Il CD di internet/CD.iso/HOWTO/INFO-SHE

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  Linux Information Sheet
  Michael K. Johnson, [e-mail]
  Version 4.0, November 12, 1994

  This document provides basic information about the Linux operating
  system, including an explanation of Linux, a list of features, some
  requirements, and some resources.

  1.  Introduction to Linux

  Linux is a completely free reimplementation of the POSIX spec, with
  SYSV and BSD extensions (which means it looks like Unix, but does not
  come from the same source code base), which is available in both
  source code and binary form.  It is copyrighted by Linus B. Torvalds
  ([e-mail]) and other contributors, and is freely
  redistributable under the terms of the GNU Public License.

  Linux is not public domain, nor is it `shareware'.  It is `free'
  software, commonly called freeware, and you may give copies away, but
  you must also give the source with it or make it available in the same
  way.  If you redistribute any modifications, you are legally bound to
  distribute the source for those modifications.  See the GNU Public
  License for details.  A copy is included with the Linux source, or you
  can get a copy via ftp from prep.ai.mit.edu in /pub/gnu/COPYING

  Linux is still free as of version 1.0, and will continue to be.
  Because of the nature of the GNU copyright which Linux is subject to,
  it would be illegal for it to be made not free.  Note carefully: it is
  perfectly legal to charge money for distributing Linux, so long as you
  also distribute the source code.  This is a generalization; if you
  want the fine points, read the GPL.

  Linux runs only on 386/486/Pentium machines with an ISA or EISA bus.
  MCA (IBM's proprietary bus) is not currently supported because there
  is little available documentation, although some patches are available
  for a few machines.  VLB and PCI local busses are both supported, and
  the driver for the NCR SCSI chip that is used in many PCI machines is
  included in the latest development versions, and will be in Linux 1.2

  There is a port in progress for multiple Motorola 680x0 platforms
  (currently running on some Amigas and Ataris), which now works quite
  well.  It requires a 68020 with an MMU, a 68030, or a 68040, and also
  requires an FPU.

  Ports to other machines, including ALPHA, MIPS, PowerPC, and PowerMAC,
  are under way and showing various amounts of progress.  Don't hold
  your breath, but if you are interested and able to contribute, you may
  well find other developers who wish to work with you.

  Linux is no longer considered to be in beta testing, as version 1.0
  was released on March 14, 1994.  There are still bugs in the system,
  and new bugs will creep up and be fixed as time goes on.  Because
  Linux follows the ``open development model'', all new versions will be
  released to the public, whether or not they are considered
  ``production quality''.  However, in order to help people tell whether
  they are getting a stable version or not, the following scheme has
  been implemented:  Versions 1.x.y, where x is an even number, are
  stable versions, and only bug fixes will be applied as y is
  incremented.  So from version 1.0.2 to 1.0.3, there were only bug
  fixes, and no new features.  Versions 1.x.y, where x is an odd number,
  are beta-quality releases for developers only, and may be unstable and
  may crash, and are having new features added to them all the time.

  >From time to time, as the currect development kernel stabilizes, it
  will be frozen as the new ``stable'' kernel, and developement will
  continue on a new development version of the kernel.
  Most versions of Linux, beta or not, are quite stable, and you can
  keep using those if they do what you need and you don't want to be on
  the bleeding edge.  One site had a computer running version 0.97
  patchlevel 1 (dating from the summer of 1992) for over 136 days
  without an error or crash.  (It would have been longer if the backhoe
  operator hadn't mistaken a main power transformer for a dumpsterots)

  One thing to be aware of is that Linux is developed using an open and
  distributed model, instead of a closed and centralized model like much
  other software.  This means that the current development version is
  always public (with up to a week or two's delay) so that anybody can
  use it.  The result is that whenever a version with new functionality
  is released, it almost always contains bugs, but it also results in a
  very rapid development so that the bugs are found and corrected
  quickly, often in hours, as many people work to fix them.

  In contrast, the closed and centralized model means that there is only
  one person or team working on the project, and they only release
  software that they think is working well.  Often this leads to long
  intervals between releases, long waiting for bug fixes, and slower
  development.  Of course, the latest release of such software to the
  public is often of higher quality, but the development speed is
  generally much slower.

  As of November 12, 1994, the current stable version of Linux is 1.0.9,
  and the development version was 1.1.62 the last time I heard.  Linux
  1.2.0 is nearing release; 1.1.62 is part of a code freeze series of
  releases intended to shake out bugs.


  2.  Linux Features


  o  multitasking: several programs running at once.

  o  multiuser: several users on the same machine at once (and NO two-
     user licenses!).

  o  runs in 386 protected mode.

  o  has memory protection between processes, so that one program can't
     bring the whole system down.

  o  demand loads executables: Linux only reads from disk those parts of
     a program that are actually used.

  o  shared copy-on-write pages among executables.  This means that
     multiple process can use the same memory to run in.  When one tries
     to write to that memory, that page (4KB piece of memory) is copied
     somewhere else.  Copy-on-write has two benefits: increasing speed
     and decreasing memory use.

  o  virtual memory using paging (not swapping whole processes) to disk:
     to a separate partition or a file in the filesystem, or both, with
     the possibility of adding more swapping areas during runtime (yes,
     they're still called swapping areas).  A total of 16 of these 128
     MB swapping areas can be used at once, for a theoretical total of 2
     GB of useable swap space.

  o  a unified memory pool for user programs and disk cache, so that all
     free memory can be used for caching, and the cache can be reduced
     when running large programs.

  o  dynamically linked shared libraries (DLL's), and static libraries
     too, of course.

  o  does core dumps for post-mortem analysis, allowing the use of a
     debugger on a program not only while it is running but also after
     it has crashed.

  o  mostly compatible with POSIX, System V, and BSD at the source
     level.

  o  through iBCS2-compliant emulation, mostly compatible with SCO,
     SVR3, and SVR4 at the binary level.

  o  all source code is available, including the whole kernel and all
     drivers, the development tools and all user programs; also, all of
     it is freely distributable.  There are some commercial programs
     being provided for Linux now without source, but everything that
     has been free is still free.

  o  POSIX job control.

  o  pseudoterminals (pty's).

  o  387-emulation in the kernel so that programs don't need to do their
     own math emulation.  Every computer running Linux appears to have a
     math coprocessor.  Of course, if your computer already contains an
     FPU, it will be used instead of the emulation, and you can even
     compile your own kernel with math emulation removed, for a small
     memory gain.

  o  support for many national or customized keyboards, and it is fairly
     easy to add new ones.

  o  multiple virtual consoles: several independent login sessions
     through the console, you switch by pressing a hot-key combination
     (not dependent on video hardware).  These are dynamically
     allocated; you can use up to 64.

  o  Supports several common filesystems, including minix-1, Xenix, and
     all the system V filesystems, and has an advanced filesystem of its
     own, which offers filesystems of up to 4 TB, and names up to 255
     characters long.

  o  transparent access to MS-DOS partitions (or OS/2 FAT partitions)
     via a special filesystem: you don't need any special commands to
     use the MS-DOS partition, it looks just like a normal Unix
     filesystem (except for funny restrictions on filenames,
     permissions, and so on).  MS-DOS 6 compressed partitions do not
     work at this time, and are not expected to.

  o  special filesystem called UMSDOS which allows Linux to be installed
     on a DOS filesystem.

  o  read-only HPFS-2 support for OS/2 2.1

  o  CD-ROM filesystem which reads all standard formats of CD-ROMs.

  o  TCP/IP networking, including ftp, telnet, NFS, etc.



  3.  Hardware Issues

  3.1.  Minimal configuration

  The following is probably the smallest possible configuration that
  Linux will work on: 386SX/16, 2 MB RAM, 1.44 MB or 1.2 MB floppy, any
  supported video card (+ keyboards, monitors, and so on of course).
  This should allow you to boot and test whether it works at all on the
  machine, but you won't be able to do anything useful.

  In order to do something, you will want some hard disk space as well,
  5 to 10 MB should suffice for a very minimal setup (with only the most
  important commands and perhaps one or two small applications
  installed, like, say, a terminal program).  This is still very, very
  limited, and very uncomfortable, as it doesn't leave enough room to do
  just about anything, unless your applications are quite limited.  It's
  generally not recommended for anything but testing if things work, and
  of course to be able to brag about small resource requirements.


  3.2.  Usable configuration

  If you are going to run computationally intensive programs, such as
  gcc, X, and TeX, you will probably want a faster processor than a
  386SX/16, but even that should suffice if you are patient.

  In practice, you need at least 4 MB of RAM if you don't use X, and 8
  MB if you do.  Also, if you want to have several users at a time, or
  run several large programs (compilations for example) at a time, you
  may want more than 4 MB of memory.  It will still work with a smaller
  amount of memory (should work even with 2 MB), but it will use virtual
  memory (using the hard drive as slow memory) and that will be so slow
  as to be unusable.

  The amount of hard disk you need depends on what software you want to
  install.  The normal basic set of Unix utilities, shells, and
  administrative programs should be comfortable in less than 10 MB, with
  a bit of room to spare for user files.  For a more complete system,
  get Slackware, MCC, or (soon) Debian, and assume that you will need 60
  to 200 MB, depending on what you choose to install and what
  distribution you get.  Add whatever space you want to reserve for user
  files to these totals.  With today's prices on hard drives, if you are
  buying a new system, it makes no sense to buy a drive that is too
  small.  Get at least 200 MB, and you will not regret it.

  Add more memory, more hard disk, a faster processor and other stuff
  depending on your needs, wishes and budget to go beyond the merely
  usable.  In general, one big difference from DOS is that with Linux,
  adding memory makes a large difference, whereas with dos, extra memory
  doesn't make that much difference.  This of course has something to do
  with DOS's 640KB limit.


  3.3.  Supported hardware


     CPU:
        Anything that runs 386 protected mode programs (all models of
        386's 486's, and 586's should work; 286s don't work, and never
        will).  Also, a version for the 680x0 CPU (for x = 2 with
        external MMU, 3, and 4) which runs on Amigas and Ataris is being
        developed, and can be found at tsx-11.mit.edu in the 680x
        directory.  Ports are also being done to the PowerPC, Alpha/AXP,
        and MIPS architecture.  More details are available elsewhere.


     Architecture:
        ISA or EISA bus.  MCA (mostly true blue PS/2's) does not work,
        although a few brave souls are doing some work to help remedy
        this for a few machines).  Local busses (VLB and PCI) work.


     RAM:
        Theoretically up to 1 GB.  This has not been tested.  Some
        people (including Linus) have noted that adding ram without
        adding more cache at the same time has slowed down their machine
        extremely, so if you add memory and find your machine slower,
        try adding more cache.  Over 64MB will require a boot-time
        parameter, as the BIOS cannot report more than 64MB, because it
        is ``broken as designed.''


     Data storage:
        Generic AT drives (IDE, 16 bit HD controllers with MFM or RLL,
        or ESDI) are supported, as are SCSI hard disks and CD-ROMs, with
        a supported SCSI adaptor.  Generic XT controllers (8 bit
        controllers with MFM or RLL) are also supported.  Supported SCSI
        adaptors: Adaptec 1542, 1522, and 1740 in extended (not 1542
        compatible) mode, Buslogic controllers via the Adaptek
        compatibility or with their own driver, Seagate ST-01 and ST-02,
        Future Domain TMC-88x series (or any board based on the TMC950
        chip) and TMC1660/1680, Ultrastor 14F, 24F and 34F, and Western
        Digital wd7000.  SCSI and some QIC-02 and QIC-80 tapes are also
        supported.  Several CD-ROM devices are also supported, including
        Matsushita/Panasonic, Mitsumi, Sony, Soundblaster, Toshiba, and
        others.  For exact models, check the hardware compatibility
        HOWTO.


     Video:
        VGA, EGA, CGA, or Hercules (and compatibles) work in text mode.
        For graphics and X, there is support for (at least) normal VGA,
        some super-VGA cards (most of the cards based on ET3000, ET4000,
        Paradise, and some Trident chipsets), S3 (except for Diamond
        Stealth cards, because the manufacturer won't tell how to
        program it), 8514/A, ATI MACH8, ATI MACH32, and hercules.
        (Linux uses the Xfree86 X server, so that determines what cards
        are supported.)


     Networking:
        Western Digital 80x3, ne1000, ne2000, 3com501 (not recommended),
        3com503, 3com507, 3com509, 3com589 PCMCIA, Allied Telliesis
        AT1500, most LANCE boards, d-link pocket adaptors, PPP, SLIP,
        CSLIP, PLIP (Parallel Link IP), and more.


     Other hardware:
        SoundBlaster, ProAudio Spectrum 16, Gravis Ultrasound, AST
        Fourport cards (with 4 serial ports), several models of Boca
        serial boards, the Usenet Serial Card II, several flavours of
        bus mice (Microsoft, Logitech, PS/2).


  4.  An Incomplete List of Ported Programs and Other Software

  Most of the common Unix tools and programs have been ported to Linux,
  including almost all of the GNU stuff and many X clients from various
  sources.  Actually, ported is often too strong a word, since many
  programs compile out of the box without modifications, or only small
  modifications, because Linux tracks POSIX quite closely.
  Unfortunately, there are not very many end-user applications at this
  time.  Nevertheless, here is an incomplete list of software that is
  known to work under Linux.


     Basic Unix commands:
        ls, tr, sed, awk and so on (you name it, Linux probably has it).


     Development tools:
        gcc, gdb, make, bison, flex, perl, rcs, cvs, prof.


     Languages and Environments:
        C, C++, Objective C, Modula-3, Modula-2, ADA, Pascal, Fortran,
        ML, scheme, Tcl/tk, Perl, Python, Common Lisp, and many others.


     Graphical environments:
        X11R5 (XFree86 2.x), X11R6 (XFree86 3.x), MGR.


     Editors:
        GNU Emacs, Lucid Emacs, MicroEmacs, jove, ez, epoch, elvis (GNU
        vi), vim, vile, joe, pico, jed.


     Shells:
        bash (POSIX sh-compatible), zsh (includes ksh compatiblity
        mode), pdksh, tcsh, csh, rc, ash (mostly sh-compatible shell
        used as /bin/sh by BSD), and many more.


     Telecommunication:
        Taylor (BNU-compatible) UUCP, SLIP, CSLIP, PPP, kermit, szrz,
        minicom, pcomm, xcomm, term (runs multiple shells, redirects
        network activity, and allows remote X, all over one modem line),
        Seyon (popular X-windows communications program), and several
        fax and voice-mail (using ZyXEL modems) packages are available.
        Of course, remote serial logins are supported.


     News and mail:
        C-news, innd, trn, nn, tin, smail, elm, mh, pine.


     Textprocessing:
        TeX, groff, doc, ez, and Linuxdoc-SGML.


     Games:
        Nethack, several Muds and X games, and lots of others.  One of
        those games is looking through all the games available at tsx-11
        and sunsite.


     Suites:
        AUIS, the Andrew User Interface System.  ez is part of this
        suite.

  All of these programs (and this isn't even a hundredth of what is
  available) are freely available.


  5.  Who uses Linux?

  Linux is freely available, and no one is required to register their
  copies with any central authority, so it is difficult to know how many
  people use Linux.  Several businesses are now surviving solely on
  selling and supporting Linux, and very few Linux users use those
  businesses, relatively speaking, and the Linux newsgroups are some of
  the most heavily read on the internet, so the number is likely in the
  hundreds of thousands, but hard numbers are hard to come by.  However,
  one brave soul, Harald T. Alvestrand, has decided to try, and asks
  that if you use Linux, you send a message to [e-mail]
  with one of the following subjects: ``I use Linux at home'', ``I use
  Linux at work'', or ``I use Linux at home and at work''.  He is also
  counting votes of ``I don't use Linux'', for some reason.  He posts
  his counts to comp.os.linux.misc.


  6.  Getting Linux

  6.1.  Anonymous FTP

  Matt Welsh has released a new version of his Installation and Getting
  Started guide, version 2.1.1.  Also, the Linux documentation project
  (the LDP) has put out several other books in various states of
  completion, and these are available at
  sunsite.unc.edu:/pub/Linux/docs/LDP.  Stay tuned to
  comp.os.linux.announce.

  At least the following anonymous ftp sites carry Linux.



       Textual name                   Numeric address  Linux directory
       =============================  ===============  ===============
       tsx-11.mit.edu                 18.172.1.2       /pub/linux
       sunsite.unc.edu                152.2.22.81      /pub/Linux
       ftp.funet.fi                   128.214.248.6    /pub/OS/Linux
       net.tamu.edu                   128.194.177.1    /pub/linux
       ftp.mcc.ac.uk                  130.88.203.12    /pub/linux
       src.doc.ic.ac.uk               146.169.2.1      /packages/linux
       fgb1.fgb.mw.tu-muenchen.de     129.187.200.1    /pub/linux
       ftp.informatik.tu-muenchen.de  131.159.0.110    /pub/comp/os/linux
       ftp.dfv.rwth-aachen.de         137.226.4.111    /pub/linux
       ftp.informatik.rwth-aachen.de  137.226.225.3    /pub/Linux
       ftp.Germany.EU.net             192.76.144.75    /pub/os/Linux
       ftp.ibp.fr                     132.227.60.2     /pub/linux
       kirk.bond.edu.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    mirrors/linux
       ftp.win.tue.nl                 131.155.70.100   /pub/linux
       ftp.stack.urc.tue.nl           131.155.2.71     /pub/linux
       srawgw.sra.co.jp               133.137.4.3      /pub/os/linux
       cair.kaist.ac.kr                                /pub/Linux
       ftp.denet.dk                   129.142.6.74     /pub/OS/linux
       NCTUCCCA.edu.tw                140.111.1.10     /Operating-Systems/Linux
       nic.switch.ch                  130.59.1.40      /mirror/linux
       monu1.monash.edu.au            130.194.1.101    /pub/linux
       cnuce_arch.cnr.it              131.114.1.10     /pub/Linux





  tsx-11.mit.edu and fgb1.fgb.mw.tu-muenchen.de are the official sites
  for Linux' GCC.  Some sites mirror other sites.  Please use the site
  closest (network-wise) to you whenever possible.

  At least sunsite.unc.edu and ftp.informatik.tu-muenchen.de offer
  ftpmail services.  Mail [e-mail] or [e-mail]-
  muenchen.de for help.

  If you are lost, try looking at
  sunsite.unc.edu:/pub/Linux/distributions/, where several distributions
  are offered.  Slackware is well-tested, being one of the most popular
  Linux distributions.


  6.2.  Other methods of obtaining Linux

  There are many BBS's that have Linux files.  A list of them is
  occasionally posted to comp.os.linux.announce.  Ask friends and user
  groups, or order one of the commmercial distributions.  A list of
  these is contained in the Linux distribution HOWTO, available as
  sunsite.unc.edu:/pub/Linux/docs/HOWTO/distribution-HOWTO, and posted
  regularily to the comp.os.linux.announce newsgroup.



  7.  Getting started

  As mentioned at the beginning, Linux is not centrally administered.
  Because of this, there is no ``official'' release that one could point
  at, and say ``That's Linux.''  Instead, there are various
  ``distributions,'' which are more or less complete collections of
  software configured and packaged so that they can be used to install a
  Linux system.

  The first thing you should do is to get and read the list of
  Frequently Asked Questions (FAQ) from one of the FTP sites, or by
  using the normal Usenet FAQ archives (e.g. rtfm.mit.edu).  This
  document has plenty of instructions on what to do to get started, what
  files you need, and how to solve most of the common problems (during
  installation or otherwise).


  8.  Legal Status of Linux

  Although Linux is supplied with the complete source code, it is
  copyrighted software, not public domain.  However, it is available for
  free under the GNU Public License.  See the GPL for more information.
  The programs that run under Linux each have their own copyright,
  although many of them use the GPL as well.  X uses the MIT X
  copyright, and some utilities are under the BSD copyright.  In any
  case, all of the software on the FTP site is freely distributable (or
  else it shouldn't be there).


  9.  News About Linux

  A new magazine called Linux Journal was recently launched.  It
  includes articles intended for almost all skill levels, and is
  intended to be helpful to all Linux users.  Subscriptions are $19 in
  the U.S., $24 in Canada and Mexico, and $29 elsewhere, payable in US
  currency.  Subscription inquiries can be sent via email to
  [e-mail] or faxed to (U.S.) 1-206-527-2806 or mailed to Linux
  Journal, PO Box 85867, Seattle, WA 98145-1867 USA.  Please do not send
  credit card numbers via email; the internet is not secure, and it is
  entirely possible that a technologically adept thief may steal your
  credit card number and cost you a large sum of money if you do.

  There are several Usenet newsgroups for Linux discussion, and also
  several mailing lists.  See the Linux FAQ for more information about
  the mailing lists (you should be able to find the FAQ either in the
  newsgroup or on the FTP sites).

  The newsgroup comp.os.linux.announce is a moderated newsgroup for
  announcements about Linux (new programs, bug fixes, etc).

  The newsgroup comp.os.linux.admin is an unmoderated newsgroup for
  discussion of administration of Linux systems.

  The newsgroup comp.os.linux.development is an unmoderated newsgroup
  specifically for discussion of Linux kernel development.  The only
  application development questions that should be discussed here are
  those that are intimately associated with the kernel.  All other
  development questions are probably generic Unix development questions
  and should be directed to a comp.unix group instead.

  The newsgroup comp.os.linux.help is an unmoderated newsgroup for any
  Linux questions that don't belong anywhere else.

  The newsgroup comp.os.linux.misc is the replacement for comp.os.linux,
  and is meant for any discussion that doesn't belong elsewhere.

  In general, do not crosspost between the Linux newsgroups.  The only
  crossposting that is appropriate is an occasional posting between one
  unmoderated group and comp.os.linux.announce.  The whole point of
  splitting comp.os.linux into many groups is to reduce traffic in each.
  Those that do not follow this rule will be flamed without mercy...

  For the current status of the Linux kernel and a summary of the most
  recent versions, finger [e-mail]

  Linux is on the Web (WWW, W3, whatever...)  The URL is
  http://sunsite.unc.edu/mdw/linux.html


  10.  The Future

  Now that Linux 1.0 has been released, work is already in progress on
  several enhancements.  Disk access speedups, TTY improvements, and
  many more things are being worked on.  Linux 1.0 is not the end of
  Linux, nor is it even very important; it is mostly intended to provide
  a stable version that people can use without being afraid that they
  are using beta software, and that can be standardized on to some
  extent.

  Linux 1.2 is nearing release.  It should be very similar to 1.1.62,
  which is a code freeze release intended to shake out bugs remaining in
  the 1.1 series.  For those interested in what will happen with the new
  development series, 1.3, Linus has promised quotas and the PC speaker
  sound driver.  Significant networking improvements will also debut in
  1.3.  Stay tuned!

  There is plenty of code left to write, and even more documentation.
  Please join the DOC channel of the mailing list if you would like to
  contribute to the documentation.


  11.  This document

  This document is maintained by Michael K. Johnson,
  [e-mail]. Please mail me with any comments, no matter
  how small.  I can't do a good job of maintaining this document without
  your help.  A more-or-less current copy of this document can always be
  found as tsx-11.mit.edu:/pub/linux/docs/INFO-SHEET, and a PostScript
  version can be found as INFO-SHEET.ps, in the same directory.


  12.  Legalese

  Trademarks are owned by their owners.  There is no warranty about the
  information in this document.  Use and distribute at your own risk.
  The content of this document is in the public domain, but please be
  polite and attribute any quotes.