process ID (PID)  number, which
is printed along  with the  job ID when  you start  the job.   In  our
example, the process ID is 164, so the command

    /home/larry# kill 164

is equivalent to

    /home/larry# kill %1

You don't need to use the ``%'' when referring to a job by its process
ID.

3.11.4 Stopping and restarting jobs

There is another way to put a job into the background.   You can start
the job normally (in the foreground),  stop the job, and  then restart
it in the background.
  First, start  the yes  process in  the foreground,  as you  normally
would:

    /home/larry# yes > /dev/null

Again, because yes  is running  in the foreground,  you shouldn't  get
your shell prompt back.
  Now, instead  of interrupting the  job with [ctrl-C], we'll  suspend
the job.  Suspending a job doesn't kill it:  it only temporarily stops
the job until you restart  it.  To do  this, you hit the  suspend key,
which is usually [ctrl-Z].

    /home/larry# yes > /dev/null
    [ctrl-Z]
    [1]+  Stopped                 yes >/dev/null
    /home/larry#

While the job is suspended, it's simply  not running.  No CPU  time is
3.11.   Job Control                                                122
_______________________________________________________________________

used for the job.  However, you can restart the job,  which will cause
the job to run again as if nothing ever happened.  It will continue to
run where it left off.
  To  restart the  job in  the  foreground, use  the  command fg  (for
``foreground'').

    /home/larry# fg
    yes >/dev/null

The shell prints  the name  of the  command again so  you're aware  of
which job you  just put  into the  foreground.   Stop  the job  again,
with [ctrl-Z]. This time, use the  command bg to put the job  into the
background.  This will cause the command to run just as if you started
the command with ``&'' as in the last section.

    /home/larry# bg
    [1]+ yes >/dev/null &
    /home/larry#

And we have our prompt  back.  jobs  should report that yes is  indeed
running, and we can kill the job with kill as we did before.
  How can we stop the  job again?  Using [ctrl-Z] won't  work, because
the job is in  the background.   The answer is to  put the job in  the
foreground, with fg, and then stop it.  As it turns out you can use fg
on either stopped jobs or jobs in the background.
  There is  a big  difference between a  job in  the background and  a
job which is stopped.   A stopped job is not running---it's  not using
any CPU time,  and it's  not doing  any work (the  job still  occupies
system memory, although it may be swapped out to disk).  A  job in the
background is running, and  using memory, as  well as completing  some
task while you do other  work.  However,  a job in the background  may
try to display  text on  to your terminal,  which can  be annoying  if
you're trying to work on something else.  For example, if you used the
command

    /home/larry# yes &

without redirecting  stdout to  /dev/null, a  stream of  y's would  be
printed to your screen, without any way of interrupting  it (you can't
use [ctrl-C] to interrupt jobs in  the background).  In order  to stop
the endless y's, you'd have to use the fg command, to bring the job to
the foreground, and then use [ctrl-C] to kill it.
  Another  note.    The fg  and  bg  commands normally  foreground  or
background the job which was  last stopped (indicated by a  ``+'' next
to the job number when you use the command jobs).  If  you are running
multiple jobs at once, you can foreground or background a specific job
by giving the job ID as an argument to fg or bg, as in

    /home/larry# fg %2
3.12.   Using the vi Editor                                        123
_______________________________________________________________________

(to foreground job number 2), or

    /home/larry# bg %3

(to background job number 3).   You can't use process ID  numbers with
fg or bg.
  Furthermore, using the job number alone, as in

    /home/larry# %2

is equivalent to

    /home/larry# fg %2

  Just remember  that using  job control  is a feature  of the  shell.
The commands fg, bg and jobs are  internal to the shell.  If  for some
reason you  use a  shell which  does not  support job  control,  don't
expect to find these commands available.
  In addition,  there are  some aspects  of job  control which  differ
between Bash and Tcsh.  In fact, some shells don't provide job control
at all---however, most shells available for Linux support job control.


3.12 Using the vi Editor

A text editor  is simply a  program used to  edit files which  contain
text, such as  a letter, C  program, or  a system configuration  file.
While there are many such editors available for Linux, the only editor
which you  are guaranteed  to find  on any  UNIX system  is vi---  the
``visual editor''.   vi is not  the easiest editor to  use, nor is  it
very self-explanatory.  However, because  it is so common in  the UNIX
world, and at times  you may be required to  use it, it deserves  some
documentation here.
  Your choice of an editor is mostly a question  of personal taste and
style.  Many users  prefer the baroque, self-explanatory  and powerful
Emacs---an editor with more features than any other single  program in
the UNIX world.   For example, Emacs  has its own built-in dialect  of
the LISP programming language, and  has many extensions (one  of which
is an ``Eliza''-like AI program).   However, because Emacs and  all of
its support files  are relatively large,  you may  not have access  to
it on many systems.   vi,  on the other hand,  is small and  powerful,
but more difficult to  use.   However, once you  know your way  around
vi, it's actually very  easy.  It's  just the learning curve which  is
sometimes difficult to cross.
  This section  is a  coherent introduction to  vi---we won't  discuss
all of  its features,  just  the ones  you  need to  know to  get  you
started.  You can  refer to the man  page for vi if you're  interested
in learning about more of  this editor's features.   Or, you can  read
the book Learning  the vi Editor  from O'Reilly and  Associates.   See
Appendix A for information.
3.12.   Using the vi Editor                                        124
_______________________________________________________________________

3.12.1 Concepts

While using vi,  at any  one time  you are  in one of  three modes  of
operation.  These  modes are known as  command mode, insert mode,  and
last line mode.
  When you start  up vi, you  are in command mode.   This mode  allows
you to use certain commands to edit files or to change to other modes.
For example, typing ``x'' while in command mode deletes  the character
underneath the cursor.  The arrow keys move the cursor around the file
which you're editing.   Generally, the  commands used in command  mode
are one or two characters long.
  You actually  insert or edit  text within insert mode.   When  using
vi, you'll probably  spend most of your  time within this  mode.   You
start insert mode by  using a command  such as ``i'' (for  ``insert'')
from command mode.  While in insert mode, you are  inserting text into
the document from your  current cursor location.   To end insert  mode
and return to command mode, press [esc].
  Last line  mode  is a  special mode  used to  give certain  extended
commands to vi.  While typing these commands, they appear  on the last
line of the screen (hence the name).  For example, when you type ``:''
from command mode, you jump into last line mode, and  can use commands
such as ``wq'' (to write  the file and quit vi),  or ``q!''   (to quit
vi without saving changes).   Last line mode is generally used  for vi
commands which are longer than one character.  In last  line mode, you
enter a single-line command and press [enter] to execute it.

3.12.2 Starting vi

The best way to  understand these concepts is  to actually fire up  vi
and edit a file.   In the example ``screens'' below, we're  only going
to show a few lines of text, as if the screen was only  six lines high
(instead of twenty-four).
  The syntax for vi is

    vi <filename>

where <filename> is the name of the file that you wish to edit.
  Start up vi by typing

    /home/larry# vi test

which will edit the file test.  You should see something like

 ____________________________________________________________________
 |~_                                                                 |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |"test"_[New_file]__________________________________________________|

3.12.   Using the vi Editor                                        125
_______________________________________________________________________

  The column  of ``~'' characters  indicates that you  are the end  of
the file.

3.12.3 Inserting text

You are now in command  mode; in order  to insert text into the  file,
press [i] (which will place you into insert mode), and begin typing.

  ____________________________________________________________________
 |Now is the time for all good men to come to the aid of the party._ |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

  While  inserting text,  you  may  type as  many  lines as  you  wish
(pressing [return]  after  each,  of  course),  and  you  may  correct
mistakes using the backspace key.
  To end insert mode, and return to command mode, press [esc].
  While in  command mode, you  can use the arrow  keys to move  around
the file.  Here, because we only have one line of text,  trying to use
the up- or down-arrow keys will probably cause vi to beep at you.
  There  are several  ways to  insert  text, other  than  using the  i
command.  For example, the a command inserts text  beginning after the
current cursor position,  instead of on  the current cursor  position.
For example, use  the left arrow  key to move  the cursor between  the
words ``good'' and ``men''.

  ____________________________________________________________________
 |Now is the time for all good_men to come to the aid of the party.  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

Press [a], to start  insert mode, type ``wo'',  and then hit [esc]  to
return to command mode.

  ____________________________________________________________________
  |Now is the time for all good women to come to the aid of the party.|
  |~                                                                  |
  |~                                                                  |
  |~                                                                  |
  |~                                                                  |
  |~__________________________________________________________________|

  To begin inserting text  at the line below the current one,  use the
o command.  For example, press [o] and type another line or two:
3.12.   Using the vi Editor                                        126
_______________________________________________________________________

  ____________________________________________________________________
 |Now is the time for all good women to come to the aid of the party.|
 |Afterwards, we'll go out for pizza and beer._                      |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

  Just  remember that  at  any  time  you're either  in  command  mode
(where commands such  as i,  a, or  o are  valid), or  in insert  mode
(where you're inserting text, followed  by [esc] to return  to command
mode), or last line mode (where you're entering extended  commands, as
discussed below).

3.12.4 Deleting text

From command  mode, the  x  command deletes  the  character under  the
cursor.  If you press [x] five times, you'll end up with:

  ____________________________________________________________________
 |Now is the time for all good women to come to the aid of the party.|
 |Afterwards, we'll go out for pizza and _                           |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

Now press [a], insert some text, followed by [esc]:
  ____________________________________________________________________
 |Now is the time for all good women to come to the aid of the party.|
 |Afterwards, we'll go out for pizza and Diet Coke._                 |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

  You can  delete entire lines  using the command  dd (that is,  press
[d] twice in a row).   If your cursor is  on the second line,  and you
type dd,
  ____________________________________________________________________
 |Now is the time for all good women to come to the aid of the party.|
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|
3.12.   Using the vi Editor                                        127
_______________________________________________________________________

  To delete  the word  which the  cursor is  on, use  the dw  command.
Place the cursor on the word ``good'', and type dw.
  ____________________________________________________________________
 |Now is the time for all women to come to the aid of the party.     |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

3.12.5 Changing text

You can replace  sections of  text using  the R  command.   Place  the
cursor on the first letter in ``party'', press [R], and  type the word
``hungry''.

  ____________________________________________________________________
 |Now is the time for all women to come to the aid of the hungry._   |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

Using R  to edit  text  is much  like  the i  and  a commands,  but  R
overwrites text, instead of inserting it.
  The r command replaces  the single character under the cursor.   For
example, move the  cursor to the  beginning of  the word ``Now'',  and
type r followed by C, you'll have:

  ____________________________________________________________________
 |Cow is the time for all women to come to the aid of the hungry._   |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

  The ``~'' command  changes the case of  the letter under the  cursor
from upper- to lower-case, and vise  versa, For example, if  you place
the cursor on the ``o'' in  ``Cow'', above, and repeatedly  press [~],
you'll end up with:
3.12.   Using the vi Editor                                        128
_______________________________________________________________________

  ____________________________________________________________________
 |COW IS THE TIME FOR ALL WOMEN TO COME TO THE AID OF THE HUNGRY.    |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~__________________________________________________________________|

3.12.6 Moving commands

You already  know  how  to use  the  arrow  keys to  move  around  the
document.   In addition,  you  can use the  h,  j, k,  and l  commands
to move the  cursor left,  down, up,  and right,  respectively.   This
comes in handy when (for  some reason) your arrow keys  aren't working
correctly.
  The w command  moves the cursor to  the beginning of the next  word;
the b moves it to the beginning of the previous word.
  The 0 (that's a  zero) command moves the cursor to the  beginning of
the current line, and the $ command moves it to the end of the line.
  When editing large files, you'll want to move  forwards or backwards
through the file a screenful at  a time.  Pressing [ctrl-F]  moves the
cursor one screenful forward, and [ctrl-B] moves it a screenful back.
  In order  to move the  cursor to the  end of the  file, type G.  You
can also move to  an arbitrary line;  for example, typing the  command
10G would move the  cursor to line  10 in the  file.   To move to  the
beginning of the file, use 1G.
  You  can  couple  moving  commands  with  other  commands,  such  as
deletion.  For example, the command d$ will delete everything from the
cursor to the  end of  the line;  dG will delete  everything from  the
cursor to the end of the file, and so on.

3.12.7 Saving files and quitting vi

To quit vi without  making changes to the  file, use the command  :q!.
When you type the ``:'', the cursor will move to the last  line on the
screen; you'll be in last line mode.

  ____________________________________________________________________
 |COW IS THE TIME FOR ALL WOMEN TO COME TO THE AID OF THE HUNGRY.    |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |:__________________________________________________________________|

In last line mode,  certain extended commands are  available.  One  of
them is q!, which quits vi without saving.  The command  :wq saves the
file and then exits vi.   The command  ZZ (from command mode,  without
3.12.   Using the vi Editor                                        129
_______________________________________________________________________

the ``:'')   is  equivalent to  :wq.   Remember  that  you must  press
[enter] after a command entered in last line mode.
  To save the file without quitting vi, just use :w.

3.12.8 Editing another file

To edit  another file,  use the  :e command.    For  example, to  stop
editing test, and edit the file foo instead, use the command

  ____________________________________________________________________
 |COW IS THE TIME FOR ALL WOMEN TO COME TO THE AID OF THE HUNGRY.    |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |:e foo_____________________________________________________________|

If you use  :e without  saving the file  first, you'll  get the  error
message
 ____________________________________________________________________
 |No_write_since_last_change_(":edit!"_overrides)____________________|

which simply means  that vi doesn't  want to  edit another file  until
you save the first  one.  At  this point, you can  use :w to save  the
original file, and then use :e, or you can use the command
  ____________________________________________________________________
 |COW IS THE TIME FOR ALL WOMEN TO COME TO THE AID OF THE HUNGRY.    |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |~                                                                  |
 |:e! foo_____________________________________________________________|

The ``!''    tells vi  that you  really mean  it---edit  the new  file
without saving changes to the first.


3.12.9 Including other files

If you use  the :r command,  you can include  the contents of  another
file in the current file.  For example, the command

    :r foo.txt

would insert  the contents  of the  file foo.txt  in the  text at  the
current cursor location.
3.13.   Customizing your Environment                               130
_______________________________________________________________________

3.12.10 Running shell commands

You can also  run shell commands  from within vi.   The  :r!   command
works like :r, but instead of reading a file, it inserts the output of
the given command into the buffer at the current cursor location.  For
example, if you use the command

    :r!  ls -F

you'll end up with

  ____________________________________________________________________
 |COW IS THE TIME FOR ALL WOMEN TO COME TO THE AID OF THE HUNGRY.    |
 |letters/                                                           |
 |misc/                                                              |
 |papers/_                                                           |
 |~                                                                  |
 |~__________________________________________________________________|

  You can  also ``shell out''  of vi,  in other words,  run a  command
from within  vi, and  return to  the editor  when  you're done.    For
example, if you use the command

    :!  ls -F

the ls -F command will be  executed, and the results displayed  on the
screen, but not inserted into the  file which you're editing.   If you
use the command

    :shell

vi will start an  instance of the  shell, allowing you to  temporarily
put vi ``on hold'' while you  execute other commands.  Just  logout of
the shell (using the exit command) to return to vi.

3.12.11 Getting help

vi doesn't provide  much in  the way  of interactive  help (most  UNIX
programs don't), but you can always read the man page for vi.  vi is a
visual front-end to the ex editor; it is ex which handles  many of the
last-line mode commands in  vi.   So, in addition  to reading the  man
page for vi, see ex as well.


3.13 Customizing your Environment

The shell provides many mechanisms to customize your work environment.
As  we've  mentioned  before,  the  shell  is  more   than  a  command
interpreter---it is  also  a powerful  programming  language.    While
writing shell scripts is an extensive subject, we'd like  to introduce
3.13.   Customizing your Environment                               131
_______________________________________________________________________

you to some  of the ways  that you can  simplify your  work on a  UNIX
system by using these advanced features of the shell.
  As  we  have  mentioned  before,   different  shells  use  different
syntaxes when  executing shell  scripts.   For  example,  Tcsh uses  a
C-like syntax, while  Bourne shells use  another type of  syntax.   In
this section, we won't be running into many of the differences between
the two, but we will assume that shell scripts are  executed using the
Bourne shell syntax.

3.13.1 Shell scripts

Let's say that you use a  series of commands often, and would  like to
shorten the amount of required typing by grouping all of them together
into a single ``command''.  For example, the commands

    /home/larry# cat chapter1 chapter2 chapter3 > book
    /home/larry# wc -l book
    /home/larry# lp book

would concatenate the files chapter1, chapter2, and chapter3 and place
the result in the file book.  Then, a count of the number  of lines in
book would be displayed, and finally book would be printed with the lp
command.
  Instead of typing all  of these commands, you could group  them into
a shell script.  We described shell scripts briefly in Section 3.13.1.
The shell script used to run all of these commands would look like

    #!/bin/sh
    # A shell script to create and print the book

    cat chapter1 chapter2 chapter3 > book
    wc -l book
    lp book

If this script was  saved in the file  makebook, you could simply  use
the command

    /home/larry# makebook

to run all  of the commands  in the script.    Shell scripts are  just
plain text files; you can create them with an editor such  as emacs or
vi (6).
  Let's look  at this shell  script.   The first line,  ``#!/bin/sh'',
identifies the file  as a  shell script,  and tells the  shell how  to
execute the script.    It instructs the  shell to  pass the script  to
/bin/sh for  execution, where  /bin/sh is  the  shell program  itself.
Why is  this  important?     On  most  UNIX  systems,   /bin/sh  is  a

----------------------------
 6. vi is covered in Section 3.12.
   3.13.   Customizing your Environment                               132
   _______________________________________________________________________

   Bourne-type shell,  such as  Bash.   By  forcing the  shell script  to
   run using /bin/sh, we  are ensuring that the  script will run under  a
   Bourne-syntax shell (instead  of, say, a  C shell).   This will  cause
   your script to run using  the Bourne syntax even  if you use Tcsh  (or
   another C shell) as your login shell.
     The second  line is a  comment.  Comments  begin with the  character
   ``#'' and continue to the  end of the line.   Comments are ignored  by
   the shell---they are commonly used to identify the shell script to the
   programmer.
     The rest of the lines in the script are just  commands, as you would
   type them to the shell directly.  In effect, the shell reads each line
   of the script and runs that line  as if you had typed it at  the shell
   prompt.
     Permissions are important for shell scripts.  If  you create a shell
   script, you must  make sure that  you have  execute permission on  the
   script in order to run it(7).  The command

       /home/larry# chmod u+x makebook

   can be used to  give yourself execute  permission on the shell  script
   makebook.

   3.13.2 Shell variables and the environment

   The shell  allows  you  to  define  variables,   as  most  programming
   languages do.  A variable is  just a piece of data which is  given the
   name.
!    Note that  Tcsh, as  well as  other C-type shells,  use a  different
   mechanism for  setting  variables  than  is  described  here.     This
   discussion assumes the  use of  a Bourne  shell, such  as Bash  (which
   you're probably using).  See the Tcsh man page for details.
     When you assign  a value to a  variable (using the ``=''  operator),
   you can access  the variable  by prepending  a ``$''  to the  variable
   name, as demonstrated below.

       /home/larry# foo=``hello there''

   The variable foo  is given  the value ``hello  there''.   You can  now
   refer to  this value  by  the variable  name,  prefixed with  a  ``$''
   character.  The command

       /home/larry# echo $foo
       hello there
       /home/larry#

   produces the same results as

   ----------------------------
    7. When you create text files, the default permissions  usually don't
   include execute permission.
   3.13.   Customizing your Environment                               133
   _______________________________________________________________________

       /home/larry# echo ``hello there''
       hello there
       /home/larry#

     These variables  are internal to  the shell.   This means that  only
   the shell can access  these variables.   This can  be useful in  shell
   scripts; if you need to keep track of a filename, for example, you can
   store it in a variable, as above.  Using the command  set will display
   a list of all defined shell variables.
     However,   the  shell  allows  you   to  export  variables  to   the
   environment.   The  environment  is the  set  of variables  which  all
   commands that you execute have access to.  Once you  define a variable
   inside the  shell,  exporting  it  makes  that variable  part  of  the
   environment as well.  The export command is used to  export a variable
   to the environment.
!    Again, here we differ between Bash and Tcsh.   If you're using Tcsh,
   another syntax is used for  setting environment variables (the  setenv
   command is used).  See the Tcsh man page for more information.
     The environment  is very important  to the UNIX system.   It  allows
   you to configure certain commands just by setting variables  which the
   commands know about.
     Here's a quick example.   The environment variable PAGER is  used by
   the man command.    It specifies  the command  to use  to display  man
   pages one screenful at a time.   If you set PAGER to be the name  of a
   command, it will use that command to display the man pages, instead of
   more (which is the default).
     Set  PAGER to  ``cat''.    This will  cause output  from  man to  be
   displayed to  the screen  all at  once,  without breaking  it up  into
   pages.

       /home/larry# PAGER=``cat''

   Now, export PAGER to the environment.

       /home/larry# export PAGER

   Try the command  man ls.   The man  page should  fly past your  screen
   without pausing for you.
     Now, if we set PAGER  to ``more'', the more command will be  used to
   display the man page.

       /home/larry# PAGER=``more''

   Note that we  don't have  to use  the export command  after we  change
   the value  of PAGER.  We only  need  to export  a variable  once;  any
   changes made to it thereafter will automatically be propagated  to the
   environment.
     The man pages for a particular command will tell  you if the command
   uses any environment variables; for example, the man man page explains
   that PAGER  is used  to  specify the  pager command.    Some  commands
3.13.   Customizing your Environment                               134
_______________________________________________________________________

share environment variables; for example, many commands use the EDITOR
environment variable to specify the default editor to use when  one is
needed.
  The environment is also used to keep track  of important information
about your  login  session.     An example  is  the  HOME  environment
variable, which contains the name of your home directory.

    /home/larry/papers# echo $HOME
    /home/larry

  Another interesting environment  variable is PS1, which  defines the
main shell prompt.  For example,

    /home/larry# PS1=``Your command, please:  ''
    Your command, please:

To set  the prompt  back  to our  usual  (which contains  the  current
working directory followed by a ``#'' symbol),

    Your command, please:  PS1=``\w# ''
    /home/larry#

The bash man page describes the syntax used for setting the prompt.

3.13.2.1 The PATH environment variable

When you use the ls command, how does the shell find the ls executable
itself?  In fact, ls is found  in /bin/ls on most systems.   The shell
uses the  environment variable  PATH to  locate  executable files  for
commands which you type.
  For example, your PATH variable may be set to:

    /bin:/usr/bin:/usr/local/bin:.

This is a list of directories for the shell to search,  each directory
separated by a ``:''.   When you use  the command ls, the shell  first
looks for /bin/ls, then /usr/bin/ls, and so on.
  Note that  the PATH has  nothing to do  with finding regular  files.
For example, if you use the command

    /home/larry# cp foo bar

The shell does not  use PATH to locate  the files foo and  bar---those
filenames are assumed to  be complete.   The shell  only uses PATH  to
locate the cp executable.
  This saves  you a  lot of  time;  it means  that you  don't have  to
remember where all  of the command  executables are stored.   On  many
systems, executables  are  scattered about  in  many places,  such  as
/usr/bin, /bin, or  /usr/local/bin.  Instead  of giving the  command's
full pathname (such as  /usr/bin/cp), you can  simply set PATH to  the
3.14.   So You Want to Strike Out on Your Own?                     135
_______________________________________________________________________

list of directories that you want the shell to automatically search.
  Notice  that PATH  contains  ``.'',  which  is the  current  working
directory.  This allows  you to create a  shell script or program  and
run it as  a command from  your current  directory, without having  to
specify it directly (as in ./makebook).  If a directory  isn't on your
PATH, then the  shell will not  search it  for commands to  run---this
includes the current directory.

3.13.3 Shell initialization scripts

In addition  to shell  scripts that  you create,  there  are a  number
of scripts  that the  shell itself  uses for  certain purposes.    The
most important  of  these  are your  initialization  scripts,  scripts
automatically executed by the shell when you login.
  The initialization scripts  themselves are simply shell scripts,  as
described above.   However, they  are very useful  in setting up  your
environment by executing commands automatically  when you login.   For
example, if you always  use the mail command  to check your mail  when
you login, you place the  command in your initialization script  so it
will be executed automatically.
  Both  Bash and  Tcsh distinguish  between a  login  shell and  other
invocations of the shell.  A  login shell is a shell invoked  at login
time; usually,  it's the only  shell which  you'll use.   However,  if
you ``shell out'' of  another program, such  as vi, you start  another
instance of the  shell, which isn't  your login shell.   In  addition,
whenever you  run  a shell  script,  you automatically  start  another
instance of the shell to execute the script.
  The initialization  files used by  Bash are:   /etc/profile (set  up
by the  system administrator,  executed  by all  Bash  users at  login
time), $HOME/.bash_profile (executed  by a  login Bash  session),  and
$HOME/.bashrc (executed  by all  non-login  instances of  Bash).    If
.bash_profile is not present, .profile is used instead.
  Tcsh  uses the  following  initialization scripts:    /etc/csh.login
(executed by all  Tcsh users at  login time), $HOME/.tcshrc  (executed
a login  time and  by all  new instances  of Tcsh),  and  $HOME/.login
(executed at  login time,  following  .tcshrc).    If .tcshrc  is  not
present, .cshrc is used instead.
  To fully  understand the  function of  these files,  you'll need  to
learn more about the shell itself.  Shell programming is a complicated
subject, far  beyond  the scope  of this  book.    See the  man  pages
for bash  and/or  tcsh to  learn  more  about customizing  your  shell
environment.


3.14 So You Want to Strike Out on Your Own?

Hopefully we have provided enough information to give you a basic idea
of how to use the system.   Keep in mind that most of  the interesting
and important aspects  of Linux  aren't covered  here---these are  the
very basics.    With this  foundation, before  long you'll  be up  and
3.14.   So You Want to Strike Out on Your Own?                     136
_______________________________________________________________________

running complicated applications and fulfilling the potential  of your
system.  If things don't seem exciting at first, don't despair---there
is much to be learned.
  One indispensable  tool for  learning about  the system  is to  read
the man pages.   While many of the  man pages may appear confusing  at
first, if you dig beneath the surface there is a wealth of information
contained therein.
  We also  suggest reading  a complete  book on using  a UNIX  system.
There is much more to UNIX than meets the eye---unfortunately, most of
it is beyond the scope of this book.  Some good UNIX books  to look at
are listed in Appendix A.








Chapter 4




System Administration



This chapter is an overview to Linux system  administration, including
a number  of advanced  features which  aren't  necessarily for  system
administrators only.   Just  as every dog  has its  day, every  system
has its administrator, and running the system is a  very important and
sometimes time-consuming job,  even if  you're the only  user on  your
system.
  We have tried to  cover here the most important things  about system
administration you  need to  know when  you use  Linux, in  sufficient
detail to get you comfortably started.  In order to keep  it short and
sweet, we have only covered the very basics, and have  skipped many an
important detail.   You should read  the Linux System  Administrator's
Guide if  you are  serious about  running Linux.    It  will help  you
understand better how  things work, and  how they hang  together.   At
least skim through it so that you know what it contains  and know what
kind of help you can expect from it.

4.1  About Root, Hats, and the Feeling of Power

As you  know, UNIX  differentiates between  different users,  so  that
what they do to  each other and  to the system  can be regulated  (one
wouldn't want  anybody to  be able  to read  one's love  letters,  for
instance).  Each user is given an account, which  includes a username,
home directory, and  so on.   In  addition to  accounts given to  real
people, there are special  system-defined accounts which have  special
privileges.  The most important of these is the root  account, for the
username root.


4.1.1 The root account

Ordinary users are generally restricted so that they can't do  harm to
anybody else on  the system,  just to  themselves.   File  permissions
on the system are  arranged such that  normal users aren't allowed  to
delete or modify  files in directories  shared by  all users (such  as
/bin and  /usr/bin.   Most  users also  protect their  own files  with
the appropriate file permissions so  that other users can't access  or

                                 137
4.1.     About Root, Hats, and the Feeling of Power                138
_______________________________________________________________________

modify those files.
  There are  no such restrictions on  root.   The user root can  read,
modify, or  delete any  file  on the  system,  change permissions  and
ownerships on any file, and run special programs, such  as those which
partition the drive or create filesystems.  The basic idea is that the
person or persons who run and take care of the system logs  in as root
whenever it is necessary to  perform tasks that cannot be  executed as
a normal user.    Because root  can do anything,  it is  easy to  make
mistakes that have catastrophic consequences when logged in using this
account.
  For example,  as  a normal  user,  if you  inadvertently attempt  to
delete all of the files in /etc, the system will not permit  you to do
so.  However,  when logged in  as root, the  system won't complain  at
all.  It is very easy to trash your system when using root.   The best
way to prevent accidents is to:

 o  Sit on your  hands before you  press [return]  on a command  which
    may cause damage.   For example,  if you're about  to clean out  a
    directory, before hitting [return], re-read the entire command and
    make sure that it is correct.

 o  Don't get accustomed to using root.  The more  comfortable you are
    in the role of the root  user, the more likely you are  to confuse
    your privileges with  those of a  normal user.   For example,  you
    might think that  you're logged  in as larry,  when you're  really
    logged in as root.

 o  Use a different prompt  for the root account.   You should  change
    root's .bashrc or .login file to set the shell prompt to something
    other than your regular user prompt.  For example, many people use
    the character ``$'' in prompts for regular users, and  reserve the
    character ``#'' for the root user prompt.

 o  Only login as  root when absolutely  necessary.   And, as soon  as
    you're finished with your work as root, log out.  The less you use
    the root account, the less likely  you'll be to do damage  on your
    system.

Of course, there is a breed of UNIX hackers out there who use root for
virtually everything.  But every one of them has, at  some point, made
a silly mistake as root and trashed the system.  The  general rule is,
until you're familiar with the lack  of restrictions on root,  and are
comfortable using the system without such restrictions, login  as root
sparingly.
  Of course,  everyone makes  mistakes.   Linus Torvalds himself  once
accidentally deleted the entire kernel  directory tree on his  system.
Hours of work were lost forever.  Fortunately, however, because of his
knowledge of the filesystem code, he was able to reboot the system and
reconstruct the directory tree by hand on disk.
  Put another way, if you picture using the root  account as wearing a
4.1.     About Root, Hats, and the Feeling of Power                139
_______________________________________________________________________

special magic hat that gives  you lots of power,  so that you can,  by
waving your hand,  destroy entire cities,  it is a good  idea to be  a
bit careful about what you  do with your hands.   Since it is  easy to
move your hand in a destructive way by accident, it is not a good idea
to wear the  magic hat when  it is not  needed, despite the  wonderful
feeling.

4.1.2 Abusing the system

Along with  the  feeling of  power  comes  the tendency  to  do  harm.
This is  one of  the grey  areas of  UNIX system  administration,  but
everyone goes through it at  some point in time.   Most users of  UNIX
systems never have  the ability  to wield  this power---on  university
and business UNIX systems,  only the highly-paid and  highly-qualified
system administrators  ever login  as root.    In fact,  at many  such
institutions, the root  password is a  highly guarded  secret:  it  is
treated as the  Holy Grail  of the  institution.   A  large amount  of
hubbub is made about logging in as root; it is portrayed as a wise and
fearsome power, given only to an exclusive cabal.
  This kind  of attitude towards  the root  account is, quite  simply,
the kind of thing which breeds  malice and contempt.  Because  root is
so fluffed-up, when some users  have their first opportunity  to login
as root (either on  a Linux system or  elsewhere), the tendency is  to
use root's privileges  in a harmful  manner.   I have known  so-called
``system administrators'' who  read other user's  mail, delete  user's
files without warning, and  generally behave like children when  given
such a powerful ``toy''.
  Because root has  such privilege on the  system, it takes a  certain
amount of  maturity and  self-control to  use the  account  as it  was
intended---to run the  system.   There  is an unspoken  code of  honor
which exists  between  the  system  administrator  and  the  users  on
the system.    How would  you feel  if your  system administrator  was
reading your e-mail or  looking over your  files?   There is still  no
strong legal precedent for electronic privacy on time-sharing computer
systems.  On  UNIX systems, the  root user has  the ability to  forego
all security and privacy  mechanisms on the system.   It is  important
that the system administrator develop a trusting relationship with the
users on the system.  I can't stress that enough.

4.1.3 Dealing with users

UNIX security is rather lax by design.  Security on the  system was an
afterthought---the system was originally  developed in an  environment
where users intruding upon other users was simply unheard of.  Because
of this, even with security  measures, there is still the  ability for
normal users to do harm.
  System  administrators  can  take  two  stances  when  dealing  with
abusive users:  they can be either paranoid or trusting.  The paranoid
system administrator usually causes more harm than he or she prevents.
One of my favorite  sayings is, ``Never  attribute to malice  anything
4.1.     About Root, Hats, and the Feeling of Power                140
_______________________________________________________________________

which can be attributed to stupidity.''   Put another way,  most users
don't have the  ability or knowledge  to do real  harm on the  system.
90% of the time, when a user is causing trouble on the system (by, for
instance, filling up the user  partition with large files,  or running
multiple instances of  a large  program), the user  is simply  unaware
that what he or she is doing is a problem.  I have  come down on users
who were causing a great deal of trouble, but they  were simply acting
out of ignorance---not malice.
  When you deal  with users who  are causing potential trouble,  don't
be accusative.  The old rule of ``innocent until proven guilty'' still
holds.   It is best  to simply talk  to the  user, and question  about
the trouble, instead of causing a  confrontation.  The last  thing you
want to do  is be  on the  user's bad  side.   This will  raise a  lot
of suspicion about you---the system administrator---running the system
correctly.  If a user believes that you distrust or dislike them, they
might accuse you of deleting files or breaching privacy on the system.
This is certainly not the kind of position that you want to be in.
  If you  do find  that a user  has been  attempting to ``crack''  the
system, or was intentionally  doing harm to  the system, don't  return
the malicious  behavior with  malice of  your own.    Instead,  simply
provide a warning---but be flexible.   In many cases, you may  catch a
user ``in the act'' of doing harm to the system---give them a warning.
Tell them not to let it happen  again.  However, if you do  catch them
causing harm again,  be absolutely  sure that  it is intentional.    I
can't even begin  to describe the  number of  cases where it  appeared
as though a user was  causing trouble, when  in fact it was either  an
accident or a fault of my own.

4.1.4 Setting the rules

The best way  to run a  system is  not with an  iron fist.   That  may
be how  you run  the military,  but  UNIX was  not  designed for  such
discipline.  It makes sense to  lay down a simple and flexible  set of
guidelines for users---but  remember, the  fewer rules  you have,  the
less chance there is of breaking them.   Even if your rules  for using
the system are perfectly  reasonable and clear,  users will always  at
times break these rules without intending to.  This is especially true
in the case of new UNIX users, who are just learning the  ropes of the
system.  It's  not patently obvious,  for example, that you  shouldn't
download a gigabyte of files and mail them to everyone  on the system.
Users need help understanding the rules, and why they are there.
  If you do specify  usage guidelines for your system, make  sure that
the reason behind a particular guideline is made clear.  If you don't,
then users will  find all  sorts of  creative ways to  get around  the
rule, and not know that they are in fact breaking it.

4.1.5 What it all means

We can't tell you how to run your system to the last detail.   Most of
the philosophy depends on how  you're using the system.   If you  have
4.2.     Booting the System                                        141
_______________________________________________________________________

many users, things  are much  different than  if you only  have a  few
users, or if you're the only user on the system.  However, it's always
a good idea---in any situation---to  understand what being the  system
administrator really means.
  Being  the system  administrator  doesn't make  you a  UNIX  wizard.
There are many  system admins  out there  who know  very little  about
UNIX. Likewise, there  are many  ``normal'' users out  there who  know
more about UNIX than any system administrator could.  Also,  being the
system administrator does  not allow  you to use  malice against  your
users.  Just because the  system gives you the privilege to  mess with
user files does not mean that you have any right to do so.
  Lastly, being  the system  administrator is really  not a big  deal.
It  doesn't  matter  if  your  system  is  a  little  386  or  a  Cray
supercomputer.  Running the system  is the same, regardless.   Knowing
the root password  isn't going to  earn you money  or fame.   It  will
allow you to maintain the system, and keep it running.  That's it.


4.2  Booting the System

There are several ways to boot the system, either from  floppy or from
the hard drive.

4.2.1 Using a boot floppy

Many people boot Linux using  a ``boot floppy'' which contains  a copy
of the Linux kernel.   This kernel has the Linux root  partition coded
into it, so it will know where to look on the hard drive  for the root
filesystem.  (The rdev command  can be used to set the  root partition
in the kernel image; see below.)   This is the type of  floppy created
by Slackware during installation, for example.
  To create  your own boot  floppy, first locate  the kernel image  on
your hard disk.  It should be in the file /Image or /etc/Image.   Some
installations use the file /vmlinux for the kernel.
  You may  instead  have a  compressed kernel.    A compressed  kernel
uncompresses itself into memory at boot  time, and takes up  much less
space on the hard drive.   If you have a compressed kernel, it  may be
found in the file /zImage or /etc/zImage.
  Once you  know  where the  kernel is,  set  the root  device in  the
kernel image to the  name of your Linux  root partition with the  rdev
command.  The format of the command is

    rdev <kernel-name> <root-device>

where <kernel-name> is the name of the  kernel image, and <root-device>
is the name of the Linux root partition.  For example, to set the root
device in the kernel /etc/Image to /dev/hda2, use the command

    # rdev /etc/Image /dev/hda2
4.2.   Booting the System                                          142
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  rdev can  set  other options  in the  kernel as  well,  such as  the
default SVGA mode to use at boot time.  Just use ``rdev -h''  to get a
help message.
  After setting the root device, you can simply  copy the kernel image
to the floppy.  Whenever copying data to a floppy, it's a good idea to
MS-DOS format the floppy first.   This lays down the sector  and track
information on the floppy, so it can be detected as either high or low
density.
  For  example, to  copy the  kernel  in the  file  /etc/Image to  the
floppy in /etc/fd0, use the command

    # cp /etc/Image /dev/fd0

  This floppy should now boot Linux.

4.2.2 Using LILO

Another method of booting is to  use LILO, a program which  resides in
the boot sector of your hard disk.  This program is  executed when the
system is booted  from the hard  disk, and  can automatically boot  up
Linux from a kernel image stored on the hard drive itself.
  LILO can  also  be used  as a  first-stage boot  loader for  several
operating systems, allowing you to select at boot time which operating
system (such  as Linux  or  MS-DOS) to  boot.    When you  boot  using
LILO, the default operating system is booted unless you  press [ctrl],
[alt], or [shift]  during the bootup sequence.   If  you press any  of
these keys, you  will be  provided with  a boot prompt,  at which  you
type the name of  the operating system to  boot (such as ``linux''  or
``msdos'').   If you  press [tab]  at the  boot prompt,  a listing  of
available operating systems will be provided.
  The easy  way to  install LILO  is to edit  the configuration  file,
/etc/lilo.conf, and then run the command

    # /sbin/lilo

  The  LILO  configuration   file  contains  a  ``stanza''  for   each
operating system that you want to  boot.  The best way  to demonstrate
this is with an example  LILO config file.   The below setup is  for a
system which has a  Linux root partition  on /dev/hda1, and an  MS-DOS
partition on /dev/hda2.

    # Tell LILO to modify the boot record on /dev/hda (the first
    #                                                             non-
    SCSI hard drive). If you boot from a drive other than /dev/hda,
    # change the following line.
    boot = /dev/hda

    #  Name  of  the  boot  loader.  No  reason  to  modify  this  un-
    less you're doing
    # some serious hacking on LILO.
4.3.   Shutting Down                                               143
_______________________________________________________________________

    install = /boot/boot.b

    # Have LILO perform some optimization.
    compact

    # Stanza for Linux root partition on /dev/hda1.
    image = /etc/Image   # Location of kernel
       label = linux     # Name of OS (for the LILO boot menu)
       root = /dev/hda1  # Location of root partition
             vga   =   ask                            #    Tell   ker-
    nel to ask for SVGA modes at boot time

    # Stanza for MSDOS partition on /dev/hda2.
    other = /dev/hda2    # Location of partition
       table = /dev/hda  # Location of partition table for /dev/hda2
       label = msdos     # Name of OS (for boot menu)

  The first  operating system stanza  in the config  file will be  the
default OS for LILO to boot.  You can select another OS to boot at the
LILO boot prompt, as discussed above.
  Remember that every  time you update the  kernel image on disk,  you
should rerun /sbin/lilo in  order for the  changes to be reflected  on
the boot sector of your drive.
  Also note  that if you use  the ``root =''  line, above, there's  no
reason to use  rdev to  set the  root partition in  the kernel  image.
LILO sets it for you at boot time.
  The Linux FAQ  (see Appendix A)  provides more information on  LILO,
including how to use LILO to boot with OS/2's Boot Manager.


4.3 Shutting Down

Shutting down a  Linux system  is a  bit tricky.    Remember that  you
should never just turn off the power or hit the reset switch while the
system is running.    The kernel  keeps track  of disk  I/O in  memory
buffers.   If  you reboot  the system  without giving  the kernel  the
chance to write its buffers to disk, you can corrupt your filesystems.
  Other  precautions  are  taken at  shutdown  time  as  well.     All
processes are  sent a  signal,  which allows  them  to die  gracefully
(writing and closing all files, and so on).  Filesystems are unmounted
for safety.   If you wish,  the system can  also alert users that  the
system is going down and give them a change to log off.
  The easiest  way to  shutdown is  with the  shutdown command.    The
format of the command is

    shutdown <time> <warning-message>

The <time> argument is the time to  shutdown the system (in the format
hh:mm:ss), and <warning-message> is a  message displayed on all user's
terminals before shutdown.   Alternately,  you can  specify the <time>
   4.4.   Managing Users                                              144
   _______________________________________________________________________

   as ``now'', to shutdown  immediately.  The  -r option may be given  to
   shutdown to reboot the system after shutting down.
     For example, to shutdown the system at 8:00pm, use the command

       # shutdown -r 20:00

     The  command halt  may  be  used  to force  an  immediate  shutdown,
   without any  warning messages  or grace  period.   halt  is useful  if
   you're the only one using the system, and want to shut down the system
   and turn it off.
!    Don't turn  off the  power or reboot  the system  until you see  the
   message:

       The system is halted

   It  is  very  important  that  you  shutdown  the  system  ``cleanly''
   using the  shutdown or  halt  commands.    On some  systems,  pressing
   [ctrl-alt-del] will be trapped and cause a shutdown; on other systems,
   however, using  the  ``Vulcan nerve  pinch''  will reboot  the  system
   immediately and may cause disaster.


   4.4 Managing Users

   Whether or not  you have  many users  on your  system, it's  important
   to understand the  aspects of user  management under Linux.   Even  if
   you're the only user,  you should presumably  have a separate  account
   for yourself (an account other than root to do most of your work).
     Each person  using the system  should have his  or her own  account.
   It is  seldom  a good  idea  to have  several  people share  the  same
   account.   Not only is  security an  issue, but  accounts are used  to
   uniquely identify users to the  system.  You  need to be able to  keep
   track of who is doing what.

   4.4.1 User management concepts

   The system keeps track of a number of pieces of information about each
   user.  They are summarized below.
   username   The username  is the unique identifier given to  every user
              on  the system.   Examples  of usernames  are larry,  karl,
              and  mdw.   Letters  and digits  may be  used,  as well  as
              the  characters ``_'' (underscore)  and  ``.''    (period).
              Usernames are usually limited to 8 characters in length.

   user ID    The  user ID, or  UID, is  a unique number  given to  every
              user  on the system.    The system usually  keeps track  of
              information by UID, not username.

   group ID   The  group ID,  or GID,  is the  ID of  the user's  default
              group.    In Section  3.9 we  discussed group  permissions;
4.4.   Managing Users                                              145
_______________________________________________________________________

           each  user belongs  to one or  more groups  defined by  the
           system administrator.  More about this below.

password   The system also stores the user's  encrypted password.  The
           passwd command is used to set and change user passwords.

full name  The user's  ``real name'' or ``full name'' is  stored along
           with the username.   For example, the user schmoj  may have
           the name ``Joe Schmo'' in real life.

home directory
           The home  directory is the directory  in which the user  is
           initially  placed at login  time.   Every user should  have
           his or her own home directory, usually found under /home.

login shell
           The user's  login shell is the  shell which is started  for
           the  user  at login  time.    Examples  are  /bin/bash  and
           /bin/tcsh.
  The file /etc/passwd  contains this information  about users.   Each
line in the file contains information about a single user;  the format
of each line is

    username:encrypted  password:UID:GID:full   name:home   direc-
    tory:login shell

An example might be:

    kiwi:Xv8Q981g71oKK:102:100:Laura Poole:/home/kiwi:/bin/bash

  As we can see, the first field, ``kiwi'', is the username.
  The  next  field,  ``Xv8Q981g71oKK'',  is  the  encrypted  password.
Passwords are not stored on  the system in any human-readable  format.
The password is encrypted using  itself as the secret  key.  In  other
words, you need  to know the  password to  decrypt it.   This form  of
encryption is fairly secure.
  Some systems use  ``shadow password'' in which password  information
is relegated  to  the  file  /etc/shadow.     Because  /etc/passwd  is
world-readable, /etc/shadow  provides some  degree  of extra  security
because it is not.  Shadow password provides some  other features such
as password expiration and so on;  we will not go into  these features
here.
  The third field, ``102'',  is the UID. This must be unique  for each
user.  The  fourth field, ``100'',  is the GID.  This user belongs  to
the group numbered  100.   Group information,  like user  information,
is stored  in  the  file /etc/group.     See Section  4.4.5  for  more
information.
  The fifth  field is  the user's  full name,  ``Laura Poole''.    The
last two fields are the  user's home directory (/home/kiwi) and  login
shell (/bin/bash), respectively.   It is not required that  the user's
4.4.   Managing Users                                              146
_______________________________________________________________________

home directory be given the same name  as the username.  It  does help
identify the directory, however.

4.4.2 Adding users

When adding a user, there are several  steps to be taken.   First, the
user must be  given an entry  in /etc/passwd,  with a unique  username
and UID. The GID, fullname,  and other information must  be specified.
The user's  home directory  must be  created, and  the permissions  on
the directory  set  so  that the  user  owns  the directory.     Shell
initialization files must be  provided in the  new home directory  and
other system-wide configuration must be done (for example,  setting up
a spool for incoming e-mail for the new user).
  While it  is not difficult  to add users  by hand  (I do), when  you
are running a system with many  users it is easy to  forget something.
The easiest way to  add users is to  use an interactive program  which
asks you for the  required information and  updates all of the  system
files automatically.  The name of this program is  useradd or adduser,
depending on what  software was installed.   The  man pages for  these
commands should be fairly self-explanatory.

4.4.3 Deleting users

Similarly,  deleting users  can  be  accomplished  with  the  commands
userdel or deluser  depending on  what software was  installed on  the
system.
  If you'd like  to temporarily ``disable''  a user from logging  into
the system  (without  deleting the  user's  account), you  can  simply
prepend an asterisk (``*'') to the password field in /etc/passwd.  For
example, changing kiwi's /etc/passwd entry to

    kiwi:*Xv8Q981g71oKK:102:100:Laura Poole:/home/kiwi:/bin/bash

will restrict kiwi from logging in.


4.4.4 Setting user attributes

After you have created a user,  you may need to change  attributes for
that user, such as home directory or password.  The easiest  way to do
this is to change the values directly in /etc/passwd.  To set a user's
password, use the passwd command.  For example,

    # passwd larry

will change  larry's password.    Only root  may  change other  user's
password in this manner.   Users can  change their own passwords  with
passwd as well.
  On some  systems, the commands  chfn and chsh  will be available  to
allow users to set their own fullname and login shell attributes.   If
4.5.   Archiving and Compressing Files                             147
_______________________________________________________________________

not, they will have  to ask the  system administrator to change  these
attributes for them.

4.4.5 Groups

As we  have  mentioned,  each user  belongs  to  one or  more  groups.
The only  real  importance of  group  relationships pertains  to  file
permissions, as  you'll  recall from  Section  3.9,  each file  has  a
``group ownership'' and a set  of group permissions which defines  how
users in that group may access the file.
  There  are several  system-defined groups  such  as bin,  mail,  and
sys.  Users should  not belong to any of  these groups; they are  used
for system  file permissions.    Instead,  users should  belong to  an
individual group such  as users.    If you want  to be  cute, you  can
maintain several groups of users such as student, staff, and faculty.
  The file /etc/group contains  information about groups.   The format
of each line is

    group name:password:GID:other members

Some example groups might be:

    root:*:0:
    users:*:100:mdw,larry
    guest:*:200:
    other:*:250:kiwi

The first group,  root,  is a special  system group  reserved for  the
root account.  The  next group, users, is for  regular users.   It has
a GID of  100.   The  users mdw  and larry  are given  access to  this
group.   Remember that in  /etc/passwd each user  was given a  default
GID. However, users may belong to more than one group, by adding their
usernames to other  group lines  in /etc/group.    The groups  command
lists what groups you are given access to.
  The  third group,  guest,  is  for guest  users,  and other  is  for
``other'' users.  The user kiwi is given access to this group as well.
  As you  can  see, the  ``password'' field  of  /etc/group is  rarely
used.  It is sometimes used to  set a password on group access.   This
is seldom necessary.   To protect users from changing  into priveleged
groups (with the newgroup command), set the password field to ``*''.
  The commands  addgroup  or groupadd  may be  used to  add groups  to
your system.  Usually, it's  easier just to add entries  in /etc/group
yourself, as no other configuration needs  to be done to add  a group.
To delete a group, simply delete its entry in /etc/group.


4.5 Archiving and Compressing Files

Before we can talk about backups, we need to introduce  the tools used
to archive files and software on UNIX systems.
4.5.   Archiving and Compressing Files                             148
_______________________________________________________________________

4.5.1 Using tar

The tar command is most often used to archive files.
  The format of the tar command is

    tar <options> <file1> <file2> ... <fileN>

where <options>  is the  list  of commands  and options  for  tar, and
<file1> through <fileN> is the list of files to add or extract from the
archive.
  For example, the command

    # tar cvf backup.tar /etc

would pack all of the files  in /etc into the tar  archive backup.tar.
The first argument to tar---``cvf''---is  the tar ``command''.   ``c''
tells tar to create a new archive  file.  The ``v'' option  forces tar
into verbose mode---printing  each filename as  it is  archived.   The
``f'' option tells  tar that  the next argument---backup.tar---is  the
name of the archive to create.   The rest of the arguments to  tar are
the file and directory names to add to the archive.
  The command

    # tar xvf backup.tar

will extract the tar file backup.tar  in the current directory.   This
can sometimes be  dangerous---when extracting files  from a tar  file,
old files are overwritten.
  Furthermore, before  extracting tar  files it is  important to  know
where the  files  should  be  unpacked.     For  example,   let's  say
you archived  the  following  files:    /etc/hosts,   /etc/group,  and
/etc/passwd.  If you use the command

    # tar cvf backup.tar /etc/hosts /etc/group /etc/passwd

the directory name /etc/ is  added to the beginning of  each filename.
In order to extract the files to the correct location,  you would need
to use the following commands:

    # cd /
    # tar xvf backup.tar

because files are  extracted with  the pathname saved  in the  archive
file.
  If, however, you archived the files with the command

    # cd /etc
    # tar cvf hosts group passwd

the directory name is not saved  in the archive file.   Therefore, you
4.5.   Archiving and Compressing Files                             149
_______________________________________________________________________

would need to ``cd  /etc'' before extracting  the files.   As you  can
see, how the tar file is created makes a large difference in where you
extract it.  The command

    # tar tvf backup.tar

may be used to display an  ``index'' of the tar file  before unpacking
it.   In this  way you  can see what  directory the  filenames in  the
archive are stored relative to,  and can extract the archive  from the
correct location.

4.5.2 gzip and compress

Unlike archiving  programs  for  MS-DOS, tar  does  not  automatically
compress files as it archives them.   Therefore, if you  are archiving
two 1-megabyte files, the resulting tar file will be  two megabytes in
size.  The gzip  command may be used to  compress a file (the  file to
compress need not be a tar file).  The command

    # gzip -9 backup.tar

will compress  backup.tar  and  leave  you  with  backup.tar.gz,   the
compressed version of the file.   The -9 switch tells gzip to  use the
highest compression factor.
  The  gunzip command  may  be  used  to uncompress  a  gzipped  file.
Equivalently, you may use ``gzip -d''.
  gzip is  a relatively  new tool  in the UNIX  community.   For  many
years, the compress  command was used  instead.   However, because  of
several factors(1), compress is being phased out.
  compressed files end in the extension .Z.  For example, backup.tar.Z
is the compressed  version of backup.tar,  while backup.tar.gz is  the
gzipped version(2).    The  uncompress command  is  used to  expand  a
compressed file; gunzip knows how to handle compressed files as well.

4.5.3 Putting them together

Therefore, to archive a  group of files  and compress the result,  you
can use the commands:

    # tar cvf backup.tar /etc
    # gzip -9 backup.tar

----------------------------
 1. These  factors  include  a  software patent  dispute  against  the
compress algorithm and the fact that gzip is much more  efficient than
compress.

 2. To  add  further  confusion,   for  some  time  the  extension  .z
(lowercase ``z'')  was used  for gzipped  files.    The official  gzip
extension is now .gz.
4.5.   Archiving and Compressing Files                             150
_______________________________________________________________________

The result  will be  backup.tar.gz.    To unpack  this file,  use  the
reverse set of commands:

    # gunzip backup.tar.gz
    # tar xvf backup.tar

Of course  always make  sure that  you are  in  the correct  directory
before unpacking a tar file.
  You can use  some UNIX cleverness to do  all of this on  one command
line, as in the following:

    # tar cvf - /etc | gzip -9c > backup.tar.gz

Here, we are  sending the tar  file to ``-'',  which stands for  tar's
standard output.  This is piped to gzip, which compresses the incoming
tar file, and the result is saved in backup.tar.gz.  The  -c option to
gzip tells gzip to send its  output to stdout, which is  redirected to
backup.tar.gz.
  A single command used to unpack this archive would be:

    # gunzip -c backup.tar.gz | tar xvf -

Again, gunzip uncompresses the contents of backup.tar.gz and sends the
resulting tar file  to stdout.    This is  piped to  tar, which  reads
``-'', this time referring to tar's standard input.
  Happily,   the  tar   command  also   includes  the   z  option   to
automatically compress/uncompress  files on  the fly,  using the  gzip
compression algorithm.
  For example, the command

    # tar cvfz backup.tar.gz /etc

is equivalent to

    # tar cvf backup.tar /etc
    # gzip backup.tar

Just as the command

    # tar xvfz backup.tar.Z

may be used instead of

    # uncompress backup.tar.Z
    # tar xvf backup.tar

  Refer to the man pages for tar and gzip for more information.
4.6.   Using Floppies and Making Backups                           151
_______________________________________________________________________

4.6 Using Floppies and Making Backups

Floppies are usually used as backup media.   If you don't have  a tape
drive connected to  your system,  floppy disks can  be used  (although
they are slower and somewhat less reliable).
  You may also  use floppies to hold individual  filesystems---in this
way, you can mount the floppy to access the data on it.

4.6.1 Using floppies for backups

The easiest way  to make a  backup using floppies  is with  tar.   The
command

    # tar cvfzM /dev/fd0 /

will make a  complete backup  of your  system using  the floppy  drive
/dev/fd0.    The  ``M'' option  to  tar  allows  the backup  to  be  a
multivolume backup; that is, when one floppy is full,  tar will prompt
for the next.  The command

    # tar xvfzM /dev/fd0

can be used to restore the complete  backup.  This method can  also be
used if you have a tape drive (/dev/rmt0) connected to your system.
  Several other  programs  exist for  making multiple-volume  backups;
the backflops program found on tsx-11.mit.edu may come in handy.
  Making  a  complete   backup  of  the   system  can  be  time-   and
resource-consuming.   Most  system  administrators use  a  incremental
backup policy, in which  every month a  complete backup is taken,  and
every week only those files which have been modified in  the last week
are backed up.  In this  case, if you trash your system in  the middle
of the month, you can simply restore the last full monthly backup, and
then restore the last weekly backups as needed.
  The find command can be useful in locating  files which have changed
since a  certain  date.    Several  scripts for  managing  incremental
backups can be found on sunsite.unc.edu.

4.6.2 Using floppies as filesystems

You can create a filesystem  on a floppy just  as you would on a  hard
drive partition.  For example,

    # mke2fs /dev/fd0 1440

creates a filesystem  on the  floppy in  /dev/fd0.   The  size of  the
filesystem must correspond to  the size of  the floppy.   High-density
3.5" disks are 1.44 megabytes, or 1440 blocks, in size.   High-density
5.25" disks are 1200 blocks.
  In  order to  access  the  floppy,  you must  mount  the  filesystem
contained on it.  The command
   4.7.   Upgrading and Installing New Software                       152
   _______________________________________________________________________

       # mount -t ext2 /dev/fd0 /mnt

   will mount the floppy in /dev/fd0 on the directory /mnt.   Now, all of
   the files on the  floppy will appear  under /mnt on  your drive.   The
   ``-t ext2''  specifies an  ext2fs filesystem  type.    If you  created
   another type of filesystem on the  floppy, you'll need to  specify its
   type to the mount command.
     The  ``mount  point''  (the  directory  where  you're  mounting  the
   filesystem) needs to  exist when  you use the  mount command.   If  it
   doesn't exist, simply create it with mkdir.
     See Section 4.8 for  more information on filesystems, mounting,  and
   mount points.
!    Note that any  I/O to the floppy is  buffered just as hard  disk I/O
   is.  If you change data on the floppy, you may not see the drive light
   come on until the kernel flushes its I/O buffers.  It's important that
   you not remove a floppy before you  unmount it; this can be  done with
   the command

       # umount /dev/fd0

   Do not  simply switch  floppies  as you  would  on an  MS-DOS  system;
   whenever you change floppies, umount the first one and mount the next.


   4.7 Upgrading and Installing New Software

   Another duty of the system  administrator is upgrading and  installing
   new software.
     The Linux  community  is very  dynamic.   New  kernel releases  come
   out every few weeks,  and other software  is updated almost as  often.
   Because of this, new Linux users often feel the need  to upgrade their
   systems constantly to keep up the the rapidly changing pace.  Not only
   is this unnecessary, it's  a waste of  time:  to  keep up with all  of
   the changes in the Linux world, you would be spending all of your time
   upgrading and none of your time using the system.
     So,  when should you  upgrade?   Some  people feel  that you  should
   upgrade when a  new distribution release  is made---for example,  when
   Slackware comes out with a new  version.  Many Linux  users completely
   reinstall their system with the  newest Slackware release every  time.
   This, also, is  a waste  of time.   In general,  changes to  Slackware
   releases are  small.    Downloading  and  reinstalling 30  disks  when
   only 10% of  the software has  been actually  modified is, of  course,
   pointless.
     The best  way to  upgrade your system  is to  do it by  hand:   only
   upgrade those  software  packages  which  you  know  that  you  should
   upgrade.   This scares a  lot of people:   they want  to know what  to
   upgrade, and  how, and  what will break  if they  don't upgrade.    In
   order to be  successful with  Linux, it's important  to overcome  your
   fears of ``doing it  yourself''--- which is  what Linux is all  about.
   In fact, once you have your system working and  all software correctly
   configured, reinstalling with  the newest release  will no doubt  wipe
4.7.   Upgrading and Installing New Software                       153
_______________________________________________________________________

all of your  configuration and things  will be  broken again, just  as
they were when you first installed your system.  Setting yourself back
in this manner is  unnecessary---all that is  needed is some  know-how
about upgrading your system, and how to do it right.
  You'll find  that when  you upgrade  one component  of your  system,
other things should not break.   For example, most of the  software on
my system is left over from an ancient 0.96 MCC  Interim installation.
Yet, I run the  newest version of the  kernel and libraries with  this
software with no problem.  For the most part, senselessly upgrading to
``keep up with the trend'' is not important at all.  This isn't MS-DOS
or Microsoft Windows.  There is no important reason to  run the newest
version of all of the  software.  If you  find that you would  like or
need features in a  new version, then  upgrade.   If not, then  don't.
In other words, only upgrade what  you have to, and when you  have to.
Don't just upgrade for the sake of  upgrading.  That will waste  a lot
of time and effort trying to keep up.
  The  most important  software  to  upgrade  on your  system  is  the
kernel, the libraries,  and the  gcc compiler.   These  are the  three
essential parts of your system, and  in some cases they all  depend on
each other for  everything to work  successfully.   Most of the  other
software on your system does not need to be upgraded periodically.

4.7.1 Upgrading the kernel

Upgrading the kernel  is simply a  matter of  getting the sources  and
compiling them yourself.    You must  compile the  kernel yourself  in
order to enable or disable certain features, as well as to ensure that
the kernel will be optimized to run  on your machine.  The  process is
quite painless.
  The kernel sources may be retrieved from any of  the Linux FTP sites
(see Section C  for a list).   On  sunsite.unc.edu, for instance,  the
kernel sources are found  in /pub/Linux/kernel.   Kernel versions  are
numbered using a version number and a patchlevel.  For example, kernel
version 0.99 patchlevel 11  is usually written  as 0.99.pl11, or  just
0.99.11.
  The kernel  sources are  released as  a gzipped  tar file(3).    For
example,  the  file   containing  the  0.99.pl11  kernel  sources   is
linux-0.99.11.tar.gz.
  Unpack this  tar file from  the directory /usr/src;  it creates  the
directory /usr/src/linux  which  contains the  kernel  sources.    You
should delete or rename your existing /usr/src/linux  before unpacking
the new version.
  Once  the sources  are unpacked,  you  need to  make  sure that  two

----------------------------
 3. Often,  a  patch file  is  also released  for the  current  kernel
version which allows you to patch your current kernel sources from the
last patchlevel to the current one (using the program patch).  In most
cases, however, it's usually easier to install the entire  new version
of the kernel sources.
4.7.   Upgrading and Installing New Software                       154
_______________________________________________________________________

symbolic links in /usr/include  are correct.   To create these  links,
use the commands

    # ln -sf /usr/src/linux/include/linux /usr/include/linux
    # ln -sf /usr/src/linux/include/asm /usr/include/asm

Once you have created these links  once, there is no reason  to create
them again when you  install the next  version of the kernel  sources.
(See Section 3.10 for more about symbolic links.)
  Note that in order to compile the kernel, you must  have the gcc and
g++ C and C++  compilers installed on  your system.   You may need  to
have the most recent versions of these compilers:  see  Section 4.7.3,
below, for more information.
  To  compile the  kernel,  first  cd  to  /usr/src/linux.    Run  the
command make  config.    This command  will prompt  you  for a  number
of configuration options,  such as what filesystem  types you wish  to
include in the new kernel.
  Next, edit  /usr/src/linux/Makefile.   Be sure  that the  definition
for ROOT_DEV is  correct---it  defines the  device  used as  the  root
filesystem at boot time.  The usual definition is

    ROOT_DEV = CURRENT

Unless you  are changing  your  root filesystem  device,  there is  no
reason to change this.
  Next,  run  the   command  make  dep  to  fix  all  of   the  source
dependencies.  This is a very important step.
  Finally,  you're ready  to compile  the kernel.    The command  make
Image will compile the  kernel and leave the  new kernel image in  the
file /usr/src/linux/Image.  Alternately, the command make  zImage will
compile a compressed kernel image,  which uncompresses itself at  boot
time and uses less drive space.
  Once you have the kernel  compiled, you need to either copy it  to a
boot floppy (with a command such as ``cp Image /dev/fd0'')  or install
it using LILO to  boot from your  hard drive.   See Section 4.2.2  for
more information.

4.7.2 Upgrading the libraries

As mentioned before, most  of the software  on the system is  compiled
to use shared libraries, which contain common subroutines shared among
different programs.
  If you see the message

    Incompatible library version

when attempting to  run a  program, then  you need to  upgrade to  the
version of the libraries  which the program  requires.  Libraries  are
back-compatible; that is, a program  compiled to use an  older version
of the libraries  should work with  the new  version of the  libraries
   4.7.   Upgrading and Installing New Software                       155
   _______________________________________________________________________

   installed.  However, the reverse is not true.
     The  newest version  of the  libraries  can be  found on  the  Linux
   FTP sites.   On sunsite.unc.edu, they  are located in  /pub/Linux/GCC.
   The ``release''  files there  should explain  what files  you need  to
   download and  how  to install  them.    Briefly,  you should  get  the
   files image-version.tar.gz and inc-version.tar.gz where version is the
   version of the libraries to install, such as 4.4.1.  These are gzipped
   tar files; the image  file contains the  library images to install  in
   /lib and /usr/lib.  The inc file contains include files  to install in
   /usr/include
     The   release-version.tar.gz   should   explain   the   installation
   procedure in detail  (the exact instructions  vary for each  release).
   In general  you  need to  install  the library  .a  and .sa  files  in
   /usr/lib.  These are the libraries used at compilation time.
     In addition,  the shared  library image  files, libc.so.version  are
   installed in /lib.    These are  the shared library  images loaded  at
   runtime by programs using the libraries.  Each library  has a symbolic
   link using the major version number of the library in /lib.
     For example,  the libc  library version  4.4.1 has  a major  version
   number of 4.   The file  containing the library  is libc.so.4.4.1.   A
   symbolic link  of the  name  libc.so.4 is  also  in /lib  pointing  to
   this file.    You need  to change  this symbolic  link when  upgrading
   the libraries.    For  example,  when  upgrading from  libc.so.4.4  to
   libc.so.4.4.1, you need to  change the symbolic  link to point to  the
   new version.
!    It is very important that you change the symbolic  link in one step,
   as given below.   If you somehow  delete the symbolic link  libc.so.4,
   then programs which depend on the link (including basic utilities like
   ls and cat) will stop  working.  Use  the following command to  update
   the symbolic link libc.so.4 to point to the file libc.so.4.4.1:

       # ln -sf /lib/libc.so.4.4.1 /lib/libc.so.4

   You also need to change the symbolic link libm.so.version in  the same
   manner.  If you are upgrading to a different version  of the libraries
   substitute to appropriate filenames above.  The library release notice
   should explain the details.   (See  Section 3.10 for more  information
   about symbolic links.)

   4.7.3 Upgrading gcc

   The gcc C and C++ compiler is used to compile software on your system,
   most importantly  the kernel.    The newest  version of  gcc is  found
   on the  Linux FTP  sites.   On  sunsite.unc.edu,  it is  found in  the
   directory /pub/Linux/GCC (along with the libraries).  There  should be
   a release file for the gcc distribution detailing what files  you need
   to download and how to install them.
4.8.   Managing Filesystems                                        156
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4.7.4 Upgrading other software

Upgrading other software is usually  just a matter of downloading  the
appropriate files and  installing them.   Most  software for Linux  is
distributed at gzipped tar files, including either sources or binaries
or both.  If  binaries are not included  in the release, you may  need
to compile  them yourself;  usually,  this means  typing  make in  the
directory where the sources are held.
  Reading the  USENET newsgroup  comp.os.linux.announce for  announce-
ments of new software  releases is the easiest  way to find out  about
new software.  Whenever you  are looking for software on an  FTP site,
downloading the ls-lR index file from  the FTP site and using  grep to
find the files in question is the easiest way to locate software.   If
you have archie available to you, it can be of  assistance as well(4).
See Appendix A for more details.
  One handy  source of  Linux software is  the Slackware  distribution
disk images.   Each  disk contains a  number of  .tgz files which  are
simply gzipped tar files.   Instead of downloading the disks,  you can
download the  desired .tgz  files from  the  Slackware directories  on
the FTP site  and install  them directly.   If  you run the  Slackware
distribution, the setup command can be used to automatically  load and
install a complete series of disks.
  Again,  it's usually  not a  good idea  to  upgrade by  reinstalling
with the newest  version of Slackware,  or another  distribution.   If
you reinstall  in this  way,  you  will no  doubt wreck  your  current
installation, including user  directories and  all of your  customized
configuration.  The  best way to upgrade  software is piecewise;  that
is, if there is a program that  you use often that has a  new version,
upgrade it.   Otherwise, don't bother.   Rule of  thumb:  If it  ain't
broke, don't  fix it.    If your  current software  works, there's  no
reason to upgrade.


4.8 Managing Filesystems

Another  task  of   the  system  administrator   is  taking  care   of
filesystems.   Most  of  this job  entails periodically  checking  the
filesystems for damage or corrupted files; many  systems automatically
check the filesystems at boot time.

4.8.1 Mounting filesystems

First, a  few concepts  about filesystems.    Before  a filesystem  is
accessible to the system, it must  be mounted on some directory.   For
example, if  you have  a filesystem  on a  floppy, you  must mount  it

----------------------------
 4. If  you don't  have archie,  you can  telnet to  an archie  server
such as archie.rutgers.edu,  login as ``archie''  and use the  command
``help''
   4.8.   Managing Filesystems                                        157
   _______________________________________________________________________

   under some directory,  say /mnt, in  order to access  the files on  it
   (see Section 4.6.2).  After mounting the filesystem, all  of the files
   in the filesystem  appear in  that directory.    After unmounting  the
   filesystem, the directory (in this case, /mnt) will be empty.
     The same  is true  of filesystems  on the hard  drive.   The  system
   automatically mounts filesystems on your hard drive for you  at bootup
   time.  The so-called  ``root filesystem'' is mounted on  the directory
   /.  If  you have a  separate filesystem for /usr,  for example, it  is
   mounted on  /usr.   If  you only  have a  root filesystem,  all  files
   (including those in /usr) exist on that filesystem.
     The command mount is used to mount a filesystem.  The command

       mount -av

   is executed from the file /etc/rc (which is the  system initialization
   file executed  at boot  time;  see Section  4.10.1).    The mount  -av
   command obtains information on filesystems  and mount points from  the
   file /etc/fstab.  An example fstab file appears below.

       # device       directory      type     options
       /dev/hda2       /             ext2     defaults
       /dev/hda3       /usr          ext2     defaults
       /dev/hda4       none          swap     sw
       /proc           /proc         proc     none

     The  first field  is  the  device---the  name of  the  partition  to
   mount.   The second  field is the  mount point.   The  third field  is
   the filesystem type---such as  ext2 (for ext2fs)  or minix (for  Minix
   filesystems).  Table 4.1 lists the various filesystem  types available
   for Linux.(5)  Not all  of these filesystem types may be  available on
   your system; your kernel must have support for them compiled in.   See
   Section 4.7 for information on building the kernel.
     The last field  of the fstab file contains  mount options---usually,
   this is set to ``defaults''.
     As you can see, swap partitions are included  in /etc/fstab as well.
   They have a mount  directory of none,  and type swap.   The swapon  -a
   command, executed from /etc/rc as well, is used to  enable swapping on
   all swap devices listed in /etc/fstab.
     The  fstab   file  contains  one   special  entry---for  the   /proc
   filesystem.  As mentioned in  Section 3.11.1, the /proc  filesystem is
   used to store  information about system  processes, available  memory,
   and so on.   If  /proc is not  mounted, commands such  as ps will  not
   work.
!    The mount  command may  only be used  by root.   This  is to  ensure
   security on the system; you  wouldn't want regular users  mounting and
   unmounting filesystems on a whim.  There are several software packages

   ----------------------------
    5. This table is current as of kernel version 1.1.37.
4.8.   Managing Filesystems                                        158
_______________________________________________________________________


Filesystem                Typename     Comment

Second Extended Filesystem  ext2       Most common Linux filesystem.
Extended Filesystem         ext        Superseded by ext2.
Minix Filesystem            minix      Original Minix filesystem; rarely
                                       used.
Xia Filesystem              xia        Like ext2, but rarely used.
UMSDOS Filesystem           umsdos     Used to install Linux on an MS-DOS
                                       partition.
MS-DOS Filesystem           msdos      Used to access MS-DOS files.
/proc Filesystem            proc       Provides process information for
                                       ps, etc.
ISO 9660 Filesystem         iso9660    Format used by most CD-ROMs.
Xenix Filesystem            xenix      Used to access files from Xenix.
System V Filesystem         sysv       Used to access files from System V
                                       variants for the x86.
Coherent Filesystem         coherent   Used to access files from Coherent.
HPFS Filesystem             hpfs       Read-only access for HPFS partitions
                                       (DoubleSpace).

                  Table 4.1:  Linux Filesystem Types



available which allow regular users  to mount and unmount  filesystems
(floppies in particular) without compromising system security.
  The mount  -av command  actually mounts all  filesystems other  than
the root  filesystem  (in the  table  above,  /dev/hda2).    The  root
filesystem is automatically mounted at boot time by the kernel.
  Instead of  using mount  -av, you  can mount a  filesystem by  hand.
The command

    # mount -t ext2 /dev/hda3 /usr

is equivalent to mounting the  filesystem with the entry /dev/hda3  in
the fstab example file above.
  In general,  you should never have  to mount or unmount  filesystems
by hand.  The mount -av command in /etc/rc takes care  of mounting the
filesystems at boot time.  Filesystems are automatically  unmounted by
the shutdown or halt commands before bringing the system down.

4.8.2 Checking filesystems

It is usually  a good  idea to  check your filesystems  for damage  or
corrupt files every now  and then.   Some systems automatically  check
their filesystems  at  boot time  (with  the appropriate  commands  in
/etc/rc).
  The command used  to check a filesystem  depends on the type of  the
filesystem in question.    For ext2fs filesystems  (the most  commonly
used type), this command is e2fsck.  For example, the command

    # e2fsck -av /dev/hda2

will check  the  ext2fs  filesystem  on  /dev/hda2  and  automatically
correct any errors.
   4.9.   Using a swap file                                           159
   _______________________________________________________________________

     It is usually  a good idea to  unmount a filesystem before  checking
   it.  For example, the command

       # umount /dev/hda2

   will unmount the filesystem  on /dev/hda2, after  which you can  check
   it.  The one exception is that you cannot unmount the root filesystem.
   In order to check the root filesystem when it's unmounted,  you should
   use a  maintenance  boot/root diskette  (see  Section  4.11.1).    You
   also cannot  unmount  a filesystem  if  any of  the  files in  it  are
   ``busy''---that is, being used by a running process.  For example, you
   cannot unmount a filesystem if any user's current working directory is
   on that filesystem.  You  will receive a ``Device busy'' error  if you
   attempt to unmount a filesystem which is in use.
     Other filesystem  types use different forms  of the e2fsck  command,
   such as efsck  and xfsck.   On some  systems, you  can simply use  the
   command fsck, which will determine the filesystem type and execute the
   appropriate command.
!    It  is important  that  you  reboot your  system  immediately  after
   checking a mounted  filesystem if  any corrections were  made to  that
   filesystem.   (However, in  general, you  shouldn't check  filesystems
   while they  are mounted.)    For example,  if e2fsck  reports that  it
   corrected any  errors  with  the filesystem,  you  should  immediately
   shutdown -r in  order to  reboot the  system.   This is  to allow  the
   system to re-sync  its information  about the  filesystem when  e2fsck
   modifies it.
     The  /proc filesystem  never needs  to be  checked  in this  manner.
   /proc is a memory filesystem, managed directly by the kernel.


   4.9 Using a swap file

   Instead of reserving an individual  partition for swap space,  you can
   use a file.  However, to do so you'll need install  the Linux software
   and get everything going before you create the swap file.
     If you  have a  Linux system installed,  you can  use the  following
   commands to create a swap file.   Below, we're going to create  a swap
   file of size 8208 blocks (about 8 megs).

       # dd if=/dev/zero of=/swap bs=1024 count=8208

   This command creates  the swap file  itself.   Replace the  ``count=''
   with the size of the swap file in blocks.

       # mkswap /swap 8208

   This command will initialize the swapfile; again, replace the name and
   size of the swapfile with the appropriate values.

       # /etc/sync
       # swapon /swap
4.10.   Miscellaneous Tasks                                        160
_______________________________________________________________________

Now we are  swapping on the  file /swap which  we have created,  after
syncing, which ensures that the file has been written to disk.
  The  one major  drawback  to using  a  swapfile  in this  manner  is
that all  access to  the swap  file is  done  through the  filesystem.
This means that  the blocks  which make up  the swap  file may not  be
contiguous.   Therefore,  performance may  not  be as  great as  using
a swap  partition, for  which  blocks are  always  contiguous and  I/O
requests are done directly to the device.
  Another drawback in using  a swapfile is the chance to  corrupt your
filesystem data---when using  large swap  files, there  is the  chance
that you can corrupt your filesystem if something goes wrong.  Keeping
your filesystems and swap partitions  separate will prevent this  from
happening.
  Using a swap  file can be very useful  if you have a  temporary need
for more swap space.  For example, if you're compiling a large program
and would like to speed things up somewhat, you can temporarily create
a swap file and use it in addition to your regular swap space.
  To get rid of a swap file, first use swapoff, as in

    # swapoff /swap

And you can safely delete the file.

    # rm /swap

  Remember that each  swap file (or partition)  may be as large as  16
megabytes, but you may  use up to 8  swap files or partitions on  your
system.


4.10 Miscellaneous Tasks

Believe it or not,  there are a number  of housekeeping tasks for  the
system administrator which don't fall into any major category.

4.10.1 System startup files

When the system boots, a number of scripts are  executed automatically
by the system before any user logs in.  Here is a  description of what
happens.
  At bootup  time,  the kernel  spawns the  process /etc/init.    init
is a program  which reads  its configuration  file, /etc/inittab,  and
spawns other processes based  on the contents  of this file.   One  of
the important processes started from inittab is the /etc/getty process
started on each virtual console.   The getty process grabs the  VC for
use, and starts a  login process on the  VC. This allows you to  login
on each VC;  if /etc/inittab does  not contain a  getty process for  a
certain VC, you will not be able to login on that VC.
  Another  process executed  from /etc/inittab  is /etc/rc,  the  main
system initialization  file.    This file  is  a simple  shell  script
4.10.   Miscellaneous Tasks                                        161
_______________________________________________________________________

which executes any initialization commands  needed at boot time,  such
as mounting the  filesystems (see Section  4.8) and initializing  swap
space.
  Your  system  may execute  other  initialization  scripts  as  well,
such as /etc/rc.local.  /etc/rc.local usually  contains initialization
commands specific to  your own  system, such as  setting the  hostname
(see the next section).  rc.local may be started from  /etc/rc or from
/etc/inittab directly.

4.10.2 Setting the hostname

In a networked environment, the hostname is used to  uniquely identify
a particular machine, while  in a standalone environment the  hostname
just gives the system personality and charm.  It's like  naming a pet:
you can always address to your dog as ``The dog,'' but  it's much more
interesting to assign the dog a name such as Spot or Woofie.
  Setting  the system's  hostname  is a  simple  matter of  using  the
hostname command.  If  you are on a  network, your hostname should  be
the full hostname  of your machine,  such as  goober.norelco.com.   If
you are not  on a network  of any  kind, you  can choose an  arbitrary
host and domainname, such as loomer.vpizza.com,  shoop.nowhere.edu, or
floof.org.
  When setting  the hostname,  the hostname  must appear  in the  file
/etc/hosts, which assigns an  IP address to each  host.  Even if  your
machine is not on a network,  you should include your own  hostname in
/etc/hosts.
  For example, if you  are not on a TCP/IP network, and  your hostname
is floof.org, simply include the following line in /etc/hosts:

    127.0.0.1       floof.org localhost

This assigns  your  hostname,   floof.org,  to  the  loopback  address
127.0.0.1 (used if you're not on  a network).  The localhost  alias is
also assigned to this address.
  If you are  on a TCP/IP network,  however, your real IP address  and
hostname should appear in /etc/hosts.   For example, if  your hostname
is goober.norelco.com, and your IP address is 128.253.154.32,  add the
following line to /etc/hosts:

    128.253.154.32       goober.norelco.com

  If your  hostname does  not appear in  /etc/hosts, you  will not  be
able to set it.
  To  set your  hostname,  simply  use  the  hostname command.     For
example, the command

    # hostname -S goober.norelco.com

sets the hostname to goober.norelco.com.  In most cases,  the hostname
command is executed  from one  of the  system startup  files, such  as
4.11.   What To Do In An Emergency                                 162
_______________________________________________________________________

/etc/rc or  /etc/rc.local.    Edit  these  two files  and  change  the
hostname command found there to set your own hostname;  upon rebooting
the system the hostname will be set to the new value.


4.11 What To Do In An Emergency

On some occasions,  the system  administrator will be  faced with  the
problem of recovering from a complete disaster, such as forgetting the
root password or  trashing filesystems.    The best  advice is,  don't
panic.  Everyone makes stupid mistakes---that's the best way  to learn
about system administration:  the hard way.
  Linux is not an unstable version of UNIX. In fact,  I have had fewer
problems with system hangs  than with commercial  versions of UNIX  on
many platforms.    Linux also  benefits from  a  strong complement  of
wizards who can help you get out of a bind.
  The first step in investigating any problem is to  attempt to fix it
yourself.  Poke around,  see how things work.   Too much of  the time,
a system  administrator will  post a  desperate plea  for help  before
looking into the problem at all.   Most of the time, you'll  find that
fixing problems yourself is  actually very easy.   It  is the path  to
guruhood.
  There are very few cases where reinstalling the  system from scratch
is necessary.    Many  new users  accidentally delete  some  essential
system file, and immediately reach  for the installation disks.   This
is not a good idea.  Before taking such drastic  measures, investigate
the problem and  ask others  to help  fix things up.    In almost  all
cases, you can recover your system from a maintenance diskette.

4.11.1 Recovering using a maintenance diskette

One indispensable tool for the  system administrator is the so  called
``boot/root disk''---a floppy which can be booted for a complete Linux
system, independent of your hard drive.  Boot/root  disks are actually
very simple---you create a root filesystem on the floppy, place all of
the necessary utilities on it, and install LILO and  a bootable kernel
on the floppy.  Another technique is to use one floppy  for the kernel
and another for the root filesystem.   In any case, the result  is the
same:  you are running a Linux system completely from floppy.
  The canonical  example of  a boot/root  disk is  the Slackware  boot
disks(6).   These  diskettes  contain a  bootable  kernel and  a  root
filesystem, all on floppy.   They are  intended to be used to  install
the Slackware distribution, but come  in very handy when  doing system
maintenance.
  The H.J  Lu boot/root disk,  available from  /pub/Linux/GCC/rootdisk

----------------------------
 6. See Section 2.1.1  for information on  downloading these from  the
Internet.  For this procedure,  you don't need to download  the entire
Slackware release---only the boot and root diskettes.
4.11.   What To Do In An Emergency                                 163
_______________________________________________________________________

on sunsite.unc.edu,  is another example  of such  a maintenance  disk.
Or, if you're  ambitious, you  can create your  own.   In most  cases,
however, using  a pre-made  boot/root  disk is  much  easier and  will
probably be more complete.
  Using a boot/root disk is  very simple.  Just boot the disk  on your
system, and login as root (usually  no password).  In order  to access
the files on your hard drive, you will need to  mount your filesystems
by hand.  For example, the command

    # mount -t ext2 /dev/hda2 /mnt

will mount an  ext2fs filesystem on  /dev/hda2 under  /mnt.   Remember
that /  is  now on  the  boot/root  disk itself;   you need  to  mount
your hard drive filesystems  under some directory  in order to  access
the files.     Therefore,  /etc/passwd  on  your  hard  drive  is  now
/mnt/etc/passwd if you mount your root filesystem on /mnt.

4.11.2 Fixing the root password

If you forget your root password, no problem.  Just boot the boot/root
disk, mount your root filesystem  on /mnt, and blank out  the password
field for root in /mnt/etc/passwd, as so:

    root::0:0:root:/:/bin/sh

Now root has  no password;  when you  reboot from the  hard drive  you
should be able to login as root and reset the password using passwd.
  Aren't you glad you learned how to use vi?   On your boot/root disk,
other editors such as Emacs  probably aren't available, but  vi should
be.

4.11.3 Fixing trashed filesystems

If you somehow trash your filesystems, you can run e2fsck  (if you use
the ext2fs filesystem type,  that is) to  correct any damaged data  on
the filesystems from  floppy.   Other filesystem  types use  different
forms of the fsck command; see Section 4.8 for details.
  When  checking your  filesystems  from  floppy,  it's best  for  the
filesystems to not be mounted.
  One  common cause  of filesystem  damage  is superblock  corruption.
The superblock  is  the ``header''  of  the filesystem  that  contains
information on the filesystem status, size, free blocks, and so forth.
If you corrupt your superblock  (for example, by accidentally  writing
data directly  to  the filesystem's  partition),  the system  may  not
recognize the filesystem at all.  Any attempt to  mount the filesystem
could fail, and e2fsck won't be able to fix the problem.
  Happily, the ext2fs  filesystem type saves copies of  the superblock
at ``block group'' boundaries on the drive---usually, every 8K blocks.
In order to tell e2fsck to use a copy of the superblock, you can use a
command such as
4.11.   What To Do In An Emergency                                 164
_______________________________________________________________________

    # e2fsck -b 8193 <partition>

where <partition> is  the partition  on which  the filesystem resides.
The -b 8193  option tells  e2fsck to  use the copy  of the  superblock
stored at block 8193 in the filesystem.

4.11.4 Recovering lost files

If you accidentally deleted important files on your system, there's no
way to ``undelete'' them.   However, you  can copy the relevant  files
from the floppy  to your  hard drive.    For example,  if you  deleted
/bin/login on your  system (which  allows you to  login), simply  boot
the boot/root floppy, mount the  root filesystem on /mnt, and  use the
command

    # cp -a /bin/login /mnt/bin/login

The -a option  tells cp  to preserve  the permissions  on the  file(s)
being copied.
  Of course, if the  files you deleted weren't essential  system files
which have counterparts on the  boot/root floppy, you're out  of luck.
If you made backups, you can always restore from them.

4.11.5 Fixing trashed libraries

If you accidentally trashed your libraries or symbolic links  in /lib,
more than likely commands  which depended on  those libraries will  no
longer run (see Section 4.7.2).  The easiest solution is  to boot your
boot/root floppy, mount your root filesystem, and fix the libraries in
/mnt/lib.








Chapter 5




Advanced Features



This chapter  will  introduce you  to  some  of the  more  interesting
features of Linux.   This assumes  that you have  at least basic  UNIX
experience, and understand the  information contained in the  previous
chapters.
  The most important aspect of Linux that distinguishes  it from other
implementations of UNIX is its open design and philosophy.   Linux was
not developed by  a small team  of programmers  headed by a  marketing
committee with  a  single goal  in  mind.    It  was developed  by  an
ever-increasing group  of hackers,  putting what  they  wanted into  a
homebrew UNIX system.  The  types of software and diversity  of design
in the  Linux world  is  large.    Some people  dislike this  lack  of
uniformity and conformity---however, some call it one of the strongest
qualities of Linux.

5.1 The X Window System

The X Window  System is a  large and  powerful (and somewhat  complex)
graphics environment for UNIX systems.   The original X  Window System
code was  developed  at MIT;  commercial  vendors  have since  made  X
the industry  standard  for UNIX  platforms.    Virtually  every  UNIX
workstation in the world runs some variant of the X Window system.
  A  free port  of the  MIT  X Window  System  version 11,  release  6
(X11R6) for 80386/80486/Pentium UNIX systems  has been developed by  a
team of  programmers originally  headed by  David Wexelblat(1).    The
release, known as XFree86(2),  is available for System V/386,  386BSD,
and other x86 UNIX implementations, including Linux.   It includes all
of the required binaries, support files, libraries, and tools.
  Configuring and using  the X Window System  is far beyond the  scope
of this book.   You  are encouraged to  read The X  Window System:   A
User's Guide---see Appendix A for information  on this book.   In this

----------------------------
 1. David may be reached on the Internet at [e-mail].
 2. XFree86 is a trademark of The XFree86 Project, Inc.



                                 165
5.1.   The X Window System                                         166
_______________________________________________________________________

section, we'll give a step-by-step  description of how to  install and
configure XFree86 for Linux, but you will have to fill in  some of the
details yourself by  reading the  documentation released with  XFree86
itself.  (This documentation is  discussed below.)  The  Linux XFree86
HOWTO is another good source of information.

5.1.1 Hardware requirements

As of XFree86 version 3.1,  released in September 1994,  the following
video chipsets are supported.   The  documentation included with  your
video adaptor should  specify the  chipset used.   If  you are in  the
market for a new video  card, or are  buying a new machine that  comes
with a video  card, have the  vendor find out  exactly what the  make,
model, and  chipset  of the  video card  is.    This may  require  the
vendor to call technical  support on your  behalf; in general  vendors
will be happy to do  this.  Many  PC hardware vendors will state  that
the video card is  a ``standard SVGA  card'' which ``should work''  on
your system.  Explain that your software (mention Linux  and XFree86!)
does not support all  video chipsets and  that you must have  detailed
information.
  You  can  also  determine your  videocard  chipset  by  running  the
SuperProbe program included with  the XFree86 distribution.   This  is
covered in more detail below.
  The following standard SVGA chipsets are supported:

 o  Tseng ET3000, ET4000AX, ET4000/W32

 o  Western Digital/Paradise PVGA1

 o  Western Digital  WD90C00,  WD90C10,   WD90C11,  WD90C24,  WD90C30,
    WD90C31, WD90C33

 o  Genoa GVGA

 o  Trident TVGA8800CS,  TVGA8900B, TVGA8900C,  TVGA8900CL,  TVGA9000,
    TVGA9000i, TVGA9100B, TVGA9200CX, TVGA9320, TVGA9400CX, TVGA9420

 o  ATI 18800, 18800-1, 28800-2,  28800-4, 28800-5, 28800-6,  68800-3,
    68800-6, 68800AX, 68800LX, 88800

 o  NCR 77C22, 77C22E, 77C22E+

 o  Cirrus Logic  CLGD5420, CLGD5422,  CLGD5424,  CLGD5426,  CLGD5428,
    CLGD5429,  CLGD5430,  CLGD5434,   CLGD6205,  CLGD6215,   CLGD6225,
    CLGD6235, CLGD6420

 o  Compaq AVGA

 o  OAK OTI067, OTI077
5.1.   The X Window System                                         167
_______________________________________________________________________

 o  Avance Logic AL2101

 o  MX MX68000, MX680010

 o  Video 7/Headland Technologies HT216-32

  The  following SVGA  chipsets  with  accelerated features  are  also
supported:

 o  8514/A (and true clones)

 o  ATI Mach8, Mach32

 o  Cirrus CLGD5420, CLGD5422, CLGD5424, CLGD5426, CLGD5428, CLGD5429,
    CLGD5430, CLGD5434, CLGD6205, CLGD6215, CLGD6225, CLGD6235

 o  S3 86C911, 86C924, 86C801, 86C805, 86C805i, 86C928, 86C864, 86C964

 o  Western Digital WD90C31, WD90C33

 o  Weitek P9000

 o  IIT AGX-014, AGX-015, AGX-016

 o  Tseng ET4000/W32, ET4000/W32i, ET4000/W32p

  Video cards  using these chipsets  are supported  on all bus  types,
including VLB and PCI.
  All of  the above  are supported  in both 256  color and  monochrome
modes,  with the  exception  of  the  Avance Logic,  MX  and  Video  7
chipsets, which  are  only supported  in  256 color  mode.    If  your
video card has enough DRAM installed,  many of the above  chipsets are
supported in 16 and 32 bits-per-pixel mode (specifically, some Mach32,
P9000, S3 and Cirrus boards).   The usual configuration is 8  bits per
pixel (that is, 256 colors).
  The monochrome server also supports generic VGA  cards, the Hercules
monochrome card,  the Hyundai  HGC1280,  Sigma LaserView,  and  Apollo
monochrome cards.   On the Compaq  AVGA, only 64k  of video memory  is
supported for the monochrome server, and the GVGA has  not been tested
with more than 64k.
  This list  will  undoubtedly expand  as time  passes.   The  release
notes for the current version  of XFree86 should contain the  complete
list of supported video chipsets.
  One  problem faced  by the  XFree86 developers  is  that some  video
card manufacturers use non-standard  mechanisms for determining  clock
frequencies used  to drive  the card.    Some  of these  manufacturers
either don't  release specifications  describing  how to  program  the
card, or they  require developers to  sign a non-disclosure  statement
to obtain the  information.   This would  obviously restrict the  free
distribution of  the  XFree86  software, something  that  the  XFree86
5.1.   The X Window System                                         168
_______________________________________________________________________

development team is  not willing to  do.   For a  long time, this  has
been a problem with certain  video cards manufactured by Diamond,  but
as of release  3.1 of XFree86,  Diamond has started  to work with  the
development team to release free drivers for these cards.
  The  suggested setup  for  XFree86  under  Linux is  a  486  machine
with at least  8 megabytes  of RAM, and  a video  card with a  chipset
listed  above.     For  optimal  performance,  we   suggest  using  an
accelerated card, such as  an S3-chipset card.   You should check  the
documentation for  XFree86 and  verify that  your  particular card  is
supported before taking the plunge and purchasing  expensive hardware.
Benchmark ratings comparisons  for various  video cards under  XFree86
are posted routinely to the USENET  newsgroups comp.windows.x.i386unix
and comp.os.linux.misc.
  As  a side  note,  my  personal  Linux system  is  a  486DX2-66,  20
megabytes of RAM, and is equipped with a VLB S3-864  chipset card with
2 megabytes of DRAM. I have  run X benchmarks on this machine  as well
as on Sun Sparc IPX workstations.  The Linux system is roughly 7 times
faster than the Sparc IPX  (for the curious, XFree86-3.1  under Linux,
with this video card,  runs at around 171,000  xstones; the Sparc  IPX
at around 24,000).   In  general, XFree86  on a  Linux system with  an
accelerated SVGA card will give you much greater performance than that
found on  commercial UNIX  workstations (which  usually employ  simple
framebuffers for graphics).
  Your machine  will need at  least 4 megabytes  of physical RAM,  and
16 megabytes  of virtual  RAM  (for example,  8  megs physical  and  8
megs swap).  Remember  that the more physical  RAM that you have,  the
less that the system will  swap to and from  disk when memory is  low.
Because swapping is inherently slow  (disks are very slow compared  to
memory), having 8 megabytes of RAM or more is necessary to run XFree86
comfortably.  A system with 4 megabytes of physical RAM could run much
(up to 10 times) more slowly than one with 8 megs or more.

5.1.2 Installing XFree86

The Linux binary  distribution of  XFree86 can  be found  on a  number
of FTP  sites.   On  sunsite.unc.edu,  it is  found  in the  directory
/pub/Linux/X11.  (As of the time of this writing,  the current version
is 3.1; newer versions are released periodically).
  It's quite  likely  that you  obtained XFree86  as part  of a  Linux
distribution, in which case downloading the software separately is not
necessary.
  If you are downloading XFree86 directly, This table  lists the files
in the XFree86-3.1 distribution.
  One of the following servers is required:
5.1.   The X Window System                                         169

     File                    Description

     XF86-3.1-8514.tar.gz    Server for 8514-based boards.
     XF86-3.1-AGX.tar.gz     Server for AGX-based boards.
     XF86-3.1-Mach32.tar.gz  Server for Mach32-based boards.
     XF86-3.1-Mach8.tar.gz   Server for Mach8-based boards.
     XF86-3.1-Mono.tar.gz    Server for monochrome video modes.
     XF86-3.1-P9000.tar.gz   Server for P9000-based boards.
     XF86-3.1-S3.tar.gz      Server for S3-based boards.
     XF86-3.1-SVGA.tar.gz    Server for Super VGA-based boards.
     XF86-3.1-VGA16.tar.gz   Server for VGA/EGA-based boards.
     XF86-3.1-W32.tar.gz     Server for ET4000/W32-based boards.

  All of the following files are required:

     File                    Description

     XF86-3.1-bin.tar.gz     The rest of the X11R6 binaries.
     XF86-3.1-cfg.tar.gz     Config files for xdm, xinit and fs.
     XF86-3.1-doc.tar.gz     Documentation and manpages.
     XF86-3.1-inc.tar.gz     Include files.
     XF86-3.1-lib.tar.gz     Shared X libraries and support files.
     XF86-3.1-fnt.tar.gz     Basic fonts.

  The following files are optional:

     File                    Description

    XF86-3.1-ctrb.tar.gz     Selected contrib programs.
    XF86-3.1-extra.tar.gz    Extra XFree86 servers and binaries.
    XF86-3.1-lkit.tar.gz     Server linkkit for customization.
    XF86-3.1-fnt75.tar.gz    75-dpi screen fonts.
    XF86-3.1-fnt100.tar.gz   100-dpi screen fonts.
    XF86-3.1-fntbig.tar.gz   Large Kanji and other fonts.
    XF86-3.1-fntscl.tar.gz   Scaled fonts (Speedo, Type1).
    XF86-3.1-man.tar.gz      Manual pages.
    XF86-3.1-pex.tar.gz      PEX binaries, includes and libraries.
    XF86-3.1-slib.tar.gz     Static X libraries and support files.
    XF86-3.1-usrbin.tar.gz   Daemons which reside in /usr/bin.
    XF86-3.1-xdmshdw.tar.gz  Shadow password version of xdm.

  The XFree86 directory  should contain README files and  installation
notes for the current version.
  All that  is  required to  install XFree86  is to  obtain the  above
files, create the directory /usr/X11R6 (as root), and unpack the files
from /usr/X11R6 with a command such as:

    # gzip --dc XF86-3.1-bin.tar.gz | tar xfB --


Remember that these tar  files are packed  relative to /usr/X11R6,  so
it's important to unpack the files there.
  After  unpacking  the  files,  you  first  need  to  link  the  file
5.1.   The X Window System                                         170
_______________________________________________________________________

/usr/X11R6/bin/X to the server that you're using.  For example, if you
wish to use  the SVGA  color server, /usr/bin/X11/X  should be  linked
to /usr/X11R6/bin/XF86_SVGA. If you  wish to use the  monochrome server
instead, relink this file to XF86_MONO with the command

    # ln --sf /usr/X11R6/bin/XF86_MONO  /usr/X11R6/bin/X

The same holds true if you are using one of the other servers.
  If  you  aren't  sure which  server  to  use,  or  don't  know  your
video card  chipset,  you can  run  the  SuperProbe program  found  in
/usr/X11R6/bin (included  in the  XF86-3.1-bin listed  above).    This
program will attempt to  determine your video  chipset type and  other
information; write down its output for later reference.
  You  need  to  make  sure  that  /usr/X11R6/bin  is  on  your  path.
This can  be  done by  editing  your  system default  /etc/profile  or
/etc/csh.login (based on the  shell that you,  or other users on  your
system, use).   Or you can simply  add the directory to your  personal
path by modifying /etc/.bashrc or /etc/.cshrc, based on your shell.
  You also  need to make  sure that /usr/X11R6/lib  can be located  by
ld.so, the runtime linker.  To do this, add the line

    /usr/X11R6/lib

to the file /etc/ld.so.conf, and run /sbin/ldconfig, as root.

5.1.3 Configuring XFree86

Setting up XFree86 is not  difficult in most cases.   However, if  you
happen to be using hardware for which drivers ar under development, or
wish to obtain the best performance or resolution from  an accelerated
graphics card, configuring XFree86 can be somewhat time-consuming.
  In  this  section we  will  describe  how  to create  and  edit  the
XF86Config file, which configures the  XFree86 server.  In  many cases
it is  best  to start  out  with  a ``basic''  XFree86  configuration,
one which uses  a low  resolution, such  as 640x480,  which should  be
supported on  all  video cards  and  monitor types.    Once  you  have
XFree86 working at  a lower,  standard resolution,  you can tweak  the
configuration to exploit the capabilities of your video hardware.  The
idea is  that you  want to  know that  XFree86 works  at  all on  your
system, and that something isn't wrong with your  installation, before
attempting the sometimes difficult task of setting up XFree86 for real
use.
  In addition  to the  information listed  here, you  should read  the
following documentation:

 o  The XFree86  documentation  in  /usr/X11R6/lib/X11/doc  (contained
    within the  XFree86-3.1-doc  package).     You  should  especially
    see the  file README.Config,  which  is an  XFree86  configuration
    tutorial.
   5.1.  The X Window System                                          171
   _______________________________________________________________________

    o  Several video chipsets  have separate  README files  in the  above
       directory (such  as README.Cirrus  and README.S3).    Read one  of
       these if applicable.

    o  The man page for XFree86.

    o  The man page for XF86Config.

    o  The man page for the particular server that you are using (such as
       XF86_SVGA or XF86_S3).

     The       main       XFree86       configuration       file       is
   /usr/X11R6/lib/X11/XF86Config.      This  file  contains   information
   on your  mouse,   video  card  parameters,  and  so  on.     The  file
   XF86Config.eg is provided with the XFree86 distribution as an example.
   Copy this file to XF86Config and edit it as a starting point.
     The XF86Config man page explains the format of  this file in detail.
   Read this man page now, if you have not done so already.
     We are going  to present a sample  XF86Config file, piece by  piece.
   This file may not  look exactly like the  sample file included in  the
   XFree86 distribution, but the structure is the same.
!    Note that the  XF86Config file format  may change with each  version
   of XFree86; this information is only valid for XFree86 version 3.1.
!    Also,  you should  not  simply copy  the configuration  file  listed
   here to your  own system and  attempt to use  it.   Attempting to  use
   a configuration file which doesn't  correspond to your hardware  could
   drive the monitor at a frequency which is too high for it;  there have
   been reports of monitors  (especially fixed-frequency monitors)  being
   damaged or  destroyed by  using an  incorrectly configured  XF86Config
   file.   The  bottom line  is this:   Make  absolutely  sure that  your
   XF86Config file corresponds to your hardware before you attempt to use
   it.
     Each section  of the XF86Config  file is surrounded  by the pair  of
   lines Section "<section-name>"...EndSection.   The first  part of the
   XF86Config file is Files, which looks like this:

       Section "Files"
           RgbPath     "/usr/X11R6/lib/X11/rgb"
           FontPath    "/usr/X11R6/lib/X11/fonts/misc/"
           FontPath    "/usr/X11R6/lib/X11/fonts/75dpi/"
       EndSection

   The RgbPath line sets  the path to the  X11R6 RGB color database,  and
   each FontPath line sets the path to a directory containing  X11 fonts.
   In general you shouldn't have to modify these lines; just be sure that
   there is a FontPath entry for  each font type that you  have installed
   (that is, for each directory in /usr/X11R6/lib/X11/fonts).
     The  next section  is ServerFlags,  which  specifies several  global
   flags for the server.  In general this section is empty.
5.1.   The X Window System                                         172
_______________________________________________________________________

  Section "ServerFlags"
  # Uncomment this to cause a core dump at the spot where a signal is
  # received. This may leave the console in an unusable state, but may
  # provide a better stack trace in the core dump to aid in debugging
  #    NoTrapSignals
  # ncomment this to disable the <Crtl><Alt><BS> server abort sequence
  #    DontZap
  EndSection

Here, we have all lines within the section commented out.
  The next section is Keyboard.  This should be fairly intuitive.

    Section "Keyboard"
        Protocol    "Standard"
        AutoRepeat  500 5
        ServerNumLock
    EndSection

Other options are available as  well---see the XF86Config file if  you
wish to modify the keyboard configuration.  The above  should work for
most systems.
  The  next section  is  Pointer which  specifies parameters  for  the
mouse device.

    Section "Pointer"

        Protocol    "MouseSystems"
        Device      "/dev/mouse"

    # Baudrate and SampleRate are only for some Logitech mice
    #    BaudRate   9600
    #    SampleRate 150

    # Emulate3Buttons is an option for 2-button Microsoft mice
    #    Emulate3Buttons

    # ChordMiddle is an option for some 3-button Logitech mice
    #    ChordMiddle

    EndSection

The only  options  that  you  should concern  yourself  with  now  are
Protocol and Device.  Protocol specifies the mouse protocol  that your
mouse uses (not the make or brand of mouse).  Valid types for Protocol
(under Linux---there are other  options available for other  operating
5.1.  The X Window System                                          173
_______________________________________________________________________

systems) are:

 o  BusMouse

 o  Logitech

 o  Microsoft

 o  MMSeries

 o  Mouseman

 o  MouseSystems

 o  PS/2

 o  MMHitTab

BusMouse should be used  for the Logitech busmouse.   Note that  older
Logitech mice should use Logitech, but newer Logitech mice  use either
Microsoft or Mouseman protocols.  This is a case in which the protocol
doesn't necessarily have anything to do with the make of the mouse.
  Device specifies the  device file where  the mouse can be  accessed.
On most Linux systems,  this is /dev/mouse.   /dev/mouse is usually  a
link to the  appropriate serial  port (such as  /dev/cua0) for  serial
mice, or to the appropriate busmouse device for busmice.  At any rate,
be sure that the device file listed in Device exists.
  The next section is Monitor, which specifies  the characteristics of
your monitor.   As with other sections  in the XF86Config file,  there
may be more  than one Monitor  section.   This is  useful if you  have
multiple monitors connected to  a system, or  use the same  XF86Config
file under multiple hardware configurations.  In general,  though, you
will need a single Monitor section.

 Section "Monitor"

   Identifier  "CTX 5468 NI"

   # These values are for a CTX 5468NI only! Don't attempt to use
   # them with your monitor (unless you have this model)

   Bandwidth    60
   HorizSync    30-38,47-50
   VertRefresh  50-90

   # Modes:  Name   dotclock    horiz                vert

   ModeLine "640x480"  25       640 664 760 800      480 491 493 525

5.1.   The X Window System                                         174
_______________________________________________________________________

   ModeLine "800x600"  36       800 824 896 1024     600 601 603 625
   ModeLine "1024x768" 65       1024 1088 1200 1328  768 783 789 818

 EndSection

  The  Identifier line  is  used to  give  an  arbitrary name  to  the
Monitor entry.  This  can be any string; you  will use it to  refer to
the Monitor entry later in the XF86Config file.
  they are listed below.
  HorizSync specifies the  valid horizontal sync frequencies for  your
monitor, in kHz.  If you have a multisync monitor, this can be a range
of values (or  several comma-separated  ranges), as  seen above.    If
you have a fixed-frequency  monitor, this will  be a list of  discrete
values, such as:

        HorizSync    31.5, 35.2, 37.9, 35.5, 48.95

Your  monitor  manual  should  list  these  values  in  the  technical
specifications  section.     If  you  do  not  have  this  information
available, you  should either contact  the manufacturer  or vendor  of
your monitor to obtain it.  There are other sources of information, as
well;
  VertRefresh specifies the valid vertical refresh  rates (or vertical
synchronization frequencies) for your monitor, in Hz.   Like HorizSync
this can be a range or a list of discrete values;  your monitor manual
should list them.
  HorizSync and  VertRefresh are  used only to  double-check that  the
monitor resolutions that you specify are in valid ranges.   This is to
reduce the chance that you  will damage your monitor by  attempting to
drive it at a frequency for which it was not designed.
  The ModeLine directive is  used to specify a single  resolution mode
for your monitor.  The format of ModeLine is

    ModeLine <name> <clock> <horiz-values> <vert-values>

<name> is an  arbitrary string,  which  you will  use to refer  to the
resolution mode later in the  file.  <dot-clock>  is the driving clock
frequency, or ``dot clock''  associated with the  resolution mode.   A
dot clock  is usually  specified in  MHz,  and is  the  rate at  which
the video card  must send pixels  to the  monitor at this  resolution.
<horiz-values> and <vert-values>  are four  numbers each  which specify
when the  electron  gun of  the  monitor  should fire,  and  when  the
horizontal and vertical sync pulses fire during a sweep.
  How can  you determine the  ModeLine values for your  monitor?   The
file VideoModes.doc, included with the XFree86 distribution, describes
in detail how to determine these values for each resolution  mode that
your monitor supports.   First of all, <clock>  must correspond to one
of the dot clock values  that your video card  can produce.  Later  in
the XF86Config file you  will specify these clocks;  you can only  use
5.1.   The X Window System                                         175
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video modes which have a <clock> value supported by your video card.
  There are two files  included in the XFree86 distribution  which may
include ModeLine data for  your monitor.   These files are  modeDB.txt
and Monitors, both of which are found in /usr/X11R6/lib/X11/doc.
  You should start with ModeLine values for the  VESA standard monitor
timings, which  most monitors  support.    modeDB.txt includes  timing
values for VESA  standard resolutions.   In  that file,  you will  see
entries such as

    # 640x480@60Hz Non-Interlaced mode
    # Horizontal Sync = 31.5kHz
    # Timing: H=(0.95us, 3.81us, 1.59us), V=(0.35ms, 0.064ms, 1.02ms)
    #
    # name      clock   horizontal timing     vertical timing    flags
    "640x480"   25.175  640  664  760  800    480  491  493  525

This is a VESA standard  timing for a 640x480 video  mode.  It  uses a
dot clock of 25.175,  which your video card  must support to use  this
mode (more on this later).   To include  this entry in the  XF86Config
file, you'd use the line

    ModeLine "640x480" 25.175  640 664 760 800  480 491 493 525

Note that the <name> argument to  ModeLine (in this case "640x480") is
an arbitrary string---the  convention is  to name the  mode after  the
resolution, but <name>  can technically be  anything descriptive which
describes the mode to you.
  For   each  ModeLine   used   the  server   will  check   that   the
specifications for the mode fall within the range of  values specified
with Bandwidth, HorizSync and VertRefresh.  If they do not, the server
will complain when  you attempt to  start up X  (more on this  later).
For one thing, the  dot clock used by  the mode should not be  greater
than the value used for Bandwidth.  (However, in many cases it is safe
to use modes with  a slightly higher  bandwidth than your monitor  can
support.)
  If the VESA standard timings do not work for  you (you'll know after
trying to  use them  later)  then the  files modeDB.txt  and  Monitors
include specific mode values for many  monitor types.  You  can create
ModeLine entries from the values found in those two files as well.  Be
sure to only  use values for  the specific model  of monitor that  you
have.  Note  that many 14 and  15-inch monitors cannot support  higher
resolution modes, and often resolutions of 1024x768 at low dot clocks.
This means  that if  you can't  find high  resolution  modes for  your
monitor in these files,  then your monitor  probably does not  support
those resolution modes.
  If you  are completely at  a loss, and  can't find working  ModeLine
values for  your  monitor, you  can  follow  the instructions  in  the
VideoModes.doc file included in  the XFree86 distribution to  generate
ModeLine values  from  the  specifications listed  in  your  monitor's
   5.1.  The X Window System                                          176
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   manual.   While your mileage  will certainly  vary when attempting  to
   generate ModeLine values by hand, this is a good place to  look if you
   can't find the values  that you need.   VideoModes.doc also  describes
   the format of the ModeLine directive and other aspects of  the XFree86
   server in gory detail.
     Lastly, if you do  obtain ModeLine values which are almost,  but not
   quite, right,  then it  may be possible  to simply  modify the  values
   slightly to obtain the desired result.  For example,  if while running
   XFree86 the image  on the  monitor is  shifted slightly,  or seems  to
   ``roll'', you can follow  the instructions in the VideoModes.doc  file
   to try to  fix these values.   Also,  be sure to  check the knobs  and
   controls on the  monitor itself!   In  many cases  it is necessary  to
   change the horizontal or vertical  size of the display after  starting
   up XFree86  in order  for  the image  to  be centered  and be  of  the
   appropriate size.  Having these  controls on the front of  the monitor
   can certainly make life easier.
!    You  shouldn't use  monitor  timing values  or ModeLine  values  for
   monitors other than the model that you  own.  If you attempt  to drive
   the monitor at  a frequency  for which it  was not  designed, you  can
   damage or even destroy it.
     The next section of  the XF86Config file is Device,  which specifies
   parameters for your video card.  Here is an example.

       Section "Device"
               Identifier "#9 GXE 64"

               # Nothing yet; we fill in these values later.

       EndSection

     This  section  defines  properties  for  a  particular  video  card.
   Identifier is an arbitrary  string describing the  card; you will  use
   this string to refer to the card later.
     Initially,  you  don't  need  to  include  anything  in  the  Device
   section, except for Identifier.  This is because we will  be using the
   X server itself  to probe for  the properties of  the video card,  and
   entering them into the  Device section later.   The XFree86 server  is
   capable of probing for the  video chipset, clocks, RAMDAC,  and amount
   of video RAM on the board.
     Before  we  do  this,  however,   we  need  to  finish  writing  the
   XF86Config file.   The  next section  is Screen,  which specifies  the
   monitor/video card combination to use for a particular server.

        Section "Screen"
            Driver     "Accel"
            Device     "#9 GXE 64"
            Monitor    "CTX 5468 NI"
            Subsection "Display"
                Depth      16
                Modes      "1024x768" "800x600" "640x480"
5.1.  The X Window System                                          177
_______________________________________________________________________

             ViewPort   0 0
             Virtual    1024 768
         EndSubsection
     EndSection

  The Driver line specifies the X server that you will be  using.  The
value values for Driver are:

 o  Accel:    For  the  XF86_S3,   XF86_Mach32,   XF86_Mach8,  XF86_8514,
    XF86_P9000, XF86_AGX, and XF86_W32 servers;

 o  SVGA: For the XF86_SVGA server;

 o  VGA16:  For the XF86_VGA16 server;

 o  VGA2:  For the XF86_Mono server;

 o  Mono:   For the non-VGA  monochrome drivers  in the  XF86_Mono  and
    XF86_VGA16 servers.

You should be  sure that /usr/X11R6/bin/X  is a  symbolic link to  the
server that you are using.
  The  Device line  specifies  the Identifier  of the  Device  section
corresponding to the video  card to use  for this server.   Above,  we
created a Device section with the line

    Identifier "#9 GXE 64"

Therefore, we use "#9 GXE 64" on the Device line here.
  Similarly,  the  Monitor line  specifies  the  name of  the  Monitor
section to be  used with  this server.   Here,  "CTX 5468  NI" is  the
Identifier used in the Monitor section described above.
  Subsection  "Display"  defines several  properties  of  the  XFree86
server corresponding  to your  monitor/video card  combination.    The
XF86Config file describes all of these options in detail; most of them
are icing on the cake and not necessary to get the system working.
  The options that you should know about are:

 o  Depth.  Defines  the number of  color planes---the number of  bits
    per pixel.  Usually, Depth is set to 8.  For the VGA16 server, you
    would use a depth of 4,  and for the monochrome server a  depth of
    1.  If you are using an accelerated video card  with enough memory
    to support more bits per  pixel, you can set  Depth to 16, 24,  or
    32.  If you have problems  with depths higher than 8, set  it back
    to 8 and attempt to debug the problem later.

 o  Modes.   This is  the list  of video  mode names  which have  been
    defined using the ModeLine directive  in the Monitor section.   In
    the above section, we used ModeLines named  "1024x768", "800x600",
    and "640x48"0.  Therefore, we use a Modes line of
5.1.   The X Window System                                         178
_______________________________________________________________________

                 Modes    "1024x768" "800x600" "640x480"


    The first  mode  listed on  this line  will  be the  default  when
    XFree86 starts  up.   After  XFree86 is  running,  you can  switch
    between the modes listed here using the keys [ctrl]-[alt]-[numeric
    +] and [ctrl]-[alt]-[numeric -].

    It might be best, when initially configuring XFree86, to use lower
    resolution video modes,  such as  640x480, which  tend to work  on
    most systems.  Once  you have the basic configuration  working you
    can modify XF86Config to support higher resolutions.

 o  Virtual.  Sets the virtual desktop size.  XFree86  has the ability
    to use any additional memory on your video card to extend the size
    of your desktop.    When you move  the mouse  pointer to the  edge
    of the display, the  desktop will scroll, bringing the  additional
    space into view.   Therefore, even if  you are running at a  lower
    video resolution such as 800x600, you can set Virtual to the total
    resolution which your video  card can support (a 1-megabyte  video
    card can  support 1024x768  at a  depth  of 8  bits per  pixel;  a
    2-megabyte card 1280x1024 at  depth 8, or  1024x768 at depth  16).
    Of course, the entire area will not be visible at once, but it can
    still be used.

    The Virtual feature is  a nice way to  utilize the memory of  your
    video card,  but it  is rather  limited.   If  you want  to use  a
    true virtual desktop, we suggest  using fvwm, or a  similar window
    manager, instead.   fvwm allows you  to have rather large  virtual
    desktops (implemented by hiding windows, and so forth,  instead of
    actually storing the entire desktop in video memory at once).  See
    the man pages  for fvwm for  more details about  this; most  Linux
    systems use fvwm by default.

 o  ViewPort.  If  you are using  the Virtual option described  above,
    ViewPort sets the coordinates of the upper-left-hand corner of the
    virtual desktop when  XFree86 starts  up.   Virtual 0  0 is  often
    used; if this is unspecified  then the desktop is centered  on the
    virtual desktop display (which may be undesirable to you).

  Many other options  for this section  exist; see the XF86Config  man
page for a complete description.  In practice these  other options are
not necessary to get XFree86 initially working.

5.1.4 Filling in video card information

Your XF86Config  file  is now  ready  to  go,  with the  exception  of
complete information on the video card.  What we're going to do is use
the X server to probe  for the rest of  this information, and fill  it
into XF86Config.
5.1.   The X Window System                                         179
_______________________________________________________________________

  Instead  of  probing  for  this  information  with   the  X  server,
the  XF86Config  values  for  many  cards  are  listed  in  the  files
modeDB.txt, AccelCards,  and  Devices.    These  files are  all  found
in /usr/X11R6/lib/X11/doc.    In addition,  there  are various  README
files for  certain chipsets.    You  should look  in  these files  for
information on your video  card, and use  that information (the  clock
values, chipset type, and any options) in the XF86Config file.  If any
information is missing, you can probe for it as described here.
  In these examples we will demonstrate configuration for  a #9 GXE 64
video card, which uses the  XF86_S3 chipset.   This card happens  to be
the one which the author uses, but the discussion here  applies to any
video card.
  The first thing to do is to determine the video  chipset used on the
card.  Running SuperProbe (found in /usr/X11R6/bin) will tell you this
information, but you need to know  the chipset name as it is  known to
the X server.
  To do this, run the command

    X -showconfig

This will give the  chipset names known  to your X  server.  (The  man
pages for each X server  list these as well.)   For example, with  the
accelerated XF86_S3 server, we obtain:

    XFree86 Version 3.1 / X Window System
    (protocol Version 11, revision 0, vendor release 6000)
    Operating System: Linux
    Configured drivers:
      S3: accelerated server for S3 graphics adaptors (Patchlevel 0)
          mmio_928, s3_generic

  The valid chipset names for this  server are mmio_928 and s3_generic.
The XF86_S3  man page  describes  these chipsets  and which  videocards
use them.    In the  case of  the #9  GXE 64  video card,  mmio_928  is
appropriate.
  If you don't  know which chipset to use,  the X server can  probe it
for you.  To do this, run the command

    X -probeonly > /tmp/x.out 2>&1

if you use bash as your shell.  If you use csh, try:

    X -probeonly &> /tmp/x.out

  You should run this  command while the system is unloaded,  that is,
while no other activity is occurring on the system.  This command will
also probe for your video card dot clocks (as seen below),  and system
load can throw off this calculation.
  The output from the  above (in /tmp/x.out should contain  lines such
as the following:
5.1.   The X Window System                                         180
_______________________________________________________________________

    XFree86 Version 3.1 / X Window System
    (protocol Version 11, revision 0, vendor release 6000)
    Operating System: Linux
    Configured drivers:
      S3: accelerated server for S3 graphics adaptors (Patch level 0)
          mmio_928, s3_generic
    Several lines deleted...
    (--) S3: card type: 386/486 localbus
    (--) S3: chipset:   864 rev. 0
    (--) S3: chipset driver: mmio_928

Here, we see  that the  two valid  chipsets for this  server (in  this
case, XF86_S3) are mmio_928 and s3_generic.   The server probed  for and
found a video card using the mmio_928 chipset.
  In the Device  section of the XF86Config  file, add a Chipset  line,
containing the name of the chipset as determined above.  For example,

    Section "Device"
            # We already had Identifier here...
            Identifier "#9 GXE 64"
            # Add this line:
            Chipset "mmio_928"
    EndSection

  Now we need to  determine the driving clock frequencies used  by the
video card.  A driving clock frequency, or dot clock, is simply a rate
at which the video card  can send pixels to the  monitor.  As  we have
seen, each monitor resolution has a dot clock associated with it.  Now
we need to determine which dot clocks are made available  by the video
card.
  First you  should look  into the  files (modeDB.txt,  and so  forth)
mentioned above and see if your  card's clocks are listed there.   The
dot clocks will usually be a list of 8 or 16 values, all  of which are
in MHz.  For example, when  looking at modeDB.txt we see an  entry for
the Cardinal ET4000 video board, which looks like this:

    #      chip                           ram                     vir-
    tual   clocks                           default-mode  flags
     ET4000   1024  1024 768   25  28  38  36  40  45  32   0  "1024x768"

As we can see, the  dot clocks for this card  are 25, 28, 38, 36,  40,
45, 32, and 0 MHz.
  In the  Devices section  of the XF86Config  file, you  should add  a
Clocks line containing  the list  of dot clocks  for your  card.   For
example, for the clocks above, we would add the line

            Clocks 25 28 38 36 40 45 32 0

to the Devices  section of the  file, after  Chipset.   Note that  the
5.1.   The X Window System                                         181
_______________________________________________________________________

order of the clocks is important!  Don't resort the list  of clocks or
remove duplicates.
  If you cannot find  the dot clocks associated with your card,  the X
server can probe for these  as well.   Using the X -probeonly  command
described above, the output should  contain lines which look  like the
following:

    (--
    ) S3: clocks:  25.18  28.32  38.02  36.15  40.33  45.32  32.00  00.00

We could then  add a Clocks  line containing all  of these values,  as
printed.  You can use  more than one Clocks line in  XF86Config should
all of  the values  (sometimes  there are  more  than 8  clock  values
printed) not fit onto one  line.  Again, be  sure to keep the  list of
clocks in order as they are printed.
  Be sure that there is  no Clocks line (or that it is  commented out)
in the Devices section  of the file when  using X -probeonly to  probe
for the clocks.   If there is a  Clocks line present, the server  will
not probe for the clocks---it will use the values given in XF86Config.
  Note that  some accelerated  video boards use  a programmable  clock
chip.    (See the  XF86_Accel  man  page for  details;  this  generally
applies to S3, AGX, and XGA-2  boards.)  This chip  essentially allows
the X server to tell the card which dot clocks to use.  If this is the
case, then you may not find a  list of dot clocks for the card  in any
of the above files.  Or,  the list of dot clocks printed when  using X
-probeonly will only contain  one or two  discrete clock values,  with
the rest being duplicates or zero.
  For boards  which use  a programmable clock  chip, you  would use  a
ClockChip line, instead  of a  Clocks line,  in your XF86Config  file.
ClockChip gives the name of the clock chip as used by  the video card;
the man pages for each server  describe what these are.   For example,
in the file README.S3, we see  that several S3-864 video cards  use an
``ICD2061A'' clock chip, and that we should use the line

            ClockChip "icd2061a"

instead of Clocks in the XF86Config  file.  As with Clocks,  this line
should go in the Devices section, after Chipset.
  Similarly, some accelerated cards require you to  specify the RAMDAC
chip type in the XF86Config file, using a Ramdac line.  The XF86_Accel
man page describes this option.  Usually, the X  server will correctly
probe for the RAMDAC.
  Some video card types require you to specify  several options in the
Devices section of  XF86Config.   These options  will be described  in
the man page for your  server, as well  as in the various files  (such
as README.cirrus or README.S3.   These  options are enabled using  the
Option line.  For example, the #9 GXE 64 card requires two options:

            Option "number_nine"
            Option "dac_8_bit"
5.1.  The X Window System                                          182
_______________________________________________________________________

Usually, the X server  will work without  these options, but they  are
necessary to obtain  the best performance.   There  are too many  such
options to list  here, and they  each depend  on the particular  video
card being used.  If you must use one of these options, fear not---the
X server man  pages and various  files in /usr/X11R6/lib/X11/doc  will
tell you what they are.
  So, when you're finished,  you should end up with a  Devices section
which looks something like this:

    Section "Device"
            # Device section for the #9 GXE 64 only !
            Identifier "#9 GXE 64"
            Chipset "mmio_928"
            ClockChip "icd2061a"
            Option "number_nine"
            Option "dac_8_bit"
    EndSection

Most video cards  will require  a Clocks line,  instead of  ClockChip,
as described  above.   The  above Device  entry is  only  valid for  a
particular video card, the  #9 GXE 64.   It is  given here only as  an
example.
  There are other options  that you can include in the  Devices entry.
Check the X  server man pages  for the gritty  details, but the  above
should suffice for most systems.

5.1.5 Running XFree86

With your XF86Config file  configured, you're ready  to fire up the  X
server and give it a spin.   First, be sure that /usr/X11R6/bin  is on
your path.
  The command to start up XFree86 is

    startx

This is a front-end to  xinit (in case you're  used to using xinit  on
other UNIX systems).
  This command will start  the X server and run the commands  found in
the file .xinitrc in your  home directory.   .xinitrc is just a  shell
script containing X clients to run.  If this file does  not exist, the
system default /usr/X11R6/lib/X11/xinit/xinitrc will be used.
  A standard .xinitrc file looks like this:

    #!/bin/sh

    xterm -fn 7x13bold -geometry 80x32+10+50 &
    xterm -fn 9x15bold -geometry 80x34+30-10 &
    oclock -geometry 70x70-7+7 &
    xsetroot -solid midnightblue &
5.1.   The X Window System                                         183
_______________________________________________________________________

    exec twm

This script will start  up two xterm clients,  an oclock, and set  the
root window (background) color to midnightblue.  It will then start up
twm, the window manager.   Note that twm is executed with  the shell's
exec statement; this causes the xinit process to be replaced with twm.
Once the twm  process exits, the  X server  will shut down.   You  can
cause twm to exit by using the root menus:  depress mouse  button 1 on
the desktop background---this will  display a pop  up menu which  will
allow you to Exit Twm.
  Be sure that the last command in .xinitrc is  started with exec, and
that it is not placed into the background (no ampersand on  the end of
the line).  Otherwise  the X server will shut  down as soon as  it has
started the clients in the .xinitrc file.
  Alternately, you can exit X by  pressing [ctrl]-[alt]-[backspace] in
combination.  This will kill the X server directly, exiting the window
system.
  The  above is  a very,  very  simple desktop  configuration.    Many
wonderful programs and configurations are available with a bit of work
on your .xinitrc  file.   For example,  the fvwm  window manager  will
provide a virtual desktop, and you can customize colors, fonts, window
sizes and positions, and so forth  to your heart's content.   Although
the X Window  System might  appear to be  simplistic at  first, it  is
extremely powerful once you customize it for yourself.
  If you  are new  to  the X  Window System  environment, we  strongly
suggest picking up  a book  such as  The X  Window System:   A  User's
Guide.  Using  and configuring X  is far too  in-depth to cover  here.
See the man  pages for  xterm, oclock,  and twm for  clues on  getting
started.

5.1.6 Running into trouble

Often, something will not  be quite right  when you initially fire  up
the X server.    This is  almost always caused  by a  problem in  your
XF86Config file.  Usually, the  monitor timing values are off,  or the
video card dot clocks set incorrectly.  If your display seems to roll,
or the edges are  fuzzy, this is a  clear indication that the  monitor
timing values or  dot clocks are  wrong.   Also be  sure that you  are
correctly specifying your video card chipset, as well as other options
for the Device section of XF86Config.  Be absolutely  certain that you
are using the right X  server and that /usr/X11R6/bin/X is  a symbolic
link to this server.
  If all else fails, try  to start X ``bare''; that is, use  a command
such as:

    X > /tmp/x.out 2>&1

You can then kill the X server (using the [ctrl]-[alt]-[backspace] key
combination) and examine  the contents of  /tmp/x.out.   The X  server
will report any warnings or  errors---for example, if your  video card
5.2.   Accessing MS-DOS Files                                      184
_______________________________________________________________________

doesn't have a  dot clock corresponding  to a  mode supported by  your
monitor.
  The  file  VideoModes.doc  included  in  the   XFree86  distribution
contains many hints for tweaking the values in your XF86Config file.
  Remember  that you  can  use  [ctrl]-[alt]-[numeric +]  and  [ctrl]-
[alt]-[numeric  -]  to  switch  between  the  video  modes  listed  on
the Modes  line  of  the  Screen  section  of  XF86Config.     If  the
highest resolution mode  doesn't look  right, try  switching to  lower
resolutions.  This will  let you know, at  least, that those parts  of
your X configuration are working correctly.
  Also,  check the  vertical and  horizontal size/hold  knobs on  your
monitor.  In many cases it is necessary to adjust  these when starting
up X. For example, if the display seems to be shifted  slightly to one
side, you can usually correct this using the monitor controls.
  The   USENET  newsgroup   comp.windows.x.i386unix  is   devoted   to
discussions about XFree86.    It might be  a good  idea to watch  that
newsgroup for  postings  relating to  your  video  configuration---you
might run across someone with the same problems as your own.


5.2 Accessing MS-DOS Files

If, for some twisted and bizarre reason, you would have need to access
files from MS-DOS, it's quite easily done under Linux.
  The  usual  way  to access  MS-DOS  files  is  to  mount  an  MS-DOS
partition or  floppy under  Linux, allowing  you to  access the  files
directly through the filesystem.   For example, if you have  an MS-DOS
floppy in /dev/fd0, the command

    # mount -t msdos /dev/fd0 /mnt

will mount it under /mnt.   See Section 4.6.2 for more  information on
mounting floppies.
  You  can also  mount an  MS-DOS  partition of  your hard  drive  for
access under Linux.  If you have an MS-DOS partition on /dev/hda1, the
command

    # mount -t msdos /dev/hda1 /mnt

will mount it.  Be sure to umount the partition when you're done using
it.  You can have your MS-DOS partitions automatically mounted at boot
time if you include  entries for them in  /etc/fstab; see Section  4.8
for details.  For example, the following line in /etc/fstab will mount
an MS-DOS partition on /dev/hda1 on the directory /dos.

    /dev/hda1     /dos     msdos      defaults

  The Mtools software  may also be used to  access MS-DOS files.   For
example, the commands mcd, mdir, and mcopy all behave  as their MS-DOS
counterparts.   If you  installed Mtools,  there should  be man  pages
available for these commands.
5.3.   Networking with TCP/IP                                      185
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  Accessing MS-DOS  files is one thing;  running MS-DOS programs  from
Linux is another.  There  is an MS-DOS Emulator under  development for
Linux; it  is  widely available,  and even  distributed  with SLS.  It
can be retrieved  from a  number of locations,  including the  various
Linux FTP sites (see Appendix C for details).  The  MS-DOS Emulator is
reportedly powerful enough to run a number of  applications, including
Wordperfect, from  Linux.     However,  Linux and  MS-DOS  are  vastly
different operating systems.   The power of any MS-DOS  emulator under
UNIX is somewhat limited.
  In addition,  work is  underway on a  Microsoft Windows emulator  to
run under X  Windows.   Watch the  newsgroups and  FTP sites for  more
information.


5.3 Networking with TCP/IP

Linux supports a full implementation of the TCP/IP  (Transport Control
Protocol/Internet Protocol) networking protocols.   TCP/IP has  become
the most  successful  mechanism for  networking  computers  worldwide.
With Linux and  an Ethernet card,  you can network  your machine to  a
local area network, or (with  the proper network connections),  to the
Internet---the worldwide TCP/IP network.
  Hooking  up a  small  LAN of  UNIX  machines is  easy.    It  simply
requires an Ethernet  controller in each  machine and the  appropriate
Ethernet cables  and  other  hardware.     Or,  if  your  business  or
university provides access to  the Internet, you  can easily add  your
Linux machine to this network.
  The  current implementation  of  TCP/IP  and related  protocols  for
Linux is called ``NET-2''.  This has no relationship  to the so-called
NET-2 release of BSD  UNIX; instead, ``NET-2''  in this context  means
the second implementation of TCP/IP for Linux.
  Linux  NET-2 also  supports  SLIP---Serial Line  Internet  Protocol.
SLIP allows you to have dialup Internet access using a modem.  If your
business or university provides  SLIP access, you  can dial in to  the
SLIP server and put your machine on the Internet over  the phone line.
Alternately, if your  Linux machine  also has Ethernet  access to  the
Internet, you can set up your Linux box as a SLIP server.
  For  complete information  on  setting  up TCP/IP  under  Linux,  we
encourage you to read the  Linux NET-2 HOWTO, available via  anonymous
FTP from sunsite.unc.edu.    The NET-2  HOWTO is a  complete guide  to
configuring TCP/IP,  including Ethernet  and SLIP  connections,  under
Linux.  The Linux Ethernet HOWTO is a related  document that describes
configuration of various Ethernet card  drivers for Linux.   The Linux
Network Administrator's Guide, from  the Linux Documentation  Project,
is also  available.   See  Appendix A  for more  information on  these
documents.
  Also  of interest  is the  book  TCP/IP Network  Administration,  by
Craig Hunt.  It contains complete information on using and configuring
TCP/IP on UNIX systems.
5.3.   Networking with TCP/IP                                      186
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5.3.1 Hardware Requirements

You  can  use  Linux  TCP/IP   without  any  networking  hardware   at
all---configuring ``loopback'' mode  allows you  to talk to  yourself.
This is  necessary  for some  applications  and  games which  use  the
``loopback'' network device.
  However, if you want  to use Linux with an Ethernet  TCP/IP network,
you need one of the following  Ethernet cards:  3com 3c503,  3c503/16;
Novell NE1000, NE2000; Western Digital WD8003, WD8013; Hewlett Packard
HP27245, HP27247, HP27250.
  The following clones are reported to work:   WD-80x3 clones:  LANNET
LEC-45; NE2000 clones:   Alta Combo,  Artisoft LANtastic AE-2,  Asante
Etherpak 2001/2003, D-Link Ethernet II, LTC E-NET/16 P/N 8300-200-002,
Network Solutions  HE-203,  SVEC  4  Dimension  Ethernet,  4-Dimension
FD0490 EtherBoard 16, and D-Link DE-600, SMC Elite 16.
  See  the Linux  Ethernet HOWTO  for a  more  complete discussion  of
Linux Ethernet hardware compatibility.
  Linux also supports SLIP, which allows you to use  a modem to access
the Internet over the phone line.   In this case, you'll need  a modem
compatible with  your SLIP  server---most  servers require  a  14.4bps
V.32bis modem.

5.3.2 Configuring TCP/IP on your system

In this section we're  going to discuss  how to configure an  Ethernet
TCP/IP connection on your system.   Note that this method  should work
for many  systems, but  certainly not  all.    This discussion  should
be enough to  get you  on the  right path to  configuring the  network
parameters of your machine,  but there are  numerous caveats and  fine
details not  mentioned here.    We  direct you  to  the Linux  Network
Administrators' Guide and the NET-2-HOWTO for more information.(3)
  First of all,  we assume that you have  a Linux system that  has the
TCP/IP software installed.  This includes basic clients such as telnet
and ftp,  system administration commands  such as  ifconfig and  route
(usually found in /etc),  and networking configuration files (such  as
/etc/hosts).  The  other Linux-related networking documents  described
above explain how to go about installing the Linux networking software
if you do not have it already.
  We also  assume that your  kernel has  been configured and  compiled
with TCP/IP  support enabled.    See Section  4.7  for information  on
compiling your kernel.  To enable networking, you  must answer ``yes''
to the appropriate questions during the make config step,  and rebuild
the kernel.
  Once this has been  done, you must modify a number  of configuration
files used by NET-2.   For the most  part this is a simple  procedure.
Unfortunately,  however,  there is  wide  disagreement  between  Linux

----------------------------
 3. Some of this information is adapted from the NET-2-HOWTO  by Terry
Dawson and Matt Welsh.
5.3.   Networking with TCP/IP                                      187
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distributions as to where the  various TCP/IP configuration files  and
support programs should go.   Much of the  time, they can be found  in
/etc, but in other cases may  be found in /usr/etc, /usr/etc/inet,  or
other bizarre locations.   In the  worst case you'll  have to use  the
find command to locate the files on  your system.  Also note  that not
all distributions keep the NET-2  configuration files and software  in
the same location---they may be spread across several directories.
  The  following information  applies  primarily to  Ethernet  connec-
tions.    If  you're  planning  to use  SLIP,  read  this  section  to
understand the concepts, and follow the SLIP-specific  instructions in
the following section.

5.3.2.1 Your network configuration

Before you can configure TCP/IP,  you need to determine the  following
information about  your network  setup.   In  most cases,  your  local
network administrator can provide you with this information.

 o  IP address.  This is the unique machine  address in dotted-decimal
    format.  An example is  128.253.153.54.  Your network  admins will
    provide you with this number.

    If you're  only  configuring loopback  mode (i.e.    no  SLIP,  no
    ethernet card, just TCP/IP  connections to your own machine)  then
    your IP address is 127.0.0.1.

 o  Your  network  mask  (``netmask'').     This  is  a  dotted  quad,
    similar to the IP address,  which determines which portion  of the
    IP address  specifies the  subnetwork  number, and  which  portion
    specifies the host  on that  subnet.   (If you're  shaky on  these
    TCP/IP networking  terms,  we  suggest reading  some  introductory
    material on  network  administration.)    The  network mask  is  a
    pattern of  bits, which  when overlayed  onto an  address on  your
    network, will tell you which subnet  that address lives on.   This
    is very important for routing, and if you find, for  example, that
    you can happily talk  to people outside  your network, but not  to
    some people within your network,  there is a good chance  that you
    have an incorrect mask specified.

    Your network administrators will have chosen the netmask  when the
    network was designed, and therefore they should be able  to supply
    you with the  correct mask  to use.    Most networks  are class  C
    subnetworks which use 255.255.255.0 as their netmask.  Other Class
    B networks use  255.255.0.0.   The NET-2  code will  automatically
    select a mask that  assumes no subnetting as  a default if you  do
    not specify one.

    This applies as  well to the  loopback port.   Since the  loopback
    port's address is always 127.0.0.1,  the netmask for this  port is
    always 255.0.0.0.  You can either specify this  explicitly or rely
5.3.   Networking with TCP/IP                                      188
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    on the default mask.

 o  Your  network  address.      This  is   your  IP  address   masked
    bitwise-ANDed the  netmask.    For  example,  if your  netmask  is
    255.255.255.0, and your IP address is 128.253.154.32, your network
    address is 128.253.154.0.    With a netmask  of 255.255.0.0,  this
    would be 128.253.0.0.

    If you're only using loopback, you don't have a network address.

 o  Your broadcast  address.     The  broadcast  address  is  used  to
    broadcast packets to every machine on your subnet.   Therefore, if
    the host number of  machines on your subnet  is given by the  last
    byte of  the IP  address (netmask  255.255.255.0), your  broadcast
    address will be your network address ORed with 0.0.0.255.

    For  example,   if  your   IP  address  is   128.253.154.32,   and
    your  netmask  is   255.255.255.0,   your  broadcast  address   is
    128.253.154.255.

    Note that for historical reasons,  some networks are setup  to use
    the network  address as  the broadcast  address, if  you have  any
    doubt, check with  your network administrators.   (In many  cases,
    it will suffice  to duplicate the  network configuration of  other
    machines on  your subnet,  substituting your  own IP  address,  of
    course.)

    If you're only using loopback, you don't have a broadcast address.

 o  Your gateway address.   This is the  address of the machine  which
    is your  ``gateway'' to  the outside  world (i.e.    machines  not
    on your subnet).    In many cases  the gateway  machine has an  IP
    address identical to yours but with a ``.1'' as  its host address;
    e.g., if your IP address is 128.253.154.32, your gateway  might be
    128.253.154.1.  Your network  admins will provide you with  the IP
    address of your gateway.

    In fact, you may  have multiple gateways.   A gateway is simply  a
    machine that lives  on two  different networks  (has IP  addresses
    on different  subnets), and  routes packets  between them.    Many
    networks have  a  single gateway  to  ``the outside  world''  (the
    network directly adjacent to your own), but in some cases you will
    have multiple gateways---one for each adjacent network.

    If you're only using loopback,  you don't have a  gateway address.
    The same is true if your network is isolated from all others.

 o  Your nameserver address.   Most  machines on the  net have a  name
    server which  translates hostnames  into  IP addresses  for  them.
    Your network admins will tell you the address of your name server.
5.3.   Networking with TCP/IP                                      189
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    You can also run  a server on your  own machine by running  named,
    in which case  the nameserver address  is 127.0.0.1.   Unless  you
    absolutely must run your own name server, we suggest using the one
    provided to you on the network  (if any).  Configuration  of named
    is another issue altogether; our priority at this point  is to get
    you talking to  the network.   You can  deal with name  resolution
    issues later.

    If you're  only  using  loopback,  you  don't  have  a  nameserver
    address.

  SLIP  users:    You  may  or  may  not  require  any  of  the  above
information, except for a nameserver  address.  When using  SLIP, your
IP address  is usually  determined in  one of  two ways:   Either  (a)
you have a  ``static'' IP address,  which is the  same every time  you
connect to the  network, or  (b) you  have a  ``dynamic'' IP  address,
which is allocated from a pool available addresses when you connect to
the server.   In the following section  on SLIP configuration this  is
covered in more detail.
  NET-2  supports full  routing,  multiple routes,  subnetworking  (at
this stage  on byte  boundaries only),  the  whole nine  yards.    The
above describes most basic TCP/IP configurations.  Yours may  be quite
different:  when in doubt, consult your local network  gurus and check
out the man pages for route and ifconfig.  Configuring TCP/IP networks
is very much beyond the scope of this book; the above should be enough
to get most people started.

5.3.2.2 The networking rc files

rc files are  systemwide configuration scripts  executed at boot  time
by init,  which start  up all  of the  basic system  daemons (such  as
sendmail, cron,  etc.)    and  configure things  such as  the  network
parameters, system hostname, and so on.  rc files are usually found in
the directory /etc/rc.d but on other systems may be in /etc.
  Here,  we're  going to  describe  the  rc files  used  to  configure
TCP/IP. There are two of  them:  rc.inet1 and  rc.inet2.  rc.inet1  is
used to configure the basic  network parameters (such as IP  addresses
and routing  information) and  rc.inet2 fires  up  the TCP/IP  daemons
(telnetd, ftpd, and so forth).
  Many  systems combine  these  two  files into  one,  usually  called
rc.inet or rc.net.  The  names given to your rc files  doesn't matter,
as long as they perform the correct functions and are executed at boot
time by init.  To ensure  this, you may need to edit  /etc/inittab and
uncomment lines to execute the appropriate  rc file(s).  In  the worst
case you will  have to  create the  rc.inet1 and  rc.inet2 files  from
scratch and add entries for them to /etc/inittab.
  As  we  said,  rc.inet1  configures  the  basic  network  interface.
This includes  your IP  and  network address,  and  the routing  table
information for your network.   The routing  tables are used to  route
outgoing (and incoming) network datagrams to other machines.   On most
5.3.  Networking with TCP/IP                                       190
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simple configurations, you have three routes:  One for sending packets
to your own machine, another for sending packets to  other machines on
your network, and another for  sending packets to machines  outside of
your network (through the gateway machine).  Two programs  are used to
configure these parameters:   ifconfig and route.   Both of these  are
usually found in /etc.
  ifconfig is used  for configuring the network device  interface with
the parameters that it requires to  function, such as the  IP address,
network mask, broadcast address and the like.  route is used to create
and modify entries in the routing table.
  For  most configurations,  an  rc.inet1  file  that looks  like  the
following should work.   You will,  of course, have  to edit this  for
your own system.    Do not  use the  sample IP  and network  addresses
listed here for your own system; they correspond to  an actual machine
on the Internet.

  #!/bin/sh
  # This is /etc/rc.d/rc.inet1 -- Configure the TCP/IP interfaces

  # First, configure the loopback device

  HOSTNAME=`hostname`

  /etc/ifconfig lo 127.0.0.1 # uses default netmask 255.0.0.0
  /etc/route add 127.0.0.1 # a route to point to the loopback device

  # Next, configure the ethernet device. If you're only  using
  # loopback or SLIP, comment out the rest of these lines.

  # Edit for your setup.
  IPADDR="128.253.154.32"     # REPLACE with YOUR IP address
  NETMASK="255.255.255.0"     # REPLACE with YOUR netmask
  NETWORK="128.253.154.0"     # REPLACE  with  YOUR  network address
  BROADCAST="128.253.154.255" # REPLACE with YOUR  broadcast address,
                              # if you have one. If not, leave blank
                              # and edit below.
  GATEWAY="128.253.154.1"     # REPLACE with  YOUR  gateway address!

  /etc/ifconfig eth0 ${IPADDR} netmask ${NETMASK} broadcast ${BROADCAST}

  # If you don't have a broadcast address, change the above line to:
  # /etc/ifconfig eth0 ${IPADDR} netmask ${NETMASK}

  /etc/route add ${NETWORK}
5.3.  Networking with TCP/IP                                       191
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  # The following is only necessary if you have a gateway; that is,
  # your network is connected to the outside world.
  /etc/route add default gw ${GATEWAY} metric 1

  # End of Ethernet Configuration

  Again, you may have  to tweak this file somewhat to get it  to work.
The above  should be  sufficient for  the majority  of simple  network
configurations, but certainly not all.
  rc.inet2 starts up  various servers used by  the TCP/IP suite.   The
most important of these is  inetd.  inetd  sits in the background  and
listens to various  network ports.   When  a machine  tries to make  a
connection to a certain port (for example, the incoming  telnet port),
inetd forks off a copy of the appropriate daemon for that port (in the
case of the telnet  port, inetd starts in.telnetd).   This is  simpler
than running  many  separate,  standalone  daemons  (e.g.,  individual
copies of telnetd, ftpd, and  so forth)---inetd starts up  the daemons
only when they are needed.
  syslogd is the  system logging daemon---it accumulates log  messages
from various  applications and  stores them  into log  files based  on
the configuration  information  in /etc/syslogd.conf.    routed  is  a
server used to maintain dynamic routing information.  When your system
attempts to send packets to another network, it may require additional
routing table  entries in  order  to do  so.    routed takes  care  of
manipulating the routing table without the need for user intervention.
  Our example  rc.inet2, below,  only starts  up the  bare minimum  of
servers.  There are many other servers as well---many of which have to
do with NFS configuration.   When attempting  to setup TCP/IP on  your
system, it's usually  best to start with  a minimal configuration  and
add more complex pieces (such as NFS) when you have things working.
  Note that  in the  below file,  we assume  that all  of the  network
daemons are  held  in  /etc.    As  usual,  edit  this  for  your  own
configuration.

    #! /bin/sh
    # Sample /etc/rc.d/rc.inet2

    # Start syslogd
    if [ -f /etc/syslogd ]
    then
          /etc/syslogd
    fi

    # Start inetd
    if [ -f /etc/inetd ]
    then
          /etc/inetd
    fi
5.3.   Networking with TCP/IP                                      192
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    # Start routed
    if [ -f /etc/routed ]
    then
          /etc/routed -q
    fi

    # Done!

  Among the various additional  servers that you may want to  start in
rc.inet2 is named.   named  is a name  server---it is responsible  for
translating (local) IP  addresses to names,  and vice versa.   If  you
don't have a nameserver elsewhere on  the network, or want  to provide
local machine  names to  other  machines in  your  domain, it  may  be
necessary to run named.  (For most configurations it is not necessary,
however.)    named  configuration  is somewhat  complex  and  requires
planning; we refer interested readers to a good book on TCP/IP network
administration.

5.3.2.3 /etc/hosts

/etc/hosts contains  a list  of IP  addresses and  the hostnames  that
they correspond  to.   In  general, /etc/hosts  only contains  entries
for your  local  machine,  and perhaps  other  ``important''  machines
(such as your  nameserver or gateway).   Your  local name server  will
provide address-to-name mappings  for other  machines on the  network,
transparently.
  For  example,  if your  machine  is  loomer.vpizza.com with  the  IP
address 128.253.154.32, your /etc/hosts would look like:

    127.0.0.1               localhost
    128.253.154.32          loomer.vpizza.com loomer

If you're only using loopback,  the only line in /etc/hosts  should be
for 127.0.0.1, with both localhost and your hostname after it.

5.3.2.4 /etc/networks

The /etc/networks file lists the names and addresses of your  own, and
other, networks.  It is used  by the route command, and allows  you to
specify a network by name, should you so desire.
  Every network  you wish to  add a route to  using the route  command
(generally called from  rc.inet1---see above)  must have  an entry  in
/etc/networks.
  As an example,

    default 0.0.0.0 # default route    - mandatory
    loopnet 127.0.0.0 # loopback network - mandatory
    mynet 128.253.154.0 # Modify for your own network address
5.3.   Networking with TCP/IP                                      193
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5.3.2.5 /etc/host.conf

This file is used to  specify how your system will  resolve hostnames.
It should contain the two lines:

    order hosts,bind
    multi on

These lines tell the resolve  libraries to first check the  /etc/hosts
file for any names to lookup,  and then ask the nameserver (if  one is
present).  The  multi entry allows you  to have multiple IP  addresses
for a given machine name in /etc/hosts.

5.3.2.6 /etc/resolv.conf

This file  configures the  name resolver,  specifying  the address  of
your name server  (if any)  and your domain  name.   Your domain  name
is your fully-qualified  hostname (if you're  a registered machine  on
the Internet, for example), with the  hostname chopped off.   That is,
if your full hostname is  loomer.vpizza.com, your domain name  is just
vpizza.com.
  For  example,  if your  machine  is goober.norelco.com,  and  has  a
nameserver at the address  128.253.154.5, your /etc/resolv.conf  would
look like:

    domain      norelco.com
    nameserver  127.253.154.5

You can specify more than one nameserver---each must have a nameserver
line of its own in resolv.conf.

5.3.2.7 Setting your hostname

You should set your system hostname  with the hostname command.   This
is usually called  from /etc/rc or  /etc/rc.local; simply search  your
system rc files to  determine where it  is invoked.   For example,  if
your (full)  hostname is  loomer.vpizza.com, edit  the appropriate  rc
file to execute the command:

    /bin/hostname loomer.vpizza.com

Note that the  hostname executable may  not be found  in /bin on  your
system.

5.3.2.8 Trying it out

Once you have all of these files set up, you should be  able to reboot
your new kernel and attempt to use the network.  There are many places
where things can  go wrong,  so it's  a good idea  to test  individual
aspects of the network configuration  (e.g., it's probably not  a good
5.3.   Networking with TCP/IP                                      194
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idea to test  your network configuration  by firing  up Mosaic over  a
network-based X connection).
  You can  use the  netstat command  to display  your routing  tables;
this is usually the source of the most trouble.  The  netstat man page
describes the exact syntax  of this command  in detail.   In order  to
test network connectivity,  we suggest using a  client such as  telnet
to connect  to machines  both on  your local  subnetwork and  external
networks.  This will  help to narrow down  the source of the  problem.
(For example, if you're unable  to connect to local machines,  but can
connect to machines  on other networks,  more than  likely there is  a
problem with your netmask and  routing table configuration).   You can
also invoke the  route command  directly (as  root) to  play with  the
entries in your routing table.
  You  should  also   test  network  connectivity  by  specifying   IP
addresses directly, instead of  hostnames.   For example, if you  have
problems with the command

    $ telnet shoop.vpizza.com

the cause may be  incorrect nameserver configuration.   Try using  the
actual IP address of the machine in question; if that  works, then you
know that your basic network setup is (more than likely)  correct, and
the problem lies in your specification of the name server address.
  Debugging network  configurations can  be a difficult  task, and  we
can't begin  to  cover it  here.    If  you  are  unable to  get  help
from a  local  guru we  strongly  suggest  reading the  Linux  Network
Administrators' Guide from the LDP.

5.3.3 SLIP Configuration

SLIP (Serial Line Internet Protocol)  allows you to use TCP/IP  over a
serial line, be that a  phone line, with a  dialup modem, or a  leased
asynchronous line of some sort.   Of course,  to use SLIP you'll  need
access to a dial-in SLIP server  in your area.  Many  universities and
businesses provide SLIP access for a modest fee.
  There  are  two  major  SLIP-related  programs  available---dip  and
slattach.    Both  of these  programs  are  used to  initiate  a  SLIP
connection over a serial device.  It is necessary to use  one of these
programs in order to enable SLIP---it will not suffice to  dial up the
SLIP server (with a communications  program such as kermit) and  issue
ifconfig and route commands.  This is because dip and slattach issue a
special ioctl() system call to  seize control of the serial  device to
be used as a SLIP interface.
  dip can  be  used to  dial up  a SLIP  server,  do some  handshaking
to login to  the server  (exchanging your username  and password,  for
example) and then  initate the  SLIP connection over  the open  serial
line.   slattach,  on  the other  hand, does  very  little other  than
grab the serial device  for use by  SLIP. It is  useful if you have  a
permanent line to your SLIP server and no modem dialup  or handshaking
is necessary  to initiate  the connection.    Most  dialup SLIP  users
5.3.   Networking with TCP/IP                                      195
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should use dip, on the other hand.
  dip can  also  be used  to configure  your Linux  system  as a  SLIP
server, where other machines can dial into your own and connect to the
network through a secondary Ethernet connection on your machine.   See
the documentation and man pages  for dip for more information  on this
procedure.
  SLIP is quite unlike  Ethernet, in that there are only  two machines
on the ``network''---the SLIP host  (that's you) and the SLIP  server.
For this reason,  SLIP is  often referred to  as a  ``point-to-point''
connection.   A generalization of  this idea, known  as PPP (Point  to
Point Protocol) has also been implemented for Linux.
  When you  initiate a connection  to a SLIP  server, the SLIP  server
will give you  an IP address  based on (usually)  one of two  methods.
Some SLIP  servers allocate  ``static'' IP  addresses---in which  case
your IP address will be the same every time you connect to the server.
However, many  SLIP  servers  allocate IP  addresses  dynamically---in
which case you receive a  different IP address each time  you connect.
In general,  the SLIP  server will  print the  values of  your IP  and
gateway addresses when you connect.   dip is capable of  reading these
values from the output of the SLIP server login session and using them
to configure the SLIP device.
  Essentially, configuring a SLIP connection is  just like configuring
for loopback or ethernet.   The main differences are  discussed below.
Read the previous section on  configuring the basic TCP/IP files,  and
apply the changes described below.

5.3.3.1 Static IP address SLIP connections using dip

If you are  using a  static-allocation SLIP  server, you  may want  to
include entries  for  your  IP  address and  hostname  in  /etc/hosts.
Also, configure these  files listed in the  above section:   rc.inet2,
host.conf, and resolv.conf.
  Also, configure  rc.inet1, as  described above.   However, you  only
want to execute ifconfig and  route commands for the loopback  device.
If you use  dip to connect  to the  SLIP server,  it will execute  the
appropriate ifconfig and route commands  for the SLIP device for  you.
(If you're using slattach, on the other hand, you will need to include
ifconfig/route commands in rc.inet1 for the SLIP device---see below.)
  dip should configure your routing tables appropriately  for the SLIP
connection when you connect.   In some cases, however,  dip's behavior
may not be  correct for  your configuration,  and you'll  have to  run
ifconfig or route commands by hand after connecting to the server with
dip (this is  most easily done  from within a  shell script that  runs
dip and immediately executes the appropriate  configuration commands).
Your gateway is, in most cases, the  address of the SLIP server.   You
may know this  address before  hand, or  the gateway  address will  be
printed by the SLIP  server when you  connect.   Your dip chat  script
(described below) can obtain this information from the SLIP server.
  ifconfig  may  require use  of  the  pointopoint  argument,  if  dip
doesn't configure  the interface  correctly.    For example,  if  your
5.3.   Networking with TCP/IP                                      196
_______________________________________________________________________

SLIP  server  address  is  128.253.154.2,  and  your   IP  address  is
128.253.154.32, you may need to run the command

    ifconfig sl0 128.253.154.32 pointopoint 128.253.154.2

as root, after connecting with dip.   The man pages for  ifconfig will
come in handy.
  Note  that SLIP  device  names  used  with the  ifconfig  and  route
commands are sl0, sl1 and so on  (as opposed to eth0, eth1, etc.   for
Ethernet devices).
  In Section 5.3.4, below, we explain how to  configure dip to connect
to the SLIP server.

5.3.3.2 Static IP address SLIP connections using slattach

If you  have a  leased line  or cable  running directly  to your  SLIP
server, then there  is no need  to use dip  to initiate a  connection.
slattach can be used to configure the SLIP device instead.
  In this  case, your  /etc/rc.inet1 file should  look something  like
the following:

    #!/bin/sh
    IPADDR="128.253.154.32"         # Replace with your IP address
    REMADDR="128.253.154.2" # Replace with your SLIP server address

    # Modify the following for the appropriate serial device for
    # the SLIP connection:
    slattach -p cslip -s 19200 /dev/ttyS0
    /etc/ifconfig sl0 $IPADDR pointopoint $REMADDR up
    /etc/route add default gw $REMADDR

  slattach  allocates the  first unallocated  SLIP device  (sl0,  sl1,
etc.)  to the serial line specified.
  Note that the  first parameter to slattach  is the SLIP protocol  to
use.  At present  the only valid values are  slip and cslip.   slip is
regular SLIP, as  you would expect,  and cslip  is SLIP with  datagram
header compression.  In most  cases you should use cslip;  however, if
you seem to be having problems with this, try slip.
  If you have more than one SLIP interface then  you will have routing
considerations to make.  You  will have to decide what routes  to add,
and those decisions can only be made on the basis of the actual layout
of your network connections.  A book on TCP/IP  network configuration,
as well as the man pages to route, will be of use.

5.3.3.3 Dynamic IP address SLIP connections using dip

If your  SLIP server  allocates an  IP address  dynamically, then  you
certainly don't know  your address in  advance---therefore, you  can't
include an entry for it in /etc/hosts.  (You should,  however, include
5.3.  Networking with TCP/IP                                       197
_______________________________________________________________________

an entry for your host with the loopback address, 127.0.0.1.)
  Many SLIP  servers print your  IP address (as  well as the  server's
address) when  you connect.    For example,  one type  of SLIP  server
prints a string such as,

    Your IP address is 128.253.154.44.
    Server address is 128.253.154.2.

dip can capture these  numbers from the output  of the server and  use
them to configure the SLIP device.
  See Section  5.3.3.1,  above, for  information  on configuring  your
various TCP/IP  files for  use with  SLIP. Below,  we  explain how  to
configure dip to connect to the SLIP server.

5.3.4 Using dip

dip can simplify the process of  connecting to a SLIP server,  logging
in, and configuring the  SLIP device.   Unless you have a leased  line
running to your SLIP server, dip is the way to go.
  To use dip,  you'll need to write  a ``chat script'' which  contains
a list of commands used to  communicate with the SLIP server  at login
time.  These commands can automatically send your username/password to
the server, as  well as get  information on your  IP address from  the
server.
  Here is  an  example dip  chat script,  for  use with  a dynamic  IP
address server.     For static  servers,  you  will need  to  set  the
variables $local and $remote  to the values  of your local IP  address
and server IP address,  respectively, at the top  of the script.   See
the dip man page for details.

    main:
      # Set Maximum Transfer Unit. This is the maximum size of packets
      # transmitted on the SLIP device. Many SLIP servers use either
      # 1500 or 1006; check with your network admins when in doubt.
      get $mtu 1500

      # Make the SLIP route the default route on your system.
      default

      # Set the desired serial port and speed.
      port cua03
      speed 38400

      # Reset the modem and terminal line. If this causes trouble
      # for you, comment it out.
      reset

      # Prepare for dialing. Replace the following with your
5.3.  Networking with TCP/IP                                       198
_______________________________________________________________________

      # modem initialization string.
      send ATT&C1&D2\\N3&Q5%M3%C1N1W1L1S48=7\r
      wait OK 2
      if $errlvl != 0 goto error
      # Dial the SLIP server
      dial 2546000
      if $errlvl != 0 goto error
      wait CONNECT 60
      if $errlvl != 0 goto error

      # We are connected.  Login to the system.
    login:
      sleep 3
      send \r\n\r\n
      # Wait for the login prompt
      wait login: 10
      if $errlvl != 0 goto error

      # Send your username
      send USERNAME\n

      # Wait for password prompt
      wait ord: 5
      if $errlvl != 0 goto error

      # Send password.
      send PASSWORD\n

      # Wait for SLIP server ready prompt
      wait annex: 30
      if $errlvl != 0 goto error

      # Send commands to SLIP server to initate connection.
      send slip\n
      wait Annex 30

      # Get the remote IP address from the SLIP server. The
      # `get...remote' command reads text in the form xxx.xxx.xxx.xxx,
      # and assigns it to the variable given as the second argument
      # (here, $remote).
      get $remote remote
      if $errlvl != 0 goto error
      wait Your 30

       # Get local IP address from SLIP server, assign to variable
       # $local.
      get $local remote
      if $errlvl != 0 goto error

      # Fire up the SLIP connection
5.4.   Networking with UUCP                                        199
_______________________________________________________________________

    done:
      print CONNECTED to $remote at $rmtip
      print GATEWAY address $rmtip
      print LOCAL address $local
      mode SLIP
      goto exit
    error:
      print SLIP to $remote failed.

    exit:

  dip automatically executes ifconfig and route commands  based on the
values of the variables $local and $remote.  Here, those variables are
assigned using the get... remote command, which obtains text  from the
SLIP server and assigns it to the named variable.
  If the  ifconfig  and route  commands that  dip runs  for you  don't
work, you can either run the correct commands in a  shell script after
executing dip, or modify the source for dip itself.   Running dip with
the -v option will print debugging information while the connection is
being set up, which should help you to determine where things might be
going awry.
  Now, in order to run  dip and open the SLIP connection, you  can use
a command such as:

    /etc/dip/dip -v /etc/dip/mychat 2>&1

Where the various  dip files,  and the chat  script (mychat.dip),  are
stored in /etc/dip.
  The above discussion  should be enough to  get you well on your  way
to talking to  the network,  either via  Ethernet or  SLIP. Again,  we
strongly suggest looking into a book on TCP/IP  network configuration,
especially if  your network  has any  special routing  considerations,
other than those mentioned here.


5.4 Networking with UUCP

UUCP (UNIX-to-UNIX  Copy)  is  an  older mechanism  used  to  transfer
information between UNIX systems.  Using UUCP, UNIX systems  dial each
other up (using a  modem) and transfer  mail messages, news  articles,
files, and so on.   If you don't have  TCP/IP or SLIP access,  you can
use UUCP to communicate  with the world.   Most  of the mail and  news
software (see Sections  5.5 and  5.6) can  be configured  to use  UUCP
to transfer information to other  machines.  In  fact, if there is  an
Internet site nearby, you  can arrange to  have Internet mail sent  to
your Linux machine via UUCP from that site.
  The   Linux   Network  Administrator's   Guide   contains   complete
information on configuring  and using  UUCP under  Linux.   Also,  the
Linux UUCP HOWTO,  available via  anonymous FTP from  sunsite.unc.edu,
should be of  help.   Another  source of  information on  UUCP is  the
book Managing UUCP and USENET, by Tim O'Reilly and Grace Todino.   See
5.5.   Electronic Mail                                             200
_______________________________________________________________________

Appendix A for more information.


5.5 Electronic Mail

Like most UNIX systems, Linux  provides a number of  software packages
for using electronic mail.  E-mail on your system can  either be local
(that is,  you only mail  other users  on your  system), or  networked
(that is,  you  mail, using  either  TCP/IP or  UUCP, users  on  other
machines on  a network).    E-mail software  usually  consists of  two
parts:   a mailer  and a  transport.   The  mailer  is the  user-level
software which is used to  actually compose and read e-mail  messages.
Popular mailers include elm and mailx.  The transport is the low-level
software which  actually takes  care of  delivering the  mail,  either
locally or remotely.  The user never sees the transport software; they
only interact with the mailer.  However, as  the system administrator,
it is  important  to  understand  the concepts  behind  the  transport
software and how to configure it.
  The  most popular  transport software  for  Linux is  Smail.    This
software is easy  to configure,  and is  able to send  both local  and
remote TCP/IP and UUCP e-mail.   The more powerful  sendmail transport
is used on  most UNIX  systems,  however, because  of its  complicated
setup mechanism, many Linux systems don't use it.
  The Linux Mail  HOWTO gives more  information on the available  mail
software for Linux and  how to configure  it on your  system.  If  you
plan to send mail remotely, you'll need to understand either TCP/IP or
UUCP, depending on how your machine is networked (see Sections 5.3 and
5.4).  The UUCP and TCP/IP documents listed in Appendix A should be of
help there.
  Most of the Linux  mail software can be retrieved via  anonymous FTP
from sunsite.unc.edu in the directory /pub/Linux/system/Mail.

5.6 News and USENET

Linux also provides  a number  of facilities  for managing  electronic
news.  You may  choose to set up a  local news server on  your system,
which will allow users to post ``articles'' to  various ``newsgroups''
on the  system... a  lively form  of  discussion.    However,  if  you
have access to  a TCP/IP or  UUCP network,  then you  will be able  to
participate in USENET---a worldwide network news service.
  There  are two  parts  to the  news  software---the server  and  the
client.  The news server is the software which controls the newsgroups
and handles delivering  articles to other  machines (if  you are on  a
network).   The  news client,  or newsreader,  is  the software  which
connects to the server to allow users to read and post news.
  There  are  several  forms of  news  servers  available  for  Linux.
They all  follow  the  same basic  protocols  and  design.    The  two
primary versions are ``C News''  and ``INN''. There are many  types of
newsreaders, as well, such as rn and tin.  The choice of newsreader is
more or less a  matter of taste;  all newsreaders should work  equally
5.6.   News and USENET                                             201
_______________________________________________________________________

well with different  versions of the  server software.   That is,  the
newsreader is independent of the server software, and vice versa.
  If you  only want  to run  news  locally (that  is, not  as part  of
USENET), then you will need to run a server on your system, as well as
install a newsreader for the  users.  The  news server will store  the
articles in a  directory such as  /usr/spool/news, and the  newsreader
will be compiled to look in this directory for news articles.
  However,  if you  wish  to run  news  over  the network,  there  are
several options  open  to you.     TCP/IP network-based  news  uses  a
protocol known as  NNTP (Network  News Transmission Protocol).    NNTP
allows a  newsreader  to read  news  over  the network,  on  a  remote
machine.  NNTP also allows news servers to send articles to each other
over the network---this is  the software upon  which USENET is  based.
Most businesses and universities have one or more NNTP servers  set up
to handle all of the USENET news  for that site.  Every  other machine
at the site runs an NNTP-based  newsreader to read and post  news over
the network via the NNTP server.  This means that only the NNTP server
actually stores the news articles on disk.
  Here are some possible scenarios for news configuration.

 o  You run news locally.  That is, you have no network connection, or
    no desire to run news over the network.  In this case, you need to
    run C News  or INN on  your machine, and  install a newsreader  to
    read the news locally.

 o  You have access to a TCP/IP network  and an NNTP server.   If your
    organization has an NNTP news server set up, you can read and post
    news from your  Linux machine by  simply installing an  NNTP-based
    newsreader.  (Most newsreaders available can be configured  to run
    locally or use NNTP). In this  case, you do not need to  install a
    news server or store news articles on your system.  The newsreader
    will take care of reading and  posting news over the network.   Of
    course, you will need to have TCP/IP configured and have access to
    the network (see Section 5.3).

 o  You have access to a TCP/IP network  but have no NNTP server.   In
    this case, you can run an  NNTP news server on your  Linux system.
    You can install either  a local or  an NNTP-based newsreader,  and
    the server will store news articles on your system.   In addition,
    you can configure the server  to communicate with other  NNTP news
    servers to transfer news articles.

 o  You want to  transfer news  using UUCP.  If you  have UUCP  access
    (see Section 5.4),  you can participate  in USENET as  well.   You
    will need to  install a  (local) news  server and  a news  reader.
    In addition,  you will  need to  configure your  UUCP software  to
    periodically transfer news articles to another nearby UUCP machine
    (known as your ``news feed'').  UUCP does not use NNTP to transfer
    news; simply,  UUCP provides  its own  mechanism for  transferring
    news articles.
5.6.   News and USENET                                             202
_______________________________________________________________________

  The one  downside of  most news  server and  newsreader software  is
that it must be compiled by hand.  Most of the news  software does not
use configuration files; instead, configuration options are determined
at compile time.
  Most  of the  ``standard'' news  software  (available via  anonymous
FTP from ftp.uu.net  in the directory  /news) will compile  out-of-the
box on  Linux.   Necessary  patches can  be  found on  sunsite.unc.edu
in /pub/Linux/system/Mail  (which is,  incidentally,  also where  mail
software for Linux is found).   Other news  binaries for Linux may  be
found in this directory as well.
  For  more  information,   refer  to   the  Linux  News  HOWTO   from
sunsite.unc.edu  in  /pub/Linux/docs/HOWTO.  Also,  the   LDP's  Linux
Network  Administrator's  Guide   contains  complete  information   on
configuring news  software for  Linux.   The  book  Managing UUCP  and
Usenet, by Tim  O'Reilly and Grace  Todino, is  an excellent guide  to
setting up UUCP and  news software.   Also of  interest is the  USENET
document ``How to become a  USENET site,'' available from  ftp.uu.net,
in the directory /usenet/news.announce.newusers.








Appendix A




Sources of Linux Information



This  appendix  contains  information  on  various  sources  of  Linux
information, such as online documents, books, and more.  Many of these
documents are available either in printed form, or electronically from
the Internet or BBS  systems.   Many Linux distributions also  include
much of this documentation  in the distribution  itself, so after  you
have installed Linux these files may be present on your system.

A.1 Online Documents

These documents should be  available on any  of the Linux FTP  archive
sites (see Appendix C for a list).   If you do not have  direct access
to FTP, you  may be  able to  locate these documents  on other  online
services (such as CompuServe,  local BBS's, and so  on).  If you  have
access to Internet mail,  you can use  the ftpmail service to  receive
these docucments.  See Appendix C for more information.
  In   particular,   the  following   documents   may  be   found   on
sunsite.unc.edu in the directory /pub/Linux/docs.   Many sites  mirror
this directory; however, if you're unable to locate a mirror site near
you, this is a good one to fall back on.
  You can  also  access Linux  files and  documentation using  gopher.
Just point  your gopher  client  to port  70 on  sunsite.unc.edu,  and
follow the menus to the Linux archive.   This is a good way  to browse
Linux documentation interactively.

The Linux Frequently Asked Questions List
           The Linux  Frequently Asked Questions list, or  ``FAQ'', is
           a  list of common  questions (and answers!)   about  Linux.
           This  document is  meant  to provide  a general  source  of
           information  about Linux,  common  problems and  solutions,
           and  a list of  other sources  of information.   Every  new
           Linux user should  read this document.  It is  available in
           a  number of  formats, including  plain ASCII,  PostScript,
           and Lout  typesetter format.   The Linux FAQ is  maintained
           by Ian Jackson, [e-mail].



                                 203
A.1.   Online Documents                                            204
_______________________________________________________________________

The Linux META-FAQ
           The  META-FAQ is  a collection  of ``metaquestions''  about
           Linux;  that is,  sources  of information  about the  Linux
           system,   and  other  general  topics.     It  is   a  good
           starting place  for the Internet user wishing to  find more
           information about the system.   It is maintained by Michael
           K. Johnson, [e-mail].

The Linux INFO-SHEET
           The  Linux INFO-SHEET  is a technical  introduction to  the
           Linux  system.    It  gives  an overview  of  the  system's
           features  and  available  software,  and  also  provides  a
           list  of   other  sources  of  Linux  information.      The
           format and  content is similar  in nature to the  META-FAQ;
           incidentally, it is also maintained by Michael K. Johnson.

The Linux Software Map
           The  Linux Software  Map  is a  list of  many  applications
           available  for  Linux, where  to  get them,  who  maintains
           them,  and  so  forth.     It  is  far  from  complete---to
           compile a  complete list of Linux software would  be nearly
           impossible.    However, it  does include many  of the  most
           popular  Linux software  packages.    If you  can't find  a
           particular  application to suit  your needs,  the LSM is  a
           good place to  start.  It is maintained by  Lars Wirzenius,
           [e-mail].

The Linux HOWTO Index
           The Linux HOWTOs are a collection  of ``how to'' documents,
           each  describing   in  detail  a  certain  aspect   of  the
           Linux  system.     They  are   maintained  by  Matt  Welsh,
           [e-mail].    The  HOWTO  Index lists  the  HOWTO
           documents which are available (several  of which are listed
           below).

The Linux Installation HOWTO
           The  Linux  Installation  HOWTO  describes  how  to  obtain
           and  install  a  distribution  of  Linux,  similar  to  the
           information presented in Chapter 2.
The Linux Distribution HOWTO
           This  document is a list  of Linux distributions  available
           via  mail  order  and  anonymous   FTP.  It  also  includes
           information  on other Linux-related  goodies and  services.
           Appendix B contains a list of  Linux vendors, many of which
           are listed in the Distribution HOWTO.

The Linux XFree86 HOWTO
           This  document describes how to  install and configure  the
           X  Window  System software  for Linux.    See  the  section
           ``5.1'' for more about the X Window System.
A.2.   Linux Documentation Project Manuals                         205
_______________________________________________________________________

The Linux Mail, News, and UUCP HOWTOs
           These  three  HOWTO documents  describe  configuration  and
           setup  of electronic  mail, news,  and UUCP  communications
           on  a  Linux system.    Because  these three  subjects  are
           often intertwined, you may wish to  read all three of these
           HOWTOs together.

The Linux Hardware HOWTO
           This   HOWTO  contains  an   extensive  list  of   hardware
           supported by Linux.  While this  list is far from complete,
           it  should give  you a  general picture  of which  hardware
           devices should be supported by the system.

The Linux SCSI HOWTO
           The Linux  SCSI HOWTO is a complete guide  to configuration
           and  usage  of  SCSI devices  under  Linux,  such  as  hard
           drives, tape drives and CD-ROM.

The Linux NET-2-HOWTO
           The  Linux NET-2-HOWTO describes  installation, setup,  and
           configuration  of  the  ``NET-2''   TCP/IP  software  under
           Linux,  including SLIP. If you want  to use TCP/IP on  your
           Linux system, this document is a must read.

The Linux Ethernet HOWTO
           Closely  related to  the  NET-2-HOWTO, the  Ethernet  HOWTO
           describes the various Ethernet devices  supported by Linux,
           and explains how  to configure each of them for use  by the
           Linux TCP/IP software.
The Linux Printing HOWTO
           This document describes how to  configure printing software
           under Linux,  such as lpr.   Configuration of printers  and
           printing  software  under UNIX  can  be very  confusing  at
           times; this document sheds some light on the subject.

Other online documents
           If you browse the docs subdirectory  of any Linux FTP site,
           you'll see many other documents which  are not listed here:
           A slew  of FAQ's, interesting tidbits, and  other important
           information.   This miscellany  is difficult to  categorize
           here; if you don't see what you're  looking for on the list
           above, just  take a look at one of the Linux  archive sites
           listed in Appendix C.



A.2 Linux Documentation Project Manuals

The Linux  Documentation Project  is working  on developing  a set  of
manuals and other documentation for Linux, including man pages.  These
manuals are in various  stages of development,  and any help  revising
A.3.   Books and Other Published Works                             206
_______________________________________________________________________

and updating them is greatly appreciated.  If you have questions about
the LDP, please contact Matt Welsh ([e-mail]).
  These  books are  available  via  anonymous  FTP from  a  number  of
Linux archive  sites,   including  sunsite.unc.edu  in  the  directory
/pub/Linux/docs/LDP. A number of  commercial distributors are  selling
printed copies of these books; in the future, you may be  able to find
the LDP manuals on the shelves of your local bookstore.

Linux Installation and Getting Started, by Matt Welsh
           A new  user's guide for Linux, covering everything  the new
           user  needs to know  to get started.    You happen to  hold
           this book in your hands.

The Linux System Administrators' Guide, by Lars Wirzenius
           This  is a  complete  guide to  running and  configuring  a
           Linux system.   There are  many issues relating to  systems
           administration which  are specific to Linux, such  as needs
           for  supporting a user  community, filesystem  maintenance,
           backups, and more.  This guide covers them all.

The Linux Network Administrators' Guide, by Olaf Kirch
           An extensive and complete guide  to networking under Linux,
           including  TCP/IP, UUCP, SLIP, and  more.   This book is  a
           very  good read;  it contains  a wealth  of information  on
           many  subjects, clarifying  the many  confusing aspects  of
           network configuration.
The Linux Kernel Hackers' Guide, by Michael Johnson
           The gritty details of kernel  hacking and development under
           Linux.  Linux is unique in  that the complete kernel source
           is  available.   This book  opens the  doors to  developers
           who  wish to  add  or modify  features within  the  kernel.
           This guide  also contains comprehensive coverage  of kernel
           concepts and conventions used by Linux.



A.3 Books and Other Published Works

Linux Journal is a monthly magazine for and about the Linux community,
written and produced by a number of Linux developers  and enthusiasts.
It is distributed worldwide, and is an excellent way to  keep in touch
with the dynamics  of the Linux  world, especially  if you don't  have
access to USENET news.
  At  the  time  of  this  writing,  subscriptions  to  Linux  Journal
are US$19/year  in  the United  States,  US$24 in  Canada,  and  US$29
elsewhere.   To subscribe,  or for  more information,  write to  Linux
Journal, PO  Box  85867, Seattle,  WA,  98145-1867,  USA, or  call  +1
206 527-3385.    Their  FAX  number is  [phone],  and  e-mail
address is  [e-mail].     You  can  also  find  a  Linux  Journal
FAQ and  sample  articles  via  anonymous FTP  on  sunsite.unc.edu  in
/pub/Linux/docs/linux-journal.
A.3.   Books and Other Published Works                             207
_______________________________________________________________________

  As we  have said, not  many books have  been published dealing  with
Linux specifically.  However, if you are new to the world  of UNIX, or
want more information than is presented here, we suggest that you take
a look at the following books which are available.

A.3.1 Using UNIX

Title:        Learning the UNIX Operating System

Author:       Grace Todino & John Strang
Publisher:    O'Reilly and Associates, 1987
ISBN:         0-937175-16-1, $9.00


     A  good introductory  book  on  learning the  UNIX  operating
    system.  Most of the information should be applicable to Linux
    as well.   I suggest reading this book  if you're new to  UNIX
    and really want to get started with using your new system.


Title:        Learning the vi Editor
Author:       Linda Lamb
Publisher:    O'Reilly and Associates, 1990

ISBN:         0-937175-67-6, $21.95


     This is  a book about the vi  editor, a powerful text  editor
    found on every UNIX system in the world.  It's often important
    to know and be able to  use vi, because you won't always  have
    access to a ``real'' editor such as Emacs.

A.3.2 Systems Administration

Title:        Essential System Administration
Author:       AEleen Frisch
Publisher:    O'Reilly and Associates, 1991

ISBN:         0-937175-80-3, $29.95


     From the  O'Reilly and Associates  Catalog, ``Like any  other
    multi-user  system,  UNIX  requires  some  care  and  feeding.
    Essential System  Administration tells  you how.    This  book
    strips away the myth and confusion surrounding  this important
    topic and provides a  compact, manageable introduction to  the
    tasks faced by  anyone responsible  for a  UNIX system.''    I
    couldn't have said it better myself.

Title:        TCP/IP Network Administration
A.3.   Books and Other Published Works                             208
_______________________________________________________________________

Author:       Craig Hunt
Publisher:    O'Reilly and Associates, 1990

ISBN:         0-937175-82-X, $24.95

     A complete guide to setting up and running  a TCP/IP network.
    While this book is  not Linux-specific, roughly  90% of it  is
    applicable to Linux.   Coupled with the Linux NET-2-HOWTO  and
    Linux Network  Administrator's Guide,  this  is a  great  book
    discussing the  concepts  and technical  details  of  managing
    TCP/IP.


Title:        Managing UUCP and Usenet

Author:       Tim O'Reilly and Grace Todino
Publisher:    O'Reilly and Associates, 1991
ISBN:         0-937175-93-5, $24.95


     This  book   covers  how  to   install  and  configure   UUCP
    networking software, including configuration for USENET  news.
    If you're at all interested in using UUCP or  accessing USENET
    news on your system, this book is a must-read.

A.3.3 The X Window System

Title:        The X Window System:  A User's Guide
Author:       Niall Mansfield

Publisher:    Addison-Wesley
ISBN:         0-201-51341-2, ??


     A  complete  tutorial  and  reference  guide   to  using  the
    X Window System.   If  you installed X  windows on your  Linux
    system, and want to  know how to get the  most out of it,  you
    should read this book.   Unlike some windowing systems, a  lot
    of the power provided by X is not obvious at first sight.

A.3.4 Programming

Title:        The C Programming Language
Author:       Brian Kernighan and Dennis Ritchie

Publisher:    Prentice-Hall, 1988
ISBN:         0-13-110362-8, $25.00


     This  book  is  a  must-have  for  anyone  wishing  to  do  C
    programming on  a UNIX  system.    (Or  any system,  for  that
A.3.   Books and Other Published Works                             209
_______________________________________________________________________

    matter.)  While this book is not obstensibly UNIX-specific, it
    is quite applicable to programming C under UNIX.


Title:        The Unix Programming Environment
Author:       Brian Kernighan and Bob Pike

Publisher:    Prentice-Hall, 1984
ISBN:         0-13-937681-X, ??


     An overview  to programming under  the UNIX  system.   Covers
    all of the tools of the  trade; a good read to  get acquainted
    with the somewhat amorphous UNIX programming world.


Title:        Advanced Programming in the UNIX Environment
Author:       W. Richard Stevens
Publisher:    Addison-Wesley
ISBN:         0-201-56317-7, $50.00


     This mighty  tome contains everything  that you need to  know
    to program  UNIX  at  the  system  level---file  I/O,  process
    control, interprocess  communication, signals,  terminal  I/O,
    the works.    This  book  focuses  on various  UNI  standards,
    including POSIX.1, which Linux mostly adheres to.


A.3.5 Kernel Hacking

Title:        The Design of the UNIX Operating System
Author:       Maurice J. Bach
Publisher:    Prentice-Hall, 1986
ISBN:         0-13-201799-7, ??


     This book  covers the  algorithms and internals  of the  UNIX
    kernel.  It is not specific to any particular kernel, although
    it does lean towards  System V-isms.   This is the best  place
    to start if you want  to understand the inner tickings of  the
    Linux system.


Title:        The Magic Garden Explained
Author:       Berny Goodheart and James Cox

Publisher:    Prentice-Hall, 1994
ISBN:         0-13-098138-9, ??
A.3.   Books and Other Published Works                             210
_______________________________________________________________________

     This  book  describes  the System  V  R4  kernel  in  detail.
    Unlike  Bach's  book,   which  concentrates  heavily  on   the
    algorithms which  make the  kernel  tick, this  book  presents
    the SVR4 implementation on a  more technical level.   Although
    Linux and SVR4  are distant  cousins, this book  can give  you
    much insight  into  the  workings  of an  actual  UNIX  kernel
    implementation.  This is also  a very modern book on the  UNIX
    kernel---published in 1994.








Appendix B




Linux Vendor List



This appendix lists contact information for a number of  vendors which
sell Linux on diskette, tape,  and CD-ROM. Many of them  provide Linux
documentation, support, and  other services as  well.   This is by  no
means a complete listing; if you purchased this book  in printed form,
it's very possible that the vendor or publishing company also provides
Linux software and services.
  The author  makes no  guarantee as  to the  accuracy of  any of  the
information listed in  this Appendix.   This  information is  included
here only as  a service to  readers, not as  an advertisement for  any
particular organization.

    Fintronic Linux Systems
    1360 Willow Rd., Suite 205
    Menlo Park, CA 94025 USA
    Tel:  [phone]
    Fax:  [phone]
    [e-mail]

    InfoMagic, Inc.
    PO Box 30370
    Flagstaff, AZ 86003-0370 USA
    Tel:  [phone]
    Fax:  [phone]
    [e-mail]

    Lasermoon Ltd
    2a Beaconsfield Road, Fareham,
    Hants, England.  PO16 0QB.
    Tel:  [phone].
    Fax:  [phone].
    [e-mail]


    Linux Journal
    P.O. Box 85867
    Seattle, WA 98145-1867 USA

                                 211
A.3.   Books and Other Published Works                             212
_______________________________________________________________________

    Tel:  [phone]
    Fax:  [phone]
    [e-mail]

    Linux Systems Labs
    18300 Tara Drive
    Clinton Twp, MI 48036 USA
    Tel:  [phone]
    Fax:  [phone]
    [e-mail]

    Morse Telecommunication, Inc.
    26 East Park Avenue, Suite 240
    Long Beach, NY 11561 USA
    Tel:  +1 800 60-MORSE
    Fax:  [phone]
    [e-mail]

    Nascent Technology
    Linux from Nascent CDROM
    P.O. Box 60669
    Sunnyvale CA 94088-0669 USA
    Tel:  [phone]
    Fax:  [phone]
    [e-mail]

    Red Hat Software
    P.O. Box 4325
    Chapel Hill, NC 27515 USA
    Tel:  [phone]
    [e-mail]


    SW Technology
    251 West Renner Suite 229
    Richardson, TX 75080 USA
    Tel:  [phone]
    [e-mail]

    Takelap Systems Ltd.
    The Reddings, Court Robin Lane,
    Llangwm, Usk, Gwent, United Kingdom NP5 1ET.
    Tel:  [phone]
    Fax:  [phone]
    [e-mail]

    Trans-Ameritech Enterprises, Inc.
    2342A Walsh Ave
    Santa Clara, CA 95051 USA
    Tel:  [phone]
    [e-mail]
A.3.   Books and Other Published Works                             213
_______________________________________________________________________

    Unifix Software GmbH
    Postfach 4918
    D-38039 Braunschweig
    Germany
    Tel:  [phone]
    Fax:  [phone]

    Yggdrasil Computing, Incorporated
    4880 Stevens Creek Blvd., Suite 205
    San Jose, CA 95129-1034 USA
    Tel:  [phone]
    Fax:  [phone]
    [e-mail]








Appendix C




FTP Tutorial and Site List



FTP (``File Transfer Protocol'') is the set of programs that  are used
for transferring files between  systems on the  Internet.  Most  UNIX,
VMS, and MS-DOS  systems on  the Internet  have a  program called  ftp
which you  use to  transfer  these files,  and  if you  have  Internet
access, the best way to download  the Linux software is by  using ftp.
This appendix covers basic ftp usage---of course, there are  many more
functions and uses of ftp than are given here.
  At the end  of this appendix there is  a listing of FTP  sites where
Linux software can be found.  Also, if you don't  have direct Internet
access but are  able to  exchange electronic mail  with the  Internet,
information on using the ftpmail service is included below.
  If you're  using an MS-DOS,  UNIX, or VMS  system to download  files
from the Internet,  then ftp is  a command-driven  program.   However,
there are  other  implementations  of  ftp  out  there,  such  as  the
Macintosh version (called  Fetch) with  a nice menu-driven  interface,
which is  quite  self-explanatory.    Even  if you're  not  using  the
command-driven version of ftp, the information given here should help.


  ftp can be  used to both upload  (send) or download (receive)  files
from other Internet  sites.   In most situations,  you're going to  be
downloading software.   On the  Internet there are  a large number  of
publicly-available FTP archive sites,  machines which allow anyone  to
ftp to them  and download  free software.   One  such archive site  is
sunsite.unc.edu, which has  a lot  of Sun  Microsystems software,  and
acts as one of the main Linux  sites.  In addition, FTP  archive sites
mirror software to each other---that is, software uploaded to one site
will be automatically  copied over  to a number  of other  sites.   So
don't be surprised if you see  the exact same files on  many different
archive sites.

C.1 Starting ftp

Note that in the  example ``screens'' printed  below I'm only  showing
the most important information,  and what you see  may differ.   Also,


                                 214
C.2.   Logging In                                                  215
_______________________________________________________________________

commands in italics represent commands that you type;  everything else
is screen output.
  To start ftp and connect to a site, simply use the command

    ftp <hostname>

where <hostname> is the name  of the site you are  connecting to.  For
example, to connect to the  mythical site shoop.vpizza.com we  can use
the command

    ftp shoop.vpizza.com


C.2 Logging In

When ftp starts up we should see something like

    Connected to shoop.vpizza.com.
    220 Shoop.vpizza.com FTPD ready at 15 Dec 1992 08:20:42 EDT
    Name (shoop.vpizza.com:mdw):

Here, ftp is asking us to give  the username that we want to  login as
on shoop.vpizza.com.   The default here is  mdw, which is my  username
on the system  I'm using  FTP from.   Since  I don't  have an  account
on shoop.vpizza.com  I can't  login as  myself.   Instead,  to  access
publicly-available software on an FTP site you login as anonymous, and
give your Internet e-mail address  (if you have one) as  the password.
So, we would type

    Name (shoop.vpizza.com:mdw):  anonymous
    331-Guest login ok, send e-mail address as password.
    Password:  [e-mail]
    230- Welcome to shoop.vpizza.com.
    230- Virtual Pizza Delivery[tm]:  Download pizza in  30 cycles
    or less
    230- or you get it FREE!
    ftp>

Of course,  you should  give  your e-mail  address,  instead of  mine,
and it  won't echo  to  the screen  as you're  typing  it (since  it's
technically a ``password'').  ftp  should allow us to login  and we'll
be ready to download software.

C.3 Poking Around

Okay, we're in.   ftp> is our prompt,  and the ftp program is  waiting
for commands.  There are a few basic commands you need  to know about.
First, the commands

    ls <file>
C.3.   Poking Around                                               216
_______________________________________________________________________

and

    dir <file>

both  give  file  listings  (where  <file>  is  an  optional  argument
specifying a particular  filename to list).    The difference is  that
ls usually  gives a  short  listing and  dir  gives a  longer  listing
(that is, with more  information on the sizes  of the files, dates  of
modification, and so on).
  The command

    cd <directory>

will move to the given directory (just like the cd command  on UNIX or
MS-DOS systems).  You can use the command

    cdup

to change to the parent directory(1).
  The command

    help <command>

will give help on the given  ftp <command> (such as ls  or cd).  If no
command is specified, ftp will list all of the available commands.
  If we type dir at this point we'll see  an initial directory listing
of where we are.

    ftp> dir
    200 PORT command successful.
    150 Opening ASCII mode data connection for /bin/ls.
    total 1337



    dr-xr-xr-x  2 root     wheel         512 Aug 13 13:55 bin
    drwxr-xr-x  2 root     wheel         512 Aug 13 13:58 dev
    drwxr-xr-x  2 root     wheel         512 Jan 25 17:35 etc
    drwxr-xr-x 19 root     wheel        1024 Jan 27 21:39 pub
    drwxrwx-wx  4 root     ftp-admi     1024 Feb  6 22:10 uploads
    drwxr-xr-x  3 root     wheel         512 Mar 11  1992 usr


    226 Transfer complete.
    921 bytes received in 0.24 seconds (3.7 Kbytes/s)
    ftp>

----------------------------
 1. The directory above the current one.
C.4.   Downloading files                                           217
_______________________________________________________________________

  Each of these entries  is a directory, not an individual  file which
we can  download  (specified by  the  d in  the  first column  of  the
listing).  On most FTP archive sites, the  publicly available software
is under the directory /pub, so let's go there.

    ftp> cd pub
    ftp> dir
    200 PORT command successful.
    150 ASCII data connection  for /bin/ls (128.84.181.1,4525)  (0
    bytes).
    total 846



    -rw-r--r--  1 root   staff     1433 Jul 12  1988 README
    -r--r--r--  1 3807   staff    15586 May 13  1991  US-DOMAIN.TXT.2
    -rw-r--r--  1 539    staff    52664 Feb 20  1991 altenergy.avail
    -r--r--r--  1 65534  65534    56456 Dec 17  1990 ataxx.tar.Z
    -rw-r--r--  1 root   other  2013041 Jul  3  1991 gesyps.tar.Z
    -rw-r--r--  1 432    staff    41831 Jan 30  1989 gnexe.arc
    -rw-rw-rw-  1 615    staff    50315 Apr 16  1992 linpack.tar.Z
    -r--r--r--  1 root   wheel    12168 Dec 25  1990 localtime.o
    -rw-r--r--  1 root   staff     7035 Aug 27  1986 manualslist.tblms
    drwxr-xr-x  2 2195   staff      512 Mar 10 00:48 mdw
    -rw-r--r--  1 root   staff     5593 Jul 19  1988 t.out.h


    226 ASCII Transfer complete.
    2443 bytes received in 0.35 seconds (6.8 Kbytes/s)
    ftp>

  Here we can see a  number of (interesting?)  files, one of  which is
called README, which we should download (most FTP sites have  a README
file in the /pub directory).


C.4 Downloading files

Before downloading files, there are a few things that you need to take
care of.

 o  Turn on hash mark printing.  Hash marks are printed  to the screen
    as files are being  transferred; they let  you know how far  along
    the transfer is, and that  your connection hasn't hung up  (so you
    don't sit for 20 minutes, thinking that you're still downloading a
C.4.   Downloading files                                           218
_______________________________________________________________________

    file).  In general, a hash  mark appears as a pound sign  (#), and
    one is printed for every 1024 or 8192 bytes transferred, depending
    on your system.

    To turn on hash mark printing, give the command hash.


        ftp> hash
        Hash mark printing on (8192 bytes/hash mark).
        ftp>


 o  Determine the type of file which  you are downloading.  As  far as
    FTP is concerned,  files come in  two flavors:   binary and  text.
    Most of the  files which you'll be  downloading are binary  files:
    that is, programs,  compressed files,  archive files,  and so  on.
    However, many files (such as READMEs and so on) are text files.

    Why does the file type matter?  Only because on some systems (such
    as MS-DOS systems),  certain characters  in a text  file, such  as
    carriage returns, need to  be converted so  that the file will  be
    readable.   While transferring  in binary mode,  no conversion  is
    done---the file is simply transferred byte after byte.

    The commands bin  and ascii set  the transfer  mode to binary  and
    text, respectively.   When  in doubt,  always use  binary mode  to
    transfer files.   If  you try to  transfer a  binary file in  text
    mode, you'll corrupt the file and  it will be unusable.   (This is
    one of the most common mistakes made when using FTP.) However, you
    can use text mode for plain text files (whose  filenames often end
    in .txt).

    For our example, we're downloading the file README, which  is most
    likely a text file, so we use the command


        ftp> ascii
        200 Type set to A.
        ftp>


 o  Set your local directory.   Your local directory is  the directory
    on your system  where you  want the  downloaded files  to end  up.
    Whereas the cd command changes the remote directory (on the remote
    machine which you're FTPing to), the lcd command changes the local
    directory.

    For example, to set  the local directory to /home/db/mdw/tmp,  use
    the command
C.5.   Quitting FTP                                                219
_______________________________________________________________________

        ftp> lcd /home/db/mdw/tmp
        Local directory now /home/db/mdw/tmp
        ftp>


  Now you're ready to actually download the file.  The command

    get <remote-name> <local-name>

is used for this, where  <remote-name> is the name  of the file on the
remote machine, and <local-name> is the name that you wish to give the
file on your local machine.  The <local-name> argument is optional; by
default, the local filename is the  same as the remote one.   However,
if for example  you're downloading  the file README,  and you  already
have a README in your local directory, you'll want to give a different
<local-filename> so that the first one isn't overwritten.
  For our example, to download the file README, we simply use

    ftp> get README
    200 PORT command successful.
    150 ASCII data connection for README (128.84.181.1,4527) (1433
    bytes).
    #
    226 ASCII Transfer complete.
    local:  README remote:  README
    1493 bytes received in 0.03 seconds (49 Kbytes/s)
    ftp>


C.5 Quitting FTP

To end your FTP session, simply use the command

    quit

The command

    close

can be used to close the connection with the current  remote FTP site;
the open command can then be used to start a session with another site
(without quitting the FTP program altogether).

    ftp> close
    221 Goodbye.
    ftp> quit
C.6.   Using ftpmail                                               220
_______________________________________________________________________

C.6 Using ftpmail

ftpmail is a service which allows you to obtain files from FTP archive
sites via Internet electronic mail.  If you don't have direct Internet
access, but are able to send mail to the Internet (from a service such
as CompuServe, for example), ftpmail is  a good way to get  files from
FTP archive sites.    Unfortunately, ftpmail can  be slow,  especially
when sending large jobs.  Before attempting to download  large amounts
of software using ftpmail, be sure  that your mail spool will  be able
to handle the incoming traffic.  Many systems keep  quotas on incoming
electronic mail, and may delete your account if your mail exceeds this
quota.  Just use common sense.
  sunsite.unc.edu, one of the  major Linux FTP archive sites,  is home
to an ftpmail server.  To use this service, send electronic mail to

    [e-mail]

with a message body containing only the word:

    help

This will  send  you back  a  list of  ftpmail  commands and  a  brief
tutorial on using the system.
  For  example,   to   get  a   listing  of  Linux   files  found   on
sunsite.unc.edu, send mail to the above address containing the text

    open sunsite.unc.edu
    cd /pub/Linux
    dir
    quit

  You may use the ftpmail service to connect to  any FTP archive site;
you are not  limited to  sunsite.unc.edu.   The next  section lists  a
number of Linux FTP archives.


C.7 Linux FTP Site List

Table C.1 is a listing of the most well-known FTP  archive sites which
carry the Linux software.   Keep in mind that many other  sites mirror
these, and more than likely you'll run into Linux on a number of sites
not on this list.
  tsx-11.mit.edu,  sunsite.unc.edu, and  nic.funet.fi  are the  ``home
sites'' for the  Linux software,  where most  of the  new software  is
uploaded.  Most of the other sites on the list mirror some combination
of these three.   To  reduce network  traffic, choose  a site that  is
geographically closest to you.
C.7.   Linux FTP Site List                                         221
_______________________________________________________________________

















 Sitename                       IP Address       Directory

 tsx-11.mit.edu                 18.172.1.2       /pub/linux
 sunsite.unc.edu                152.2.22.81      /pub/Linux
 nic.funet.fi                   128.214.6.100    /pub/OS/Linux
 ftp.mcc.ac.uk                  130.88.200.7     /pub/linux
 fgb1.fgb.mw.tu-muenchen.de     129.187.200.1    /pub/linux
 ftp.informatik.tu-muenchen.de  131.159.0.110    /pub/Linux
 ftp.dfv.rwth-aachen.de         137.226.4.105    /pub/linux
 ftp.informatik.rwth-aachen.de  137.226.112.172  /pub/Linux
 ftp.ibp.fr                     132.227.60.2     /pub/linux
 kirk.bu.oz.au                  131.244.1.1      /pub/OS/Linux
 ftp.uu.net                     137.39.1.9       /systems/unix/linux
 wuarchive.wustl.edu            128.252.135.4    /systems/linux
 ftp.win.tue.nl                 131.155.70.100   /pub/linux
 ftp.ibr.cs.tu-bs.de            134.169.34.15    /pub/os/linux
 ftp.denet.dk                   129.142.6.74     /pub/OS/linux

                     Table C.1:  Linux FTP Sites








Appendix D




Linux BBS List



Printed here is  a list of  bulletin board  systems (BBS) which  carry
Linux software.  Zane Healy ([e-mail]) maintains this list.
If you know of or run a BBS which provides Linux  software which isn't
on this list, you should get in touch with him.
  The Linux  community  is no  longer an  Internet-only society.    In
fact, it is now estimated that the majority of Linux  users don't have
Internet access.    Therefore, it  is especially  important that  BBSs
continue to provide and support Linux to users worldwide.

D.1 United States

Citrus Grove Public Access, 916-381-5822.  ZyXEL 16.8/14.4 Sacramento,
  CA. Internet:  citrus.sac.ca.us
Higher Powered BBS, 408-737-7040.  ?  CA. RIME ->HIGHER
hip-hop, 408-773-0768.  19.2k Sunnyvale, CA. USENET access
hip-hop, 408-773-0768.  38.4k Sunnyvale, CA.
Unix Online, 707-765-4631.  9600 Petaluma, CA. USENET access
The Outer Rim, 805-252-6342.    Santa Clarita, CA.
Programmer's Exchange, 818-444-3507.    El Monte, CA. Fidonet
Programmer's Exchange, 818-579-9711.    El Monte, CA.
Micro Oasis, 510-895-5985.  14.4k San Leandro, CA.
Test Engineering, 916-928-0504.    Sacramento, CA.
Slut Club, 813-975-2603.   USR/DS 16.8k  HST/14.4K Tampa, FL.  Fidonet
  1:377/42
Lost City Atlantis, 904-727-9334.  14.4k Jacksonville, FL. FidoNet
Aquired Knowledge, 305-720-3669.   14.4k v.32bis Ft.  Lauderdale,  FL.
  Internet, UUCP
The Computer Mechanic, 813-544-9345.   14.4k v.32bis St.   Petersburg,
  FL. Fidonet, Sailnet, MXBBSnet
AVSync, 404-320-6202.    Atlanta, GA.
Information Overload, 404-471-1549.  19.2k ZyXEL Atlanta,  GA. Fidonet
  1:133/308
Atlanta Radio Club, 404-850-0546.  9600 Atlanta, GA.
Rebel BBS, 208-887-3937.  9600 Boise, ID.
Rocky Mountain HUB, 208-232-3405.  38.4k Pocatello, ID. Fionet, SLNet,


                                 222
D.1.   United States                                               223
_______________________________________________________________________

  CinemaNet
EchoMania, 618-233-1659.  14.4k HST Belleville, IL.  Fidonet 1:2250/1,
  f'req LINUX
UNIX USER, 708-879-8633.  14.4k Batavia, IL. USENET, Internet mail
PBS BBS, 309-663-7675.  2400 Bloomington, IL.
Third World, 217-356-9512.  9600 v.32 IL.
Digital Underground, 812-941-9427.  14.4k v.32bis IN. USENET
The OA  Southern Star,  504-885-5928.       New  Orleans, LA.  Fidonet
  1:396/1
Channel One, 617-354-8873.    Boston, MA. RIME ->CHANNEL
VWIS Linux Support BBS, 508-793-1570.  9600 Worcester, MA.
WayStar BBS, 508-481-7147.    14.4k V.32bis  USR/HST Marlborough,  MA.
  Fidonet 1:333/14
WayStar BBS, 508-481-7293.    14.4k V.32bis  USR/HST Marlborough,  MA.
  Fidonet 1:333/15
WayStar BBS, 508-480-8371.  9600 V.32bis or 14.4k USR/HST Marlborough,
  MA. Fidonet 1:333/16
Programmer's Center, 301-596-1180.  9600 Columbia, MD. RIME
Brodmann's Place, 301-843-5732.   14.4k Waldorf, MD. RIME  ->BRODMANN,
  Fidonet
Main Frame, 301-654-2554.  9600 Gaithersburg, MD. RIME ->MAINFRAME
1 Zero Cybernet BBS, 301-589-4064.    MD.
WaterDeep BBS, 410-614-2190.  9600 v.32 Baltimore, MD.
Harbor Heights BBS, 207-663-0391.  14.4k Boothbay Harbor, ME.
Part-Time BBS, 612-544-5552.  14.4k v.32bis Plymouth, MN.
The Sole  Survivor, 314-846-2702.    14.4k  v.32bis St.    Louis,  MO.
  WWIVnet, WWIVlink, etc
MAC's Place, 919-891-1111.  16.8k, DS modem Dunn, NC. RIME ->MAC
Digital Designs, 919-423-4216.  14.4k, 2400 Hope Mills, NC.
Flite Line, 402-421-2434.    Lincoln, NE. RIME ->FLITE, DS modem
Legend, 402-438-2433.    Lincoln, NE. DS modem
MegaByte Mansion, 402-551-8681.  14.4 V,32bis Omaha, NE.
Mycroft QNX, 201-858-3429.  14.4k NJ.
Steve Leon's, 201-886-8041.  14.4k Cliffside Park, NJ.
Dwight-Englewood BBS, 201-569-3543.  9600 v.42 Englewood, NJ. USENET
The Mothership Cnection, 908-940-1012.  38.4k Franklin Park, NJ.
The Laboratory, 212-927-4980.   16.8k HST,  14.4k v.32bis NY.  FidoNet
  1:278/707
Valhalla,  516-321-6819.     14.4k  HST  v.32  Babylon,   NY.  Fidonet
  (1:107/255), UseNet (die.linet.org)
Intermittent Connection, 503-344-9838.  14.4k HST v.32bis  Eugene, OR.
  1:152/35
Horizon Systems, 216-899-1086.  USR v.32 Westlake, OH.
Horizon Systems, 216-899-1293.  2400 Westlake, OH.
Centre Programmers Unit, 814-353-0566.  14.4k  V.32bis/HST Bellefonte,
  PA.
Allentown Technical, 215-432-5699.   9600 v.32/v.42bis Allentown,  PA.
  WWIVNet 2578
Tactical-Operations, 814-861-7637.  14.4k V32bis/V42bis State College,
  PA. Fidonet 1:129/226, tac_ops.UUCP
D.2.   Outside of the United States                                224
_______________________________________________________________________

North Shore BBS, 713-251-9757.    Houston, TX.
The Annex, 512-575-1188.  9600 HST TX. Fidonet 1:3802/217
The Annex, 512-575-0667.  2400 TX. Fidonet 1:3802/216
Walt Fairs, 713-947-9866.    Houston, TX. FidoNet 1:106/18
CyberVille, 817-249-6261.  9600 TX. FidoNet 1:130/78
splat-ooh, 512-578-2720.  14.4k Victoria, TX.
splat-ooh, 512-578-5436.  14.4k Victoria, TX.
alaree, 512-575-5554.  14.4k Victoria, TX.
Ronin BBS, 214-938-2840.   14.4 HST/DS Waxahachie (Dallas),  TX. RIME,
  Intelec, Smartnet, etc.
VTBBS, 703-231-7498.    Blacksburg, VA.
MBT, 703-953-0640.    Blacksburg, VA.
NOVA, 703-323-3321.  9600 Annandale, VA. Fidonet 1:109/305
Rem-Jem, 703-503-9410.  9600 Fairfax, VA.
Enlightend, 703-370-9528.  14.4k Alexandria, VA. Fidonet 1:109/615
My UnKnown BBS, 703-690-0669.  14.4k V.32bis VA. Fidonet 1:109/370
Georgia Peach BBS, 804-727-0399.  14.4k Newport News, VA.
Top Hat BBS, 206-244-9661.  14.4k WA. Fidonet 1:343/40
victrola.sea.wa.us, 206-838-7456.  19.2k Federal Way, WA. USENET



D.2 Outside of the United States

Galaktische Archive,   0043-2228303804.     16.8  ZYX  Wien,  Austria.
  Fidonet 2:310/77 (19:00-7:00)
Linux-Support-Oz,  [phone].      v.32bis  14.4k  Sydney,   NSW,
  Austrailia.  Internet/Usenet, E-Mail/News
500cc  Formula  1  BBS,   [phone].      V.32bis  Sydney,   NSW,
  Australia.
Magic BBS, 403-569-2882.   14.4k HST/Telebit/MNP Calgary, AB,  Canada.
  Internet/Usenet
Logical Solutions, 299-9900 through 9911.  2400 AB, Canada.
Logical Solutions, 299-9912, 299-9913.  14.4k Canada.
Logical Solutions, 299-9914 through 9917.  16.8k v.32bis Canada.
V.A.L.I.S., 403-478-1281.  14.4k v.32bis Edmonton, AB, Canada.  USENET
The Windsor Download, (519)-973-9330.  v32bis 14.4 ON, Canada.
r-node, 416-249-5366.  2400 Toronto, ON, Canada.  USENET
Synapse, 819-246-2344.    819-561-5268 Gatineau,  QC, Canada.
  RIME->SYNAPSE
Radio Free Nyongwa, 514-524-0829.  v.32bis ZyXEL Montreal, QC, Canada.
  USENET, Fidonet
DataComm1, +49.531.132-16.  14.4 HST Braunschweig, NDS, Germany.  Fido
  2:240/550, LinuxNet
DataComm2, +49.531.132-17.  14.4 HST Braunschweig, NDS, Germany.  Fido
  2:240/551, LinuxNet
Linux Server /Braukmann,  +49.441.592-963.   16.8 ZYX Oldenburg,  NDS,
  Germany.  Fido 2:241/2012, LinuxNet
MM's Spielebox, +49.5323.3515.  14.4 ZYX Clausthal-Zfd., NDS, Germany.
  Fido 2:241/3420
MM's Spielebox, +49.5323.3516.  16.8 ZYX Clausthal-Zfd., NDS, Germany.
D.2.   Outside of the United States                                225
_______________________________________________________________________

  Fido 2:241/3421
MM's Spielebox,  +49.5323.3540.   9600  Clausthal-Zfd., NDS,  Germany.
  Fido 2:241/3422
Bit-Company / J. Bartz,  +49.5323.2539.   16.8 ZYX MO  Clausthal-Zfd.,
  NDS, Germany.  Fido 2:241/3430
Fractal Zone BBS  /Maass, +49.721.863-066.   16.8  ZYX Karlsruhe,  BW,
  Germany.  Fido 2:241/7462
Hipposoft /M. Junius, +49.241.875-090.  14.4 HST Aachen, NRW, Germany.
  Fido 2:242/6, 4:30-7,8-23:30
UB-HOFF /A. Hoffmann, +49.203.584-155.   19.2 ZYX+ Duisburg,  Germany.
  Fido 2:242/37
FORMEL-Box, +49.4191.2846.    16.8  ZYX Kaltenkirchen,  SHL,  Germany.
  Fido 2:242/329, LinuxNet (6:00-20:00)
BOX/2, +49.89.601-96-77.    16.8 ZYX  Muenchen,  BAY, Germany.    Fido
  2:246/147, info magic:  LINUX (22-24,0:30-2,5-8)
Die Box Passau 2+1, +49.851.555-96.   14.4 V32b Passau,  BAY, Germany.
  Fido 2:246/200 (8:00-3:30)
Die Box  Passau  Line 1,  +49.851.753-789.    16.8  ZYX  Passau,  BAY,
  Germany.  Fido 2:246/2000 (8:00-3:30)
Die Box Passau Line 3, +49.851.732-73.  14.4 HST Passau, BAY, Germany.
  Fido 2:246/202 (5:00-3:30)
Die Box Passau  ISDN, +49.851.950-464.    38.4/64k V.110/X.75  Passau,
  BAY, Germany.  Fido 2:246/201 (8:00-24:00,1:00-3:30)
Public Domain Kiste, +49.30.686-62-50.   16.8 ZYX BLN, Germany.   Fido
  2:2403/17
CS-Port /  C.  Schmidt,  +49.30.491-34-18.    19.2  Z19  Berlin,  BLN,
  Germany.  Fido 2:2403/13
BigBrother /  R. Gmelch,  +49.30.335-63-28.    16.8 Z16  Berlin,  BLN,
  Germany.  Fido 2:2403/36.4 (16-23:00)
CRYSTAL BBS, +49.7152.240-86.  14.4  HST Leonberg, BW, Germany.   Fido
  2:2407/3, LinuxNet
Echoblaster BBS  #1,   +49.7142.213-92.     HST/V32b  Bietigheim,  BW,
  Germany.  Fido 2:2407/4, LinuxNet (7-19,23-01h
Echoblaster BBS #2,  +49.7142.212-35.   V32b Bietigheim, BW,  Germany.
  Fido 2:2407/40, LinuxNet (20h-6h)
LinuxServer / P.  Berger, +49.711.756-275.   16.8  HST Stuttgart,  BW,
  Germany.  Fido 2:2407/34, LinuxNet (8:3-17:5,19-2)
Rising Sun BBS,  +49.7147.3845.   16.8 ZYX  Sachsenheim, BW,  Germany.
  Fido 2:2407/41, LinuxNet (5:30-2:30)
bakunin.north.de, +49.421.870-532.  14.4  D 2800 Bremen, HB,  Germany.
  [e-mail]
oytix.north.de,    +49.421.396-57-62.           ZYX    HB,    Germany.
  [e-mail], login as gast
Fiffis Inn BBS, [phone].   14.4-19.2 Munich, Germany.   FidoNet
  2:246/69,Internet,USENET,LinuxNet
The Field  of  Inverse Chaos,  [phone].    14.4k  v32bis/HST
  Helsinki, Finland.  USENET; ichaos.nullnet.fi
Modula BBS, [phone].  HST 14.4 v.32bis Paris, France.
Modula BBS, [phone].  HST 14.4 V.32bis Paris, France.
STDIN BBS, [phone].  v.32bis Lyon, Laurent Cas, France.   FidoNet
D.2.   Outside of the United States                                226
_______________________________________________________________________

  2:323/8
Le Lien, [phone].  HST 14.4/V32bis Lyon, Pascal  Valette, France.
  FidoNet 2:323/5
Basil, [phone].  v.32bis Paris, Laurent Chemla, France.
Cafard Naum, [phone].  v.32bis Nantes, Yann Dupont, France.
DUBBS, [phone].  19.2 ZyXEL Dublin, Ireland.  Fidonet 2:263/167
Galway Online,  [phone].   14.4k v32b  Galway, Ireland.    RIME,
  @iol.ie
Nemesis' Dungeon,  [phone]  or 326900.    14.4k  v32bis  Dublin,
  Ireland.  Fidonet 2:263/150
nonsolosoftware, [phone].   v.32bis, v.42bis  Italy.   Fidonet
  2:332/407
nonsolosoftware, [phone].  ZyXEL 19.2k Italy.  Fidonet 2:332/417
Advanced Systems, [phone].  ZyXEL 16.8k Auckland,  New Zealand.
  Singet, INTLnet, Fidonet
Thunderball Cave, 472567018.    Norway.  RIME ->CAVE
DownTown BBS Lelystad, [phone].   14.4k Lelystad,  Netherlands.
  Fido 2:512/155, UUCP
MUGNET Intl-Cistron  BBS,  [phone].    38.4k Alphen  a/d  Rijn,
  Netherlands.  UUCP
The Controversy, (65)560-6040.  14.4k V.32bis/HST Singapore.   Fidonet
  6:600/201
Pats System,  [phone].    14.4k  v.32bis/HST  Pretoria,  South
  Africa.  Fidonet 5:71-1/36
Gunship BBS, [phone].  14.4k HST DS Gothenburg Sweden.
Baboon BBS, [phone].   19.2k  Switzerland.   Fido 2:301/580  and
  /581
The Purple Tentacle, [phone].  HST/V32bis Reading,  UK. Fidonet
  2:252/305
A6 BBS, [phone].  14.4k Herts, UK. Fidonet 2:440/111
On the  Beach, [phone].    14.4k/16.8k Brighton,  UK.  Fidonet
  2:441/122








Appendix E




The GNU General Public License



Printed below is the GNU General Public License (the GPL or copyleft),
under which Linux  is licensed.   It  is reproduced  here to clear  up
some of the  confusion about Linux's  copyright status---Linux is  not
shareware, and it is not in the public domain.  The bulk  of the Linux
kernel is copyright Oc1993 by Linus  Torvalds, and other software  and
parts of the kernel are copyrighted by their authors.   Thus, Linux is
copyrighted, however, you may redistribute  it under the terms  of the
GPL printed below.


                      GNU GENERAL PUBLIC LICENSE
                         Version 2, June 1991
  Copyright cO1989, 1991 Free Software Foundation, Inc.  675 Mass Ave,
Cambridge, MA 02139, USA Everyone is permitted to copy  and distribute
verbatim copies  of this  license  document, but  changing  it is  not
allowed.

E.1 Preamble

The licenses for most software are designed to take away  your freedom
to share  and  change  it.    By  contrast,  the  GNU  General  Public
License is  intended to  guarantee your  freedom to  share and  change
free software--to make sure  the software is  free for all its  users.
This General  Public License  applies  to most  of the  Free  Software
Foundation's software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can  apply it to
your programs, too.
  When we  speak of free  software, we are  referring to freedom,  not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or  can get it
if you want it, that you can  change the software or use pieces  of it
in new free programs; and that you know you can do these things.
  To protect  your rights,  we need to  make restrictions that  forbid


                                 227
E.2.Terms and Conditions for Copying, Distribution, and Modification228
_______________________________________________________________________

anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate  to certain  responsibilities for you  if
you distribute copies of the software, or if you modify it.
  For example,  if you distribute  copies of  such a program,  whether
gratis or for a fee, you must give the recipients all  the rights that
you have.  You must make  sure that they, too, receive or can  get the
source code.  And  you must show them  these terms so they know  their
rights.
  We protect your rights with two steps:   (1) copyright the software,
and (2) offer  you this license  which gives  you legal permission  to
copy, distribute and/or modify the software.
  Also,  for  each author's  protection  and  ours, we  want  to  make
certain that everyone understands that  there is no warranty for  this
free software.  If the software is modified by someone else and passed
on, we want  its recipients  to know that  what they  have is not  the
original, so that any problems  introduced by others will  not reflect
on the original authors' reputations.
  Finally,  any  free program  is  threatened constantly  by  software
patents.  We wish  to avoid the danger  that redistributors of a  free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it  clear that any
patent must be  licensed for everyone's  free use  or not licensed  at
all.
  The  precise terms  and  conditions for  copying,  distribution  and
modification follow.


E.2 Terms and Conditions for Copying, Distribution, and Modification

0.  This License applies to any  program or other work  which contains
    a  notice  placed  by  the  copyright  holder  saying  it  may  be
    distributed under the terms of  this General Public License.   The
    ``Program'', below,  refers  to  any  such program  or  work,  and
    a ``work  based  on the  Program''  means  either the  Program  or
    any derivative  work under  copyright  law:   that  is to  say,  a
    work containing the Program  or a portion  of it, either  verbatim
    or with  modifications and/or  translated  into another  language.
    (Hereinafter, translation  is included without  limitation in  the
    term ``modification''.)  Each licensee is addressed as ``you''.

    Activities other than copying,  distribution and modification  are
    not covered by this License; they are outside its scope.   The act
    of running the Program is not restricted, and the  output from the
    Program is covered  only if its contents  constitute a work  based
    on the Program  (independent of  having been made  by running  the
    Program).  Whether that is true depends on what the Program does.

1.  You may  copy  and distribute  verbatim  copies of  the  Program's
    source code  as  you receive  it,  in  any medium,  provided  that
    you conspicuously  and  appropriately  publish  on  each  copy  an
    appropriate copyright  notice  and disclaimer  of  warranty;  keep
E.2.Terms and Conditions for Copying, Distribution, and Modification229
_______________________________________________________________________

    intact all  the notices  that refer  to this  License  and to  the
    absence of  any warranty;  and give  any other  recipients of  the
    Program a copy of this License along with the Program.

    You may charge a fee for the physical act of  transferring a copy,
    and you may at your  option offer warranty protection  in exchange
    for a fee.

2.  You may modify your copy or  copies of the Program or  any portion
    of it, thus  forming a  work based  on the Program,  and copy  and
    distribute such modifications or work under the terms of Section 1
    above, provided that you also meet all of these conditions:


    a.  You must cause the  modified files to carry prominent  notices
        stating that you changed the files and the date of any change.

    b.  You must cause any work  that you distribute or publish,  that
        in whole or in part contains or is derived from the Program or
        any part thereof, to  be licensed as a  whole at no charge  to
        all third parties under the terms of this License.

    c.  If the modified program normally reads  commands interactively
        when run, you  must cause  it, when  started running for  such
        interactive use in the most ordinary way, to  print or display
        an announcement including an appropriate copyright  notice and
        a notice  that there  is  no warranty  (or else,  saying  that
        you provide a  warranty) and that  users may redistribute  the
        program under these  conditions, and telling  the user how  to
        view a copy  of this  License.   (Exception:   if the  Program
        itself is  interactive but  does not  normally  print such  an
        announcement, your work based  on the Program is not  required
        to print an announcement.)


    These requirements apply  to the  modified work  as a whole.    If
    identifiable sections  of  that  work  are not  derived  from  the
    Program, and can be reasonably considered independent and separate
    works in  themselves, then  this License,  and its  terms, do  not
    apply to  those  sections when  you  distribute them  as  separate
    works.   But when you distribute  the same sections  as part of  a
    whole which is a  work based on  the Program, the distribution  of
    the whole must be on the terms of this License,  whose permissions
    for other licensees extend to  the entire whole, and thus  to each
    and every part regardless of who wrote it.

    Thus, it is  not the  intent of  this section to  claim rights  or
    contest your rights to work  written entirely by you; rather,  the
    intent is to  exercise the  right to control  the distribution  of
    derivative or collective works based on the Program.
E.2.Terms and Conditions for Copying, Distribution, and Modification230
_______________________________________________________________________

    In addition, mere  aggregation of  another work  not based on  the
    Program with the Program (or with a work based on  the Program) on
    a volume of a  storage or distribution  medium does not bring  the
    other work under the scope of this License.

3.  You may copy and  distribute the Program (or  a work based on  it,
    under Section 2) in object code or executable form under the terms
    of Sections 1  and 2 above provided  that you also  do one of  the
    following:


    a.  Accompany it with the complete  corresponding machine-readable
        source code,  which must  be  distributed under  the terms  of
        Sections 1  and  2 above  on  a  medium customarily  used  for
        software interchange; or,

    b.  Accompany it with  a written offer,  valid for at least  three
        years, to give any third party, for a charge no more than your
        cost of physically performing source distribution,  a complete
        machine-readable copy of the corresponding source code,  to be
        distributed under the  terms of Sections  1 and  2 above on  a
        medium customarily used for software interchange; or,

    c.  Accompany it with the information you received as to the offer
        to distribute corresponding source code.  (This alternative is
        allowed only for  noncommercial distribution  and only if  you
        received the program  in object code  or executable form  with
        such an offer, in accord with Subsection b above.)


    The source code for  a work means the  preferred form of the  work
    for making modifications to it.  For an executable  work, complete
    source code means all the source code for all modules it contains,
    plus any associated interface  definition files, plus the  scripts
    used to control  compilation and  installation of the  executable.
    However, as  a  special  exception,  the source  code  distributed
    need not include anything that is normally distributed  (in either
    source or  binary  form)  with  the  major  components  (compiler,
    kernel, and so on) of the operating system on which the executable
    runs, unless that component itself accompanies the executable.

    If distribution of executable or  object code is made  by offering
    access to copy from a  designated place, then offering  equivalent
    access to  copy the  source code  from the  same  place counts  as
    distribution of the source code, even though third parties are not
    compelled to copy the source along with the object code.

4.  You may not  copy, modify, sublicense,  or distribute the  Program
    except as  expressly provided  under this  License.   Any  attempt
    otherwise to copy,  modify, sublicense  or distribute the  Program
E.2.Terms and Conditions for Copying, Distribution, and Modification231
_______________________________________________________________________

    is void,   and will  automatically  terminate  your  rights  under
    this License.    However,  parties who  have received  copies,  or
    rights, from you under this  License will not have  their licenses
    terminated so long as such parties remain in full compliance.

5.  You are  not  required to  accept  this License,  since  you  have
    not signed it.   However,  nothing else  grants you permission  to
    modify or distribute the Program  or its derivative works.   These
    actions are prohibited by law  if you do not accept  this License.
    Therefore, by modifying or  distributing the Program (or any  work
    based on  the  Program),  you  indicate your  acceptance  of  this
    License to do so,  and all its  terms and conditions for  copying,
    distributing or modifying the Program or works based on it.

6.  Each time  you redistribute  the  Program (or  any work  based  on
    the Program), the recipient automatically receives a  license from
    the original licensor  to copy, distribute  or modify the  Program
    subject to these  terms and conditions.   You  may not impose  any
    further restrictions  on the  recipients' exercise  of the  rights
    granted herein.  You are not responsible for  enforcing compliance
    by third parties to this License.

7.  If, as a consequence of  a court judgment or allegation  of patent
    infringement or  for  any  other  reason (not  limited  to  patent
    issues), conditions are  imposed on you  (whether by court  order,
    agreement or  otherwise) that  contradict the  conditions of  this
    License, they  do  not  excuse you  from  the conditions  of  this
    License.  If you cannot distribute so as to satisfy simultaneously
    your obligations  under  this  License  and  any  other  pertinent
    obligations, then  as a  consequence you  may  not distribute  the
    Program at  all.   For  example,  if a  patent  license would  not
    permit royalty-free redistribution of the Program by all those who
    receive copies directly or indirectly  through you, then the  only
    way you could satisfy both it and this License would be to refrain
    entirely from distribution of the Program.

    If any portion  of this section is  held invalid or  unenforceable
    under any particular circumstance,  the balance of the section  is
    intended to apply and the section as a whole is  intended to apply
    in other circumstances.

    It  is  not  the  purpose  of  this  section  to   induce  you  to
    infringe any patents or other property right claims or  to contest
    validity of any  such claims;  this section  has the sole  purpose
    of protecting  the integrity  of  the free  software  distribution
    system, which is  implemented by public license  practices.   Many
    people have  made  generous contributions  to  the wide  range  of
    software distributed through that system in reliance on consistent
    application of that system; it is up to the author/donor to decide
    if he or she is  willing to distribute software through  any other
E.2.Terms and Conditions for Copying, Distribution, and Modification232
_______________________________________________________________________

    system and a licensee cannot impose that choice.

    This section is intended to make thoroughly clear what is believed
    to be a consequence of the rest of this License.

8.  If the distribution  and/or use  of the Program  is restricted  in
    certain countries either by patents or by  copyrighted interfaces,
    the original copyright  holder who places  the Program under  this
    License may add an  explicit geographical distribution  limitation
    excluding those countries, so that distribution is  permitted only
    in or  among countries  not thus  excluded.   In  such case,  this
    License incorporates the limitation as  if written in the  body of
    this License.

9.  The Free  Software  Foundation  may  publish  revised  and/or  new
    versions of the General  Public License from time  to time.   Such
    new versions will be similar in spirit to the present version, but
    may differ in detail to address new problems or concerns.

    Each version is  given a distinguishing  version number.   If  the
    Program specifies a version  number of this License which  applies
    to it and ``any later version'', you have the  option of following
    the terms and conditions  either of that  version or of any  later
    version published by the Free Software Foundation.  If the Program
    does not specify a version number of this License,  you may choose
    any version ever published by the Free Software Foundation.

10. If you wish to  incorporate parts of  the Program into other  free
    programs whose distribution conditions are different, write to the
    author to ask for permission.   For software which  is copyrighted
    by the  Free  Software  Foundation,  write to  the  Free  Software
    Foundation; we sometimes make exceptions  for this.   Our decision
    will be guided by the two  goals of preserving the free  status of
    all derivatives of our free software and of promoting  the sharing
    and reuse of software generally.


                             NO WARRANTY

11. BECAUSE THE  PROGRAM  IS LICENSED  FREE  OF  CHARGE, THERE  IS  NO
    WARRANTY FOR THE  PROGRAM, TO THE  EXTENT PERMITTED BY  APPLICABLE
    LAW.  EXCEPT  WHEN  OTHERWISE  STATED  IN  WRITING  THE  COPYRIGHT
    HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM ``AS IS'' WITHOUT
    WARRANTY OF  ANY KIND,  EITHER  EXPRESSED OR  IMPLIED,  INCLUDING,
    BUT NOT  LIMITED TO,  THE  IMPLIED WARRANTIES  OF  MERCHANTABILITY
    AND FITNESS FOR A  PARTICULAR PURPOSE. THE  ENTIRE RISK AS TO  THE
    QUALITY AND PERFORMANCE  OF THE  PROGRAM IS WITH  YOU. SHOULD  THE
    PROGRAM PROVE  DEFECTIVE, YOU  ASSUME THE  COST  OF ALL  NECESSARY
    SERVICING, REPAIR OR CORRECTION.
E.3.   Appendix:  How to Apply These Terms to Your New Programs    233
_______________________________________________________________________

12. IN NO  EVENT  UNLESS  REQUIRED  BY APPLICABLE  LAW  OR  AGREED  TO
    IN WRITING  WILL ANY  COPYRIGHT  HOLDER, OR  ANY OTHER  PARTY  WHO
    MAY MODIFY  AND/OR REDISTRIBUTE  THE PROGRAM  AS PERMITTED  ABOVE,
    BE LIABLE  TO YOU  FOR DAMAGES,  INCLUDING  ANY GENERAL,  SPECIAL,
    INCIDENTAL OR  CONSEQUENTIAL DAMAGES  ARISING OUT  OF  THE USE  OR
    INABILITY TO USE  THE PROGRAM (INCLUDING BUT  NOT LIMITED TO  LOSS
    OF DATA OR DATA BEING  RENDERED INACCURATE OR LOSSES  SUSTAINED BY
    YOU OR THIRD PARTIES OR A  FAILURE OF THE PROGRAM TO  OPERATE WITH
    ANY OTHER PROGRAMS), EVEN IF  SUCH HOLDER OR OTHER PARTY  HAS BEEN
    ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

                     END OF TERMS AND CONDITIONS


E.3 Appendix:  How to Apply These Terms to Your New Programs

If you develop a new  program, and you want  it to be of the  greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can  redistribute and change under  these
terms.
  To do  so,  attach the  following notices  to the  program.   It  is
safest to  attach  them to  the  start of  each  source file  to  most
effectively convey the  exclusion of  warranty; and  each file  should
have at least the ``copyright'' line  and a pointer to where  the full
notice is found.

    <one line to give the program's name and  a brief idea of what
    it does.> Copyright cO19yy <name of author>

    This program is free software; you can redistribute  it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of
    the License, or (at your option) any later version.

    This program  is  distributed in  the  hope  that it  will  be
    useful, but  WITHOUT ANY  WARRANTY; without  even the  implied
    warranty  of  MERCHANTABILITY  or  FITNESS  FOR  A  PARTICULAR
    PURPOSE. See the GNU General Public License for more details.

    You should  have received  a copy  of the  GNU General  Public
    License along with  this program;  if not,  write to the  Free
    Software Foundation, Inc., 675 Mass Ave, Cambridge,  MA 02139,
    USA.

  Also add information on  how to contact you by electronic  and paper
mail.
  If the program  is interactive, make it  output a short notice  like
this when it starts in an interactive mode:

    Gnomovision version  69,  Copyright (C)  19yy name  of  author
E.3.   Appendix:  How to Apply These Terms to Your New Programs    234
_______________________________________________________________________

    Gnomovision comes  with ABSOLUTELY  NO WARRANTY;  for  details
    type `show w'.   This  is free software,  and you are  welcome
    to redistribute it under certain conditions; type `show c' for
    details.

  The hypothetical  commands `show  w' and  `show c'  should show  the
appropriate parts  of the  General Public  License.   Of  course,  the
commands you use may be called something other than `show w' and `show
c'; they could even be mouse-clicks or menu items--whatever suits your
program.
  You should  also get  your employer  (if you work  as a  programmer)
or your school,  if any,  to sign a  ``copyright disclaimer'' for  the
program, if necessary.  Here is a sample; alter the names:

    Yoyodyne, Inc.,  hereby disclaims  all  copyright interest  in
    the program `Gnomovision'  (which makes  passes at  compilers)
    written by James Hacker.

    <signature of Ty Coon>, 1 April 1989
    Ty Coon, President of Vice


  This  General Public  License  does  not permit  incorporating  your
program into proprietary programs.   If  your program is a  subroutine
library, you may consider it more useful to permit linking proprietary
applications with the library.   If this is  what you want to do,  use
the GNU Library General Public License instead of this License.






Index



*, 106                               /proc, 102
- to begin command options, 98           mounting of, 157
.bash_profile, 135                   /sbin, 102
.bashrc, 135                         /tmp, 102
.profile, 135                        /usr, 102
.tcshrc, 135                         /usr/X11R6/lib/X11/XF86Config,
/                                           171
   in pathnames, 90                  /usr/X386, 103
   root directory name, 90           /usr/etc, 103
/Image, 141                          /urs/g++-include, 103
/bin/bash, 105                       /usr/include, 103
/bin/csh, 105                        /usr/lib, 103
/bin/sh, 105                         /usr/local, 104
/bin/tcsh, 105                       /usr/man, 104
/dev/console, 101                    /usr/src, 104
/dev/cua, 101                        /var, 104
/dev/hd, 101                         /var/adm, 104
/dev/lp, 101                         /var spool, 104
/dev/null, 101                       /vmlinux, 141
/dev/pty, 102                        /zImage, 141
/dev/tty, 102                        <, 110
/dev/ttyS, 101                       >, 109
/etc, 102                            ?, 107
/etc/Image, 141                      ~
csh.login, 135                           to refer  to home  directory,
/etc/fstab, 157                             92
/etc/getty, 160                      386BSD, 26
/etc/group
   format of, 147                    account
/etc/host.conf, 193                      creating, 86
/etc/hosts, 192                      addgroup, 147
/etc/init, 160                       adding users, 144
/etc/inittab, 160                        with adduser, 146
/etc/networks, 192                       with useradd, 146
/etc/passwd, 145                     adduser, 146
/etc/profile, 135                    afio, 151
/etc/rc, 160                         alpha, 20
/etc/rc.local, 160                   archiving files, 147--150
/etc/resolve.conf, 193               argument
/etc/zImage, 141                         command
/home, 102                                defined, 88
/lib, 102                            backflops, 151


                                 235
INDEX                                                              236
_______________________________________________________________________

background process, 118                  grouping with shell  scripts,
backgrounding jobs, 120                     131
backups, 151                             summary of basic, 98--100
   incremental, 151                  commercial support, 37
   multi-volume, 151                 compress, 149
   to floppy disk, 151               compressing files, 147--150
bash, 105                            configuration scripts
BBS list, 222--226                       for TCP/IP, 189
BBS software, 15                     console
   FidoNet, 15                           defined, 87
beta, 21                                 device name for, 101
bg, 122                                  virtual, 87
/bin, 100                            copy files, 96
books, 206--210                      copying   Linux,   18--19,    26,
boot floppy, 69--70, 162                    227--234
   creating, 141                     copyright, 18--19, 227--234
boot scripts, 160                    core dumps, 6
booting, 56, 141--143                cp, 96, 99
   from maintenance floppy, 162      csh, 8
   problems, 72--74, 81, 82          current working directory
   with LILO, 142--143                   defined, 90
booting Linux
   with boot floppy, 141             databases, 17
booting non-Linux systems, 142       debugging
Bourne again shell, 105                  core dumps, 6
Bourne shell, 8, 105                 delete
broadcast address                        directory, 97
   defined, 188                          files, 96
bugs, 20                             deleting users, 146
                                     deluser, 146
C News, 200                          /dev, 101
C Shell (csh), 8, 105                /dev/sd, 101
cat, 100                             /dev/sr, 101
   to view file contents, 97         /dev/st, 101
cd, 92--93, 98                       development
chfn, 146                                alpha, 20
chmod, 115                               beta, 21
chsh, 146                                conventions, 21
client                               device driver, 101
   news                              devices
    defined, 200                         /dev/console, 101
Coherent, 27                             /dev/cua, 101
command                                  /dev/hd, 101
   argument                              /dev/lp, 101
    defined, 88                          /dev/null, 101
   defined, 88                           /dev/pty, 102
command not found error message,         /dev/sd, 101
      88                                 /dev/sr, 101
commands                                 /dev/st, 101
   - to begin options, 98                /dev/tty, 102
INDEX                                                              237
_______________________________________________________________________

   /dev/ttyS, 101                        nesting, 90
   accessing, 101                        parent, 90
   console, 101                           ..  to refer to, 93
   fd, 101                               permisions
   floppy disk, 101                       execute, 113
   hard drives, 101                       read, 113
   null, 101                              write, 113
   parallel ports, 101                   permissions
   pseudo-terminals, 102                  changing, 115
   SCSI, 101                              dependencies of, 114
   serial ports, 101                     root
   virtual consoles, 102                  defined, 90
dip, 194                                 structure, 90
   chat script for, 197--199              moving  around  in with  cd,
   connecting  to  SLIP   server            92
      with, 197--199                     tree, 90
   dynamic IP address with, 196          working
   static IP address with, 195            defined, 90
directory                            disabling users, 146
   .  to refer to, 93                disasters
   /etc, 102                             recovery from, 162--164
   /home, 102                             with   maintenance   floppy,
   /lib, 102                                162
   /proc, 102                        distributions, 21, 40--50
   /sbin, 102                            Internet, getting  from  the,
   /tmp, 102                                41
   /usr, 102                             list, 211--213
   /usr/X386, 103                        mail order, 42
   /usr/bin, 103                         online sources, 42
   /usr/etc, 103                     documentation, 203--210
   /urs/g++-include, 103                 books, 33, 206--210
   /usr/include, 103                     Frequently  Asked  Questions,
   /usr/lib, 103                            203
   /usr/local, 104                       HOWTO documents, 204
   /usr/man, 104                         info files, 9
   /usr/src, 104                         Linux Documentation  Project,
   /var, 104                                33, 205--206
   /var/adm, 104                         Linux Software Map, 17
   /var spool, 104                       online, 32, 203--205
   /bin, 100                              FAQ, 33
   creating, 95                           HOWTO documents, 33
   current working                       texinfo, 9
    defined, 90                      Doom, 17
   defined, 89
   delete, 97                        e-mail, 200
   /dev, 101                             mailer
   home                                   defined, 200
    ~ to refer to, 92                    transport
    defined, 90                           defined, 200
   listing contents of, 93--95       e2fsck, 158, 163
INDEX                                                              238
_______________________________________________________________________

echo, 100                                backing up, 151
editor                                   compressing, 147--150
   defined, 123                          defined, 89
editors, 7                               device, 101
efsck, 159                               hidden
elm, 200                                  not  matched  by  wildcards,
Emacs, 7, 123                               107
emergencies                              inode numbers of, 115
   recovery from, 162--164               links, 115--117
    with   maintenance   floppy,         listing, 93--95
      162                                listing permissions  of  with
end-of-text signal, 109                     ls, 113
environment                              MS-DOS, 184
   customizing, 130--135                 owership of by group, 112
   variables                             owership of by user, 112
    PATH, 134                            permisions
EOT (end of text) signal, 109             execute, 113
error messages                            read, 113
   error messages                         write, 113
    command not found, 88                permissions
ethernet, 14                              changing, 115
   supported cards, 186                   defined, 112
executable                                dependencies of, 114
   defined, 94                            group, 147
executables, 6                            interpreting, 113
exit, 89                                 permissions of, 112--115
export, 133                              recovering, 164
                                         viewing contents of, 97
FAQ, 33                              filesystem
fdisk, 55, 60--63                        exploring, 100--104
   under MS-DOS, 55                  filesystems, 5, 52, 53, 156--159
features                                 /etc/fstab, 157
   kernel, 5--6                          checking, 158
   system, 5--6                          creating, 64--65
fg, 122                                  fixing corrupted, 163
FidoNet, 15                              mounting, 156--158
file                                     on floppy disk, 151
   copy, 96                              root, 52
   delete, 96                            unmounting, 158
   executable                             unmounting with  shutdown or
    defined, 94                             halt, 158
   move, 96                          filter
filename                                 defined, 110
   defined, 89                       find
filenames                                for incremental backups, 151
   wildcard characters in, 106--     FIPS, 54
      108                            floating-point math, 5
files                                floppy disk
   appeding to, 112                      boot/root, 162
   archiving, 147--150                   device names for, 101
INDEX                                                              239
_______________________________________________________________________

   maintenance, 162                      device names for, 101
   unmounting, 152                   hardware
floppy disks                             problems, 74--79
   as backup medium, 151                  conflicts, 75--76
   file systems on, 151                   hard drive, 76--78
forground process, 118                    SCSI, 78--79
free software, 18                    hardware support, 27--32
Free  Software  Foundation,  18,         CD-ROM, 31
      227                                controller, 29
Frequently Asked Questions, 203          CPU, 28
fsck, 159, 163                           drive space, 29
FTP                                      ethernet cards, 31, 186
   anonymous, 41                         hard drive, 29
   archive site list, 220                memory, 28
   using, 214--220                       mice, 30
ftpmail, 220                             modems, 31
fullname                                 monitor, 30
   setting with chfn, 146                motherboard, 28
functionality, 22                        printers, 31
                                         SCSI, 29, 31
games, 17                                tape drives, 31
   Doom, 17                              video card, 30, 166
gateway address                      help
   defined, 188                          getting, 37--39
gcc                                      online, 97
   upgrading, 155                    home directory
gdb, 11                                  ~ to refer to, 92
General Public License,  18--19,         defined, 90, 145
      227--234                       hostname
getting help, 32                         hostname, 161
getty, 160                               defined, 86
GNU, 7                                   setting, 161, 193
   General Public License,  18--     hostname, 193
      19, 227--234                   HOWTO documents, 33, 204
gprof, 11                            HURD, 27
grep, 100
groff, 8                             ifconfig, 190
group ID                             inetd, 191
   defined, 144                      Ingres, 17
groupadd, 147                        init, 160
groups, 112, 147                     initialization files
   adding, 147                           for shells, 135
   deleting, 147                     initialization scripts
groups, 147                              for shells, 135
gzip, 149                            inittab, 160
                                     INN, 200
hacker, 20                           inode number
halt, 144                                defined, 115
hard drive                           input
   problems, 77                          redirecting, 110
hard drives
INDEX                                                              240
_______________________________________________________________________

installation, 40--84                 LaTeX, 8
   boot floppy, 69--70               libraries, 11
   booting Linux, 56                     fixing corrupted, 164
   LILO, 69--70                          shared, 6
   mke2fs, 64--65                        upgrading, 154
   mkswap, 63--64                    LILO, 69--70, 142--143
   other procedures, 70                  as boot loader, 142
   overview, 50--51                      installing, 142
   preparation, 50--56                   problems booting, 72
   problems, 71--84                      problems installing, 83
    booting, 72--74, 81, 82              selecting  default  operating
    errors, 79                              system for, 143
    file permissions, 84             links, 115--117
    hardware, 74--79                     display number of, 116
    LILO, 83                             hard, 115
    logging in, 83                       symbolic, 117
    media errors, 79                 Linux, 1--234
    postinstallation, 81--84             and cost, 26
   repartitioning, 52, 54--56            bugs, 20
Internet, 14, 41                         commercial support, 37
   mailing lists, 36                     copying, 26
IP address                               copyright, 18--19, 227--234
   defined, 187                          development, 20
IRQ, 75                                  distributions, 21

job                                      getting,h41istory, 3
   background, 118, 120, 122             installing, 40--84
    kill, 120                            philosophy, 19--23
   defined, 118                          pronunciation, 1
   forground, 118                        sources of information, 32
   interupt, 119                         stability, 26
   inturpting, 119                       system features, 5--6
   kill, 119                         Linux  Documentation Project, 33,
   restarting, 122                          205--206
   stopping, 121                     Linux Journal, 206
   suspended, 119                    Linux Software Map, 17, 204
job control, 5, 117--123             Linux-Activists mailing list, 36
jobs, 120                            listing  directory contents, 93--
                                         95
kernel                               logging in, 86
   compiling, 154                        problems, 83
   compiling  compressed  image,     logging out
      154                                with exit command, 89
   features, 5--6                    login, 86
   sources for, 153                  login name
   upgrading, 153                        defined, 86
kernel image                         login shell
   compressed, 141                       defined, 135, 145
   file name of, 141                     setting with chsh, 146
kill, 120                            ls, 93--95, 98
INDEX                                                              241
_______________________________________________________________________

   listing   file    permissions     nameserver address
      with, 113                          defined, 188
                                     NET-2, 185
mail order, 42                           support for  serial line  In-
mailer                                      ternet  protocol   (SLIP),
   for e-mail, 200                          185
mailers, 14                          NetBSD, 26
mailing lists, 36                    netstat, 194
   Linux-Activists, 36               network address
mailx, 200                               defined, 188
maintenance floppy, 162              network mask
man, 97, 99                              defined, 187
manual pages, 97                     networking, 5, 14--15
master boot record, 52                   and X Windows, 14
Mbase, 17                                ethernet  cards,   supported,
METAFONT, 11                                31, 186
Microsoft Windows, 16                    FTP, 14
   emulator, 185                         NET-2, 185
Minix, 3, 27                             news, 14, 200--202
mkdir, 95, 99                            NFS, 14, 191
mke2fs, 64--65                           NNTP, 14
   for floppy disk, 151                  PPP, 195
mkswap, 63--64, 159                      SLIP, 14, 185
money, 26                                TCP/IP, 185--199
more, 97, 99                             UUCP, 14, 199--200
Motif, 13                            news, 200--202
mount, 157                               client
   mounting  floppy  disk  with,          defined, 200
      151                                news readers
   to  mount  MS-DOS  partition,          defined, 200
      184                                 rn, 200
mount point                               rn, 200
   defined, 152                          server
move files, 96                            C News, 200
MS-DOS, 24--25                            defined, 200
   accessing files from, 16, 184          INN, 200
   emulator, 16, 184                     UUCP, 199
   mounting partion under Linux,     news readers, 14
      184                                defined, 200
   repartitioning, 55                NFS, 191
   running programs from  Linux,     null file, 101
      184
   using Mtools to access files,     operating sytems
      184                                booting non-Linux, 142, 143
multitasking, 5                      OS/2, 25
   defined, 86                       output
multiuser                                redirecting, 109
   defined, 86
mv, 96, 99                           parallel port
                                         device name for, 101
named, 192                           parent directory, 90
INDEX                                                              242
_______________________________________________________________________

   ..  to refer to, 93                   core dumps, 6
partition table, 52                      languages, 11
partitions, 52, 53                       libraries, 11
   fdisk, 55, 60--63                     UNIX, 12
   Linux, 58--60                         utilities, 11
   size, 54                          protected mode, 6
passwd, 89, 146                      ps, 118
password                             pseudo-terminals, 102
   changing with passwd, 89
   defined, 86                       RAWRITE.EXE, 41
   fixing root, 163                  rc, 160
password file                            files
   format of, 145                         defined, 189
pathname                                  for TCP/IP, 189
   absolute, 92                      rc.inet, 189
   defined, 89                       rc.inet1, 189
   full, 92                              sample, 190
   relative, 91                      rc.inet2, 189, 191
permissions                              sample, 191
   changing, 115                     rc.local, 160
   defined, 112                      rc.net, 189
   dependencies of, 114              rdev, 141
   execute, 113                      reading
   for shell scripts, 132                suggested, 206--210
   group, 147                        redirection
   interpreting, 113                     non-destructive, 112
   of files, 112--115                    standard input, 109
   problems, 84                          standard output, 109
   read, 113                         repartitioning, 54--56
   write, 113                            concepts, 52
pipelining                               fdisk, 55
   defined, 111                           under MS-DOS, 55
pipes                                    FIPS, 54
   creating, 111                     rm, 96, 99
   using, 110--112                   rmdir, 97, 99
POSIX.1, 5                           rn, 200
Postgres, 17                         root
PPP, 5, 195                              fixing password for, 163
process                              root account, 137--139
   background, 118                       eithical issues, 139
    kill, 120                            privleges of, 138
   defined, 118                          using different  prompt  for,
   forground, 118                           138
   ID                                root device
    defined, 118                         setting name  of  with  rdev,
   interupt, 119                            141
   interupting, 119                  root directory
   kill, 119                             defined, 90
   ps to list, 118                   root filesystem, 52
programming, 11--12                  route, 190
INDEX                                                              243
_______________________________________________________________________

   entry  in  /etc/networks  re-         device names for, 196
      quired for, 192                    dynamic IP address with  dip,
routed, 191                                 196
                                         static IP  address with  dip,
scientific software, 17                     195
SCSI                                     static IP address with  slat-
   problems, 78--79                         tach, 196
SCSI devices                         Smail, 200
   names for, 101                    software, 6--17
security, 139                            bash, 8
sendmail, 200                            installing, 152--156
serial line  Internet  protocol,         tcsh, 8
      185, 194--199                      upgrading, 152--156
serial ports                             where to find releases, 156
   device names for, 101             sound support, 17
setenv, 133                          sources of information, 203--210
Seyon, 15                            stability, 26
shareware, 18                        standard input, 108--112
shell script, 7                          redirecting, 110
   defined, 131                      standard output, 108--112
shell scripts                            redirecting, 109
   comments in, 132                  standards, 5
   defined, 105                      startup scripts, 160
   initializtion, 135                slattach
   permissions for, 132                  static IP addresses with, 196
   variables in, 132                 stdin, 108
shell variables                      stdout, 108
   exporting to environment, 133     superblock
shells, 7, 105                           defined, 163
   Bourne again shell, 105               fixing corrupted, 163
   Bourne shell, 105                 swap file, 53, 159--160
   C shell, 105                          deleting, 160
   defined, 87                       swap partition
   initializtion files, 135              in /etc/fstab, 157
   job control provided by, 117      swap space, 6, 53
   prompt, 88                            creating, 63--64
   variables                             creating temporary, 160
    defined, 132                     swapoff, 160
   wildcard characters for, 106-     swapon, 157, 159
      -108                           syslogd, 191
   wildcard expansion, 106           system administration
shutdown command, 71, 143                adding users, 144
shutting down, 143--144                  booting Linux, 141--143
Slackware                                duties, 140
   getting, 43--50                       security issues, 139
   installing, 66--69                    shutting down, 143--144
slattach, 194                        system security, 139
SLIP, 5, 14, 185, 194--199           system-defined accounts
   connecting  to  servier  with         root, 137
      dip, 197                       Tanenbaum, Andy, 3
INDEX                                                              244
_______________________________________________________________________

tar, 148                             TeX, 8
TCP/IP, 5, 14--15, 185--199          texinfo, 9
   /etc/host.conf, 193               text editor
   /etc/hosts, 192                       comparing, 123
   /etc/networks, 192                    defined, 123
   /etc/resolve.conf, 193            text editors, 7
   broadcast address, 188            text processing, 8--11
   configuration  scripts   for,     tin, 200
      189                            Torvalds, Linus, 3, 20
   configuring, 186, 187             transport
   debugging, 193                        for e-mail, 200
   displaying  routing   tables,     trouble
      194                                running into, 71--84
   gateway address, 188
   hardware  requirements   for,     UID
      186                                defined, 144
   ifconfig, 190                     umount, 158
   inetd, 191                            unmounting floppy disks with,
   IP address, 187                          152
   named, 192                        UNIX
   nameserver address, 188               basic concepts, 86--92
   NET-2 implementation of, 185          commercial, 19, 22, 25--27
   network address, 188                  directory structure, 90
   network mask, 187                     for the PC, 25--27
   over serial line, 194--199            free implementations, 26
   point-to-point    connection,         manual pages for, 97
      195                                multitasking
   PPP, 195                               defined, 86
   rc.inet, 189                          popularity, 3
   rc.inet1, 189                         wizards, 1
    sample, 190                      unmounting filesystems, 158
   rc.inet2, 189                     upgrading, 23
    sample, 191                      USENET, 200--202
   rc.net, 189                           Linux-related newsgroups, 34
   route, 190                            posting tips, 38
   routed, 191                       user account
   SLIP, 194--199                        creating, 86
    device names for, 196            user ID
    dynamic   IP  address   with         defined, 144
      dip, 196                       useradd, 146
    static IP  address with dip,     userdel, 146
      195                            username
    static   IP   address   with         defined, 144
      slattach, 196                  users
   syslogd, 191                          adding, 144
   troubleshooting, 193                   adding with adduser, 146
Tcsh, 105                                 adding with useradd, 146
tcsh, 105                                changing fullname for, 146
telecommunications, 15                   changing login shell for, 146
term, 15                                 deleting, 146
INDEX                                                              245
_______________________________________________________________________

   disabling, 146                        defined, 90
   full name of, 145
   group ID of, 144                  X11R6, 165
   home directory of, 145            XF86Config, 171
   in groups, 112                    XFree86, 12, 165
   list groups for, 147                  configuration file for, 171
   login shell of, 145                   configuring, 170
   password of, 145                      hardware  requirements   for,
   setting attributes for, 146              166
   setting guidelines for, 140           installing, 168
   setting password for, 146             RAM requirements for, 168
   system security and, 139              video chipsets supported  by,
   user ID of, 144                          166
   username of, 144                  xfsck, 159
UUCP, 14, 199--200                   X Window System, 12--13, 165--184
                                         defined, 165
variables
   environment, 133
   in shell scripts, 132
   shell, 132
vendor
   list, 211--213
vi, 7, 123--130
   changing text, 127--128
   command mode, 124
   deleting text, 126--127
   edit mode, 124
   including files, 129
   inserting text, 125--126
   last line mode, 124
   moving cursor, 128
   quitting, 128
   saving changes, 128
   shell commands from, 130
   starting, 124
   switching files, 129
   writing changes, 128
virtual consoles, 5, 102
Volkerding, Patrick, 43

wildcard characters
   *, 106
   ?, 107
   defined, 106
   in filnames, 106--108
wildcard expansion
   defined, 106
Windows NT, 25
WINE, 16
word processing, 10
working directory