Subject: Linux Frequently Asked Questions with Answers (FAQ: 1/2)
From: [email-masked] (Ian Jackson)
Date: Wed, 13 Jul 1994 09:01:12 GMT
Newsgroups: comp.os.linux.announce,comp.os.linux.help,comp.answers,news.answers

Archive-Name: linux/faq/part1
Last-Modified: 13 Jul 1994

This is the list of Frequently Asked Questions about Linux, the free Unix
for 386/486 [see Q1.1 `What is Linux ?' for more details].  It should be
read in conjunction with the HOWTO documents, which are available in
   ftp.funet.fi (128.214.6.100)   /pub/OS/Linux/doc/HOWTO
   tsx-11.mit.edu (18.172.1.2)    /pub/linux/docs/HOWTO
   sunsite.unc.edu (152.2.22.81)  /pub/Linux/docs/HOWTO
and mirror sites thereof -- see Q2.5 `Where can I get Linux material by
FTP ?'.  See Q2.1 `Where can I get the HOWTOs and other documentation ?'
for a list of the HOWTOs and more information.  The INFO-SHEET and
META-FAQ, found in the same place, also list other sources of Linux
information.

The Linux Documentation Project documentation is available on
sunsite.unc.edu in /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 Q9.1 `You still
haven't answered my question !', before posting your question to the
newsgroup comp.os.linux.help.

You can skip to a particular question by searching for `Question n.n'.
See Q10.2 `Formats in which this FAQ is available' for details of where to
get the PostScript and Emacs Info versions of this document.

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

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copy is more than a month old it may be out of date.

===============================================================================

Index

 Section 1.  Introduction and General Information
 Q1.1        What is Linux ?
 Q1.2        What software does it support ?
 Q1.3        Does it run on my computer ?  What hardware is supported ?
 Q1.4        How much hard disk space does Linux need ?
 Q1.5        Is Linux PD ?  Copyrighted ?
 Q1.6        How should I pronounce Linux ?

 Section 2.  Network sources and resources
 Q2.1        Where can I get the HOWTOs and other documentation ?
 Q2.2        Where should I look on the World Wide Web for Linux stuff ?
 Q2.3        What newsgroups are there for Linux ?
 Q2.4        How do I install Linux ?
 Q2.5        Where can I get Linux material by FTP ?
 Q2.6        I don't have FTP access.  Where do I get Linux ?
 Q2.7        I don't have Usenet access.  Where do I get information ?
 Q2.8        What's this mailing list thing at niksula.hut.fi ?
 Q2.9        Are the newsgroups archived anywhere ?
 Q2.10       What is the Linux Journal and where can I get it ?

 Section 3.  Compatibility with other operating systems
 Q3.1        Can Linux coexist with DOS ?  OS/2 ?  386BSD ?  Minix ?
 Q3.2        How do I access files on my DOS partition or floppy ?
 Q3.3        Can I use my Stacked/DBLSPC/etc. DOS drive ?
 Q3.4        Can I access OS/2 HPFS partitions from Linux ?
 Q3.5        Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ?
 Q3.6        Can I run Microsoft Windows programs under Linux ?
 Q3.7        How can I boot Linux from OS/2's Boot Manager ?
 Q3.8        How can I share a swap partition between Linux and MS Windows ?

 Section 4.  Linux's handling of filesystems, disks and drives
 Q4.1        How can I undelete files ?
 Q4.2        Is there a defragmenter for ext2fs etc. ?
 Q4.3        How do I format and create a filesystem on a floppy ?
 Q4.4        I get nasty messages about inodes, blocks, and the suchlike
 Q4.5        My swap area isn't working.
 Q4.6        How can I have more than 16Mb of swap ?
 Q4.7        How do I remove LILO so my system boots DOS again ?
 Q4.8        Why can't I use fdformat except as root ?
 Q4.9        Is there something like Stacker or Doublespace for Linux ?
 Q4.10       My ext2fs partitions are checked each time I reboot.
 Q4.11       I have a huge /proc/kcore !  Can I delete it ?
 Q4.12       My AHA1542C doesn't work with Linux.

 Section 5.  Porting, compiling and obtaining programs
 Q5.1        What is ld.so and where do I get it ?
 Q5.2        During linking I get Undefined symbol _mcount
 Q5.3        Has anyone ported / compiled / written XXX for Linux ?
 Q5.4        How do I port XXX to Linux ?
 Q5.5        Can I use code or a compiler compiled for a 486 on my 386 ?
 Q5.6        GCC sometimes uses huge amounts of virtual memory and thrashes
 Q5.7        What does gcc -O6 do ?
 Q5.8        Where are <linux/*.h> and <asm/*.h> ?
 Q5.9        I get errors when I try to compile the kernel.
 Q5.10       How do I make a shared library ?
 Q5.11       How do I make my executables smaller ?

 Section 6.  Miscellaneous questions and problems
 Q6.1        How many people use Linux ?
 Q6.2        How can I get scrollback on text VC's ?
 Q6.3        How do I switch VC's ?  How do I enable them ?
 Q6.4        Setuid scripts don't seem to work.
 Q6.5        Free memory as reported by free keeps shrinking.
 Q6.6        What is a BogoMip ?
 Q6.7        How do I set the timezone ?
 Q6.8        What version of Linux and what machine name am I using ?
 Q6.9        When I add more memory it slows to a crawl.
 Q6.10       Some programs (e.g. xdm) won't let me log in.
 Q6.11       Some programs let me log in with no password.
 Q6.12       My machine runs very slowly when I run GCC / X / ...
 Q6.13       I can only log in as root.
 Q6.14       How can I produce core files ?
 Q6.15       How do I stop producing core files ?
 Q6.16       My keyboard goes all funny after I switch VC's.
 Q6.17       My screen is all full of weird characters instead of letters.
 Q6.18       What is a .gz file ? And a .tgz ? And ... ?
 Q6.19       I have screwed up my system and can't log in to fix it.
 Q6.20       How do I upgrade/recompile my kernel ?
 Q6.21       Can I have more than 3 serial ports by sharing interrupts ?
 Q6.22       Emacs just dumps core.
 Q6.23       How do I make a bootable floppy ?
 Q6.24       How do I remap my keyboard to UK, French, etc. ?
 Q6.25       I've discovered a huge security hole in rm !
 Q6.26       lpr and/or lpd aren't working.
 Q6.27       What does VFS stand for ?
 Q6.28       How do I get NUM LOCK to default to on ?

 Section 7.  Frequently Encountered Error messages
 Q7.1        fdisk says Partition X has different phsyical/logical ...
 Q7.2        fdisk: Partition 1 does not start on cylinder boundary
 Q7.3        lp1 on fire
 Q7.4        INET: Warning: old style ioctl(IP_SET_DEV) called!
 Q7.5        ld: unrecognized option '-m486'
 Q7.6        GCC says Internal compiler error
 Q7.7        make says Error 139
 Q7.8        df says Cannot read table of mounted filesystems
 Q7.9        shell-init: permission denied when I log in.
 Q7.10       No utmp entry.  You must exec ... when I log in.
 Q7.11       EXT2-fs: warning: mounting unchecked filesystem
 Q7.12       EXT2-fs warning: maximal count reached
 Q7.13       EXT2-fs warning: checktime reached
 Q7.14       fdisk says cannot use nnn sectors of this partition
 Q7.15       fdisk says partition n has an odd number of sectors
 Q7.16       mtools says cannot initialise drive XYZ
 Q7.17       Warning - bdflush not running
 Q7.18       Warning: obsolete routing request made.

 Section 8.  The X Window System
 Q8.1        Does Linux support X Windows ?
 Q8.2        Where can I get an Xconfig for my video card and monitor ?
 Q8.3        xterm logins show up strangely in who, finger
 Q8.4        I can't get X Windows to work right.

 Section 9.  How to get further assistance
 Q9.1        You still haven't answered my question !
 Q9.2        What to put in a posting to comp.os.linux.help

 Section 10. Administrative information and acknowledgements
 Q10.1       Feedback is invited
 Q10.2       Formats in which this FAQ is available
 Q10.3       Authorship and acknowledgements
 Q10.4       Disclaimer and Copyright

===============================================================================

Section 1.  Introduction and General Information

 Q1.1        What is Linux ?
 Q1.2        What software does it support ?
 Q1.3        Does it run on my computer ?  What hardware is supported ?
 Q1.4        How much hard disk space does Linux need ?
 Q1.5        Is Linux PD ?  Copyrighted ?
 Q1.6        How should I pronounce Linux ?

-------------------------------------------------------------------------------

Question 1.1.  What is Linux ?

Linux is a Unix clone for 386/486-based PCs 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 uses the hardware features of the 386 processor family (TSS segments et
al) to implement these features.

See the Linux INFO-SHEET [Q2.1 `Where can I get the HOWTOs and other
documentation ?'] for more details.

It is distributed under the GNU General Public License - see Q1.5 `Is
Linux PD ?  Copyrighted ?' for more details.

-------------------------------------------------------------------------------

Question 1.2.  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 [Q3.1 `Can Linux coexist with DOS ?  OS/2 ?
386BSD ?  Minix ?'] and work is progressing on a facilities to allow SVR4
ELF, SVR3.2 COFF and Microsoft Windows binaries [Q3.6 `Can I run Microsoft
Windows programs under Linux ?'] to be run under Linux and X Windows.

For more information see the INFO-SHEET, which is one of the the HOWTOs
--- see above, or Q2.1 `Where can I get the HOWTOs and other documentation
?'.  See also Q5.4 `How do I port XXX to Linux ?'.

Some companies have commercial software available, including Motif.  They
announce their availability in comp.os.linux.announce --- try searching
the archives [Q2.9 `Are the newsgroups archived anywhere ?'].

-------------------------------------------------------------------------------

Question 1.3.  Does it run on my computer ?  What hardware is supported ?

You need a 386 or 486, with at least 2Mb of RAM and a single floppy, to
try it out.  To do anything useful more RAM and a hard disk are required.
Reportedly Linux also works on a Pentium.

VESA local bus and PCI are both supported.  However, a driver for the NCR
SCSI chip in many PCI machines is not yet available, but is under
development.

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 invaders.dcrl.nd.edu in /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-masked]>.

Linux is reported to run on 386/486-based laptops, with X on most of them.

For details of exactly which PC's, video cards, disk controllers, etc.
work see the INFO-SHEET and the Hardware Compatibility HOWTO [Q2.1 `Where
can I get the HOWTOs and other documentation ?'].

Linux will never run on a 286, because it uses task-switching and memory
management facilities only found on 386/486 processors.

A project has been underway for nearly a year now to port Linux to
suitable 68000-series based systems such as Amigas and Ataris, but this is
still at an early stage of development.  Don't post asking about it unless
you think you can contribute to it, and don't hold your breath.

Work has just been started on a port to the PowerPC.  Currently this will
be based on the PowerMAC architecture.  Again, don't post asking about it
unless you have experience to offer, and don't hold your breath.

Neither of these ports will be capable of running Linux/386 binaries.

-------------------------------------------------------------------------------

Question 1.4.  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.  The SLS 1.03 distribution (which I would recommend you stay well
clear of - it has a number of serious and annoying bugs) takes around
100Mb.

-------------------------------------------------------------------------------

Question 1.5.  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.

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

The copyright 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 gnu.misc.discuss and not to the comp.os.linux groups.

-------------------------------------------------------------------------------

Question 1.6.  How should I pronounce Linux ?

This is a matter of religious debate, of course !

If you want to hear the Linus himself say how he pronounces it download
english.au or swedish.au from ftp.funet.fi (in
/pub/OS/Linux/PEOPLE/Linus/SillySounds).  If you have a soundcard or the
PC-speaker audio driver you can hear them by typing
   cat english.au >/dev/audio
The difference isn't in the pronunciation of Linux but in the language
Linus uses to say hello.

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.

===============================================================================

Section 2.  Network sources and resources

 Q2.1        Where can I get the HOWTOs and other documentation ?
 Q2.2        Where should I look on the World Wide Web for Linux stuff ?
 Q2.3        What newsgroups are there for Linux ?
 Q2.4        How do I install Linux ?
 Q2.5        Where can I get Linux material by FTP ?
 Q2.6        I don't have FTP access.  Where do I get Linux ?
 Q2.7        I don't have Usenet access.  Where do I get information ?
 Q2.8        What's this mailing list thing at niksula.hut.fi ?
 Q2.9        Are the newsgroups archived anywhere ?
 Q2.10       What is the Linux Journal and where can I get it ?

-------------------------------------------------------------------------------

Question 2.1.  Where can I get the HOWTOs and other documentation ?

Look in the following places, and on sites that mirror them.
   ftp.funet.fi (128.214.6.100)   /pub/OS/Linux/doc/HOWTO
   tsx-11.mit.edu (18.172.1.2)    /pub/linux/docs/HOWTO
   sunsite.unc.edu (152.2.22.81)  /pub/Linux/docs/HOWTO
For a complete list of Linux FTP sites see Q2.4 `How do I install Linux
?'.

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

A complete list of HOWTO's is available in the file HOWTO.INDEX in the
docs/HOWTO directory at the FTP sites, but here is a (possibly incomplete)
list:

          Installation HOWTO            Electronic Mail HOWTO
          Linux INFO-SHEET              UUCP HOWTO
          Linux META-FAQ                SCSI HOWTO
          NET-2 HOWTO                   Printing HOWTO
          Ethernet HOWTO                Hardware Comaptibility HOWTO
          News HOWTO                    XFree86 HOWTO
          Distribution HOWTO            MGR HOWTO
          Ftape HOWTO                   Sound HOWTO
          JE HOWTO                      Busmouse HOWTO
          Keystroke HOWTO

Some more of these documents are 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 a few mini-HOWTOs in the docs/HOWTO/mini
directory.

The HOWTO.INDEX also contains information on how to write a new HOWTO.

The HOWTOs are coordinated by Matt Welsh, <[email-masked]>.

The `books' produced by the Linux Documentation Project are available in
/pub/Linux/docs/LDP on sunsite.unc.edu.  Please read them if you are new
to Unix and Linux.  Here is a list of those released so far:

          The Linux Documentation Project manifesto
          Installation and Setup Guide for Linux
          The Kernel Hacker's Guide
          Network Administration Guide
          Linux System Administrator's Guide

-------------------------------------------------------------------------------

Question 2.2.  Where should I look on the World Wide Web for Linux stuff ?

Matt Welsh maintains the Linux Home Page, at
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 and those which aren't.

-------------------------------------------------------------------------------

Question 2.3.  What newsgroups are there for Linux ?

There are five international Usenet newsgroups devoted to Linux.

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 [email-masked].

comp.os.linux.help, comp.os.linux.development, comp.os.linux.admin and
comp.os.linux.misc are also worth reading -- you may find that many common
problems are too recent to find in this FAQ but are answered in the
newsgroups.

Remember that since Linux is a Unix clone, most all of the material in
comp.unix.* and 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 Q9.1 `You still haven't answered my question !' before
posting, and make sure you post to the right newsgroup.  Crossposting is
rarely a good idea.

See also Q2.7 `I don't have Usenet access.  Where do I get information ?'.

Other regional and local newsgroups also exist - you may find the traffic
more manageable there.  The French Linux newsgroup is fr.comp.os.linux;
there is probably also a German one.  In Australia, try
aus.computers.linux.

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

-------------------------------------------------------------------------------

Question 2.4.  How do I install Linux ?

There are several pre-packaged releases of Linux available, including the
MCC-Interim release, the TAMU release and the Slackware release.  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.  If you prefer a small, clean distribution to one
with everything but the kitchen sink you might like to try the MCC-Interim
release.

All of these releases are available via anonymous FTP from the Linux
archive sites [Q2.5 `Where can I get Linux material by FTP ?'].

-------------------------------------------------------------------------------

Question 2.5.  Where can I get Linux material by FTP ?

There are three main archive sites for Linux:
   ftp.funet.fi (128.214.248.6)   /pub/OS/Linux
   sunsite.unc.edu (152.2.22.81)  /pub/Linux
   tsx-11.mit.edu (18.172.1.2)    /pub/linux
The MCC-Interim release is available from:
   ftp.mcc.ac.uk (130.88.200.7)   /pub/linux
The TAMU release is available from:
   net.tamu.edu (128.194.177.1)   /pub/linux

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.
   src.doc.ic.ac.uk                     wuarchive.wustl.edu
   sunacm.swan.ac.uk                    ftp.eecs.umich.edu
   ftp.ibp.fr                           mrcnext.cso.uiuc.edu

   ftp.informatik.tu-muenchen.de        bond.edu.au
   ftp.ibr.cs.tu-bs.de                  monu1.cc.monash.edu.au
   ftp.dfv.rwth-aachen.de               ftp.sun.ac.za
   ftp.informatik.rwth-aachen.de        cair.kaist.ac.kr
Not all of these mirror all of the other `source' sites, and some have
material not available on the `source' sites.

-------------------------------------------------------------------------------

Question 2.6.  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 [email-masked], [email-masked] or
[email-masked].

Linux is also available via traditional mail on diskette, CD-ROM and tape.
The Installation HOWTO, and the file /pub/Linux/docs/distributions on
sunsite.unc.edu, contains information on these distributions.

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

-------------------------------------------------------------------------------

Question 2.7.  I don't have Usenet access.  Where do I get information ?

Digests of postings to the comp.os.linux.* groups are available by
subscribing to the bidirectional gateway at
[email-masked], where * is one of announce,
development, help, misc or admin.

You are strongly advised to subscribe to at least
[email-masked], as this carries important
information and documentation about Linux.

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

-------------------------------------------------------------------------------

Question 2.8.  What's this mailing list thing at niksula.hut.fi ?

It's a multi-channel mailing list, mainly used by the developers of Linux
to talk about technical issues and future developments.  Most of the
channels are not intended for new users to ask their questions on.

The ANNOUNCE channel is a digest of postings to comp.os.linux.announce,
for the benefit of those without Usenet access.  However since
niksula.hut.fi is slow and overloaded I'd recommend subscribing to the MIT
digestifier instead [Q2.7 `I don't have Usenet access.  Where do I get
information ?'].

There is also a NEWBIE channel where `no question is too stupid';
unfortunately it seems that few of the experienced users read that
channel, probably because of all the `stupid' questions !

If you want to subscribe to one or more of the channels at the
multi-channel list, send an empty mail message to
[email-masked] and you'll receive the instructions
for operating the list subscription software.

If you want to unsubscribe send a mail message like this
  From: [email-masked]
  To: [email-masked]
  Subject: irrelevant

  X-Mn-Admin: leave CHANNEL
to leave a channel called CHANNEL.  Do *not* put an X-Mn-Key line in your
message - that will cause it to be posted to the list.

Note that you *must* remember to unsubscribe *before* you change your
email address, as due to a design flaw in the list server it is virtually
impossible to get yourself unsubscribed after such a change.

-------------------------------------------------------------------------------

Question 2.9.  Are the newsgroups archived anywhere ?

Yes.  ftp.funet.fi and tsx-11.mit.edu contain archives of both
comp.os.linux.announce and the old group comp.os.linux, in their Linux
areas.  The comp.os.linux.announce archives are mirrored from /usenet on
src.doc.ic.ac.uk (which also contains another archive of comp.os.linux).

-------------------------------------------------------------------------------

Question 2.10.  What is the Linux Journal and where can I get it ?

It's a normal magazine published monthly on paper (not electronically) by
Lasermoon Ltd.  Contact their semiautomatic mail server on
[email-masked] for details.

===============================================================================

Section 3.  Compatibility with other operating systems

 Q3.1        Can Linux coexist with DOS ?  OS/2 ?  386BSD ?  Minix ?
 Q3.2        How do I access files on my DOS partition or floppy ?
 Q3.3        Can I use my Stacked/DBLSPC/etc. DOS drive ?
 Q3.4        Can I access OS/2 HPFS partitions from Linux ?
 Q3.5        Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ?
 Q3.6        Can I run Microsoft Windows programs under Linux ?
 Q3.7        How can I boot Linux from OS/2's Boot Manager ?
 Q3.8        How can I share a swap partition between Linux and MS Windows ?

-------------------------------------------------------------------------------

Question 3.1.  Can Linux coexist with DOS ?  OS/2 ?  386BSD ?  Minix ?

Yes.  Linux uses the standard PC partitioning scheme, so it can share your
disk with other operating systems.

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 a DOS emulator (look on tsx-11.mit.edu in
/pub/linux/ALPHA/dosemu) which can run DOS itself and some (but not all)
DOS applications.

Linux can also access Minix and System V UFS filesystems.

-------------------------------------------------------------------------------

Question 3.2.  How do I access files on my DOS partition or floppy ?

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

You can use the conv=text/binary/auto, umask=nnn, uid=nnn and 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 /etc/fstab you can
record the options (comma-separated) there, instead of defaults.

Alternatively you can use `mtools', available in both binary and source
form on the FTP sites -- see Q2.4 `How do I install Linux ?'.

-------------------------------------------------------------------------------

Question 3.3.  Can I use my Stacked/DBLSPC/etc. DOS drive ?

Not easily.  You can access them from within the DOS emulator [Q3.1 `Can
Linux coexist with DOS ?  OS/2 ?  386BSD ?  Minix ?'], but not as a normal
filesystem under Linux or using mtools.

-------------------------------------------------------------------------------

Question 3.4.  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 [Q6.20 `How do I upgrade/recompile my
kernel ?'].  Then you can mount it using the mount command, for example:
        mkdir /hpfs
        mount -t hpfs /dev/hda5 /hpfs

-------------------------------------------------------------------------------

Question 3.5.  Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ?

I'm told that there is an alpha test read-only Amiga filesystem on
sunsite.unc.edu, probably in /pub/Linux/kernel/misc-patches/ffs-patch.
Work may well be progressing on upgrading this to read-write for the 680x0
Linux project.

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

-------------------------------------------------------------------------------

Question 3.6.  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
comp.os.linux.announce.

The advert from Softlanding (producers of SLS) stating that Linux could
run MS Windows binaries was at best grossly exaggerated.  I'm told that
you can run Windoze 3.0 in real mode in a dosemu [Q3.1 `Can Linux coexist
with DOS ?  OS/2 ?  386BSD ?  Minix ?'].

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 3.7.  How can I boot Linux from OS/2's Boot Manager ?

1. Create a partition using OS/2's FDISK (Not Linux's 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.

3. Add the partition to the Boot Manager.

4. Boot Linux, and create a filesystem on the partition using mkfs -t ext2
or mke2fs.  At this point you may, if you like, use Linux's 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
   boot = /dev/hda2
(where /dev/hda2 is the *partition* you want to boot off) in your
/etc/lilo/config or /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 3.8.  How can I share a swap partition between Linux and MS Windows ?

See the Mini-HOWTO on the subject by H. Peter Anvin, <[email-masked]>.
It is available on sunsite.unc.edu in /pub/Linux/docs.

===============================================================================

Section 4.  Linux's handling of filesystems, disks and drives

 Q4.1        How can I undelete files ?
 Q4.2        Is there a defragmenter for ext2fs etc. ?
 Q4.3        How do I format and create a filesystem on a floppy ?
 Q4.4        I get nasty messages about inodes, blocks, and the suchlike
 Q4.5        My swap area isn't working.
 Q4.6        How can I have more than 16Mb of swap ?
 Q4.7        How do I remove LILO so my system boots DOS again ?
 Q4.8        Why can't I use fdformat except as root ?
 Q4.9        Is there something like Stacker or Doublespace for Linux ?
 Q4.10       My ext2fs partitions are checked each time I reboot.
 Q4.11       I have a huge /proc/kcore !  Can I delete it ?
 Q4.12       My AHA1542C doesn't work with Linux.

-------------------------------------------------------------------------------

Question 4.1.  How can I undelete files ?

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

In the meantime you can search the raw disk device which holds the
filesystem in question.  The strings command may help you do this, if the
file you've lost was a text file: for example strings /dev/hdb3.  You will
need to be root to do this, and you should take care to put the output
file on a different filesystem, of course ! The output will be large and
full of extra unwanted crud, so make sure you have enough space.

-------------------------------------------------------------------------------

Question 4.2.  Is there a defragmenter for ext2fs etc. ?

You can probably do without, since the ext2 filesystem code tries to
reduce fragmentation as it goes, during normal operation.

If you really need to defragment a filesystem you could back it up,
reinitialise the partition using mkfs -t ext2 and restore it.

I'm told that a defragmenter for Minix and old-style `ext' filesystems is
available on sunsite.unc.edu in system/Filesystems/defrag-0.4.tar.z.

-------------------------------------------------------------------------------

Question 4.3.  How do I format and create a filesystem on a floppy ?

For a 3.5 inch high density floppy:
   fdformat /dev/fd0H1440
   mkfs -t ext2 -m 0 /dev/fd0H1440 1440
For a 5.25 inch floppy use fd0h1200 and 1200 as appropriate.  For the `B'
drive use fd1 instead of fd0.  Full details of which floppy devices do
what can be found in the Linux Device List [Q2.1 `Where can I get the
HOWTOs and other documentation ?'].  If you don't have the fsutils package
you'll have to run mke2fs instead of mkfs -t ext2.  The -m 0 option tells
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 cp and mv files, etc.

-------------------------------------------------------------------------------

Question 4.4.  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 shutdown program to do this --- for example, the one
included in the bootutils package, available on sunsite and tsx-11.

If you're lucky the program fsck (or e2fsck or xfsck as appropriate if you
don't have the fsutils package) will be able to repair your filesystem; if
you're unlucky the filesystem is trashed and you'll have to reinitialise
it with mkfs (or mke2fs, 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
   VFS: mounted root ... read-only
at boot time.

-------------------------------------------------------------------------------

Question 4.5.  My swap area isn't working.

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

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

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

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

-------------------------------------------------------------------------------

Question 4.6.  How can I have more than 16Mb of swap ?

Use a recent kernel -- from at least 0.99.14 Linux can use swap partitions
of up to 128Mb.

If you use an older kernel which only supports swap area sizes up to 16Mb
you have to set up more than one swap partition or swapfile.

-------------------------------------------------------------------------------

Question 4.7.  How do I remove LILO so my system boots DOS again ?

Using DOS (MS-DOS 5.0 or later, or OS/2), type FDISK /MBR.  This will
restore a standard MS-DOS Master Boot Record.  If you have DR-DOS 6.0, go
into 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 boot.0301 or some such.  Type
   dd if=boot.0301 of=/dev/hda bs=445 count=1
(or 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
   dd if=/dev/zero of=/dev/hda bs=512 count=1
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 4.8.  Why can't I use fdformat except as root ?

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

-------------------------------------------------------------------------------

Question 4.9.  Is there something like Stacker or Doublespace for Linux ?

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

There is a transparently uncompressing C library, which is a drop-in
replacement for the standard C library.  It allows programs to read
compressed (ie, GNU zipped) files as if they were not compressed.  You
install it, and then you can compress files using gzip and have programs
still find them.  Look on sunsite.unc.edu in /pub/Linux/libs.  The author
is Alain Knaff <[email-masked]>.

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 sunsite.unc.edu
in /pub/Linux/utils/compress; the auther is Jean-Marc Verbavatz
<[email-masked]>.  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 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 [Q2.5 `Where can I get Linux
material by FTP ?']; it was also announced in comp.os.linux.announce.
Note - this is not the same as gzexe, which is an inferior implementation
of the same concept.

-------------------------------------------------------------------------------

Question 4.10.  My ext2fs partitions are checked each time I reboot.

See Q7.11 `EXT2-fs: warning: mounting unchecked filesystem'.

-------------------------------------------------------------------------------

Question 4.11.  I have a huge /proc/kcore !  Can I delete it ?

None of the files in /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.

/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 4.12.  My AHA1542C doesn't work with 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.
The option to allow disks with more than 1024 cylinders is only required
as a workaround for a DOS misfeature and should be turned *off* under
Linux.

===============================================================================

Section 5.  Porting, compiling and obtaining programs

 Q5.1        What is ld.so and where do I get it ?
 Q5.2        During linking I get Undefined symbol _mcount
 Q5.3        Has anyone ported / compiled / written XXX for Linux ?
 Q5.4        How do I port XXX to Linux ?
 Q5.5        Can I use code or a compiler compiled for a 486 on my 386 ?
 Q5.6        GCC sometimes uses huge amounts of virtual memory and thrashes
 Q5.7        What does gcc -O6 do ?
 Q5.8        Where are <linux/*.h> and <asm/*.h> ?
 Q5.9        I get errors when I try to compile the kernel.
 Q5.10       How do I make a shared library ?
 Q5.11       How do I make my executables smaller ?

-------------------------------------------------------------------------------

Question 5.1.  What is ld.so and where do I get it ?

ld.so is the new 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,
/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 tsx-11.mit.edu in /pub/linux/packages/GCC and
mirror sites thereof.  The latest version at the time of writing is
ld.so.1.4.4.tar.gz.

-------------------------------------------------------------------------------

Question 5.2.  During linking I get Undefined symbol _mcount

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

-------------------------------------------------------------------------------

Question 5.3.  Has anyone ported / compiled / written XXX for Linux ?

First, look in the Linux Software Map (LSM) --- it's in the docs directory
on sunsite.unc.edu, and on the other FTP sties.

Check the FTP sites (see Q2.1 `Where can I get the HOWTOs and other
documentation ?') first --- search the find-ls or INDEX files for
appropriate strings.

If you don't find anything, you could either download the sources to the
program yourself and compile them -- see Q5.4 `How do I port XXX to Linux
?' -- or, if it's a large package which may require some porting, post a
message to the newsgroup.

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

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

You should also check the Projects-FAQ, available in
/pub/Linux/docs/faqs/Projects-FAQ on sunsite.unc.edu.

-------------------------------------------------------------------------------

Question 5.4.  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 -I/usr/include/bsd and
-lbsd on the appropriate parts of the compilation lines.

-------------------------------------------------------------------------------

Question 5.5.  Can I use code or a compiler compiled for a 486 on my 386 ?

Yes.

The -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.

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

-------------------------------------------------------------------------------

Question 5.6.  GCC sometimes uses huge amounts of virtual memory and thrashes

Older versions of GCC had a bug which makes it use lots of memory if you
try to compile a program which has a large static data table in it.

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

-------------------------------------------------------------------------------

Question 5.7.  What does gcc -O6 do ?

The same as -O2; any number greater than 2 currently works just like 2.
The Makefiles of newer kernels use -O2, and so should you.

-------------------------------------------------------------------------------

Question 5.8.  Where are <linux/*.h> and <asm/*.h> ?

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

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

If you don't have the kernel sources download them --- see Q6.20 `How do I
upgrade/recompile my kernel ?'.

Then use rm to remove any garbage, and ln to create the links:
   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

-------------------------------------------------------------------------------

Question 5.9.  I get errors when I try to compile the kernel.

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

If necessary, delete them using rm and then use ln -s to make the links as
in Q5.8 `Where are <linux/*.h> and <asm/*.h> ?'.

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

-------------------------------------------------------------------------------

Question 5.10.  How do I make a shared library ?

Get tools-n.nn.tar.gz from tsx-11.mit.edu, in /pub/linux/packages/GCC/src.
It comes with documentation that will tell you what to do.

-------------------------------------------------------------------------------

Question 5.11.  How do I make my executables smaller ?

The most common cause of large executables is the -g 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 -O and -O2 which enable
optimisation (check the GCC documentation) and -s which strips the symbol
information from the resulting binary (making debugging totally
impossible).

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

===============================================================================

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

-- 
Ian Jackson, at home.         [email-masked] or [email-masked]
+44 223 575512    Escoerea on IRC.    http://www.cl.cam.ac.uk/users/iwj10/
2 Lexington Close, Cambridge, CB4 3LS, England.   Urgent: [email-masked]