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\comment This is the source for the new Linux FAQ list, in
\comment the Bizarre Format With No Name.  It is turned into Lout
\comment input, plain ASCII and an Info document by a Perl script
\comment
\set brieftitle Linux FAQ
\set author     <A href="http://www.cl.cam.ac.uk/users/iwj10/">Ian Jackson</A> / <A href="http://www.cl.cam.ac.uk/users/iwj10/contact.html">[e-mail]</A>
\set authormail [e-mail]
\set title      Linux Frequently Asked Questions with Answers
\set copyholder Ian Jackson
\set copyrightref faqcopyright
\call-lout startup
\call-html startup html.refs
\copyto ASCII
            LINUX FREQUENTLY ASKED QUESTIONS WITH ANSWERS
                            `date '+%d %b %Y'`
                Ian Jackson <[e-mail]>

\endcopy
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#!/bin/sh
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cat <<'END-OF-HEADER' >linux-faq.post-part1
From: [e-mail] (Ian Jackson)
Newsgroups: comp.os.linux.answers,comp.os.linux.setup,comp.os.linux.development.apps,comp.os.linux.misc,comp.os.linux.announce,comp.os.linux.help,comp.answers,news.answers
Subject: Linux Frequently Asked Questions with Answers (FAQ: 1/2)
Keywords: FAQ, Linux, part1
Summary: Please read the whole FAQ before posting to comp.os.linux.help.
Followup-To: poster
Approved: *.answers moderation team <[e-mail]>,
          Matt Welsh <[e-mail]>
`./expirydate`

Archive-Name: linux/faq/part1
Last-Modified: `date '+%d %b %Y'`

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* Linux FAQ: (linux-faq). Linux Frequently Asked Questions with Answers.
END-INFO-DIR-ENTRY


File: $prefix.info, Node: Top, Next: Question 1.1, Up: (dir)

            LINUX FREQUENTLY ASKED QUESTIONS WITH ANSWERS
                            `date '+%d %b %Y'`
                Ian Jackson <[e-mail]>

\endcopy

This is the list of Frequently Asked Questions about Linux, the free
Unix for 386/486/586 [see \qref whatislinux for more details].  It
should be read in conjunction with the HOWTO documents, which are
available in
\call startlist
\call item
\ftpon ftp.funet.fi (128.214.6.100) : \ftpin /pub/OS/Linux/doc/HOWTO
\call item
\ftpon tsx-11.mit.edu (18.172.1.2) : \ftpin /pub/linux/docs/HOWTO
\call item
\ftpon sunsite.unc.edu (152.2.22.81) : \ftpin /pub/Linux/docs/HOWTO
\call endlist
and mirror sites thereof -- see \qref ftpsites.  See \qref howtos for
a list of the HOWTOs and more information.  The \docref INFO-SHEET and
\docref META-FAQ, found in the same place, also list other sources
of Linux information.

The \docref{Linux Documentation Project\} documentation is available
on \ftpon sunsite.unc.edu in \ftpin /pub/Linux/docs/LDP.  These
documents (more are in preparation) are invaluable to the newcomer or
for use as a reference work.

Please check out these documents and this FAQ, especially \qref
notanswered, before posting your question to a newsgroup.

See \qref formats for details of where to get the PostScript, Emacs
Info, HTML (WWW) and plain ASCII versions of this document.

\only post
You can skip to a particular question by searching for `Question n.n'.

Note that this posting has been split into two parts because of its
size.
\endonly

A new version of this document appears approximately monthly.
If this copy is more than a month old it may be out of date.

\section  Index

\index

\comment ######################################################################

\section  Introduction and General Information

\question 18sep:whatislinux  What is Linux ?

Linux is a Unix clone written from scratch by Linus Torvalds with
assistance from a loosely-knit team of hackers across the Net.  It
aims towards POSIX compliance.

It has all the features you would expect in a modern fully-fledged
Unix, including true multitasking, virtual memory, shared libraries,
demand loading, shared copy-on-write executables, proper memory
management and TCP/IP networking.

It runs mainly on 386/486/586-based PCs, using the hardware facilities
of the 386 processor family (TSS segments et al) to implement these
features.  Ports to other architectures are underway [\qref cpu].

See the Linux \docref INFO-SHEET [\qref howtos] for more details.

The Linux kernel is distributed under the GNU General Public License -
see \qref copyright for more details.


\question 09sep:supportedsoftware  What software does it support ?

Linux has GCC, Emacs, X-Windows, all the standard Unix utilities,
TCP/IP (including SLIP and PPP) and all the hundreds of programs that
people have compiled or ported for it.

There is a DOS emulator (look on \ftpon tsx-11.mit.edu in \ftpin
/pub/linux/ALPHA/dosemu) which can run DOS itself and some (but not
all) DOS applications.  I'm told that it can now run Windows 3.1 in
Enhanced Mode.

An iBCS2 (Intel Binary Compatibility Standard) emulator for SVR4 ELF
and SVR3.2 COFF binaries is at a fairly advanced stage of development.
See the file \ftpsilent{tsx-11.mit.edu\}\ftpin
/pub/linux/BETA/ibcs2/README on \ftpon tsx-11.mit.edu.

Work is progressing on an emulator for Microsoft Windows binaries
[\qref wine]; alternatively, I'm told that the DOS emulator team have
been having some success getting MS Windows to run inside dosemu -
there will be an announcement if and when they get it working.

For more information see the \docref INFO-SHEET, which is one of the
the HOWTOs [\qref howtos].  See also \qref compiling.

Some companies have commercial software available, including Motif.
They announce their availability in \newsgroup comp.os.linux.announce
--- try searching the archives [\qref newsarchives].


\question 09sep  Does it run on my computer ?  What hardware is supported ?

You need a 386, 486 or 586, with at least 2Mb of RAM and a single
floppy, to try it out.  To do anything useful more RAM (4Mb to install
most distributions, and 8Mb is highly recommended for running X) and a
hard disk are required.

VESA local bus and PCI are both supported.

There are problems with machines using MCA (IBM's proprietary bus),
mainly to do with the hard disk controller.  There is a developers'
release for PS/2 ESDI drives on \ftpon invaders.dcrl.nd.edu in \ftpin
/pub/misc/linux.  Certain kinds of SCSI controllers also work, I
understand.  Work is in progress to create a suitable version of the
Slackware distribution.  I'm afraid I don't have any further details;
you could try asking Arindam Banerji \email [e-mail].

Linux runs on 386 family based laptops, with X on most of them.  There
is a relevant Web page at
\docref{\fn http://www.cs.utexas.edu/users/kharker/linux-laptop/\}.

For details of exactly which PC's, video cards, disk controllers, etc.
work see the \docref INFO-SHEET and the \docref{Hardware HOWTO\}
[\qref howtos].

There is a port of Linux to the 8086, known as the Embeddable Linux
Kernel Subset (ELKS).  This is a 16-bit subset of the Linux kernel
which will mainly be used for embedded systems.  See \docref{\fn
http://www.linux.org.uk/Linux8086.html\} for more information.  Linux
will never run fully on an 8086 or '286, because it requires
task-switching and memory management facilities not found on these
processors.

Recent versions of Linux (1.3.35 and later) do support multiprocessor
machines, though this is still rather less stable than one would hope.


\question 07sep:cpu  What ports to other processors are there ?

A project has been underway for a while to port Linux to suitable
68000-series based systems such as Amigas and Ataris.  This has now
reached beta test quality and there is an X server.  There is a
\fn linux-680x0 mailing list [\qref multilist], and a
\docref{Linux/68K FAQ\} at
\courier{http://pfah.informatik.uni-kl.de:8000/pers/jmayer/linux68k-faq\}
and on \fn tsx-11.mit.edu in \fn /pub/linux/680x0/FAQ; further
information is at
\docref{\fn http://www-users.informatik.rwth-aachen.de/~hn/linux68k.html\}.
There is a mailing list for the Atari port - mail \email
[e-mail] with a body containing only
\courier{subscribe atarix\} - and an ftp area on \ftpon
ftp.phil.uni-sb.de in \ftpin /pub/atari/linux.

There used to be a project to port Linux too 68K-based Macintoshes,
but its FTP site disappeared recently and the project appears to be
dead.

There is a port to the PowerPC.  As of the 7th of July it is rather
fragmentary and cannot recompile itself, and only supports Motorola
1603 boards.  Work on Motorola Ultra, PowerStack, RS/6000 and NuBus
machines continues.  If you wish to contribute to the project join the
\fn linux-ppc mailing list [\qref multilist].  There is a FAQ on
\ftpon liber.stanford.edu in \ftpin /pub/linuxppc/linux-ppc-FAQ or on
the WWW at
\docref{\fn http://liber.stanford.edu/linuxppc/linux-ppc-FAQ.html\}.

Apple and the OSF are working on a PowerPC port of Linux based on the
OSF Mach microkernel. See \docref{\fn http://mklinux.apple.com/\}.

There is a port to the 64-bit DEC Alpha/AXP.  See \docref{\fn
http://www.azstarnet.com/~axplinux/\}.  Again, there is a mailing list
at \fn vger.rutgers.edu.

Ralf Baechle is working on a port to the MIPS, initially for the R4600
on Deskstation Tyne machines.  The \docref{Linux/MIPS FAQ\} is
available on the WWW and in the MIPS port area on \ftpon
ftp.waldorf-gmbh.de in \ftpin /pub/linux/mips.  There is also a \fn
MIPS channel on the Linux Activists mailserver and a \fn linux-mips
mailing list [\qref multilist].  Interested people may mail their
questions and offers of assistance to \email [e-mail].

There are currently two ports of Linux to the ARM family of processors
ongoing; one of these is to the ARM3 as fitted to the Acorn A5000, and
includes I/O drivers for the 82710/11 as appropriate, and the other is
to the ARM610 as fitted to the Acorn Risc PC.  The Risc PC port is
currently in its early to middle stages, owing to the need to rewrite
much of the memory handling.  The A5000 port is in restricted beta
testing; a release is likely fairly soon.  For more up to date
information watch the newsgroup \newsgroup comp.sys.acorn.misc, or
look on the WWW at
\docref{\fn http://whirligig.ecs.soton.ac.uk/~rmk92/armlinux.html\};
if you want to volunteer you should contact Martin Ebourne \email
[e-mail].

David Miller is working on a port to the Sparc.  It is at a very early
stage; people who are willing to dedicate lots of time and have access
to Sparc boxes for testing should get in touch with \email
[e-mail].

None of the above ports will be capable of running Linux/386 binaries.

Linux port to the Aleph One 486 card (\italic{not\} the second
processor card for the Risc PC yet, but the original PC-on-a-podule
card) has been completed and appears stable.  Full details on this
version, and updates on general ports in progress, can be found on the
WWW at \docref{\fn http://www.ph.kcl.ac.uk/~amb/linux.html\}.


\question 18sep  How much hard disk space does Linux need ?

10Mb for a very minimal installation, suitable for trying it out and
not much else.

You can squeeze a more complete installation including X Windows into
80Mb.  Installating almost all of Debian 0.93R6 takes around 500Mb,
including some space for user files and spool areas.


\question 09sep:copyright  Is Linux PD ?  Copyrighted ?

The Linux kernel copyright belongs to Linus Torvalds.  He has placed
it under the GNU General Public Licence, which basically means that
you may freely copy, change and distribute it, but that you may not
impose any restrictions on further distribution, and that you must
make the source code available.  This is not the same as Public Domain
(see the \docref{Copyright FAQ\}, available on \fn rtfm.mit.edu in \fn
/pub/usenet/news.answers/law/Copyright-FAQ, for details).

Full details are in the file \fn COPYING in the Linux kernel sources
(probably in \fn /usr/src/linux on your system).

The licences of the utilities and programs which come with the
installations vary; much of the code is from the GNU Project at the
Free Software Foundation, and is also under the GPL.

Note that discussion about the merits or otherwise of the GPL should
be posted to \newsgroup gnu.misc.discuss and not to the \fn
comp.os.linux groups.


\comment #######################################################################

\section  Network sources and resources

\question 18sep:howtos  Where can I get the HOWTOs and other documentation ?

Look in the following places, and on sites that mirror them.
\call startlist
\call item
\ftpon ftp.funet.fi (128.214.6.100) : \ftpin /pub/OS/Linux/doc/HOWTO
\call item
\ftpon tsx-11.mit.edu (18.172.1.2) : \ftpin /pub/linux/docs/HOWTO
\call item
\ftpon sunsite.unc.edu (152.2.22.81) : \ftpin /pub/Linux/docs/HOWTO
\call endlist
For a complete list of Linux FTP sites see \qref ftpsites.

If you don't have access to FTP try using the FTP-by-mail servers at
\fn [e-mail], \fn [e-mail] or \fn
[e-mail].

A complete list of HOWTO's is available in the file \fn HOWTO.INDEX in
the \fn docs/HOWTO directory at the FTP sites, or on the Web at
\docref{\fn http://sunsite.unc.edu/mdw/HOWTO/HOWTO-INDEX.html\}
but here is a (possibly incomplete) list:

\call startpackedlist
\call packeditem
Linux \docref INFO-SHEET
\call packeditem
Linux \docref META-FAQ
\call packeditem
\docref{Bootdisk HOWTO\}
\call packeditem
\docref{Busmouse HOWTO\}
\call packeditem
\docref{CDROM HOWTO\}
\call packeditem
\docref{Commercial HOWTO\}
\call packeditem
\docref{Cyrillic HOWTO\}
\call packeditem
\docref{DOSEMU HOWTO\}
\call packeditem
\docref{Danish HOWTO\}
\call packeditem
\docref{Distribution HOWTO\}
\call packeditem
\docref{ELF HOWTO\}
\call packeditem
\docref{Ethernet HOWTO\}
\call packeditem
\docref{Firewall HOWTO\}
\call packeditem
\docref{Ftape HOWTO\}
\call packeditem
\docref{German HOWTO\}
\call packeditem
\docref{HAM HOWTO\}
\call packeditem
\docref{Hardware HOWTO\}
\call packeditem
\docref{Installation HOWTO\}
\call packeditem
\docref{JE HOWTO\}
\call packeditem
\docref{Kernel HOWTO\}
\call packeditem
\docref{MGR HOWTO\}
\call packeditem
\docref{Electronic Mail HOWTO\}
\call packeditem
\docref{NET-2 HOWTO\}
\call packeditem
\docref{NIS HOWTO\}
\call packeditem
\docref{News HOWTO\}
\call packeditem
\docref{PCI-HOWTO\}
\call packeditem
\docref{PCMCIA HOWTO\}
\call packeditem
\docref{PPP HOWTO\}
\call packeditem
\docref{Printing HOWTO\}
\call packeditem
\docref{SCSI HOWTO\}
\call packeditem
\docref{SCSI Programming HOWTO\}
\call packeditem
\docref{Serial HOWTO\}
\call packeditem
\docref{Sound HOWTO\}
\call packeditem
\docref{Term HOWTO\}
\call packeditem
\docref{Tips HOWTO\}
\call packeditem
\docref{UPS HOWTO\}
\call packeditem
\docref{UUCP HOWTO\}
\call packeditem
\docref{XFree86 HOWTO\}
\call endpackedlist

More of these documents are always in preparation.  You should check
in nearby directories on the FTP sites if you can't find the answer in
one of the HOWTOs.  There are also several \docref{mini-HOWTOs\} on \fn
sunsite.unc.edu in the \fn /pub/Linux/docs/HOWTO/mini directory.

The file \fn WRITING contains
\docref{information on how to write a new HOWTO\}.

The HOWTOs are coordinated by Greg Hankins, \email
[e-mail].

The `books' produced by the Linux Documentation Project are available
in \ftpsilent{sunsite.unc.edu\}\ftpin /pub/Linux/docs/LDP on \fn
sunsite.unc.edu.  Please read them if you are new to Unix and Linux.
Here is a list of those released so far:
\call startlist
\call item
\docref{The Linux Documentation Project manifesto\}
\call item
\docref{Installation and Getting Started Guide\}
\call item
\docref{The Kernel Hacker's Guide\}
\call item
\docref{Network Administration Guide\}
\call item
\docref{Linux System Administrator's Guide\}

\call endlist

\question 09sep  Where should I look on the World Wide Web for Linux stuff ?

Matt Welsh maintains the Linux Documentation Project Home Page, at
\docref{\fn http://sunsite.unc.edu/mdw/linux.html\}.

This page refers to all the FAQs and HOWTOs, both those which are
available in HTML (WWW) format, like this FAQ, and those which aren't.


\question 18sep:newsgroups  What newsgroups are there for Linux ?

There are ten international Usenet newsgroups devoted to Linux.

\newsgroup comp.os.linux.announce is the moderated announcements
group; you should read this if you intend to use Linux.  Submissions
for that group should be emailed to \fn [e-mail].

\newsgroup comp.os.linux.answers contains all the FAQs, HOWTOs and
other important documentation.  You should subscribe to this too.

Also worth reading are the other groups in the
\courier{comp.os.linux.*\} hierarchy -- you may find that many common
problems are too recent to find in this FAQ but are answered in the
newsgroups.  These groups are \newsgroup comp.os.linux.setup,
\newsgroup comp.os.linux.hardware, \newsgroup
comp.os.linux.networking, \newsgroup comp.os.linux.x, \newsgroup
comp.os.linux.development.apps, \newsgroup
comp.os.linux.development.system, \newsgroup comp.os.linux.advocacy
and \newsgroup comp.os.linux.misc.

Remember that since Linux is a Unix clone, most all of the material in
\courier{comp.unix.*\} and \courier{comp.windows.x.*\} groups will be
relevant.  Apart from hardware considerations, and some obscure or
very technical low-level issues, you'll find that these groups are the
right place to start.

Please read \qref notanswered before posting, and make sure you post
to the right newsgroup -- see `Welcome to the
\courier{comp.os.linux.*\} hierarchy' which is posted every two weeks
to \newsgroup comp.os.linux.announce, \newsgroup comp.os.linux.answers
and other groups.

Crossposting between different \courier{comp.os.linux.*\} groups is
rarely a good idea.

There may well be Linux groups local to your institution or area -
check there first.

The groups \newsgroup comp.os.linux.development, \newsgroup
comp.os.linux.admin and \newsgroup comp.os.linux.help were superseded
in a recent newsgroup reorganisation.  You should no longer use them.

See also \qref nousenet.

Other regional and local newsgroups also exist - you may find the
traffic more manageable there.  The French Linux newsgroup is
\newsgroup fr.comp.os.linux; The German one is \newsgroup
de.comp.os.linux.  In Australia, try \newsgroup aus.computers.linux.
In Croatia there is the moderated group \newsgroup hr.comp.linux.m.
In Italy, \newsgroup it.comp.linux.


\question 10feb:howinstall  How do I install Linux ?

There are several pre-packaged releases of Linux available, including
Debian, Red Hat and Slackware.  Each contains the software you need to
run Linux, ready to install and use.  The exact details of which
software is included and how to install them vary from release to
release.

You should read the Installation HOWTO for more details on how to go
about installing Slackware.  Red Hat and Debian are both more recent
and less buggy, and have more sophisticated installation schemes, but
they are less widely used and don't contain quite as wide a range of
software.

All of those releases are available via anonymous FTP from various
Linux archive sites [\qref ftpsites].  There are also a large number
of other releases which are distributed less globally, which suit
special local and national requirements (for example, better
internationalisation support).


\question 09sep:ftpsites  Where can I get Linux material by FTP ?

There are three main archive sites for Linux:
\call startlist
\call item
\ftpon ftp.funet.fi (Finland, 128.214.6.100) : \ftpin /pub/OS/Linux
\call item
\ftpon sunsite.unc.edu (US, 152.2.22.81) : \ftpin /pub/Linux
\call item
\ftpon tsx-11.mit.edu (US, 18.172.1.2) : \ftpin /pub/linux
\call endlist

The best place to get the Linux kernel is on \ftpon ftp.cs.helsinki.fi
in /pub/Software/Linux/Kernel; Linus Torvalds uploads the most recent
kernel versions to this site.

The Debian distribution is available at \docref{\fn ftp.debian.org\}
and the Red Hat distribution at \docref{\fn ftp.redhat.com\}.

The contents of these sites is mirrored (copied, usually approximately
daily) by a number of other sites.  Please use one close to you --
that will be faster for you and easier on the network.
\call startlist
\call item
\ftpon{src.doc.ic.ac.uk\} : \ftpin{/packages/Linux\} (UK)
\call item
\ftpon{sunacm.swan.ac.uk\} : \ftpin{/pub/Linux\} (UK)
\call item
\ftpon{ftp.ibp.fr\} : \ftpin{/pub/linux\} (France)
\call item
\ftpon{ftp.cc.gatech.edu\} : \ftpin{/pub/linux\} (US - southeast: Suranet)
\call item
\ftpon{wuarchive.wustl.edu\} : \ftpin{/systems/linux\} (US)
\call item
\ftpon{uiarchive.cso.uiuc.edu\} : \ftpin{/pub/systems/linux\} (US)
\call item
\ftpon{ftp.cdrom.com\} : \ftpin{/pub/linux\} (US)
\call item
\ftpon{ftp.informatik.tu-muenchen.de\} : \ftpin{/pub/comp/os/linux\} (Germany)
\call item
\ftpon{ftp.ibr.cs.tu-bs.de\} : \ftpin{/pub/os/linux\} (Germany)
\call item
\ftpon{ftp.dfv.rwth-aachen.de\} : \ftpin{/pub/linux\} (Germany)
\call item
\ftpon{ftp.informatik.rwth-aachen.de\} : \ftpin{/pub/Linux\} (Germany)
\call item
\ftpon{bond.edu.au\} : \ftpin{/pub/OS/Linux\} (Australia)
\call item
\ftpon{ftp.cc.monash.edu.au\} : \ftpin{/pub/linux\} (Australia)
\call item
\ftpon{ftp.dstc.edu.au\} : \ftpin{/pub/Linux\} (Australia: Queensland)
\call item
\ftpon{ftp.sun.ac.za\} : \ftpin{/pub/linux\} (South Africa)
\call item
\ftpon{ftp.inf.utfsm.cl\} : \ftpin{/pub/Linux\} (Chile)
\call item
\ftpon{ftp.zel.fer.hr\} : \ftpin{/pub/Linux\} (Croatia)
\call endlist
Not all of these mirror all of the other `source' sites, and some have
material not available on the `source' sites.


\question 18sep  I don't have FTP access.  Where do I get Linux ?

The easiest thing is probably to find a friend with FTP access.  If
there is a Linux users group near you they may be able to help.

If you have a reasonably good email connection you could try the
FTP-by-mail servers at \fn [e-mail], \fn
[e-mail] or \fn [e-mail].

Linux is also available via traditional mail on diskette, CD-ROM and
tape.  The \docref{Installation HOWTO\}, and the file
\ftpsilent{sunsite.unc.edu\}\ftpin /pub/Linux/docs/distributions on
\fn sunsite.unc.edu, contain information on these distributions.

You could also try Zane Healy \email [e-mail]'s list of
Linux BBS's, which is posted regularly (1st and 15th of each month) to
\newsgroup comp.os.linux.announce and occasionally to the Fidonet and
RIME UNIX echoes.


\question 18sep:nousenet  I don't have Usenet access.  Where do I get information ?

A digest of \fn comp.os.linux.announce is available by mailing the
word \fn subscribe as the body of a message to
\email [e-mail].
You are strongly advised to subscribe to this list, as it carries
important information and documentation about Linux.

Please remember to use the \fn -request addresses for your
subscription and unsubscription messages; mail to the other address is
posted to the newsgroup !


\question 18sep:multilist  What mailing lists are there ?

The Linux developers now mainly use the Majordomo server at \email
[e-mail].  Send a message with \fn lists in the body
to get a list of the lists there; add a line with \fn help to get the
standard Majordomo help file which has instructions for subscribing
and unsubscribing.

Note that most of these lists are used by the developers of Linux to
talk about technical issues and future developments.  These are not
intended for new users' questions.

There is a \fn linux-newbie list where `no question is too stupid';
unfortunately it seems that few of the experienced users read that
channel.  It does have very low volume.

There used to be a multi-channel Linux mailing list server on \fn
niksula.hut.fi.  This shut down during the summer of 1995.


\question 09sep:newsarchives  Are the newsgroups archived anywhere ?

\ftpon sunsite.unc.edu contains archives of \newsgroup
comp.os.linux.announce, in \ftpin
/pub/Linux/docs/linux-announce.archive.  These are mirrored from
\ftpsilent{src.doc.ic.ac.uk\}\ftpin /usenet on \fn src.doc.ic.ac.uk.

There is an `easy to access' archive of \fn comp.os.linux.announce on
the World Wide Web at
\docref{\fn http://www.leo.org/archiv/linux/archiv/ann_index.html\}.  It
supports searching and browsing.

I do not know of any (current) archives of the other groups in the \fn
comp.os.linux hierarchy.


\comment #######################################################################

\section  Compatibility with other operating systems

\question 27jun:coexist  Can Linux share my disk with DOS ?  OS/2 ?  386BSD ?  Win95 ?

Yes.  Linux uses the standard PC partitioning scheme, so it can share
your disk with other operating systems.  Note, however, that many of
these other operating systems are rather cranky: DOS FDISK and FORMAT
can sometimes overwrite data in a Linux partition because they
sometimes incorrectly use partition data from the partition's boot
sector rather than the partition table.  In order to prevent them from
doing this it is a good idea to zero out under Linux the start of a
partition you've just created, before you use MSDOS or whatever to
format it.  Type:
\verbatim
   dd if=/dev/zero of=/dev/hdXY bs=512 count=1
\endverbatim
where \fn hdXY is the relevant partition, eg, \fn hda1 for the first
partition of the first (IDE) disk.

Linux can read and write the files on your DOS and OS/2 FAT partitions
and floppies using either the DOS filesystem type built into the
kernel or mtools.  There is an alpha version of kernel support for the
VFAT filesystem used by Windows 95 and Windows NT; it is available
from \ftpon mm-ftp.cs.berkeley.edu in \ftpin
/pub/multimedia/linux/vfat/vfat-0.3.0.tgz.  This was integrated
into the standard kernel in version 1.3.60.

See \qref supportedsoftware for details and status of the emulators
for DOS, MS Windows and System V programs.

See also \qref otherfsys.


\question 18sep:msdosfs  How do I access files on my DOS partition or floppy ?

Use the DOS filesystem, i.e. type, for example:
\verbatim
        mkdir /dos
        mount -t msdos -o conv=text,umask=022,uid=100,gid=100 /dev/hda3 /dos
\endverbatim
If it's a floppy, don't forget to \fn umount it before ejecting it !

You can use the \fn conv=text/binary/auto, \fn umask=nnn, \fn uid=nnn
and \fn gid=nnn options to control the automatic line-ending
conversion, permissions and ownerships of the files in the DOS
filesystem as they appear under Linux.  If you mount your DOS
filesystem by putting it in your \fn /etc/fstab you can record the
options (comma-separated) there, instead of \fn defaults.

Alternatively you can use `mtools', available in both binary and
source form on the FTP sites -- see \qref ftpsites.

A kernel patch (known as the fd-patches) is available which allows
floppies with nonstandard numbers of tracks and/or sectors to be used;
this patch is included in the 1.1 alpha testing kernel series.


\question 18sep  Can I use my Stacked/DBLSPC/etc. DOS drive ?

Not very easily.  You can access them from within the DOS emulator
[\qref supportedsoftware], but it's harder to do as a normal
filesystem under Linux or using mtools.  There is a module available
for the Linux kernel which can do read-only access of the compressed
volume.  Look on \ftpon sunsite.unc.edu in \ftpin
/pub/Linux/system/Filesystems, for the \fn ths package.


\question 09sep  Can I access OS/2 HPFS partitions from Linux ?

Yes, but it's only read-only at the moment.  To use it you must
compile a kernel with support for it enabled [\qref kernelcompile].
Then you can mount it using the \fn mount command, for example:
\verbatim
        mkdir /hpfs
        mount -t hpfs /dev/hda5 /hpfs
\endverbatim


\question 09sep:otherfsys  Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ?

I'm told that there is a primitive, alpha test read-only Amiga
filesystem on \ftpon sunsite.unc.edu in \ftpin
/pub/Linux/patches/amigaffs.tar.Z.  More information is in \fn
affs-readme in the tarfile.

Recent kernels contain support for the UFS filesystem used by System
V, Coherent and Xenix.

There is alpha kernel support, readonly for the moment, for the 4.2BSD
UFS, on \ftpon sunsite.unc.edu in \ftpin /pub/Linux/ALPHA/ufs.

There is a set of user-level programs that provides read-only access
to the Macintosh hierarchical filing system (HFS). It is available on
\ftpon sunsite.unc.edu in \ftpin
/pub/Linux/utils/disk-management/hfs0_36.tgz.  This is being turned
into a kernel module, which is available on \fn sunsite.

A suite of programs called Samba provide support for Windows for
Workgroups networked filesystems (provided it's configured to use
TCP/IP).  Information is available at \docref{\fn
http://lake.canberra.edu.au/samba/samba.html\}.  There is alpha kernel
support for mounting such filesystems, on \ftpon sunsite.unc.edu in
\ftpin{/pub/Linux/ALPHA/smbfs\}.

There is no support for the rest of those yet; I have not heard of any
recent work on providing some.


\question 09sep:wine  Can I run Microsoft Windows programs under Linux ?

Not yet.  There is a project, known as WINE, to build an MS Windows
emulator for Linux, but it is not ready for users yet.  Don't ask
about it unless you think you can contribute; look out for the status
reports in \newsgroup comp.emulators.ms-windows.wine.

In the meantime if you need to run MS Windows programs your best bet
is probably to reboot when you want to switch environments.  LILO (the
Linux bootloader) has the facility for a boot menu --- see its
documentation for more details.


\question 18sep:os2boot  How can I boot Linux from OS/2's Boot Manager ?

1. Create a partition using OS/2's \fn FDISK (Not Linux's \fn fdisk).

2. Format the partition under OS/2, either with FAT or HPFS.  This is
so that OS/2 knows about the partition being formatted.  (This step is
not necessary with OS/2 "warp" 3.0.)

3. Add the partition to the Boot Manager.

4. Boot Linux, and create a filesystem on the partition using
\courier{mkfs -t ext2\} or \fn mke2fs.  At this point you may, if you
like, use Linux's \fn fdisk to change the partition type code of the
new partition to type 83 (Linux Native) -- this may help some
automated installation scripts find the right partition to use.

5. Install Linux on the partition.

6. Install LILO on the Linux partition -- NOT on the master boot
record of the hard drive.  This installs LILO as a second-stage boot
loader on the Linux partition itself, to start up the kernel specified
in the LILO config file.  To do this you should put
\verbatim
   boot = /dev/hda2
\endverbatim
(where \fn /dev/hda2 is the \italic{partition\} you want to boot off)
in your \fn /etc/lilo/config or \fn /etc/lilo.config file.

7. Make sure that it is the Boot Manager partition that is marked
active, so that you can use Boot Manager to choose what to boot.


\question 09sep  How can I share a swap partition between Linux and MS Windows ?

See the Mini-HOWTO on the subject by H. Peter Anvin, \email
[e-mail].  It is available on \ftpon sunsite.unc.edu in
\ftpin /pub/Linux/docs/HOWTO/mini/Swap-Space.


\comment ######################################################################

\section  Linux's handling of filesystems, disks and drives


\question 08may:largedisk  How can I get Linux to work with my large disk ?

If your disk is an IDE or EIDE drive you should read the file
\docref{/usr/src/linux/drivers/block/README.ide\} (part of the Linux
kernel source code).  This README contains many helpful hints about
IDE drives.  Many modern IDE controllers do translation between
`physical' cylinders/heads/sectors and `logical' ones.

SCSI disks are accessed by linear block numbers; the BIOS invents some
`logical' cylinders/heads/sectors fiction to support DOS.

DOS will usually not be able to access partitions which extend beyond
1024 logical cylinders, and will make booting a Linux kernel from such
partitions using LILO problematic at best.

You can still use such partitions for Linux or other operating systems
that access the controller directly.

I'd recommend creating at least one Linux partition entirely under the
1024-logical-cylinder limit and booting off that; the other
partitions will then be OK.


\question 09sep  How can I undelete files ?

In general, this is very hard to do on Unices because of their
multitasking nature.  Undelete functionality for the ext2fs is being
worked on, but don't hold your breath.

There are a number of packages available that work by providing new
commands for deletion and sometimes copying that move deleted files
into a `wastebasket' directory instead; they can then be recovered
until cleaned out automatically by background processing.

Alternatively you can search the raw disk device which holds the
filesystem in question.  This is hard work, and you will need to be
root to do this.


\question 17jun  Is there a defragmenter for ext2fs etc. ?

Yes.  There is a Linux filesystem defragmenter for ext2, minix and
old-style ext filesystems available on \fn sunsite.unc.edu in
\ftpsilent{sunsite.unc.edu:/pub/Linux\}\ftpin
system/Filesystems/defrag-0.6.tar.gz.

Users of the ext2 filesystem can probably do without defrag since ext2
contains extra code to keep fragmentation reduced even in very full
filesystems.


\question 18sep  How do I format and create a filesystem on a floppy ?

For a 3.5 inch high density floppy:
\verbatim
   fdformat /dev/fd0H1440
   mkfs -t ext2 -m 0 /dev/fd0H1440 1440
\endverbatim
For a 5.25 inch floppy use \fn fd0h1200 and \fn 1200 as appropriate.
For the `B' drive use \fn fd1 instead of \fn fd0.  Full details of
which floppy devices do what can be found in the Linux Device List
[\qref howtos].  You may have to run \fn mke2fs directly instead of
\courier{mkfs -t ext2\}.  The \courier{-m 0\} option tells \fn
mkfs.ext2 not to reserve any space on the disk for the superuser ---
usually the last 10% is reserved for root.

The first command low-level formats the floppy; the second creates an
empty filesystem on it.  After doing this you can mount the floppy
like a hard disk partition and simply \fn cp and \fn mv files, etc.


\question 18sep  I get nasty messages about inodes, blocks, and the suchlike

You probably have a corrupted filesystem, probably caused by not
shutting Linux down properly before turning off the power or
resetting.  You need to use a recent \fn shutdown program to do this
--- for example, the one included in the util-linux package, available
on \fn sunsite and \fn tsx-11.

If you're lucky the program \fn fsck (or \fn e2fsck or \fn xfsck as
appropriate if you don't have the automatic \fn fsck front-end) will
be able to repair your filesystem; if you're unlucky the filesystem is
trashed and you'll have to reinitialise it with \fn mkfs (or \fn
mke2fs, \fn mkxfs etc.) it and restore from a backup.

NB: don't try to check a filesystem that's mounted read-write - this
includes the root partition if you don't see
\verbatim
   VFS: mounted root ... read-only
\endverbatim
at boot time.


\question 20aug:swapnotworking  My swap area isn't working.

When you boot (or enable swapping manually) you should see
\verbatim
        Adding Swap: NNNNk swap-space
\endverbatim

If you don't see any messages at all you are probably missing
\courier{swapon -av\} (the command to enable swapping) in your \fn
/etc/rc.local or \courier{/etc/rc.d/*\} (the system startup scripts),
or have forgotten to make the right entry in \fn /etc/fstab:
\verbatim
        /dev/hda2       none       swap       sw
\endverbatim
for example.

If you see
\verbatim
        Unable to find swap-space signature
\endverbatim
you have forgotten to run \fn mkswap.  See the manpage for details; it
works much like \fn mkfs.

Check the \docref{Installation HOWTO\} for detailed instructions of
how to set up a swap area.


\question 18sep  How do I remove LILO so my system boots DOS again ?

Using DOS (MS-DOS 5.0 or later, or OS/2), type \courier{FDISK /MBR\}
(which is not documented).  This will restore a standard MS-DOS Master
Boot Record.  If you have DR-DOS 6.0, go into \fn FDISK in the normal
way and then select the `Re-write Master Boot Record' option.

If you don't have DOS 5 or DR-DOS you need to have the boot sector
that LILO saved when you first installed it.  You did keep that file,
didn't you ?  It's probably called \fn boot.0301 or some such.  Type
\verbatim
   dd if=boot.0301 of=/dev/hda bs=445 count=1
\endverbatim
(or \fn sda if you're using a SCSI disk).  This may also wipe out
your partition table, so beware !  If you're desperate, you could use
\verbatim
   dd if=/dev/zero of=/dev/hda bs=512 count=1
\endverbatim
which will erase your partition table and boot sector completely: you
can then reformat the disk using your favourite software; however this
will render the contents of your disk inaccessible --- you'll lose it
all unless you're an expert.

Note that the DOS MBR boots whichever (single!) partition is flagged
as `active'; you may need to use fdisk to set and clear the active
flags on partitions appropriately.


\question 26jun  Why can't I use \fn fdformat except as root ?

The system call to format a floppy may only be done as root,
regardless of the permissions of \courier{/dev/fd0*\}.  If you want
any user to be able to format a floppy try getting the \fn fdformat2
program; this works around the problems by being setuid to root.


\question 09sep  Is there something like Stacker or Doublespace for Linux ?

Currently none of the Linux filesystems can do compression in the
filesystem.

There is a program called Zlibc which allows existing applications to
read compressed (GNU zipped) files as if they were not compressed.
After installing it you can compress files using \fn gzip and programs
will still find them, without having to change the programs.  Look on
\ftpon sunsite.unc.edu in \ftpin /pub/Linux/libs.  The author is
\email [e-mail].

There is a compressing block device driver that can provide
filesystem-independant on the fly disk compression in the kernel.  It
is called `DouBle'.  There is a source only distribution on \ftpon
sunsite.unc.edu in \ftpin /pub/Linux/kernel/patches/diskdrives; the
author is Jean-Marc Verbavatz \email [e-mail].
Note that since this compresses inodes (administrative information)
and directories as well as file contents any corruption is quite
likely to be serious.

There is also a package available called \fn tcx (Transparently
Compressed Executables) which allows you to keep infrequently used
executables compressed and only uncompress them temporarily while you
use them.  You'll find it on the Linux FTP sites [\qref ftpsites]; it
was also announced in \newsgroup comp.os.linux.announce.  Note - this
is not the same as \fn gzexe, which is an inferior implementation of
the same concept.


\question 09sep  My ext2fs partitions are checked each time I reboot.

See \qref uncheckedfs.


\question 21dec  My root filesystem is read-only !

Remount it.  If \fn /etc/fstab is correct you can simply
\courier{mount -n -o remount /\}. If \fn /etc/fstab is wrong you must
give the device name and posibly the type too: e.g. \courier{mount -n
-o remount -t ext2 /dev/hda2 /\}.  To understand why you got into this
state see \qref uncheckedfs.


\question 09sep  I have a huge \fn /proc/kcore !  Can I delete it ?

None of the files in \fn /proc are really there - they're all
"pretend" files made up by the kernel, to give you information about
the system, and don't take up any hard disk space.

\fn /proc/kcore is like an "alias" for the memory in your computer;
its size is the same as the amount of RAM you have, and if you ask to
read it as a file the kernel does memory reads.


\question 09sep  My AHA1542C doesn't work with Linux.

The option to allow disks with more than 1024 cylinders is only
required as a workaround for a DOS misfeature and should be turned
\italic{off\} under Linux.  For older Linux kernels you need to turn
off most of the "advanced BIOS" options - all but the one about
scanning the bus for bootable devices.


\comment ######################################################################

\section  Porting, compiling and obtaining programs

Please see also the Linux GCC-FAQ, available in HTML format by FTP
from \ftpon www.mrc-apu.cam.ac.uk in \ftpin /pub/linux/GCC-FAQ.html.

\question 26jun:compiling  How do I port XXX to Linux ?

In general Unix programs need very little porting.  Simply follow the
installation instructions.  If you don't know and don't know how to
find out the answers to some of the questions asked during or by the
installation procedure you can guess, but this tends to produce buggy
programs.  In this case you're probably better off asking someone else
to do the port.

If you have a BSD-ish program you should try using \fn
-I/usr/include/bsd and \fn -lbsd on the appropriate parts of the
compilation lines.


\question 26jun  What is \fn ld.so and where do I get it ?

\fn ld.so is the dynamic library loader.  Each binary using shared
libraries used to have about 3K of start-up code to find and load the
shared libraries.  Now that code has been put in a special shared
library, \fn /lib/ld.so, where all binaries can look for it, so that
it wastes less disk space, and can be upgraded more easily.

It can be obtained from \ftpon tsx-11.mit.edu in \ftpin
/pub/linux/packages/GCC and mirror sites thereof.  The latest version
at the time of writing is \fn ld.so.1.7.11.tar.gz.

\fn /lib/ld-linux.so.1 is the same thing for ELF [\qref elf], and
comes in the same package as the a.out loader.


\question 09sep  Has anyone ported / compiled / written XXX for Linux ?

First, look in the Linux Software Map (LSM) --- it's in the
\ftpsilent{sunsite.unc.edu:/pub/Linux\}\ftpin docs directory on \fn
sunsite.unc.edu, and on the other FTP sites.  A search engine is
available on the WWW at \docref{\fn http://www.boutell.com/lsm/\}.

Check the FTP sites (see \qref ftpsites) first --- search the \fn
find-ls or \fn INDEX files for appropriate strings.  Check the Linux
Projects Map (LPM), on \ftpon ftp.ix.de in \ftpin
/pub/Linux/docs/Projects-Map.gz.

If you don't find anything, you could either download the sources to
the program yourself and compile them -- see \qref compiling -- or, if
it's a large package which may require some porting, post a message to
the newsgroup \newsgroup comp.os.linux.development.apps.

If you compile a largeish program please upload it to one or more of
the FTP sites and post a message to \newsgroup comp.os.linux.announce
(submit your posting to \email [e-mail]).

If you're looking for an application-type program the chances are
someone has already written a free verson.  Try reading the FAQ in
\newsgroup comp.sources.wanted for instructions on how to find
sources.

You should also check the Projects-FAQ, available in
\ftpsilent{sunsite.unc.edu\}\ftpin /pub/Linux/docs/faqs/Projects-FAQ
on \fn sunsite.unc.edu.


\question 26jun  Can I use code or a compiler compiled for a 486 on my 386 ?

Yes, unless it's the kernel.

The \fn -m486 option to GCC, which is used to compile binaries for 486
machines, merely changes certain optimisations.  This makes for
slightly larger binaries which run somewhat faster on a 486.  They
still work fine on a 386, though, with little performance hit.

However, from version 1.3.35 the kernel will use 486- or
Pentium-specific instructions if configured for a 486 or Pentium, thus
making it unusable on a 386.

GCC can be configured for a 386 or 486; the only difference is that
configuring it for a 386 makes \fn -m386 the default and configuring
for a 486 makes \fn -m486 the default; in either case these can be
overriden on a per-compilation basis or by editing \fn
/usr/lib/gcc-lib/i*-linux/n.n.n/specs.

There is an alpha version of GCC that knows how to do optimisation
well for the 586, but it is quite unreliable, especially at high
optimisation settings.  The Pentium GCC can be found on \ftpon
tsx-11.mit.edu in \ftpin /pub/linux/ALPHA/pentium-gcc.  I'd recommend
using the ordinary 486 GCC instead; word has it that using \fn -m386
produces code that's better for the Pentium, or at least slightly
smaller.


\question 09sep  What does \courier{gcc -O6\} do ?

Currently the same as \fn -O2 (GCC 2.5) or \fn -O3 (GCC 2.6, 2.7); any
number greater than that currently does the same thing.  The Makefiles
of newer kernels use \fn -O2, you should probably do the same.


\question 26jun:linuxinclude  Where are \courier{<linux/*.h>\} and \courier{<asm/*.h>\} ?

These are in the directories \fn /usr/include/linux and
\fn /usr/include/asm.

However they should be symbolic links to your kernel sources in \fn
/usr/src/linux and not real directories.

If you don't have the kernel sources download them --- see
\qref kernelcompile.

Then use \fn rm to remove any garbage, and \fn ln to create the links:
\verbatim
   rm -rf /usr/include/linux /usr/include/asm
   ln -sf /usr/src/linux/include/linux /usr/include/linux
   ln -sf /usr/src/linux/include/asm /usr/include/asm
\endverbatim

Nowadays \fn /usr/src/linux/include/asm is a symbolic link to an
architecture-specific \courier{asm-<arch>\} directory - if you have a
freshly unpacked kernel source tree you must use \courier{make
symlinks\}.  You'll also find that you may need to do \courier{make
config\} in a newly-unpacked kernel source tree, to create
\courier{<linux/autoconf.h>\}.


\question 26jun  I get errors when I try to compile the kernel.

Make sure that \fn /usr/include/linux and \fn /usr/include/asm aren't actual
directories but instead symbolic links to \fn /usr/src/linux/include/linux
and \fn /usr/src/linux/include/asm respectively.

If necessary, delete them using \fn rm and then use \courier{ln -s\} to make
the links as in \qref linuxinclude.

Remember that when you apply a patch to the kernel you must use the
\fn -p0 or \fn -p1 option: otherwise the patch may be misapplied.  See
the manpage for \fn patch for details.

If you're patching to a kernel more recent than 1.1.44 you should find
that there are new directories \fn /usr/src/linux/include/asm-i386.
The directory \fn asm there should be removed.  The \fn symlinks \fn
Makefile target will make these be symbolic links to \fn asm-i36 and
\fn arch/i386/boot respectively.  The easiest way to make sure all
this gets done is not to try to patch 1.1.44 to make 1.1.45, but to
download \fn linux-1.1.45.tar.gz instead.

\courier{ld: unrecognised option `-qmagic'\} means you should get a
newer linker, from \ftpon tsx-11.mit.edu in \ftpin
/pub/linux/packages/GCC, in the file
\fn binutils-2.6.0.2.bin.tar.gz.

\question 18sep  How do I make a shared library ?

For ELF,
\verbatim
   gcc -fPIC -c *.c
   gcc -shared -Wl,-soname,libfoo.so.1 -o libfoo.so.1.0 *.o
\endverbatim

For a.out, get \fn tools-n.nn.tar.gz from \ftpon tsx-11.mit.edu, in
\ftpin /pub/linux/packages/GCC/src.  It comes with documentation that
will tell you what to do.  Note that a.out shared libraries are a very
tricky business.


\question 09sep  My executables are (very) large.

With an ELF compiler (see \qref elf) the most common cause of large
executables is the lack of an appropriate \fn .so library link for one
of the libraries you're using.  There should be a link like \fn
libc.so for every library like \fn libc.so.5.2.18.

With an a.out compiler (see \qref elf) the most common cause of large
executables is the \fn -g linker (compiler) flag.  This produces (as
well as debugging information in the output file) a program which is
statically linked, i.e. one which includes a copy of the C library
instead of using a dynamically linked copy.

Other things that are worth investigating are \fn -O and \fn -O2 which
enable optimisation (check the GCC documentation) and -s (or the \fn
strip command) which strip the symbol information from the resulting
binary (making debugging totally impossible).

You may wish to use \fn -N on very small executables (less than 8K
with the \fn -N), but you shouldn't do this unless you understand its
performance implications, and definitely never with daemons.


\question 30oct  Does Linux support threads or lightweight processes ?

As well as the Unix multiprocessing model involving heavyweight
processes, which is of course part of the standard Linux kernel, there
are several implementations of lightweight processes or threads, most
of which are generic packages for any Unix:

\call startlist
\call item
In \ftpon{sipb.mit.edu\}:\ftpin /pub/pthread or
\ftpon{ftp.ibp.fr\}:\ftpin /pub/unix/threads/pthreads.  Documentation
isn't in the package, but is available on the World Wide Web at
\docref{\fn http://www.mit.edu:8001/people/proven/home_page.html\}.
Newer Linux libcs contain the pthreads source; the GNU Ada compiler on
\ftpon sunsite.unc.edu in \ftpin
/pub/Linux/devel/lang/ada/gnat-3.01-linux+elf.tar.gz contains binaries
made from that source code.
\call item
In \ftpon{ftp.cs.washington.edu\}:\ftpin /pub/qt-001.tar.Z is
QuickThreads.  More information can be found in the technical report,
available on the same site as \ftpin /tr/1993/05/UW-CSE-93-05-06.PS.Z.
\call item
In \ftpon{gummo.doc.ic.ac.uk\}:\ftpin /rex is lwp, a very minimal
implementation.
\call item
In \ftpon{ftp.cs.fsu.edu\}:\ftpin /pub/PART, an Ada implementation.
This is useful mainly because it has a lot of PostScript papers that
you'll find useful in learning more about threads.  This is not
directly usable under Linux.
\call endlist

Please contact the authors of the packages in question for details.

Kernel version 1.3.35 contains some support for kernel threads, but
this code has not been well-tested.


\question 31jan  Where can I get `lint' for Linux ?

Roughly equivalent functionality is built into the GNU C compiler (\fn
gcc) which is used by Linux systems.  Use the \fn -Wall option to turn
on most of the useful extra warnings.  Check the GCC manual for more
details (type control-\fn h followed by \fn i in Emacs and select the
entry for GCC).

There is a freely available program called `lclint' that does much the
same thing as traditional lint.  The announcement and source code are
available at on \ftpon larch.lcs.mit.edu in \ftpin /pub/Larch/lclint;
on the World Wide Web look at
\docref{\fn http://larch-www.lcs.mit.edu:8001/larch/lclint.html\}.


\question 27mar  Where can I find `kermit' for Linux ?

Kermit has a restrictive copyright which has forced most distribution
maintainers to remove it, or to move the package containing it into an
obscure directory.

The source code is available on \ftpon kermit.columbia.edu in \ftpin
/kermit/archives/cku190.tar.gz; Linux binaries are available in \ftpin
/kermit/bin/ckuker.linux and \ftpin /kermit/bin/ckuker.linuxtcp.


\copyto POST
===============================================================================

The remainder of the FAQ is in the next part ...

END-OF-PORTION
cat <<'END-OF-HEADER' >linux-faq.post-part2
From: [e-mail] (Ian Jackson)
Newsgroups: comp.os.linux.answers,comp.os.linux.setup,comp.os.linux.development.apps,comp.os.linux.misc,comp.os.linux.announce,comp.os.linux.help,comp.answers,news.answers
Subject: Linux Frequently Asked Questions with Answers (FAQ: 2/2)
Keywords: FAQ, Linux, part2
Summary: Please read the whole FAQ before posting to comp.os.linux.help.
Followup-To: poster
Approved: *.answers moderation team <[e-mail]>,
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Archive-Name: linux/faq/part2
Last-Modified: `date '+%d %b %Y'`

END-OF-HEADER
pgp-auto +batchmode +force -fast <<'END-OF-PORTION' >>linux-faq.post-part2
(Continued from part 1, where you'll find the introduction and
 table of contents.)
\endcopy

\comment ######################################################################

\section  Solutions to common miscellaneous problems


\question 10feb  \fn free dumps core.

In Linux 1.3.57 and later the format of \fn /proc/meminfo was changed
in a way that the implementation of \fn free doesn't understand.

Get the latest version, from \ftpon sunsite.unc.edu in \ftpin
/pub/Linux/system/Status/ps/procps-0.99.tgz.


\question 04feb  My clock is very wrong.

There are two clocks in your computer.  The hardware (CMOS) clock runs
even when the computer is off and is used to when the system starts up
and by DOS (if you use it).  The ordinary system time, shown and set
by \fn date, is maintained by the kernel while Linux is running.

You can display the CMOS clock time, or set either clock from the
other, with \fn /sbin/clock program - see \courier{man 8 clock\}.

There are various other programs that can correct either or both
clocks for systematic drift or transfer time across the network.  Some
of them may already be installed on your system.  Try looking at or
for \fn adjtimex (corrects for drift), \fn netdate and \fn getdate
(simply get the time from the network) or \fn xntp (accurate
fully-featured network time daemon).


\question 26jun  Setuid scripts don't seem to work.

That's right.  This feature has been deliberately disabled in the
Linux kernel because setuid scripts are almost always a security hole.
If you want to know why read the FAQ for \newsgroup
comp.unix.questions.


\question 10feb  Free memory as reported by \fn free keeps shrinking.

The `free' figure printed by \fn free doesn't include memory used as a
disk buffer cache - shown in the `buffers' column.  If you want to
know how much memory is really free add the `buffers' amount to `free'
- newer versions of \fn free print an extra line with this info.

The disk buffer cache tends to grow soon after starting Linux up, as
you load more programs and use more files and the contents get cached.
It will stabilise after a while.


\question 26jun:nocache  When I add more memory it slows to a crawl.

This is quite a common symptom of a failure to cache the additional
memory.  The exact problem depends on your motherboard.

Sometimes you have to enable caching of certain regions in your BIOS
setup.  Look in the CMOS setup and see if there is an option to cache
the new memory area which is currently switched off.  This is
apparently most common on a 486.

Sometimes the RAMs have to be in certain sockets to be cached.

Sometimes you have to set jumpers to enable the caching.

Some motherboards don't cache all the RAM if you have more RAM per
amount of cache than they expect.  Usually a full 256K cache will
solve this problem.

If in doubt, check your motherboard manual.  If you still can't fix it
because the documentation is inadequate you might like to post a
message to \newsgroup comp.os.linux.hardware giving \italic{all\} the
details - make, model number, date code, etc. so that other Linux
users can avoid it.


\question 26jun:shadowpassword  Some programs (e.g. \fn xdm) won't let me log in.

You are probably using non-shadow-password programs but are using
shadow passwords.

If so, you have to get or compile a shadow password version of the
program(s) in question.  The shadow password suite can be found in
(amongst other places):
\verbatim
   tsx-11.mit.edu:/pub/linux/sources/usr.bin/shadow-*
\endverbatim
This is the source code; you will probably find the binaries in \fn
.../linux/binaries/usr.bin.


\question 10feb  Some programs let me log in with no password.

You probably have the same problem as in \qref shadowpassword, with an
added wrinkle:

If you are using shadow passords you should put a letter \fn x or an
asterisk in the password field of \fn /etc/passwd for each account, so
that if a program doesn't know about the shadow passwords it won't
think it's a passwordless account and let anyone in.


\question 26jun:lackofmemory  My machine runs very slowly when I run GCC / X / ...

You may not have any swap enabled.  You need to enable swapping to
allow Linux to page out bits of data programs aren't using at the
moment to disk to make more room for other programs and data.  If you
don't Linux has to keep data in memory and throw away in-memory copies
of programs (which are paged straight from the filesystem) and so less
and less program is in memory and everything runs very slowly.

See the \docref{Installation HOWTO\} and the
\docref{Installation and Getting Started Guide\}
[\qref howtos] for details of how to set up a
swap partition or swapfile; see also \qref swapnotworking.

Alternatively you may have too little real memory.  If you have less
RAM than all the programs you're running at once use Linux will use
your hard disk instead and thrash horribly.  The solution in this case
is to not run so many things at once or to buy more memory.  You can
also reclaim some memory by compiling and using a kernel with less
options configured.  See \qref kernelcompile.

You can tell how much memory and/or swap you're using by using the \fn
free command, or by typing
\verbatim
    cat /proc/meminfo
\endverbatim

If your kernel is configured with a ramdisk this is probably wasted
space and will cause things to go slowly.  Use LILO or \fn rdev to
tell the kernel not to allocate a ramdisk (see the LILO documentation
or type \courier{man rdev\}).


\question 26jun  I can only log in as root.

You probably have some permission problems, or you have a file \fn
/etc/nologin.

If the latter put \courier{rm -f /etc/nologin\} in your \fn
/etc/rc.local or \courier{/etc/rc.d/*\} scripts.

Otherwise check the permissions on your shell, and any filenames which
appear in error messages, and also the directories containing these
files all the way up the tree, up to and including the root directory.


\question 09sep  My screen is all full of weird characters instead of letters.

You probably sent some binary data to your screen by mistake.  Type
\courier{echo '\\033c'\} to fix it.  Many Linux distributions have a
command \fn reset that does this.


\question 17jun:screwedup  I have screwed up my system and can't log in to fix it.

Reboot from an emergency floppy or floppy pair, for example the
Slackware boot- and root-disk pair (in the \fn install subdirectory of
the Slackware mirrors) or the MCC installation boot floppy.  There are
also two diy rescue disk creation packages on \ftpon sunsite.unc.edu
in \ftpin /pub/Linux/system/Recovery.  These are better as they'll
have your own kernel on them, so that you don't run the risk of
missing devices, filesystems, etc.

Get to a shell prompt and mount your hard
disk with something like
\verbatim
   mount -t ext2 /dev/hda1 /mnt
\endverbatim

Then your filesystem is available under the directory \fn /mnt and you
can fix the problem.  Remember to unmount your hard disk before
rebooting (\fn cd back down to \courier{/\} first or it will say it's
busy).


\question 09sep  I've discovered a huge security hole in \fn rm !

No you haven't.  You are obviously new to Unix and need to read a good
book on it to find out how things work.  Clue: ability to delete files
under Unix depends on permission to write the directory they are in.


\question 17jun  \fn lpr and/or \fn lpd aren't working.

Check the \docref{Printing HOWTO\} [\qref howtos].


\question 31jan  Timestamps on files on msdos partitions are set incorrectly.

There is a bug in the program \fn clock (often found in \fn /sbin) -
it miscounts a timezone offset, confusing seconds with minutes or some
such.  Get a new version of it.


\question 27mar  How do I get LILO to boot the \fn vmlinux file ?

In kernel versions 1.1.80 and later the compressed kernel image, which
is what you have to give to LILO, has been moved to \fn
arch/i386/boot/zImage.  The \fn vmlinux file in the root directory is
the uncompressed kernel, and you shouldn't try to boot it.

This change has been made to make it easier to build the versions for
several different processors from the same source tree.


\comment ######################################################################

\section  How do I do this or find out that ... ?


\question 09sep  How can I get scrollback in text mode ?

With the default US keymap you can use Shift with the PageUp and
PageDown keys (NB: these must be the grey ones, not the ones on the
numeric keypad !).  With other keymaps check the maps in \fn
/usr/lib/keytables; you can remap the scroll up and down keys to be
whatever you like --- for example, in order to remap them to keys that
exist on an 84-key AT keyboard.

You can't increase the amount of scrollback, because of the way it is
implemented using the video memory to store the scrollback text,
though you may be able to get more scrollback in each virtual console
by reducing the total number of VC's --- see \courier{<linux/tty.h>\}.


\question 13jul  How do I switch virtual consoles ?  How do I enable them ?

In text mode, press Left Alt-F1 to Alt-F12 to select the consoles \fn
tty1 to \fn tty12; Right Alt-F1 gives \fn tty13 and so on.  To switch
out of X windows you must press Ctrl-Alt-F1 etc; Alt-F5 or whatever
will switch back.

If you want to use a VC for ordinary login you need to list it in \fn
/etc/inittab, which controls which terminals and virtual consoles have
login prompts.  NB: X needs at least one free VC in order to start.

Kernels earlier than around 1.1.59 have a compiled-in limit on the
number of consoles, for which the default is 8.  See \fn NR_CONSOLES
in \fn linux/include/linux/tty.h.  Newer kernels allocate them
dynamically, up to a maximum of 63.


\question 26jun:timezone  How do I set the timezone ?

Change directory to \fn /usr/lib/zoneinfo; get the timezone package if
you don't have this directory.  The source can be found on \ftpon
sunsite.unc.edu in \ftpin /pub/Linux/system/Admin/timesrc-1.2.tar.gz.

Then make a symbolic link named \fn localtime pointing to one of the
files in this directory (or a subdirectory), and one called \fn
posixrules pointing to \fn localtime.  For example:
\verbatim
   ln -sf US/Mountain localtime
   ln -sf localtime posixrules
\endverbatim
This change will take effect immediately - try \fn date.

Don't try to use the \fn TZ variable - leave it unset.

You should also make sure that your Linux kernel clock is set to the
correct GMT time - type \courier{date -u\} and check that the correct
universal time is displayed.


\question 26jun  What version of Linux and what machine name am I using ?

Type:
\verbatim
   uname -a
\endverbatim


\question 09sep  How can I enable or disable \fn core dumps ?

Linux now has corefiles turned off by default for all processes.

You can turn them on or off by using the \fn ulimit command in \fn
bash, the \fn limit command in \fn tcsh, or the \fn rlimit command in
\fn ksh.  See the manpage for the shell for more details.

That command affects all programs run from that shell (directly or
indirectly), not the whole system.

If you wish to enable or disable coredumping for all processes by
default you can change the default setting in
\courier{<linux/sched.h>\} - see the definition of \fn INIT_TASK, and
look also in \courier{<linux/resource.h>\}.

1.2.13 will produce a.out core dumps [\qref elf].


\question 09sep:kernelcompile  How do I upgrade/recompile my kernel ?

See the \docref{Kernel HOWTO\} or the \fn README which comes with the
kernel release on \ftpon ftp.cs.helsinki.fi, in \ftpin
/pub/Software/Linux/Kernel and mirrors thereof [\qref ftpsites].  You
may already have a version of the kernel source code installed on your
system, but if you got it as part of a standard distribution it is
likely to be somewhat out of date (this is not a problem if you only
want a custom-configured kernel, but it probably is if you need to
upgrade.)

Remember that to make the new kernel boot you must run LILO after
copying the kernel into your root partition -- the \fn Makefile in
recent kernels has a special \fn zlilo target for this; try
\courier{make zlilo\}.

Kernel version numbers with an odd minor version (ie, 1.1.x, 1.3.x)
are the testing releases; stable production kernels have even minor
versions (1.0.x, 1.2.x).  If you want to try the testing kernels you
should probably subscribe to the \fn linux-kernel mailing list [\qref
multilist].

Russel Nelson posts summaries of what changes in recent kernel patches
to \newsgroup comp.os.linux.development, and these are archived on
\ftpon ftp.emlist.com in \ftpin /pub/kchanges.


\question 26jun  Can I have more than 3 serial ports by sharing interrupts ?

Yes, but you won't be able to use simultaneously two ordinary ports
which share an interrupt (without some trickery).  This is a
limitation of the ISA bus architecture.

See the \docref{Serial HOWTO\} for information about possible
solutions to and workarounds for this problem.


\question 26jun  How do I make a bootable floppy ?

Make a filesystem on it with \fn bin, \fn etc, \fn lib and \fn dev
directories -- everything you need.  Install a kernel on it and
arrange to have LILO boot it from the floppy (see the LILO
documentation, in \fn lilo.u.*.ps).

If you build the kernel (or tell LILO to tell the kernel) to have a
ramdisk the same size as the floppy the ramdisk will be loaded at
boot-time and mounted as root in place of the floppy.

See the \docref{Bootdisk HOWTO\}.


\question 26jun:kbd  How do I remap my keyboard to UK, French, etc. ?

For recent kernels, get
\ftpsilent{sunsite.unc.edu\}\ftpin /pub/Linux/system/Keyboards/kbd-0.90.tar.gz
from \fn sunsite.unc.edu.  Make sure you get the appropriate version; you
have to use the right keyboard-mapping package to go with your kernel
version.  \fn 0.90 should work with kernel versions from 1.0.

For older kernels you have to edit the top-level kernel \fn Makefile,
in \fn /usr/src/linux.

You may find more helpful information in the \docref{Keystroke
HOWTO\}, on \fn sunsite.unc.edu in \fn
/pub/Linux/docs/HOWTO/Keystroke-HOWTO.


\question 26jun  How do I get NUM LOCK to default to on ?

Use the \fn setleds program, for example (in \fn /etc/rc.local or one
of the \courier{/etc/rc.d/*\} files):
\verbatim
   for t in 1 2 3 4 5 6 7 8
   do
        setleds +num < /dev/tty$t > /dev/null
   done
\endverbatim

\fn setleds is part of the kbd package (see \qref kbd).

Alternatively, patch your kernel.  You need to arrange for \fn
KBD_DEFLEDS to be defined to \courier{(1 << VC_NUMLOCK)\} when
compiling \fn drivers/char/keyboard.c.


\question 21dec  How can I have more than 128Mb of swap ?

Use several swap partitions or swapfiles - Linux supports up to 16
swap areas, each of up to 128Mb.

Very old kernels only supported swap area sizes up to 16Mb.


\comment ######################################################################

\section  Miscellaneous information and questions answered


\question 07feb  How do I program XYZ under Linux ?

Read the manuals, or a good book on Unix.  manpages (type \courier{man
man\}) are usually a good source of reference information on exactly
how to use a particular command or function.

There is also a lot of GNU Info documentation, which is often more
useful as a tutorial.  Run Emacs and type \courier{C-h i\}, or type
\courier{info info\} if you don't have or don't like Emacs.  Note that
the Emacs \courier{libc\} node doesn't exactly describe the Linux libc
(which is more like a traditional Unix libc, not having some of the
GNU oddities), but it's close enough to make a fair tutorial in Unix C
programming.

The latest release of the Linux manpages and a collection of useful
GNU Info documentation various other information related to
programming Linux can be found on \ftpon sunsite.unc.edu in \ftpin
/pub/Linux/docs/man-pages.


\question 10feb:elf  What's all this about ELF ?

See the \docref{ELF HOWTO\} by Daniel Barlow - note, this is not the
file \fn move-to-elf, which is a blow-by-blow account of how to
upgrade to ELF manually.

Linux is switching to a different format for executables, object files
and object code libraries, known as `ELF' (the old format is called
`a.out').  This will have many advantages, including better support
for shared libraries and dynamic linking.

Both a.out and ELF binaries can coexist on a system.  However, they
use different shared C libraries, both of which will have to be
installed to do this.

If you want to find out whether your system can run ELF binaries, look
in \fn /lib for a filename \fn libc.so.5.  If this exists it
probably can.  If you want to know whether your installation actually
\italic{is\} ELF you can pick a representative program, like \fn ls,
and run \fn file on it:
\verbatim
   -chiark:~> file /bin/ls
   /bin/ls: Linux/i386 impure executable (OMAGIC) - stripped

   valour:~> file /bin/ls
   /bin/ls: ELF 32-bit LSB executable, Intel 80386, version 1, stripped
\endverbatim

There is a patch to get 1.2.x to compile using the ELF compilers, and
produce ELF coredumps, on \ftpon tsx-11.mit.edu in /pub/packages/GCC.
You do not need the patch merely to run ELF binaries.  1.3.x and later
do not need a patch at all.


\question 26jun  What is a \fn .gz file ? And a \fn .tgz ? And ... ?

\fn .gz (and \fn .z) files have been compressed using GNU \fn gzip.
You need to use \fn gunzip (which is as a symlink to the \fn gzip
command which comes with most Linux installations) to unpack the file.

\fn .taz and \fn .tz are tarfiles (made with Unix \fn tar) compressed
using standard Unix \fn compress.

\fn .tgz (or \fn .tpz) is a tarfile compressed with \fn gzip.

\fn .lsm is a Linux Software Map entry, in the form of a short text
file.  Details about the LSM and the LSM itself are available in the
\ftpsilent{sunsite.unc.edu:/pub/Linux\}\ftpin docs subdirectory on \fn
sunsite.unc.edu.

\fn .deb is a Debian Binary Package - the binary package format used
by the Debian GNU/Linux distribution.  It is manipulated using \fn
dpkg and \fn dpkg-deb (available on Debian systems and from \fn
ftp.debian.org).

\fn .rpm is a Red Hat RPM package, which is used in the Red Hat
distribution.  These can be found on \docref{\fn ftp.redhat.com\}.

The \fn file command can often tell you what a file is.

If you find that \fn gzip complains when you try to uncompress a
gzipped file you probably downloaded it in ASCII mode by mistake.  You
must download most things in binary mode - remember to type \fn binary
as a command in FTP before using \fn get to get the file.


\question 26jun  What does \fn VFS stand for ?

Virtual File System.  It's the abstraction layer between the user and
real filesystems like ext2, minix and msdos.  Amongst other things,
its job is to flush the read buffer when it detects a disk change on
the floppy disk drive:
\verbatim
   VFS: Disk change detected on device 2/0
\endverbatim


\question 09sep  What is a BogoMip ?

`BogoMips' is a contraction of `Bogus MIPS'.  MIPS stands for
(depending who you listen to) Millions of Instructions per Second, or
Meaningless Indication of Processor Speed.

The number printed at boot-time is the result of a kernel timing
calibration, used for very short delay loops by some device drivers.

As a very rough guide the BogoMips will be approximately:
\verbatim
     386SX              clock * 0.14
     386DX              clock * 0.18
     486Cyrix/IBM       clock * 0.33
     486SX/DX/DX2       clock * 0.50
     586                clock * 0.39
\endverbatim

If the number you're seeing is wildly lower than this you may have the
Turbo button or CPU speed set incorrectly, or have some kind of
caching problem [as described in \qref nocache.]

For values people have seen with other, rarer, chips, see the BogoMips
Mini-HOWTO, on \ftpon sunsite.unc.edu in \ftpin
/pub/Linux/docs/howto/mini/BogoMips.


\question 18may  What is the Linux Journal and where can I get it ?

Linux Journal is a monthly magazine (printed on paper) that is
available on newsstands and via subscription worldwide. Email \email
[e-mail] for details.  They are on the Web at
\docref{\fn http://www.ssc.com/\}.


\question 22jun  How many people use Linux ?

Linux is freely available, and no one is required to register their
copies with any central authority, so it is difficult to know.
Several businesses are now surviving solely on selling and supporting
Linux, and very few Linux users use those businesses, relatively
speaking.  The Linux newsgroups are some of the most heavily read on
the Net, so the number is likely in the hundreds of thousands, but
firm numbers are hard to come by.

However, one brave soul, Harald T. Alvestrand \email
[e-mail], has decided to try, and asks that if
you use Linux, you send a message to \email [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 will also
accept `third-party' registrations - ask him for details.

Alternatively, you can register using the WWW forms found at
\docref{http://domen.uninett.no/~hta/linux/counter.html\}.

He posts his counts to comp.os.linux.misc each month; alternatively
look on \ftpon aun.uninett.no in \ftpin /pub/misc/linux-counter or at
the web page above.


\question 18sep  How should I pronounce Linux ?

This is a matter of religious debate, of course !

If you want to hear Linus himself say how he pronounces it
download \ftpsilent
ftp.funet.fi:/pub/OS/Linux/PEOPLE/Linus/SillySounds \ftpin english.au
or \ftpin swedish.au from \fn ftp.funet.fi (in \fn
/pub/OS/Linux/PEOPLE/Linus/SillySounds).  If you have a soundcard or
the PC-speaker audio driver you can hear them by typing
\verbatim
   cat english.au >/dev/audio
\endverbatim
The difference isn't in the pronunciation of Linux but in the language
Linus uses to say hello.  The English version was parodied very well
by Jin Choi as "Hi, my name is Leenoos Torvahlds and I pronounce
Leenooks as Leenooks."

For the benefit of those of you who don't have the equipment or
inclination: Linus pronounces Linux approximately as Leenus, where the
ee is as in feet but rather shorter and the u is like a much shorter
version of the French eu sound in peur (pronouncing it as the u in put
is probably passable).

When speaking English I pronounce it Lie-nucks (u as in bucket) ---
this is an anglicised pronunciation based on the analogy with Linus'
name, which in English is usually pronounced Lie-nus (u as in put).
It is of course quite acceptable and common to modify the
pronunciation of a proper noun when it changes languages.

I think I can safely say that the pronunciation Linnucks (short i as
in pit, short u as in bucket) is wrong in English, as it is not the
original Swedish pronunciation, not a sensible direct anglicisation of
it, and not based on the anglicised version of Linus' name.


\comment ######################################################################

\section  Frequently encountered error messages


\question 31aug  Unknown terminal type \courier{linux\} and similar

In an early 1.3.x kernel the default console terminal type has changed
from \courier{console\} to \courier{linux\}.  You must edit \fn /etc/termcap
to change the line reading:
\verbatim
   console|con80x25:\
\endverbatim
to
\verbatim
   linux|console|con80x25:\
\endverbatim
(there may be an additional \courier{dumb\} in there - if so it should be removed.)

In order to get the editor to work you may need say
\courier{TERM=console\} (for \fn bash and \fn ksh) or \courier{setenv
TERM console\} (\fn csh, \fn tcsh) first.

Some programs use \fn /usr/lib/terminfo instead of \fn /etc/termcap.
For these programs you should upgrade your terminfo, which is part of
ncurses.


\question 18sep  During linking I get \courier{Undefined symbol _mcount\}

This is usually due to a bad interaction between a brokenness in SLS
and the C library release notes.  Your \fn libc.a has been replaced by
the profiling library.  You should remove \fn libc.a, \fn libg.a and
\fn libc_p.a and once again install the new libraries (following the
release notes, of course).


\question 09sep  \courier{lp1 on fire\}

This is a joke/traditional error message indicating that some sort of
error is being reported by your printer, but that the error status
isn't a valid one.  It may be that you have some kind of I/O or IRQ
conflict - check your cards' settings.  Some people report that they
get this message when their printer is switched off.  Hopefully it
isn't really on fire ...

In newer kernels this message reads \courier{lp1 reported invalid
error status (on fire, eh?)\}.


\question 26jun  \courier{INET: Warning: old style ioctl(IP_SET_DEV) called!\}

You are trying to use the old network configuration utilities; the new
ones can be found on \ftpon ftp.linux.org.uk in \ftpin
/pub/linux/Networking/PROGRAMS/NetTools (source only, I'm afraid).

Note that they cannot be used just like the old-style programs; see
the \docref{NET-2 HOWTO\} for instructions on how to set up networking
correctly.


\question 10feb  \courier{ld: unrecognized option '-m486'\}

You have an old version of \fn ld.  Install a newer binutils package
-- this will contain an updated \fn ld.  Look on \ftpon tsx-11.mit.edu
in \ftpin /pub/linux/packages/GCC for \fn binutils-2.6.0.2.bin.tar.gz.


\question 26jun  GCC says \courier{Internal compiler error\}

If the fault is repeatable (ie, it always happens at the same place in
the same file --- even after rebooting and trying again, using a
stable kernel) you have discovered a bug in GCC.  See the GCC Info
documentation (type Control-\fn h \fn i in Emacs, and select GCC from
the menu) for details on how to report this -- make sure you have the
latest version though.

Note that this is probably not a Linux-specific problem; unless you
were compiling a program many other Linux users also compile you
should not post your bug report to any of the \fn comp.os.linux
groups.

If the problem is not repeatable you are very probably experiencing
memory corruption --- see \qref memorycorrupt.


\question 09sep:memorycorrupt  \fn make says \courier{Error 139\}

Your compiler driver (\fn gcc) dumped core.  You probably have a
corrupted, buggy or old version of GCC --- get the latest release.
Alternatively you may be running out of swap space --- see \qref
lackofmemory for more info.

If this doesn't fix the problem you are probably having problems with
memory or disk corruption.  Check that the clock rate, wait states and
refresh timing for your SIMMs and cache are correct (hardware manuals
are sometimes wrong, too).  If so you may have some dodgy SIMMs or a
faulty motherboard or hard disk or controller.

Linux, like any Unix, is a very good memory tester --- much better
than DOS-based memory test programs.

Reportedly some clone x87 maths coprocessors can cause problems; try
compiling a kernel with maths emulation [\qref kernelcompile]; you may
need to use the \fn no387 kernel command line flag on the LILO prompt
to force the kernel to use it, or it may be able to work and still use
the 387, with the maths emulation compiled in but mainly unused.

Much more information about this problem is available on the WWW at
\docref{\fn http://einstein.et.tudelft.nl/~wolff/sig11/\}.


\question 26jun  \courier{shell-init: permission denied\} when I log in.

Your root directory and all the directories up to your home directory
must be readable and executable by everybody.  See the manpage for
\fn chmod or a book on Unix for how to fix the problem.


\question 26jun  \courier{No utmp entry.  You must exec ...\} when I log in.

Your \fn /var/run/utmp is screwed up.  You should have
\verbatim
   > /var/run/utmp
\endverbatim
in your \fn /etc/rc.local or \courier{/etc/rc.d/*\}.  See \qref
screwedup for how to be able to do this.  Note that \fn utmp may also
be found in \fn /var/adm/utmp or \fn /etc/utmp on some older systems.


\question 17jun  \courier{Warning - bdflush not running\}

Modern kernels use a better strategy for writing cached disk blocks.
In addition to the kernel changes, this involves replacing the old \fn
update program which used to write everything every 30 seconds with a
more subtle daemon (actually a pair), known as \fn bdflush.

Get \fn bdflush-n.n.tar.gz from the same place as the kernel source
code [\qref kernelcompile] and compile and install it; it should be
started before the usual boot-time filesystem checks.  It will work
fine with older kernels as well, so there's no need to keep the old
\fn update around.


\question 18sep  \courier{Warning: obsolete routing request made.\}

This is nothing to worry about; it just means that the version of \fn
route you have is a little out of date compared to the kernel.  You
can make the message go away by getting a new version of \fn route
from the same place as the kernel source code [\qref kernelcompile].


\question 09sep:uncheckedfs  \courier{EXT2-fs: warning: mounting unchecked filesystem\}

You need to run \fn e2fsck (or \courier{fsck -t ext2\} if you have the
\fn fsck front-end program) with the \fn -a option to get it to clear
the `dirty' flag, and then cleanly unmount the partition during each
shutdown.

The easiest way to do this is to get the latest \fn fsck, \fn umount
and \fn shutdown commands, available in Rik Faith's util-linux package
[\qref ftpsites].  You have to make sure that your /etc/rc* scripts
use them correctly.

NB: don't try to check a filesystem that's mounted read-write - this
includes the root partition if you don't see
\verbatim
   VFS: mounted root ... read-only
\endverbatim
at boot time.  You must arrange to mount the root filesystem readonly
to start with, check it if necessary, and then remount it read-write.
Read the documentation that comes with util-linux to find out how to
do this.

Note that you need to specify the \fn -n option to \fn mount to get it
not to try to update \fn /etc/mtab, since the root filesystem is still
read-only and this will otherwise cause it to fail !


\question 09sep:maxcounts  \courier{EXT2-fs warning: maximal count reached\}

This message is issued by the kernel when it mounts a filesystem
that's marked as clean, but whose `number of mounts since check'
counter has reached the predefined value.  The solution is to get the
latest version of the ext2fs utilities (\fn e2fsprogs-0.5b.tar.gz at
the time of writing) from the usual sites [\qref ftpsites].

The maximal number of mounts value can be examined and changed using
the \fn tune2fs program from this package.


\question 09sep  \courier{EXT2-fs warning: checktime reached\}

Kernels from 1.0 onwards support checking a filesystem based on the
elapsed time since the last check as well as by the number of mounts.
Get the latest version of the ext2fs utilities [see \qref maxcounts].


\question 26jun  \fn df says \courier{Cannot read table of mounted filesystems\}

There is probably something wrong with your \fn /etc/mtab or \fn
/etc/fstab files.  If you have a reasonably new version of \fn mount,
\fn /etc/mtab should be emptied or deleted at boot time (in \fn
/etc/rc.local or \courier{/etc/rc.d/*\}), using something like
\verbatim
   rm -f /etc/mtab*
\endverbatim

Some versions of SLS have an entry for the root partition in \fn
/etc/mtab made in \courier{/etc/rc*\} by using \fn rdev.  This is
incorrect -- the newer versions of \fn mount do this automatically.

Other versions of SLS have a line in \fn /etc/fstab that looks like:
\verbatim
    /dev/sdb1   /root   ext2   defaults
\endverbatim
This is wrong.  \fn /root should read simply \courier{/\}.


\question 17jun  \fn fdisk says \courier{Partition X has different physical/logical ...\}

If the partition number (\fn X, above) is 1 this is the same problem
as \qref badpart1.

If the partition begins or ends on a cylinder numbered beyond 1024
this is because standard DOS disk geometry information format in the
partition table can't cope with cylinder numbers with more than 10
bits.  You should see \qref largedisk.


\question 20sep:badpart1  \courier{fdisk: Partition 1 does not start on cylinder boundary\}

The version of \fn fdisk that comes with many Linux systems creates
partitions that fail its own validity checking.  Unfortunately if
you've already installed your system there's not much you can do about
this, apart from copying the data off the partition, deleting and
remaking it, and copying the data back.

You can avoid the problem by getting the latest version of \fn fdisk,
from Rik Faith's util-linux package (available on all good FTP sites).
Alternatively, if you are creating a new partition 1 that starts in
the first cylinder, you can do the following to get a partition that
fdisk likes.

1. Create partition 1 in the normal way.  A \fn p listing will produce
the mismatch complaint.

2. Type \fn u to set sector mode and do \fn p again.  Copy down the
number from the "End" column.

3. Delete partition 1.

4. While still in sector mode recreate partition 1.  Set the first
sector to match the number of sectors per track.  This is the sector
number in the first line of the \fn p output.  Set the last sector to
the value noted in 2. above.

5. Type \fn u to reset cylinder mode and continue with other
partitions.

Ignore the message about unallocated sectors - they refer to the
sectors on the first track apart from the Master Boot Record, which
are not used if you start the first partition in track 2.


\question 26jun  \fn fdisk says \courier{partition n has an odd number of sectors\}

The PC disk partitioning scheme works in 512-byte sectors, but Linux
uses 1K blocks.  If you have a partition with an odd number of sectors
the last sector is wasted.  Ignore the message.


\question 09sep  mtools says \courier{cannot initialise drive XYZ\}

This means that mtools is having trouble accessing the drive.  This
can be due to several things.

Often this is due to the permissions on floppy drive devices
(\courier{/dev/fd0*\} and \courier{/dev/fd1*\}) being incorrect ---
the user running mtools must have the appropriate access.  See the
manpage for \fn chmod for details.

Most versions of mtools distributed with Linux systems (not the
standard GNU version) use the contents of a file \fn /etc/mtools to
discover which devices and densities to use, in place of having this
information compiled into the binary.  Mistakes in this file often
cause problems.  There is often no documentation about this ---
distribution packagers please note that this is \italic{evil\}.

For the easiest way to access your DOS files (especially those on a
hard disk partition) see \qref msdosfs.  Note - you should never use
mtools to access files on an msdosfs mounted partition or disk !


\question 31jan  At the start of booting: \courier{Memory tight\}

This means that you have an extra large kernel that means that Linux
has to do some special memory-management magic to be able to boot
itself from the BIOS.  It isn't related to the amount of physical
memory in your machine.  Ignore the message, or compile a kernel
containing only the drivers and features you need [\qref
kernelcompile].


\question 12sep  \courier{You don't exist. Go away.\}

This is not a viral infection \courier{:-)\}.  It comes from various
programs such as \fn write, \fn talk and \fn wall, if your invoking
uid doesn't correspond to a valid user (probably due to \fn
/etc/passwd being corrupted), or if the session (pseudoterminal,
specifically) you're using isn't properly registered in the \fn utmp
file (probably because you invoked it in a funny way).


\comment ######################################################################

\section  The X Window System

\question 10feb:x  Does Linux support X Windows ?

Yes.  Linux uses XFree86 (the current version is 3.1.2, which is based
on X11R6).  You need to have a video card which is supported by
XFree86.  See the Linux XFree86 HOWTO for more details.

Most Linux distributions nowadays come with an X installation.

However, you can install or upgrade your own, from
\ftpsilent{sunsite.unc.edu\}\ftpin /pub/Linux/X11/Xfree86-* on \fn
sunsite.unc.edu and its mirror sites.  Read the \docref{XFree86
HOWTO\} for installation instructions.


\question 09sep  Where can I get an \fn XF86Config for my system ?

See the Linux XFree86 HOWTO.

You'll need to put together your own \fn XF86Config file, because it
depends on the exact combination of video card and monitor you have.
It's not that hard to do -- read the instructions that came with
XFree86, in \fn /usr/X11R6/lib/X11/etc.  The file you probably most
need to look at is \fn README.Config.

For a quick start you may run the program \fn xf86config.  Note that
\fn ConfigXF86 is now obsolete and you shouldn't use it.

Please don't post to \fn comp.os.linux.x asking for an \fn XF86Config,
and please don't answer such requests - especially not in the group.


\question 26jun  \fn xterm logins show up strangely in \fn who, \fn finger

The \fn xterm that comes with XFree86 2.1 and earlier doesn't
correctly understand the format that Linux uses for the \fn
/var/adm/utmp file, where the system records who is logged in.  It
therefore doesn't set all the information correctly.

XFree86 3.1 fixes this problem.


\question 26jun  I can't get X Windows to work right.

Read the XFree86 HOWTO - note the question and answer section.

Try reading \newsgroup comp.windows.x.i386unix -- specifically read
the the FAQ for that group.

Please don't post X Windows or XFree86 related questions to \newsgroup
comp.os.linux.x unless they are Linux-specific.


\comment ######################################################################

\section  Questions applicable to very out-of-date software

The questions in this section are only relevant to users of software
that is at least 3 months old.

Please let me know if you find the answer to a problem you had here,
as unused questions in this section will eventually disappear [\qref
feedback].


\question 11feb  Emacs just dumps core.

You probably have a version of Emacs that was compiled to work with
X11; this requires the X11 libraries to work.  If you're using
Slackware you can change the \fn /usr/bin/emacs symbolic link to point
to \fn emacs-19.29-no-x11 instead (see \courier{man ln\}).  This is in
the file \fn emac_nox.tgz on Slackware 3.0's E6 disk.


\question 26jun  \fn fdisk says \courier{cannot use nnn sectors of this partition\}

Originally Linux only supported the Minix filesystem, which cannot use
more than 64Mb per parition.  This limitation is not present in the
more advanced filesystems now available, such as ext2fs (the 2nd
version of the Extended Filesystem, the `standard' Linux filesystem).

If you intend to use ext2fs you can ignore the message.


\question 09sep  GCC sometimes uses huge amounts of virtual memory and thrashes

Older versions of GCC had a bug which made them use lots of memory if
you tried to compile a program which had a large static data table in
it.

You can either upgrade your version of GCC to at least version 2.5, or
add more swap if necessary and just grin and bear it; it'll work in
the end.


\question 09sep  My keyboard goes all funny after I switch VC's.

This is a bug in kernel versions before 0.99pl14-alpha-n.  Sometimes
Linux loses track of what modifier keys (Shift, Alt, Control etc.) are
pressed or not, and believes that one or more are pressed when they
are not.  The solution is to press and release each of the modifier
keys (without pressing any other keys) --- this will ensure that Linux
knows what state the keyboard is actually in.

This problem often occurs when switching out of X windows; it can
sometimes be avoided by releasing Ctrl and Alt very quickly after
pressing the F-key of the VC you are switching to.


\comment ######################################################################

\section  How to get further assistance

\question 26jun:notanswered  You still haven't answered my question !

Please read all of this answer before posting.  I know it's a bit
long, but you may be about to make a fool of yourself in front of
50000 people and waste hundreds of hours of their time.  Don't you
think it's worth it to spend some of your time reading and following
these instructions ?

If you think an answer is incomplete or inaccurate, please mail Ian
Jackson at \email [e-mail].

Read the appropriate Linux Documentation Project books - see \qref
howtos.

If you're a Unix newbie read the FAQ for \newsgroup
comp.unix.questions, and those for any of the other
\courier{comp.unix.*\} groups that may be relevant.

Linux is a Unix clone, so almost everything you read there will apply
to Linux.  Those FAQs can, like all FAQs, be found on \ftpon
rtfm.mit.edu in \ftpin /pub/usenet/news.answers (the \fn
[e-mail] can send you these files, for those who don't
have FTP access).  There are mirrors of \courier{rtfm\}'s FAQ
archives on various sites - check the Introduction to \fn *.answers
posting, posted, or look in \fn news-answers/introduction in the
directory above.

Check the relevant HOWTO for the subject in question, if there is one,
or an appropriate old-style sub-FAQ document.  Check the FTP sites.

Try experimenting --- that's the best way to get to know Unix and Linux.

Read the documentation.  Check the manpages (type \courier{man man\}
if you don't know about manpages.  Try \courier{man -k <subject>\} ---
it often lists useful and relevant manpages.

Check the Info documentation (type \courier{C-h i\}, i.e. Control H
followed by I in Emacs) --- NB: this isn't just for Emacs; for example
the GCC documentation lives here as well.

There will also often be a \fn README file with a package giving
installation and/or usage instructions.

Make sure that you don't have a corrupted or out-of-date copy of the
program in question.  If possible, download it again and reinstall it
--- perhaps you made a mistake the first time.

Read \newsgroup comp.os.linux.announce --- this often contains very
important information for all Linux users.

General X-Windows questions belong in \newsgroup
comp.windows.x.i386unix, not in \fn comp.os.linux.x.  But read the
group first (including the FAQ), before you post !

Only if you have done all of these things and are still stuck should
you post to the appropriate \courier{comp.os.linux.*\} newsgroup.  Make
sure you read the next question, \qref whatinposting, first.


\question 09sep:whatinposting  What to put in a request for help

Please read carefully the following advice about how to write your
posting or email.  Taking heed of it will greatly increase the chances
that an expert and/or fellow user reading it will have enough
information and motivation to reply.

This advice applies both to postings asking for advice and to personal
email sent to experts and fellow users.

Make sure you give full details of the problem, including:
\call startlist
\call item
What program, exactly, you are having problems with.
Include the version number if known and say where you got it.
Many standard commands tell you their version number if you
give them a \fn --version option.

\call item
Which Linux release you're using (MCC, Slackware, Debian or whatever)
and what version of that release.

\call item
The \italic{exact\} and \italic{complete\} text of any error messages
printed.

\call item
Exactly what behaviour you were expecting, and exactly what
behaviour you observed.  A transcript of an example session is a good
way of showing this.

\call item
The contents of any configuration files used by the program in
question and any related programs.

\call item
What version of the kernel and of the shared libraries you are using.
The kernel version can be found by typing \courier{uname -a\}, and the
shared library version by typing \courier{ls -l /lib/libc.so.4\}.

\call item
Details of what hardware you're running on, if it seems appropriate.

\call endlist
You are in little danger of making your posting too long unless you
include large chunks of source code or uuencoded files, so err on the
side of giving too much information.

Use a clear, detailed Subject line.  Don't put things like `doesn't
work', `Linux', `help' or `question' in it --- we already knew that !
Save the space for the name of the program, a fragment of the error
message, summary of the unusual behaviour, etc.

If you are reporting an `unable to handle kernel paging request'
message, follow the instructions in the Linux kernel sources \fn
README for turning the numbers into something more meaningful.  If you
don't do this noone who reads your post will be able to do it for you,
as the mapping from numbers to function names varies from one kernel
to another.

Put a summary paragraph at the top of your posting.

At the bottom of your posting, ask for responses by email and say
you'll post a summary.  Back this up by using \courier{Followup-To:
poster\}.  Then, do actually post a summary in a few days or a week or
so.  Don't just concatenate the replies you got --- summarise.
Putting the word \fn SUMMARY in your summary's Subject line is also a
good idea.  Consider submitting the summary to comp.os.linux.announce.

Make sure your posting doesn't have an inappropriate \fn References
header line.  This marks your article as part of the thread of the
article referred to, which will often cause it to be junked by the
readers with the rest of a boring thread.

You might like to say in your posting that you've read this FAQ and
the appropriate HOWTOs - this may make people less likely to skip your
posting.

Remember that you should not post email sent to you personally without
the sender's permission.


\question 21dec  I want to mail someone about my problem.

Try to find the author or developer of whatever program or component
is causing you difficulty.  If you have a contact point for the Linux
distribution you are using you should use it.

Please put everything in your email that you would put in a posting
asking for help.

Finally, remember that despite the fact that most of the Linux
community are very helpful and responsive to emailed questions you'll
be asking for help from an unpaid volunteer, so you have no right to
expect an answer.


\comment ######################################################################

\section  Administrative information and acknowledgements

\question 26jun:feedback  Feedback is invited

Please send me your comments on this FAQ.

I accept submissions for the FAQ in any format;  All contributions
comments and corrections are gratefully received.

Please send them to \email [e-mail].

If you wish to refer to a question(s) in the FAQ it's most useful for
me if you do so by the question heading, rather than the number, as
the question numbers are generated automatically and I don't see them
in the source file I edit.

I prefer comments in English to patchfiles - I write the FAQ in a
different internal format anyway, so I can't use a patchfile.


\question 26jun:formats  Formats in which this FAQ is available

This document is available as an ASCII text file, an Emacs Info
document, an HTML World Wide Web page, PostScript and as a USENET news
posting.

The ASCII, Emacs Info, HTML and posted versions and a Lout typesetter
file (from which the PostScript is produced) are generated
automatically by a Perl script which takes as input a file in the
Bizarre Format with No Name.

The output files \fn linux-faq.ascii, \fn .info and \fn .ps and a
tarfile \fn linux-faq.source.tar.gz, containing the BFNN source and
Perl script converter, are available in the \fn docs directories of
the major Linux FTP sites.

The HTML version of this FAQ is available as
\courier{http://www.cl.cam.ac.uk/users/iwj10/linux-faq/index.html\}
and is mirrored at \fn www.li.org and other sites.

The USENET version is posted regularly to \newsgroup
comp.os.linux.announce, \newsgroup comp.os.linux.answers, \newsgroup
comp.answers and \newsgroup news.answers.


\question 11feb  Authorship and acknowledgements

This FAQ was compiled by Ian Jackson \email [e-mail],
with assistance and comments from others too numerous to mention.

Special thanks are due to Matt Welsh, who moderated \newsgroup
comp.os.linux.announce and \newsgroup comp.os.linux.answers, used to
coordinate the HOWTOs and has written substantial portions of many of
them, to Greg Hankins, who currently coordinates the HOWTOS, to Lars
Wirzenius, who currently moderates \fn comp.os.linux.announce, and to
Marc-Michel Corsini, who wrote the original Linux FAQ.

Thanks also to the many people who have sent comments and suggestions;
they are too numerous to list here, but their input has been
invaluable.

Last but not least, thanks to Linus Torvalds and the other
contributors to Linux for giving us something to write about !


\question 30oct:faqcopyright  Disclaimer and Copyright

Note that this document is provided as is.  The information in it is
\italic{not\} warranted to be correct; you use it at your own risk.

Linux Frequently Asked Questions with Answers is Copyright 1994, 1995,
1996 by Ian Jackson \email [e-mail].

It may be reproduced and distributed in its entirety (including this
authorship, copyright and permission notice) provided that either:
\call startlist
\call item
the distribution is not commercial (commercial means any
situation in which you benefit financially - directly or indirectly
such as by inclusion in a publication which carries commercial
advertising), or
\call item
the distribution is in machine-readable form (ie, a form intended to
be easily processed by a computer).
\call endlist
Note that this restriction is not intended to prohibit charging for
the service of printing or copying a document supplied by your
customer.

Any distribution of a partial copy or extract, a translation or a
derivative work must be approved by me before distribution.  Email me
- I'll probably be happy to oblige !

Exceptions to these rules may be granted, and I shall be happy to
answer any questions about this copyright --- write to Ian Jackson,
Churchill College, Cambridge, CB3 0DS, United Kingdom or email \email
[e-mail].  These restrictions are here to protect the
contributors, not to restrict you as educators and learners.

Ian Jackson asserts the right to be identified as the author of this
work, and claims the moral rights of paternity and integrity, in
accordance with the Copyright, Designs and Patents Act, 1988.

\copyto POST
END-OF-PORTION
echo posting part 1 ...
inews -h <linux-faq.post-part1
sleep 20
echo posting part 2 ...
inews -h <linux-faq.post-part2
\endcopy
\comment Here it ends!