Linux Frequently Asked Questions with Answers
Linux Frequently Asked Questions with Answers (Part 1 of 6)
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Last-modified: 12/04/2001
Linux Frequently Asked Questions with Answers
This is the list of Frequently Asked Questions for Linux, the free
operating system kernel that runs on many modern computer systems. The
kernel source code documentation says that Linux "aims for POSIX
compliance." Linux uses mostly free, GNU system utilities and
application software, although commercial programs are available also.
Originally written for 386/486/586 Intel/ISA bus machines, Linux
versions exist for nearly every hardware platform in existence that is
capable of running it. (Please refer to the question, "What Is Linux?"
below.) This FAQ is meant to be read in conjunction with the Linux
Documentation Project's HOWTO series. ("Where Are the Linux FTP
Archives?" and, "Where Is the Documentation?") The INFO-SHEET and
META-FAQ also list sources of Linux information. Please read them,
and, "If this Document Still Hasn't Answered Your Question...." before
posting to a Usenet news group. You can also get Postscript, PDF,
HTML, and SGML versions of this document. ("Formats in Which This FAQ
Is Available.") Linux Frequently Asked Questions with Answers is
distributed under the terms of the GNU Free Documentation License.
Refer to "Disclaimer and Copyright.."
1. Introduction and General Information
1.1. What Is Linux?
1.2. How to Get Started.
1.3. What Software does Linux Support?
1.4. How to Find a Particular Application.
1.5. What Hardware Is Supported?
1.6. Ports to Other Processors.
1.7. Disk Space Requirements: Minimal, Server, and Workstation.
1.8. Minimum and Maximum Memory Requirements.
1.9. Does Linux Support Universal System Bus Devices?
1.10. What Is Linux's Open-Source License?
1.11. Is Linux *nix?
2. Network Sources and Resources
2.1. Where Is the Latest Kernel Version on the Internet?
2.2. Where Is the Documentation?
2.3. Where Is the Linux Stuff on the World Wide Web?
2.4. What News Groups Are There for Linux?
2.5. What Other FAQ's and Documentation Are There for Linux?
2.6. Where Are the Linux FTP Archives?
2.7. How To Get Linux without FTP Access.
2.8. How To Get Information without Usenet Access.
2.9. What Mailing Lists Are There?
2.10. Where Are Linux Legal Issues Discussed?
2.11. Sources of Information for Unmaintained Free Software
Projects.
2.12. Are the News Groups Archived Anywhere?
2.13. Where To Find Information About Security Related Issues.
2.14. Where To Find Linux System Specifications.
3. Compatibility with Other Operating Systems
3.1. Can Linux Use the Same Hard Drive as MS-DOS? OS/2? 386BSD?
Win95?
3.2. How To Access Files on a MS-DOS Partition or Floppy.
3.3. Does Linux Support Compressed Ext2 File Systems?
3.4. Can Linux Use Stacked/DBLSPC/Etc. DOS Drives?
3.5. Can Linux Access OS/2 HPFS Partitions?
3.6. Can Linux Access Amiga File Systems?
3.7. Can Linux Access BSD, SysV, Etc. UFS?
3.8. Can Linux Access SMB File Systems?
3.9. Can Linux Access Macintosh File Systems?
3.10. Can Linux Run Microsoft Windows Programs?
3.11. Where Is Information about NFS Compatibility?
3.12. Can Linux Use True Type Fonts?
3.13. Can Linux Boot from MS-DOS?
3.14. How Can Linux Boot from OS/2's Boot Manager?
4. File Systems, Disks, and Drives
4.1. How To Get Linux to Work with a Disk.
4.2. How To Undelete Files.
4.3. How To Make Backups.
4.4. How To Resize a Partition (Non-Destructively).
4.5. Is There a Defragmenter for Ext2fs?
4.6. How To Create a File System on a Floppy.
4.7. Does Linux Support Virtualized File Systems Like RAID?
4.8. Does Linux Support File System Encryption?
4.9. Linux Prints Nasty Messages about Inodes, Blocks, and the
Like.
4.10. The Swap Area Isn't Working.
4.11. How To Add Temporary Swap Space.
4.12. How To Remove LILO So the System Boots DOS Again?
4.13. Why Does fdformat Require Superuser Privileges?
4.14. The System Checks the Ext2fs Partitions Each Reboot.
4.15. Root File System Is Read-Only.
4.16. What Is /proc/kcore?
4.17. The AHA1542C Doesn't Work with Linux.
4.18. Where Is the Journalling File System on the Net?
5. Porting, Compiling and Obtaining Programs
5.1. How To Compile Programs.
5.2. How To Install GNU Software.
5.3. Where To Get Java.
5.4. How To Port XXX to Linux.
5.5. What Is ld.so and How To Get It?
5.6. How To Upgrade the Libraries without Trashing the System.
5.7. How To Use Code or a Compiler Compiled for a 486 on a 386.
5.8. What Does "gcc -O6" Do?
5.9. Where Are linux/*.h and asm/*.h?
5.10. What To Do about Errors Trying to Compile the Kernel.
5.11. How To Make a Shared Library.
5.12. Programs Are Very Large.
5.13. Does Linux Support Threads or Lightweight Processes?
5.14. Where To Find lint for Linux.
5.15. Where To Find Kermit for Linux.
5.16. How To Use Linux with a Cable Modem.
5.17. Is There an ICQ Program That Runs under Linux?
6. Solutions to Common Miscellaneous Problems
6.1. FTP Transfers Seem to Hang.
6.2. Free Dumps Core.
6.3. Netscape Crashes Frequently.
6.4. FTP or Telnet Server Won't Allow Logins.
6.5. How To Keep Track of Bookmarks in Netscape?
6.6. The Computer Has the Wrong Time.
6.7. Setuid Scripts Don't Seem to Work.
6.8. Free Memory as Reported by free Keeps Shrinking.
6.9. When Adding More Memory, the System Slows to a Crawl.
6.10. Some Programs (E.g. xdm) Won't Allow Logins.
6.11. Some Programs Allow Logins with No Password.
6.12. The Machine Runs Very Slowly with GCC / X / ...
6.13. System Only Allows Root Logins.
6.14. The Screen Is All Full of Weird Characters Instead of
Letters.
6.15. I Screwed Up the System and Can't Log In to Fix It.
6.16. I Forgot the root Password.
6.17. There's a Huge Security Hole in rm!
6.18. lpr and/or lpd Don't Work.
6.19. Timestamps on Files on MS-DOS Partitions Are Set
Incorrectly
6.20. How To Get LILO to Boot the Kernel Image.
6.21. How To Make Sure the System Boots after Re-Installing the
Operating System.
6.22. The PCMCIA Card Doesn't Work after Upgrading the Kernel.
6.23. How To Remove (or Change) the Colors in the ls Display.
6.24. Why Won't a Program Work in the Current Directory?
7. How To Do This or Find Out That...
7.1. How To Find Out If a Notebook Runs Linux.
7.2. Installing Linux Using FTP.
7.3. Resuming an Interrupted Download.
7.4. Boot-Time Configuration.
7.5. Formatting Man Pages without man or groff.
7.6. How To Scroll Backwards in Text Mode.
7.7. How To Get Email to Work.
7.8. Sendmail Pauses for Up to a Minute at Each Command.
7.9. How To Enable and Select Virtual Consoles.
7.10. How To Set the Time Zone.
7.11. Dial-up PPP Configuration.
7.12. What Version of Linux and What Machine Name Is This?
7.13. What Is a "core" File?
7.14. How To Enable or Disable Core Dumps.
7.15. How To Upgrade/Recompile a Kernel.
7.16. Can Linux Use More than 3 Serial Ports by Sharing
Interrupts?
7.17. Configuring Emacs's Default Settings.
7.18. How To Make a Rescue Floppy.
7.19. How To Remap a Keyboard to UK, French, Etc.?
7.20. How To Get NUM LOCK to Default to On.
7.21. How To Set (Or Reset) Initial Terminal Colors.
7.22. How To Have More Than 128Mb of Swap.
How To Prevent Errors when Linking Programs with Math Functions.
8. Miscellaneous Information and Questions Answered
8.1. How To Program XYZ Under Linux.
8.2. What's All This about ELF? glibc?
8.3. How To Determine What Packages Are Installed on a System.
8.4. What Is a .gz File? And a .tgz? And .bz2? And... ?
8.5. What Does VFS Stand For?
8.6. What is a BogoMip?
8.7. What Online/Free Periodicals Exist for Linux?
8.8. How Many People Use Linux?
8.9. How Many People Use Linux? (Redux.)
8.10. What Is the Best (Distribution|SCSI Card|Editor|CD-ROM
Drive|....)
8.11. How Does One Pronounce Linux?
9. Frequently Encountered Error Messages
9.1. Modprobe Can't Locate Module, XXX, and Similar Messages.
9.2. Unknown Terminal Type "linux" and Similar.
9.3. INET: Warning: old style ioctl... called!
9.4. ld: unrecognized option '-m486'
9.5. GCC Says, "Internal compiler error."
9.6. Make Says, "Error 139."
9.7. Shell-Init: Permission Denied when I Log In.
9.8. No Utmp Entry. You Must Exec ... when Logging In.
9.9. Warning--bdflush Not Running.
9.10. Warning: obsolete routing request made.
9.11. EXT2-fs: warning: mounting unchecked file system.
9.12. EXT2-fs warning: maximal count reached.
9.13. EXT2-fs warning: checktime reached.
9.14. df Says, "Cannot read table of mounted file systems."
9.15. fdisk Says, "Partition X has different physical/logical..."
9.16. fdisk: Partition 1 does not start on cylinder boundary.
9.17. fdisk Says Partition n Has an Odd Number of Sectors.
9.18. Mtools Utilities Say They Cannot Initialize Drive X.
9.19. At the Start of Booting: Memory tight
9.20. The System Log Says, "end_request: I/O error, ...."
9.21. "You don't exist. Go away."
9.22. "Operation not permitted."
9.23. programname: error in loading shared libraries: lib
xxx..so. x: cannot open shared object file: No such file
or directory.
9.24. "init: Id "x" respawning too fast: disabled for 5 minutes."
9.25. FTP server says: "421 service not available, remote server
has closed connection."
10. The X Window System
10.1. Does Linux Support X?
10.2. How To Get the X Window System to Work.
10.3. Where To Find a Ready-Made XF86Config file.
10.4. What Desktop Environments Run on Linux?
10.5. xterm Logins Show Up Strangely in who, finger.
10.6. How to Start a X Client on Another Display.
11. How to Get Further Assistance
11.1. If this Document Still Hasn't Answered Your Question....
11.2. What to Put in a Request for Help.
11.3. How To Email Someone about Your Problem.
12. Acknowledgments and Administrivia
12.1. Where To Send Comments.
12.2. Formats in Which This FAQ Is Available.
12.3. Authorship and Acknowledgments.
12.4. Disclaimer and Copyright.
1. Introduction and General Information
1.1. What Is Linux?
Linux is the kernel of operating systems that look like and perform as
well or better than the famous operating system from AT&T Bell Labs.
Linus Torvalds and a loosely knit team of volunteer hackers from
across the Internet wrote (and still are writing) Linux from scratch.
It has all of the features of a modern, fully fledged operating
system: true multitasking, threads, virtual memory, shared libraries,
demand loading, shared, copy-on-write executables, proper memory
management, loadable device driver modules, video frame buffering, and
TCP/IP networking.
Most people, however, refer to the operating system kernel, system
software, and application software, collectively, as "Linux," and that
convention is used in this FAQ as well.
Linux was written originally for 386/486/586-based PC's, using the
hardware facilities of the 80386 processor family to implement its
features. There are now many ports to other hardware platforms.
("Ports to Other Processors.")
There are also Linux distributions specifically for mobile and
handheld platforms. An API specification and developers kit for the
Crusoe Smart Microprocessor developed by Transmeta Corporation are at
http://www.transmeta.com/. Information on the Linux distribution for
the Compaq iPAQ is at http://www.handhelds.org/
Refer also to the Linux INFO-SHEET for more details as well as the
answers to "Where Is the Documentation?", "What Hardware Is
Supported?", and "Ports to Other Processors.", below. A list updated
weekly is at: http://lwn.net/ Archive of many of the distributions are
on line at: ftp://ftp.tux.org/ and http://planetmirror.com/pub/linux.
The Linux kernel is distributed under the GNU General Public License.
("What Is Linux's Open-Source License?")
There is a historical archive of all versions of the Linux kernel at
http://ps.cus.umist.ac.uk/~rhw/kernel.versions.html.
1.2. How to Get Started.
There are a handful of major Linux distributions. For information
about them, and how they are installed, see Matthew Welsh's
Installation and Getting Started, or IGS for short. It's located at
the Linux Documentation Project Home Page, http://www.linuxdoc.org/ ,
and on the Linux FAQ home page, http://www.mainmatter.com/
The information in IGS is somewhat dated now. More up-to-date
information about first-time Linux installation is located in the
LDP's Installation HOWTO, also located at the LDP Home Page.
Postings on the Usenet News groups, including the FAQ, are archived on
http://groups.google.com/. Search for "comp.os.linux.*,"
"alt.uu.comp.os.linux.*, or whatever is appropriate, to retrieve
articles from the Linux News groups. ("What News Groups Are There for
Linux?")
Commercial distributions are available from book and electronics
stores. Some hardware vendors now ship systems with Linux
pre-installed.
There is a very thorough installation guide on line at
http://heather.cs.ucdavis.edu/~matloff/linux.html.
Some distributions can still be installed via anonymous FTP from
various Linux archive sites, but in many cases, the size of the
distribution makes this impractical. ("Where Are the Linux FTP
Archives?") There are also a large number of releases which are
distributed less globally that suit special local and national needs.
Many of them are archived at ftp://ftp.tux.org/
1.3. What Software does Linux Support?
All of the standard open source utilities, like GCC, (X)Emacs, the X
Window System, all the standard Unix utilities, TCP/IP (including SLIP
and PPP), and all of the hundreds of programs that people have
compiled or ported to it.
There is a DOS emulator, called DOSEMU. The latest stable release is
0.98.3. The FTP archives are at ftp://ftp.dosemu.org/ The Web
site is http://www.dosemu.org.
The emulator can run DOS itself and some (but not all) DOS
applications. Be sure to look at the README file to determine which
version you should get. Also, see the DOSEMU-HOWTO (slightly dated at
this point--it doesn't cover the most recent version of the program),
at ftp://metalab.unc.edu/pub/Linux/docs/HOWTO.
Work has been progressing on an emulator for Microsoft Windows
binaries. ("Can Linux Run Microsoft Windows Programs?")
iBCS2 (Intel Binary Compatibility Standard) emulator code for SVR4 ELF
and SVR3.2 COFF binaries can be included in the kernel as a
compile-time option. There is information at
ftp://tsx-11.mit.edu/pub/linux/BETA/ibcs2/.
For more information see the INFO-SHEET, which is one of the HOWTO's
("Where Is the Documentation?" and "How To Port XXX to Linux.")
Some companies have commercial software available. They often announce
their availability on comp.os.linux.announce-- try searching the
archives. ("Are the News Groups Archived Anywhere?")
1.4. How to Find a Particular Application.
Look first in the Linux Software Map. It's at:
ftp://ibiblio.org/pub/Linux/docs/linux-software-map/ , and on the other
FTP sites. A search engine is available on the World Wide Web at
http://www.boutell.com/lsm/.
Also check out the Freshmeat Web site: http://www.freshmeat.net , which
is where many new announcements of free software first appear.
Freshmeat is basically a site index that continuously updates the
notices of new or upgraded software for Linux, and maintains indexes
of the announcements and links to their URL's.
The FTP sites ("Where Are the Linux FTP Archives?") often have ls-lR
or INDEX directory listings which you can search using grep or a text
editor. The directory listings files can be very large, however,
making them unwieldy for quick searches.
Also look at the Linux Projects Map:
ftp://ftp.ix.de/pub/ix/Linux/docs/Projects-Map.gz.
There's a search engine for Linux FTP archives at:
http://lfw.linuxhq.com/.
Searching for "Linux" on the World Wide Web provides copious
references. ("Where Is the Linux Stuff on the World Wide Web?")
If you don't find anything, you could download the sources to the
program yourself and compile them. See (See: "How To Port XXX to
Linux.") If it's a large package that may require some porting, post a
message to comp.os.linux.development.apps.
If you compile a large-ish 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 protected] ).
If you're looking for an application program, the chances are that
someone has already written a free version. The comp.sources.wanted
FAQ has instructions for finding the source code.
1.5. What Hardware Is Supported?
A minimal Linux installation requires a machine for which a port
exists, at least 2Mb of RAM, and a single floppy drive. But to do
anything even remotely useful, more RAM and disk space are needed.
Refer to: "Ports to Other Processors.", "Disk Space Requirements:
Minimal, Server, and Workstation.", and "Minimum and Maximum Memory
Requirements."
Intel CPU, PC-compatible machines require at least an 80386 processor
to run the standard Linux kernel.
Linux, including the X Window System GUI, runs on most current
laptops. Refer to the answer for: "How To Find Out If a Notebook Runs
Linux." There are numerous sources of information about specific PC's,
video cards, disk controllers, and other hardware. Refer to the
INFO-SHEET, Laptop HOWTO, and the Hardware HOWTO. ("Where Is the
Documentation?")
1.6. Ports to Other Processors.
The Web site, Overview of Linux Ports:
http://www.itp.uni-hannover.de/~kreutzm/de/lin_plattforms.html
provides a listing of known ports.
Another site with a list of ports is:
http://lodda.igo.uni-hannover.de/ports/linux_ports.html
In addition, the following information is available about specific
ports:
On Intel platforms, VESA Local Bus and PCI bus are supported.
MCA (IBM's proprietary bus) and ESDI hard drives are mostly supported.
There is further information on the MCA bus and what cards Linux
supports on the Micro Channel Linux Web page,
http://www.dgmicro.com/mca. Refer also to the answer for: "Where Is
the Linux Stuff on the World Wide Web?"
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, at:
http://www.linux.org.uk/Linux8086.html. Standard Linux does not run
8086 or 80286 processors, because it requires task-switching and
memory management facilities found on 80386 and later processors.
Linux supports multiprocessing with Intel MP architecture. See the
file Documentation/smp.tex in the Linux kernel source code
distribution.
A project has been underway for a while to port Linux to suitable
68000-series based systems like Amigas and Ataris. The Linux/m68K FAQ
is located at http://www.clark.net/pub/lawrencc/linux/faq/faq.html.
The URL of the Linux/m68k home page is
http://www.linux-m68k.org/faq/faq.html.
There is a m68k port for the Amiga by Jes Sorensen, which is located
at ftp://sunsite.auc.dk/pub/os/linux/680x0/redhat/. The installation
FAQ for the package, by Ron Flory, is at
http://www.feist.com/~rjflory/linux/rh/.
There is also a linux-680x0 mailing list. ("What Mailing Lists Are
There?")
There is (or was) a FTP site for the Linux-m68k project on
ftp.phil.uni-sb.de/pub/atari/linux-68k, but this address may no longer
be current.
Debian GNU/Linux is being ported to Alpha, Sparc, PowerPC, and ARM
platforms. There are mailing lists for all of them. See
http://www.debian.org/MailingLists/subscribe
One of the Linux-PPC project pages has moved recently. Its location is
http://www.debian.org/MailingLists/subscribe. http://www.linuxppc.org ,
and the archive site is ftp://ftp.linuxppc.org/.
There is a Linux-PPC support page at http://www.cs.nmt.edu/~linuxppc/.
There you will find the kernel that is distributed with Linux.
There are two sites for the Linux iMac port:
http://w3.one.net/~johnb/imaclinux , and
http://www.imaclinux.net:8080/content/index.html.
A port to the 64-bit DEC Alpha/AXP is at
http://www.azstarnet.com/~axplinux/. There is a mailing list at
vger.redhat.com: ("What Mailing Lists Are There?")
Ralf Baechle is working on a port to the MIPS, initially for the R4600
on Deskstation Tyne machines. The Linux-MIPS FTP sites are
ftp://ftp.fnet.fr/ and
ftp://ftp.linux.sgi.com/pub/mips-linux. Interested people may mail
their questions and offers of assistance to [email protected] .
There is (or was) also a MIPS channel on the Linux Activists mail
server and a linux-mips mailing list. ("What Mailing Lists Are
There?")
There are currently two ports of Linux to the ARM family of
processors. One of these is for the ARM3, fitted to the Acorn A5000,
and it includes I/O drivers for the 82710/11 as appropriate. The other
is to the ARM610 of 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 soon.
For more, up-to-date information, read the newsgroup
comp.sys.acorn.misc. There is a FAQ at http://www.arm.uk.linux.org.
The Linux SPARC project is a hotbed of activity. There is a FAQ and
plenty of other information available from the UltraLinux page,
http://www.ultralinux.org/.
The Home Page of the UltraSPARC port ("UltraPenguin") is located at
http://sunsite.mff.cuni.cz/linux/ultrapenguin-1.0/ , although the URL
may not be current.
There is also a port to SGI/Indy machines ("Hardhat"). The URL is
http://www.linux.sgi.com/.
1.7. Disk Space Requirements: Minimal, Server, and Workstation.
About 10Mb for a very minimal installation, suitable for trying Linux,
and not much else.
You can fit a typical server installation, including the X Window
Systemt GUI, into 80Mb. Installing Debian GNU/Linux takes 500Mb-1GB,
including kernel source code, some space for user files, and spool
areas.
Installing a commercial distribution that has a desktop GUI
environment, commercial word processor, and front-office productivity
suite, will claim 1-1.5 GB of disk space, approximately.
1.8. Minimum and Maximum Memory Requirements.
At least 4MB, and then you will need to use special installation
procedures until the disk swap space is installed. Linux will run
comfortably in 4MB of RAM, although running GUI apps is impractically
slow because they need to swap out to disk.
Some applications, like StarOffice, require 32 MB of physical memory,
and compiling C++ code can easily consume over 100 MB of combined
physical and virtual memory.
There is a distribution, "Small Linux," that will run on machines with
2MB of RAM. Refer to the answer to: "Where Are the Linux FTP
Archives?"
A number of people have asked how to address more than 64 MB of
memory, which is the default upper limit in most standard kernels.
Either type, at the BOOT lilo: prompt:
mem=XXM
Or place the following in your /etc/lilo.conf file:
append="mem=XXM"
The parameter "XXM" is the amount of memory, specified as megabytes;
for example, "128M."
If an "append=" directive with other configuration options already
exists in /etc/lilo.conf, then add the mem= directive to the end of
the existing argument, and separated from the previous arguments by a
space; e.g.:
# Example only; do not use.
append="parport=0x3bc,none serial=0x3f8,4 mem=XXM"
Be sure to run the "lilo" command to install the new configuration.
If Linux still doesn't recognize the extra memory, the kernel may need
additional configuration. Refer to the
/usr/src/linux/Documentation/memory.txt file in the kernel source as a
start.
For further information about LILO, refer to the manual pages for lilo
and lilo.conf, the documentation in /usr/doc/lilo, and the answer for:
"Boot-Time Configuration.", below.
1.9. Does Linux Support Universal System Bus Devices?
Linux supports a few dozen USB devices at present, and work is
underway to develop additional device drivers. There is a Web page
devoted to the subject, at http://www.linux-usb.org/. There is also
LDP documentation, at: ("Where Is the Linux Stuff on the World Wide
Web?")
1.10. What Is Linux's Open-Source License?
The Linux trademark belongs to Linus Torvalds. He has placed the Linux
kernel under the GNU General Public License, which basically means
that you may freely copy, change, and distribute it, but you may not
impose any restrictions on further distribution, and you must make the
source code available.
There is a FAQ for the GPL at:
http://www.gnu.org/copyleft/gnu-faq.html.
This is not the same as Public Domain. See the Copyright FAQ,
ftp://rtfm.mit.edu/pub/usenet/news.answers/law/ , for details.
Full details are in the file COPYING in the Linux kernel sources
(probably in /usr/src/linux on your system).
The licenses 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 the news group gnu.misc.discuss, and not to the
comp.os.linux hierarchy.
For legal questions, refer to the answer: ("Where Are Linux Legal
Issues Discussed?")
1.11. Is Linux *nix?
Not officially, until it passes the Open Group's certification tests,
and supports the necessary API's. Even very few of the commercial
operating systems have passed the Open Group tests. For more
information, see http://www.unix-systems.org/what_is_unix.html.
[Bob Friesenhahn]
2. Network Sources and Resources
2.1. Where Is the Latest Kernel Version on the Internet?
Make that versions. The 2.0 series kernels are still available for
older machines. The latest production kernel series is 2.2.x. The
updates to this kernel are bug fixes. The new 2.4 kernel sources are
also on-line.
The Web page at http://www.kernel.org/ lists the current versions of
the development and production kernels.
If you want to download the source code, FTP to ftp.xx.kernel.org,
where "xx" is the two-letter Internet domain abbreviation of your
country; e.g., "us" for United States, "ca" for Canada, or "de" for
Germany. Kernel versions 2.2.x are archived in the directory
pub/linux/kernel/v2.2, as are patches for the prerelease versions. The
kernel source code is archived as a .tar.gz file, and as a .tar.bz2
file.
Follow the instructions in any of the standard references to compile
the kernel, as you would with any other custom kernel. The
Documentation subdirectory contains information by the authors of
various subsystems and drivers, and much of that information is not
documented elsewhere.
If you want to participate in kernel development, make sure that you
sign on to the linux-kernel mailing list to find out what people are
working on. Refer to the answer: "What Mailing Lists Are There?"
There is a story about the features of the 2.4 series kernels at
http://features.linuxtoday.com/stories/8191.html.
2.2. Where Is the Documentation?
Look in the following places, and the sites that mirror them.
* http://www.linuxdoc.org/
* ftp://ftp.funet.fi/pub/OS/Linux/doc/HOWTO/
* ftp://tsx-11.mit.edu/pub/linux/docs/HOWTO/
* ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/
For a list of Linux FTP sites, refer to the answer for: "Where Are the
Linux FTP Archives?"
If you don't have access to FTP, try the FTP-by-mail servers:
[email protected] , [email protected] , or:
[email protected] .
A complete list of HOWTO's is available in the file HOWTO-INDEX at
http://www.linuxdoc.org/HOWTO/HOWTO-INDEX/howtos.html. The
mini-HOWTO's are indexed at
http://www.linuxdoc.org/HOWTO/HOWTO-INDEX/mini.html.
A search engine at the Linux FAQ Home Page,
http://www.mainmatter.com/ , allows you to search LDP HOWTO's, the
Linux FAQ, man pages, and Network Administrator's Guide.
In addition, translations are available from
ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/translations/ and mirrors
worldwide. The HOWTO's and other documentation have been translated
into the following languages:
Chinese (Big5) (zh) Croatian (hr) French (fr)
German (de Hellenic (el) Indonesian (id)
Italian (it) Japanese (ja) Korean (ko)
Polish (pl) Slovenian (sl) Spanish (es)
Swedish (sv) Turkish (tr)
Additional documents are always in preparation. Please get in touch
with the coordinators if you are interested in writing one. Contact
and submission information is at
http://www.linuxdoc.org/mailinfo.html.
There is also a LDP HOWTO page at http://howto.tucows.org/.
The Guide Series produced by the Linux Documentation Project is
available from http://www.linuxdoc.org/. Please read them if you are
new to Unix and Linux.
The Linux Mobile Guide is an expanded version of the
Linux-Laptop-HOWTO. The URL is: http://home.snafu.de/wehe/howtos.html.
And, of course, a number of people have written documentation
independently of the LDP:
* Linux Administrators Security Guide, by Kurt Seifried.
http://www.freek.com/lasg/.
* Newbie's Linux Manual. http://www.linuxdoc.org/nlm/.
* One-Page Linux Manual. http://www.powerup.com.au/~squadron/.
* Rute Users Tutorial and Exposition. http://rute.sourceforge.net/.
* Short beginners' manual for Linux. Also available in Dutch.
http://www.stuwww.kub.nl/people/b.vannunen/linux-man.php3.
* Virtual Frame buffer HOWTO, by Alex Buell.
http://www.tahallah.demon.co.uk/programming/prog.html.
* X11 & TrueType Fonts, by Peter Kleiweg.
http://www.let.rug.nl/~kleiweg/.
Documentation for kernel developers is on-line:
http://kernelbook.sourceforge.net/.
To find out about Linux memory management, including performance
tuning, see Rik van Riel's Web page at
http://humbolt.geo.uu.nl/Linux-MM/.
The Linux Consultants HOWTO has a directory of Linux consultants at
http://www.linuxports.com/.
Gary's Encyclopedia lists over 4,000 Linux related links. Its URL is
http://members.aa.net/~swear/pedia/index.html.
There is also a FAQ specifically for the Red Hat Linux distribution,
at http://www.best.com/~aturner/RedHat-FAQ/faq_index.html.
And the Home Page of this FAQ is http://www.mainmatter.com/.
2.3. Where Is the Linux Stuff on the World Wide Web?
In addition to the Linux Documentation Project Home Page:
http://www.linuxdoc.org/ , there are many pages that provide beginning
and advanced information about Linux.
These two pages provide a good starting point for general Linux
information: Linux International's Home Page, at http://www.li.org/ ,
and the Linux Online's Linux Home Page at http://www.linux.org/.
Both of these pages provide links to other sites, information about
general information, distributions, new software, documentation, and
news.
Documentation for kernel developers is on-line:
http://kernelbook.sourceforge.net/.
The tutorial, Unix is a Four Letter Word..., is located at
http://www.linuxbox.com/~taylor/4ltrwrd/. It is a general introduction
to Unix operating systems and is not Linux specific.
Archive-Name: linux/faq/part2
URL: http://www.mainmatter.com/
Reply-to: [email protected]
Posting-Frequency: weekly
Last-modified: 12/04/2001
Additionally, here is a certainly incomplete list of Web pages devoted
to Linux:
* AboutLinux.com: http://www.aboutlinux.com/.
* Adventures in Linux Programming:
http://members.tripod.com/rpragana/.
* Dave Central Linux Software Archive:
http://linux.davecentral.com/.
* debianHELP http://www.debianhelp.org/.
* Erlug Webzine (Italian): http://www.erlug.linux.it/.
* Free Unix Giveaway List: http://visar.csustan.edu/giveaway.html.
Lists offers of free Linux CDs. Also available via E-mail:
[email protected] , with the Subject: send giveaway_list.
* Information on Linux in corporate environments:
http://www.smartstocks.com/linux.html.
* Jeanette Russo's Linux Newbie Information:
http://www.stormloader.com/jrusso2/index.html.
* JustLinux.com: http://www.justlinux.com/.
* Linux Cartoons:
http://www.cse.unsw.edu.au/~conradp/linux/cartoons/.
* LinuxArtist.org: http://www.linuxartist.org/.
* Linuxinfor.com - Online Linux Resources:
http://www.linuxinfor.com/.
* linuXChiX.org: http://www.linuxchix.org/.
* LinuxDevices.com: The Embedded Linux Portal:
http://www.linuxdevices.com.
* Linux Educational Needs Posting Page:
http://www.slip.net/~brk/linuxedpp.htm.
* Linux in Business: Case Studies:
http://www.bynari.com/collateral/case_studies.html.
* Linux Hardware Database Laptop Superguide:
http://lhd.zdnet.com/db/superguide.php3?catid=18.
* Linux Inside: http://linuxinside.org/.
* Linux Links: http://www.linuxlinks.com/.
* Linux Memory Management Home Page:
http://humbolt.geo.uu.nl/Linux-MM/.
* Linux Newbie Project: http://kusma.hypermart.net/.
* Linux on the Thinkpad 760ED: http://www.e-oasis.com/linux-tp.html.
* LinuxOrbit: http://www.linuxorbit.com/
* Linux Parallel Port Home Page:
http://www.torque.net/linux-pp.html.
* Linux MIDI & Sound Applications: http://sound.condorow.net/.
* Linux Start: http://www.linuxstart.com/.
* Linux Tips and Tricks Page: http://www.patoche.org/LTT/.
* Linux Today PR: http://www.linuxpr.com/.
* Mandrakeuser.Org: http://mandrakeuser.org/
* My Linux Contributions by Richard Gooch:
http://www.atnf.csiro.au/~rgooch/linux/.
* Micro Channel Linux Web Page: http://www.dgmicro.com/mca/.
* Parallel port scanners and SANE:
http://www2.prestel.co.uk/hex/scanners.html.
* Pascal Central: http://www.pascal-central.com/
* PegaSoft Portal: http://www.vaxxine.com/pegasoft/portal/
* PocketLinux. http://www.pocketlinux.com/.
* Red Hat and ISDN4Linux: http://www.webideal.de/.
* SearchLinux: http://www.searchlinux.com/.
* The Free Linux CD Project: http://www.freelinuxcd.org/.
* The Site for People Learning Perl: http://learn.perl.org/.
* USB Linux Home Page: http://peloncho.fis.ucm.es/~inaky/uusbd-www/.
* VLUG: The Virtual Linux Users Group: http://www.vlug.com/.
Searching for "Linux" on Web Search Engines, like Yahoo!
(http://www.yahoo.com/) , Altavista (http://www.altavista.com/) , or
Google (http://www.google.com/) will provide copious references to
Linux Web sites. Further information about about Web search engines is
in the Web and Internet Search Engine Faq:
http://www.infobasic.com/pagefaq.html.
Refer also to the answer for: "What Other FAQ's and Documentation Are
There for Linux?"
2.4. What News Groups Are There for Linux?
Comp.os.linux.announce is the moderated announcements group. You
should read this if you intend to use Linux. It contains information
about software updates, new ports, user group meetings, and commercial
products. It is the only newsgroup that may carry commercial postings.
Submissions for that group should be e-mailed to
[email protected] .
Comp.os.linux.announce is archived at:
http://www.iki.fi/mjr/linux/cola.html , and
ftp://src.doc.ic.ac.uk/usenet/comp.os.linux.announce/.
Also worth reading are the following other groups in the
comp.os.linux.* and alt.uu.comp.os.linux.* hierarchies--you may find
many common problems too recent for the documentation but are answered
in the newsgroups.
* alt.uu.comp.os.linux
* alt.uu.comp.os.linux.questions
* alt.os.linux
* alt.os.linux.mandrake
* comp.os.linux.admin
* comp.os.linux.advocacy
* comp.os.linux.alpha
* comp.os.linux.answers
* comp.os.linux.development
* comp.os.linux.development.apps
* comp.os.linux.development.system
* comp.os.linux.embedded
* comp.os.linux.hardware
* comp.os.linux.help
* comp.os.linux.m68k
* comp.os.linux.misc
* comp.os.linux.network
* comp.os.linux.networking
* comp.os.linux.portable
* comp.os.linux.powerpc
* comp.os.linux.questions
* comp.os.linux.redhat
* comp.os.linux.security
* comp.os.linux.setup
* comp.os.linux.test
* comp.os.linux.x
* comp.os.linux.x.video
Remember that Linux is POSIX compatible, and most all of the material
in the 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 good places to
start.
Information about e-mail clients (MUA's), mail transfer agents
(MTA's), and other related software are in the comp.mail.* groups,
especially:
* comp.mail.misc
* comp.mail.pine
* comp.mail.sendmail
Questions and information about News reading software are in:
news.software.readers.
Please read "If this Document Still Hasn't Answered Your Question...."
before posting. Cross posting between different comp.os.linux.* groups
is rarely a good idea.
There may well be Linux groups local to your institution or
area--check there first.
See also "How To Get Information without Usenet Access."
Other regional and local newsgroups also exist--you may find the
traffic more manageable there. The French Linux newsgroup is
fr.comp.os.linux. In Germany there is de.comp.os.linux.*. In
Australia, try aus.computers.linux. In Croatia there is hr.comp.linux.
In Italy, there is it.comp.linux.
A search of http://groups.google.com/ can provide an up-to-date list
of News groups.
[Axel Boldt, Robert Kiesling]
2.5. What Other FAQ's and Documentation Are There for Linux?
There are a number of special interest FAQ's on different subjects
related to system administration and use, and also on miscellaneous
topics like Flying Saucer Attacks (the music) and support for
recovering sysadmins.
The official Usenet FAQ archives are: ftp://rtfm.mit.edu/pub/usenet/.
The Internet FAQ Consortium provides a searchable archive at:
http://www.faqs.org/. The site also maintains a current archive of
Internet Request For Comment (RFC), Best Current Practices (BCP), and
For Your Information (FYI) documents.
Here are some FAQ's and documents that might be especially useful, and
their network addresses:
* A FAQ for new users:
http://homes.arealcity.com/swietanowski/LinuxFAQ/.
* AfterStep FAQ:
http://www.linuxinfor.com/en/astepfaq/AfterStep-FAQ.html.
* BASH Frequently Asked Questions: ftp://ftp.cwru.edu/pug/bash/FAQ/.
* de.comp.os.unix.linux.infos - FAQ: http://www.dcoul.de/.
* Frequently Asked Questions about Open Source:
http://www.opensource.org/faq.html.
* Ftape-FAQ: http://www.linuxinfor.com/en/ftapefaq/Ftape-FAQ.html.
* GNU Emacs: http://www.lerner.co.il/emacs/faq-body.shtml.
* GNU Linux in Science and Engineering:
http://www.comsoc.org/vancouver/scieng.html.
* GNU Troff (groff) Info: http://www.cs.pdx.edu/~trent/gnu/groff/.
* Gnus 5.x: http://www.ccs.neu.edu/software/contrib/gnus/.
* KDE FAQ: http://www.kde.org/faq.html.
* GNU General Public License FAQ:
http://www.gnu.org/copyleft/gpl-faq.html.
* Linux PPP FAQ: http://www.linuxinfor.com/en/pppfaq/PPP-FAQ.html.
* Linux-Raid FAQ: http://www.linuxinfor.com/en/raidfaq/index.html.
* List of Periodic Information Postings:
ftp://rtfm.mit.edu/pub/usenet/news.answers/periodic-postings/.
* News.newusers.announce FAQ http://web.presby.edu/~nnqadmin/nan/.
* Online Linux Resources: http://www.linuxinfor.com/en/docfaq.htm.
* O'Reilly & Associates Openbook Project:
http://www.oreilly.com/openbook/.
* Sendmail: http://www.sendmail.org/faq/.
* Sendmail: Installation and Operation Guide: Formatted and me
source versions are in the doc/ subdirectory of Sendmail source
code distributions. http://www.sendmail.org/.
* Technical FAQ for Linux Users:
http://www-106.ibm.com/developerworks/library/l-faq/?n-l-7261.
* Web Internet Search Engine: http://www.infobasic.com/pagefaq.html
* Wu-ftpd: http://www.wu-ftpd.org/man/ (really a collection of man
pages), with HOWTO's at: http://www.wu-ftpd.org/HOWTO/
* XTERM--Frequently Asked Questions.
http://dickey.his.com/xterm/xterm.faq.html.
2.6. Where Are the Linux FTP Archives?
There are three main archive sites for Linux:
* ftp://ftp.funet.fi/pub/OS/Linux/ (Finland).
* ftp://metalab.unc.edu/pub/Linux/. Recently renamed to
http://ibiblio.org/pub/linux/ with a nice WWW interface. (US).
* ftp://tsx-11.mit.edu/pub/linux/ (US).
The best place to get the Linux kernel is
ftp://ftp.kernel.org/pub/linux/kernel/. Linus Torvalds uploads the
most recent kernel versions to this site.
Of the U.S. distributions, Debian GNU/Linux is available at
ftp://ftp.debian.org/pub/debian/. Red Hat Linux's home site is
ftp://ftp.redhat.com/ , and Linux Slackware's is
ftp://ftp.freesoftware.com/.
The Small Linux distribution, which can run in 2 MB of RAM, is located
at http://smalllinux.netpedia.net/.
The contents of these sites is mirrored (copied, usually approximately
daily) by a number of other sites. Please use a site close to you--it
will be faster for you and easier on the network.
* ftp://ftp.sun.ac.za/pub/linux/sunsite/ (South Africa)
* ftp://ftp.is.co.za/linux/sunsite/ (South Africa).
* ftp://ftp.cs.cuhk.hk/pub/Linux/ (Hong Kong).
* ftp://sunsite.ust.hk/pub/Linux/ (Hong Kong).
* ftp://ftp.spin.ad.jp/pub/linux/ (Japan).
* ftp://ftp.nuri.net/pub/Linux/ (Korea).
* ftp://ftp.jaring.my/pub/Linux/ (Malaysia).
* ftp://ftp.nus.sg/pub/unix/Linux/ (Singapore).
* ftp://ftp.nectec.or.th/pub/mirrors/linux/ (Thailand).
* ftp://planetmirror.com/pub/linux (Australia). (Also take a look at
http://planetmirror.com/archives.php.)
* ftp://ftp.monash.edu.au/pub/linux/ (Australia).
* ftp://ftp.univie.ac.at/systems/linux/sunsite/ (Austria).
* ftp://ftp.fi.muni.cz/pub/UNIX/linux/ (Czech Republic).
* ftp://ftp.funet.fi/pub/Linux/sunsite/ (Finland).
* ftp://ftp.univ-angers.fr/pub/Linux/ (France).
* ftp://ftp.iut-bm.univ-fcomte.fr/ (France).
* ftp://ftp.ibp.fr/pub/linux/sunsite/ (France)
* ftp://ftp.loria.fr/pub/linux/sunsite/ (France).
* ftp://ftp.dfv.rwth-aachen.de/pub/linux/sunsite/ (Germany).
* ftp://ftp.germany.eu.net/pub/os/Linux/Mirror.SunSITE/).
* ftp://ftp.tu-dresden.de/pub/Linux/sunsite/ (Germany).
* ftp://ftp.uni-erlangen.de/pub/Linux/MIRROR.sunsite/ (Germany).
* ftp://ftp.gwdg.de/pub/linux/mirrors/sunsite/ (Germany).
* ftp.rz.uni-karlsruhe.de/pub/linux/mirror.sunsite/ (Germany).
* ftp://ftp.ba-mannheim.de/pub/linux/mirror.sunsite/ (Germany).
* ftp://ftp.uni-paderborn.de/pub/Mirrors/sunsite.unc.edu/(Germany).
* ftp://ftp.uni-rostock.de/Linux/sunsite/ (Germany).
* ftp.rus.uni-stuttgart.de/pub/unix/systems/linux/MIRROR.sunsite/(Ge
rmany).
* ftp://ftp.uni-tuebingen.de/pub/linux/Mirror.sunsite/ (Germany).
* ftp://ftp.kfki.hu/pub/linux/(Hungary).
* ftp://linux.italnet.it/pub/Linux/).
* ftp://ftp.unina.it/pub/linux/sunsite/ (Italy).
* ftp://giotto.unipd.it/pub/unix/Linux/ (Italy).
* ftp://cnuce-arch.cnr.it/pub/Linux/ (Italy).
* ftp://ftp.flashnet.it/mirror2/metalab.unc.edu/ (Italy).
* ftp://ftp.nijenrode.nl/pub/linux/ (Netherlands).
* ftp://ftp.LeidenUniv.nl/pub/linux/sunsite/ (Netherlands).
* ftp://ftp.nvg.unit.no/pub/linux/sunsite/ (Norway).
* ftp://sunsite.icm.edu.pl/pub/Linux/metalab.unc.edu/ (Poland).
* ftp://ftp.rediris.es/software/os/linux/sunsite/ (Spain).
* ftp://sunsite.rediris.es/software/linux/ (Spain).
* ftp://ftp.cs.us.es/pub/Linux/sunsite-mirror/ (Spain).
* ftp://ftp.etse.urv.es/pub/mirror/linux/ (Spain).
* ftp://tp.etsimo.uniovi.es/pub/linux/ (Spain).
* ftp://ftp.luna.gui.es/pub/linux.new/ (Spain).
* ftp://ftp.metu.edu.tr/pub/linux/sunsite/ (Turkey).
* ftp://unix.hensa.ac.uk/mirrors/sunsite/pub/Linux/ (UK).
* ftp.maths.warwick.ac.uk/mirrors/linux/sunsite.unc-mirror/(UK).
* ftp://ftp.idiscover.co.uk/pub/Linux/sunsite.unc-mirror/).
* ftp://sunsite.doc.ic.ac.uk/packa ... te.unc-mirror/(UK).
* (UK)
* ftp://ftp.io.org/pub/mirrors/linux/sunsite/ (Canada).
* ftp://ftp.cc.gatech.edu/pub/linux/ (US).
* ftp://ftp.freesoftware.com/pub/linux/sunsite/ (US).
* ftp://ftp.siriuscc.com/pub/Linux/Sunsite/ (US).
* ftp://ftp.engr.uark.edu/pub/linux/sunsite/ (US).
* ftp://ftp.infomagic.com/pub/mirrors/linux/sunsite/ (US).
* ftp://linux.if.usp.br/pub/mirror/metalab.unc.edu/pub/Linux/
).
* ftp://farofa.ime.usp.br/pub/linux/ (Brazil).
Please send updates and corrections to this list to the Linux FAQ
the other "source" sites, and some have material not available on the
"source" sites.
2.7. How To Get Linux without FTP Access.
The easiest thing is probably to find a friend with FTP access. If
there is a Linux user's 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 protected] , or
[email protected] .
Linux is also available via traditional mail on CD-ROM. The file
ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/Installation-HOWTO , and the
file ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/Distribution-HOWTO
contain information on these distributions.
2.8. How To Get Information without Usenet Access.
A digest of comp.os.linux.announce is available by mailing the word
"subscribe" (without the quotes) as the body of a message to
[email protected] . Subscribing to this list
is a good idea, as it carries important information and documentation
about Linux.
Please remember to use the *-request addresses for your subscribe and
unsubscribe messages; mail to the other address is posted to the news
group.
2.9. What Mailing Lists Are There?
The Linux developers now mainly use the Majordomo server at
[email protected] . Send a message with the word "lists"
(without the quotes) in the body to get a list of lists there. Add a
line with the word, "help," to get the standard Majordomo help file
that lists instructions for subscribing and unsubscribing to the
lists.
Currently, the kernel list is archived at:
http://www.uwsg.indiana.edu/hypermail/linux/kernel/ , and
http://www.lib.uaa.alaska.edu/linux-kernel/archive/
Please do not post off-topic material to the mailing lists. Most of
them are used by Linux developers to talk about technical issues and
future developments. They are not intended for new users' questions,
advertisements, or public postings that are not directly related to
the mailing list's subject matter. Comp.os.linux.announce is the place
for all public announcements. This is a common Internet policy. If you
don't observe this guideline, there's a good chance that you'll be
flamed.
There is a linux-newbie list where, "no question is too stupid."
Unfortunately, it seems that few experienced users read that list, and
it has very low volume.
There are numerous Linux related mailing lists at
http://www.onelist.com/. Go to the categories page and choose "Linux."
There are also mailing list subscription links at:
http://oslab.snu.ac.kr/~djshin/linux/mail-list/.
The Mailing Lists Available in Usenet page is: http://paml.net/. The
list information is also on: ftp://rtfm.mit.edu/ , and is posted to the
groups: news.announce.newgroups, news.lists, and news.groups, among
others.
2.10. Where Are Linux Legal Issues Discussed?
On the linux-legal mailing list, of course. You can subscribe to it,
as with many of the other Linux related lists, by sending a message
with the word "help" in the body of the message to
[email protected] .
2.11. Sources of Information for Unmaintained Free Software Projects.
There are Web pages at: http://unmaintained.sourceforge.net , and:
http://www.orphansource.org/.
Please try to contact the original author(s) via e-mail, or the person
who listed the software as unmaintained, before even thinking to place
a license on the package.
2.12. Are the News Groups Archived Anywhere?
The Usenet Linux news groups are archived at
http://groups.google.com/.
ftp://metalab.unc.edu/pub/Linux/docs/linux-announce.archive contains
archives of comp.os.linux.announce. These are mirrored from
ftp://src.doc.ic.ac.uk/usenet/ , which also archives comp.os.linux,
comp.os.linux.development.apps, and comp.os.linux.development.system.
2.13. Where To Find Information About Security Related Issues.
There's a page of Linux related security information at:
http://www.linuxsecurity.com/.
Another site is: http://www.rootshell.com/ , which has information
about Internet security and privacy issues.
For information about the Weekly Linux Security Digest email
newsletter and numerous security related databases, look at
http://securityportal.com/.
2.14. Where To Find Linux System Specifications.
As a start, look at the Linux Standards Base,
http://www.linuxbase.org/. The site contains information about test
software, file system organization, and shared library naming
conventions.
3. Compatibility with Other Operating Systems
3.1. Can Linux Use the Same Hard Drive as MS-DOS? OS/2? 386BSD? Win95?
Yes. Linux uses the standard MS-DOS partitioning scheme, so it can
share your disk with other operating systems.
Linux has loadable kernel modules for (presumably) all versions of
Microsoft FAT and VFAT file systems, including Windows 2000 and
WindowsMe. In a correctly configured system, they should load
automatically when the partitions are mounted.
Note, however, that many other operating systems may not be exactly
compatible. DOS's FDISK.EXE and FORMAT.EXE, for example, can 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 programs from doing this, it is a good idea to
zero out--under Linux--the start of a partition you created, before
you use MS-DOS--or whatever--to format it. Type:
$ dd if=/dev/zero of=/dev/hdXY bs=512 count=1
where hdXY is the relevant partition; e.g., /dev/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 file system type built into the
kernel or mtools. There is kernel support for the VFAT file system
used by Windows 9x and Windows NT.
There is reportedly a GPL'd OS/2 device driver that will read and
write Linux ext2 partitions.
For information about FAT32 partition support, see
http://bmrc.berkeley.edu/people/chaffee/fat32.html.
See, ("What Software does Linux Support?") for details and status of
the emulators for DOS, MS Windows, and System V programs.
See also, "Can Linux access Amiga file systems? ", "Can Linux access
Macintosh file systems? ", "Can Linux access BSD, SysV, etc., UFS? ",
and "Can Linux access SMB file systems? "
There are said to be NTFS drivers under development, which should
support compression as a standard feature.
3.2. How To Access Files on a MS-DOS Partition or Floppy.
Use the DOS file system, 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 file system as they appear
under Linux. If you mount your DOS file system 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. ("Where Are the Linux FTP Archives?")
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.
3.3. Does Linux Support Compressed Ext2 File Systems?
The ext2compr project provides a kernel patch Information about them
is located at http://e2ompr.memalpha.cx/e2compr/.
There is also a Web site for the e2compr patches. The code is still
experimental and consists of patches for the 2.0 and 2.1 kernels. For
more information about the project, including the latest patches, and
the address of the mailing list, look up the URL at
http://debs.fuller.edu/e2compr/.
[Roderich Schupp, Peter Moulder]
zlibc is a program that allows existing applications to read
compressed (GNU gzip'ed) files as if they were not compressed. Look at
ftp://metalab.unc.edu/pub/Linux/libs/. The author is Alain Knaff.
There is also a compressing block device driver, "DouBle," by
Jean-Marc Verbavatz, which can provide on-the-fly disk compression in
the kernel. The source-only distribution is located at
ftp://metalab.unc.edu/pub/Linux/patches/diskdrives/. This driver
compresses inodes and directory information as well as files, so any
corruption of the file system is likely to be serious.
There is also a package called tcx (Transparently Compressed
Executables), which allows you to keep infrequently used executables
compressed and only uncompress them temporarily when in use. It is
located at ftp://metalab.unc.edu/pub/Linux/utils/compress/.
3.4. Can Linux Use Stacked/DBLSPC/Etc. DOS Drives?
Until recently, not very easily. You can access DOS 6.X volumes from
the DOS emulator ("What software does Linux support? "), but it's
harder than accessing a normal DOS volume via the DOS kernel option, a
module, or mtools.
There is a recently added package, dmsdos, that reads and writes
compressed file systems like DoubleSpace/DriveSpace in MS-DOS 6.x and
Win95, as well as Stacker versions 3 and 4. It is a loadable kernel
module. Look at
ftp://metalab.unc.edu/pub/Linux/system/filesystems/dosfs/.
3.5. Can Linux Access OS/2 HPFS Partitions?
Yes, but Linux access to HPFS partitions is read-only. HPFS file
system access is available as an option when compiling the kernel or
as a module. See the Documentation/filesystems/hpfs.txt file in the
kernel source distribution. ("How To Upgrade/Recompile a Kernel.")
Then you can mount HPFS partition, using, for example:
$ mkdir /hpfs
$ mount -t hpfs /dev/hda5 /hpfs
3.6. Can Linux Access Amiga File Systems?
The Linux kernel has support for the Amiga Fast File System (AFFS)
version 1.3 and later, both as a compile-time option and as a module.
The file Documentation/filesystems/affs.txt in the Linux kernel source
distribution has more information.
See ("How To Upgrade/Recompile a Kernel.")
Linux supports AFFS hard-drive partitions only. Floppy access is not
supported due to incompatibilities between Amiga floppy controllers
and PC and workstation controllers. The AFFS driver can also mount
disk partitions used by the Un*x Amiga Emulator, by Bernd Schmidt.
3.7. Can Linux Access BSD, SysV, Etc. UFS?
Recent kernels can mount (read only) the UFS file system used by
System V; Coherent; Xenix; BSD; and derivatives like SunOS, FreeBSD,
NetBSD, and NeXTStep. UFS support is available as a kernel
compile-time option and a module.
See, ("How To Upgrade/Recompile a Kernel.")
3.8. Can Linux Access SMB File Systems?
Linux supports read/write access of Windows for Workgroups and Windows
NT SMB volumes. See the file Documentation/filesystems/smbfs.txt of
the Linux kernel source distribution, and ("How To Upgrade/Recompile a
Kernel.")
There is also a suite of programs called Samba which provide support
for WfW networked file systems (provided they're for TCP/IP).
Information is available in the README file at
metalab.unc.edu/pub/Linux/system/network/samba/.
The SMB Web site is http://www.samba.org/ , and there is also a Web
site at samba.anu.edu.au/samba/.
3.9. Can Linux Access Macintosh File Systems?
There is a set of user-level programs that read and write the older
Macintosh Hierarchical File System (HFS). It is available at
metalab.unc.edu/pub/Linux/utils/disk-management/.
Access to the newer, HFS+ file systems is still under development.
3.10. Can Linux Run Microsoft Windows Programs?
WINE, a MS Windows emulator for Linux, is still not ready for general
distribution. If you want to contribute to its development, look for
the status reports in the comp.emulators.ms-windows.wine newsgroup.
There is also a FAQ, compiled by P. David Gardner, at
ftp://metalab.unc.edu/pub/Linux/docs/faqs/Wine-FAQ/.
In the meantime, if you need to run MS Windows programs, the best
bet--seriously--is to reboot. LILO, the Linux boot loader, can boot
one of several operating systems from a menu. See the LILO
documentation for details.
Also, LOADLIN.EXE (a DOS program to load a Linux, or other OS, kernel
is one way to make Linux co-exist with DOS. LOADLIN.EXE is
particularly handy when you want to install Linux on a 3rd or 4th
drive on a system (or when you're adding a SCSI drive to a system with
an existing IDE).
In these cases, it is common for LILO's boot loader to be unable to
find or load the kernel on the "other" drive. So you just create a
C:/LINUX directory (or whatever), put LOADLIN.EXE in it with a copy of
your kernel, and use that.
LOADLIN.EXE is a VCPI compliant program. Win95 will want to, "shutdown
into DOS mode," to run it (as it would with certain other DOS
protected-mode programs).
Earlier versions of LOADLIN.EXE sometimes required a package called
REALBIOS.COM, which required a boot procedure on an (almost) blank
floppy to map the interrupt vectors (prior to the loading of any
software drivers). (Current versions don't seem to ship with it, and
don't seem to need it).
[Jim Dennis]
3.11. Where Is Information about NFS Compatibility?
This information is partly taken from Nicolai Langfeldt's excellent
NFS HOWTO, and is current as of 10/1/1999.
Most version 2.2.x kernels need a set of patches to install the knfsd
subsystem, maintained by H.J. Lu, to communicate efficiently (if at
all) with Sparc, IBM RS, and Alpha machines, and probably others. This
package is actually a collection of patches to the kernel sources.
Better support for non-Intel architectures is included in the 2.4
kernels.
There is also a user-space server. Although it lacks remote file
locking, it is easier to install. It may be equally efficient.
In the Documentation/Changes of recent kernel distributions, there is
a list of URL's for both the knfsd server and the user-space server.
There is a CVS server available for the kernel-space NFS subsystem, as
well as a NFS WWW page at http://www.linuxnfs.sourceforge.org/ ,
although the URL requires a password for access. The relevant URL's
are listed in the README.nfs file at ftp://ftp.us.kernel.org/ , and
other kernel archive sites, along with login information. Patches are
at ftp://ftp.varesearch.com/pub/kernel/latest/patches/.
The source archives of the user-space server and utilities currently
reside on
ftp://linux.mathematik.tu-darmstadt.de:/pub/linux/people/okir/.
In the case of older Solaris releases, the lack of statd or lockd on a
client or server machine may cause incompatibility. On some versions
of Solaris, statd can be used to exploit features of the automounter.
Sun released a patch to correct this, but statd still needs to be
started by root on such systems. On recent Solaris systems, refer to
the information in /etc/dfs/dfstab and the share(1M) manual page to
enable volume sharing. In addition, the rpcinfo program can tell you
if statd or lockd are available on the local or remote machines.
The linux-kernel mailing list has on-and-off discussions of the status
of the NFS subsystem, which appears to be changing rapidly.
[Nicolai Langfeldt, Robert Kiesling, Anders Hammarquist]
3.12. Can Linux Use True Type Fonts?
Yes. There are a number of True Type font servers for the X Window
System. One of them is xfsft. Its home page is
http://www.dcs.ed.ac.uk/home/jec/programs/xfsft/. There are also
instructions for configuration.
People have reported success with other True Type font servers. There
are links from the xfsft Home Page to them as well.
You can also compile True Type Font support into your X server
directly. Again, refer to the xfsft Home Page for details.
3.13. Can Linux Boot from MS-DOS?
If LILO doesn't work, and if the machine has MS-DOS or Microsoft
Windows, you may be left with a computer that won't boot. This can
also happen on an upgrade to your Linux distribution. Re-installing
LILO is the last thing that the installation does. So it is vitally
important when installing or upgrading Linux on a dual boot machine,
to have a MS-DOS or Windows rescue disk nearby so you can FDISK -MBR.
Then you can go about using LOADLIN.EXE instead of LILO.
This config.sys file is one possible way to invoke LOADLIN.EXE and
boot MS-DOS or Linux.
[menu]
menuitem=DOS, Dos Boot
menuitem=LINUX, Linux Boot
[LINUX]
shell=c:/redhat/loadlin.exe c:/redhat/autoboot/vmlinuz vga=5 root=/dev
[DOS]
STACKS = 0,0
rem all the other DOS drivers get loaded here.
This creates a menu where you can directly jump to LOADLIN.EXE before
all of the MS-DOS drivers get loaded.
The paths and options are peculiar to one machine and should be
intuitively obvious to the most casual observer. See the LOADLIN.EXE
docs for options. They are the same as LILO, and options are just
passed to the kernel, anyhow.
[Jim Harvey]
3.14. How Can Linux Boot from OS/2's Boot Manager?
1. Create a partition using OS/2's FDISK.EXE (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. (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 file system on the partition using mkfs
-t ext2 or mke2fs. At this point you may, if you like, use Linux's
fdisk to change the 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 configuration file. To do this, you should
put
boot = /dev/hda2
(where /dev/hda2 is the partition you want to boot from) 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.
There is a set of HOWTO's on the subject of multi-boot systems at the
LDP Home Page, http://www.linuxdoc.org/.
4. File Systems, Disks, and Drives
4.1. How To Get Linux to Work with a Disk.
If your disk is an IDE or EIDE drive, you should read the file
/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' cylinder/head/sector fiction to support DOS.
Older IBM PC-compatible BIOS's 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.
Archive-Name: linux/faq/part3
URL: http://www.mainmatter.com/
Reply-to: [email protected]
Posting-Frequency: weekly
Last-modified: 12/04/2001
It's recommend that you create at least one Linux partition entirely
under the 1024 logical cylinder limit, and boot from that. The other
partitions will then be okay.
Also there seems to be a bit of trouble with the newer Ultra-DMA
drives. I haven't gotten the straight scoop on them--but they are
becoming a very common problem at the SVLUG installfests. When you can
get 8 to 12 Gig drives for $200 to $300 it's no wonder.
[Jim Dennis]
4.2. How To Undelete Files.
In general, this is very hard to do on unices because of their
multitasking nature. Undelete functionality for the ext2fs file system
is being worked on, but don't hold your breath.
There are a number of packages available which instead provide new
commands for deleting and copying which move deleted files into a
`wastebasket' directory. The files can be recovered until cleaned out
automatically by background processing.
The Midnight Commander file manager provides an undelete facility that
uses Ext2 file system library functions and an undelete directory for
each file system. Commercial distribution packages of MC may or may
not have this feature enabled, so be sure to look in the source code
distribution for instructions on how to enable the undelete feature.
Alternatively, you can search the raw disk device which holds the file
system in question. This is hard work, and you will need to be logged
in as root to do this. But it can be done. Run grep on the raw device;
e.g.:
grep -b 'bookmarks' /dev/hda
If the data has not been overwritten, you should be able to recover it
with a text editor.
[Dave Cinege, Daniel Novotny]
4.3. How To Make Backups.
You can back up a directory hierarchy or complete file system to any
media using GNU tar or cpio, the standard *nix tools for this purpose.
tar seems to be the more commonly used program currently, and includes
command line options to make compressed, incremental, and multi-volume
backups. Complete information is contained in the documentation, which
is in GNU Texinfo format.
The free program, Amanda, receives a lot of mentions on Usenet. Its
home page is http://www.amanda.org/.
Several commercial backup utilities also exist. They are often
included in commercial distributions.
4.4. How To Resize a Partition (Non-Destructively).
Use the FIPS.EXE program, included with most Linux distributions,under
MS-DOS.
GNU parted, a partition editor, is stable enough for non-guru,
mere-mortal use with relative confidence. Source code for the latest
version is at: ftp://ftp.gnu.org/pub/gnu/parted/. There's also a boot
disk image for resizing root partitions and for running parted on
non-Linux machines. The disk image may be easier for beginners.
Building from source could require some extra configuration.
Parted also has tutorial-style, plain-text documentation for Linux and
FAT (MS-DOS) file systems.
Also, some commercial distributions come with their own partitioning
software, like Partition Magic.
4.5. Is There a Defragmenter for Ext2fs?
Yes. There is defrag, a Linux file system defragmenter for ext2,
Minix, and old-style ext file systems. It is available at
ftp://metalab.unc.edu/pub/Linux/ ... defrag-0.70.tar.gz.
Users of the ext2 file system can probably do without defrag, because
ext2 contains extra code to keep fragmentation reduced even in very
full file systems.
4.6. How To Create a File System on a Floppy.
To format 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.
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 performs a low-level format. The second creates an
empty file system. You can mount the floppy like a hard disk partition
and simply cp and mv files, etc.
Device naming conventions generally are the same as for other unices.
They can be found in Matt Welsh's Installation and Getting Started
guide. Refer to ("Where Is the Documentation?") A more detailed and
technical description is Linux Allocated Devices by H. Peter Anvin,
[email protected] , which is included in LaTeX and ASCII form in the kernel
source distribution (probably in /usr/src/kernel/Documentation/), as
devices.tex and devices.txt.
4.7. Does Linux Support Virtualized File Systems Like RAID?
The most recent Linux kernels support software RAID, and they will
work with RAID disk controllers.
An automounter for NFS partitions is part of most Linux distributions.
In addition, several virtual file system projects exist. One of them,
the Linux Logical Volume Manager, is located at
http://linux.msede.com/lvm/.
4.8. Does Linux Support File System Encryption?
Yes. One file system, ppdd, is archived at
http://pweb.de.uu.net/flexsys.mtk/.
4.9. Linux Prints Nasty Messages about Inodes, Blocks, and the Like.
You may have a corrupted file system, 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 util-linux 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 automatic fsck front-end) will be able to repair
your file system. If you're unlucky, the file system is trashed, and
you'll have to re-initialize it with mkfs (or mke2fs, mkxfs, etc.),
and restore from a backup.
NB: don't try to check a file system that's mounted read/write--this
includes the root partition, if you don't see
VFS: mounted root ... read-only
at boot time.
4.10. The 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.local or /etc/rc.d/*
(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 manual page for details; it
works much like mkfs.
Running, free in addition to showing free memory, should display:
total used free
Swap: 10188 2960 7228
If typing "cat /proc/swaps" reveals only file or partition names, but
no swap space information, then the swap file or partition needs
re-initialization.
Use fdisk (as root) to determine which partition on a hard drive has
been designated as the swap partition. The partition still needs to be
initialized with mkswap before enabling it with swapon.
[Andy Jefferson, Steve Withers]
4.11. How To Add Temporary Swap Space.
In addition to a swap partition, Linux can also use a swap file. Some
programs, like g++, can use huge amounts of virtual memory, requiring
the temporary creation of extra space. To install an extra 64 MB of
swap space, for example, use the following shell commands:
# dd if=/dev/zero of=/swap bs=1024 count=65535
# mkswap /swap
# swapon /swap
The count= argument to dd determines how big the swap file will be. In
this example the swap file's name is /swap, but the name and location
are, generally, arbitrary, depending only on the file system's
available space and your having write permissions in the directory.
When you don't need the swap space any more, remove it with the
following statements:
# swapoff /swap
# rm /swap
Take a look also at the Installation HOWTO and Installation & Getting
Started for detailed instructions.
If that still doesn't provide enough swap space, refer to ("How To
Have More Than 128Mb of Swap.")
4.12. How To Remove LILO So the System Boots DOS Again?
The lilo program (not the complete LILO package), uses the command
line option -u to uninstall the LILO boot loader. You have to supply
the device name of the device you installed LILO on, for example:
lilo -u /dev/hda
This rewrites the original, pre-LILO master boot record back to the
first hard drive, from the boot record saved in /boot/boot.0300. If
you installed LILO to a partition as a secondary boot loader, for
example, /dev/hda1, lilo re-installs the original boot sector from the
save file /boot/boot.0301. Refer to the lilo manual page for details.
Thanks to Villy Kruse for reminding me to update this answer.
If you have an earlier version of LILO, you will have to use the DOS
(MS-DOS 5.0 or later, or OS/2) 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 FDISK.EXE in the normal way and then select the
Re-write Master Boot Record option.
If you create a boot floppy during the Windows installation process,
make sure that it contains the programs FDISK.EXE, FORMAT.COM, and
SYS.COM, and use that to re-install MS-DOS on the hard disk.
If you don't have MS-DOS 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 /dev/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
This will erase your partition table and boot sector completely: you
can then reformat the disk using your favorite software. But 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.
4.13. Why Does fdformat Require Superuser Privileges?
The system call to format a floppy can 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.
4.14. The System Checks the Ext2fs Partitions Each Reboot.
Refer to ("EXT2-fs: warning: mounting unchecked file system.)
4.15. Root File System Is Read-Only.
Remount it. If /etc/fstab is correct, you can simply type:
mount -n -o remount /
If /etc/fstab is wrong, you must give the device name and possibly the
type, too: e.g.
mount -n -o remount -t ext2 /dev/hda2 /
To understand how you got into this state, see, ("EXT2-fs: warning:
mounting unchecked file system.")
4.16. What Is /proc/kcore?
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 read it as
a file, the kernel does memory reads.
4.17. The AHA1542C Doesn't Work with Linux.
The option to allow disks with more than 1024 cylinders, which the
AHA1542C card can recognize, is only required as a workaround for a
PC-compatible BIOS misfeature and should be turned `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.
4.18. Where Is the Journalling File System on the Net?
The journalling file system, named Reiserfs has just been released
from testing. It is said to make Linux even faster than Linux with the
Ext2 file system installed. Complete information is available at
http://devlinux.org/namesys/.
5. Porting, Compiling and Obtaining Programs
5.1. How To Compile Programs.
Most Linux software is written in C and compiled with the GNU C
compiler. GCC is a part of every Linux distribution. The latest
compiler version, documentation, and patches are on
ftp://ftp.gnu.org/pub/gnu/.
Programs that are written in C++ must be compiled with the GNU G++
compiler, which is also included in Linux distributions and available
from the same place as GCC.
To build version 2.0.x kernels, you will need GCC version 2.7.2.x,
approximately. Trying to build an early Linux kernel with a different
compiler, like GCC 2.8.x, EGCS, or PGCC, may cause problems because of
GCC related code dependencies. Kernel versions 2.3 and 2.4 should
compile correctly with more recent compilers.
Information on the EGCS compiler is at
http://www.gnu.org/software/gcc/gcc.html.
Note that at this time, the kernel developers are not answering bug
requests for earlier kernels, but instead are concentrating on
developing 2.4.x version kernels and maintaining 2.2.x version
kernels.
[J.H.M. Dassen, Axel Boldt]
5.2. How To Install GNU Software.
On a correctly configured system, installing a GNU software package
requires four steps:
* With the source.tar.gz archive in the /usr/src/ directory, or
wherever you maintain your source files, untar and decompress the
package with the command:
tar zxvf package-name.tar.gz
* Run the ./configure script in the untarred source archive's
top-level directory with whatever command line arguments you need.
The options that configure recognizes are usually contained in a
file called INSTALL or README.
* Run make. This will build the source code into an executable
program (or programs) and may take a few minutes or a few hours,
depending on the speed of the computer and the size of the
package.
* Run make install. This will install the compiled binaries,
configuration files, and any libraries in the appropriate
directories.
5.3. Where To Get Java.
The Sun Microsystems Java runtime environments and developer's kits
are at http://java.sun.com/java/.
You can also get the source code, which is licensed by Sun
Microsystems.
The home page of IBM's Jikes Java compiler is
http://www10.software.ibm.com/developerworks/opensource/jikes.
There is a version of Sun's HotJava browser for Linux at:
http://www.java.sun.com/products/hotjava/.
Kaffee, a free Java clone, is available from: http://www.kaffe.org/.
There is a resource page of free and commercial Java packages at:
http://www.blackdown.org/java-linux.html.
Netscape Communicator comes with its own version of the Java Runtime
Environment, so if you need Java only to view Web graphics, you may
already have the runtime version of the Java Virtual Machine and
libraries that you need installed on your system. You can download
Communicator from http://www.netscape.com/.
5.4. How To Port XXX to Linux.
In general, *nix 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 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.
5.5. What Is ld.so and How To Get It?
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, /lib/ld.so, where all binaries can look for it, so that it
wastes less disk space, and can be upgraded more easily. ld.so can be
obtained from http://tsx-11.mit.edu/pub/linux/packages/GCC/ and mirror
sites. The latest version at the time of writing is
ld.so.1.9.5.tar.gz. /lib/ld-linux.so.1 is the same thing for ELF
("What's all this about ELF? ") and comes in the same package as the
a.out loader.
5.6. How To Upgrade the Libraries without Trashing the System.
Warning
Note: You should always have a rescue disk set ready when you perform
this procedure, in the likely event that something goes wrong!
This procedure is especially difficult if you're upgrading very old
libraries like libc4. But you should be able to keep libc4 on the same
system with libc5 libraries for the programs that still need them. The
same holds true for upgrading from libc5 to the newer-yet glibc2
libraries.
The problem with upgrading dynamic libraries is that, the moment you
remove the old libraries, the utilities that you need to upgrade to
the new version of the libraries don't work. There are ways around
around this. One is to temporarily place a spare copy of the run time
libraries, which are in /lib/, in /usr/lib/, or /usr/local/lib/, or
another directory that is listed in the /etc/ld.so.conf file.
For example, when upgrading libc5 libraries, the files in /lib/ might
look something like:
libc.so.5
libc.so.5.4.33
libm.so.5
libm.so.5.0.9
These are the C libraries and the math libraries. Copy them to another
directory that is listed in /etc/ld.so.conf, like /usr/lib/:
$ cp -df /lib/libc.so.5* /usr/lib/
$ cp -df /lib/libm.so.5* /usr/lib/
$ ldconfig
Be sure to run ldconfig to upgrade the library configuration.
The files libc.so.5 and libm.so.5 are symbolic links to the actual
library files. When you upgrade, the new links will not be created if
the old links are still there, unless you use the -f flag with cp. The
-d flag to cp will copy the symbolic link itself, and not the file it
points to.
If you need to overwrite the link to the library directly, use the -f
flag with ln.
For example, to copy new libraries over the old ones, try this. Make a
symbolic link to the new libraries first, then copy both the libraries
and the links to /lib/, with the following commands.
$ ln -sf ./libm.so.5.0.48 libm.so.5
$ ln -sf ./libc.so.5.0.48 libc.so.5
$ cp -df libm.so.5* /lib
$ cp -df libc.so.5* /lib
Again, remember to run ldconfig after you copy the libraries.
If you are satisfied that everything is working correctly, you can
remove the temporary copies of the old libraries from /usr/lib/ or
wherever you copied them.
5.7. How To Use Code or a Compiler Compiled for a 486 on a 386.
Yes, unless it's the kernel.
The -m486 option to GCC, which is used to compile binaries for x486
machines, merely changes certain optimizations. This makes for
slightly larger binaries that run somewhat faster on a 486. They still
work fine on a 386, though, with a small performance hit.
However, from version 1.3.35 the kernel uses 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 -m386 the default and configuring for a
486 makes -m486 the default. In either case, these can be overridden
on a per-compilation basis or by editing /usr/lib/gcc-lib/i*-linux/
n.n.n/specs.
There is an alpha version of GCC that knows how to do optimization
well for the 586, but it is quite unreliable, especially at high
optimization settings. The Pentium GCC can be found on
ftp://tsx-11.mit.edu/pub/linux/ALPHA/pentium-gcc/. The ordinary 486
GCC supposedly produces better code for the Pentium using the -m386,
or at least slightly smaller.
5.8. What Does "gcc -O6" Do?
Currently, the same as -O2 (GCC 2.5) or -O3 (GCC 2.6, 2.7). Any number
greater than that does the same thing. The Makefiles of newer kernels
use -O2, and you should probably do the same.
5.9. Where Are linux/*.h and asm/*.h?
The files /usr/include/linux/ and /usr/include/asm/ are often soft
links to the directories where the kernel headers are. They are
usually under /usr/src/kernel*/.
If you don't have the kernel sources, download them. Refer to the
answer: ("How To Upgrade/Recompile a 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-
The assembly language files reside in architecture-specific
directories, so you need to link /usr/src/include/asm to
/usr/src/linux/include/asm-i386 on PC compatible systems, to
/usr/src/linux/include/asm-sparc on Sun Sparc systems, to
/usr/src/linux/include/asm-ppc on PPC systems, and so on.
You'll also find that you may need to do `make config' as in a
newly-unpacked kernel source tree, to create linux/autoconf.h.
5.10. What To Do about Errors Trying to Compile the Kernel.
See the previous question regarding the header files.
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
patch manual page for details.
"ld: unrecognized option `-qmagic'" means that you should get a newer
linker, from ftp://tsx-11.mit.edu/pub/linux/packages/GCC/ , in the file
binutils-2.8.1.0.1.bin.tar.gz.
5.11. How To Make a Shared Library.
For ELF,
$ gcc -fPIC -c *.c
$ gcc -shared -Wl,-soname,libfoo.so.1 -o libfoo.so.1.0 *.o
For a.out, get tools-n.nn.tar.gz from
tsx-11.mit.edu/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. Consider upgrading your
libraries to ELF shared libraries. See the ELF HOWTO, at
ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/
5.12. Programs Are Very Large.
With an ELF compiler ("What's All This about ELF? glibc?"), the most
common cause of large executables is the lack of an appropriate .so
library link for one of the libraries you're using. There should be a
link like libc.so for every library like libc.so.5.2.18.
With an a.out compiler the most common cause of large executables is
the -g linker (compiler) flag. This produces (as well as debugging
information in the output file) a program which is statically
linked--one which includes a copy of the C library instead of a
dynamically linked copy.
Other things worth investigating are -O and -O2, which enable
optimization (check the GCC documentation), and -s (or the strip
command) which strip 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.
5.13. 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.
Recent kernels implement a thread model, kthreads. In addition, there
are the following packages available for Linux.
* GNU glibc2 for Linux has optional support for threads. The archive
is available from the same place as glibc2,
ftp://ftp.gnu.org/pub/gnu/
* In ftp://sipb.mit.edu/pub/pthread/ or
ftp://ftp.ibp.fr/pub/unix/threads/. Documentation isn't in the
package, but is available on the World Wide Web at
http://www.mit.edu:8001/people/proven/home_page.html. Newer Linux
libc's contain the pthreads source. The GNU Ada compiler on
ftp://metalab.unc.edu/pub/Linux/ ... gnat-3.01-linux+elf
.tar.gz contains binaries made from that source code.
* In ftp://ftp.cs.washington.edu:/pub/qt-001.tar.Z is QuickThreads.
More information can be found in the technical report, available
on the same site is /tr/1993/05/UW-CSE-93-05-06.PS.Z.
* In gummo.doc.ic.ac.uk/rex/ is lwp, a very minimal implementation.
* In ftp://ftp.cs.fsu.edu:/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.
Please contact the authors of the packages in question for details.
5.14. Where To Find lint for Linux.
Roughly equivalent functionality is built into GCC. Use the -Wall
option to turn on most of the useful extra warnings. See the GCC
manual for more details (type F1-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 ftp://larch.lcs.mit.edu/pub/Larch/lclint/; on the
World Wide Web, look at http://lclint.cs.virginia.edu/.
5.15. Where To Find Kermit for Linux.
Kermit is distributed under a non-GPL copyright that makes its terms
of distribution somewhat different. The sources and some binaries are
available on ftp://kermit.columbia.edu.
The WWW Home Page of the Columbia University Kermit project is
http://www.columbia.edu/kermit/.
5.16. How To Use Linux with a Cable Modem.
The www.CablemodemInfo.com and xDSL Web page at
http://www.cablemodeminfo.com/ has a section devoted to Linux.
5.17. Is There an ICQ Program That Runs under Linux?
Several ICQ clients are available on metalab.unc.edu. (Refer to:
"Where Are the Linux FTP Archives?") ICQ itself does not have a Linux
client, but there is a Java client at
http://www.mirabilis.com/download/.
6. Solutions to Common Miscellaneous Problems
6.1. FTP Transfers Seem to Hang.
FTP transfers that die suddenly are due, apparently, to some form of
overrunning buffer. It occurs both with Linux and Microsoft servers.
On Linux systems, The problem seems to occur most commonly with the
distribution's server software.
If you receive ftp: connection refused errors, then the problem is
likely due to a lack of authentication. Refer to "FTP or Telnet Server
Won't Allow Logins.."
One remedy is to be replacing the distribution FTP server with the
Linux port of the OpenBSD FTP server. The home page is:
http://www.eleves.ens.fr:8080/home/madore/programs/
To install the BSD server, follow the installation instructions, and
refer to the manual pages for inetd and inetd.conf. (If you have the
newer xinetd, see below.) Be sure to tell inetd to run the BSD daemon
alone, not as a subprocess of, for example, tcpd. Comment out the line
that begins "ftp" in the /etc/inetd.conf file and replace it with a
line similar to (if you install the new ftpd in /usr/local/sbin/):
# Original entry, commented out.
#ftp stream tcp nowait root /usr/sbin/tcpd /usr/sbin/in.ftpd
# Replacement entry:
ftp stream tcp nowait root /usr/local/sbin/ftpd -l
The replacement daemon will become effective after rebooting or
sending (as root) a SIGHUP to inetd, e.g.:
# kill -HUP inetd
To configure xinetd, create an entry in /etc/xinetd.d per the
instructions in the xinetd.conf manual page. Make sure, again, that
the command-line arguments for ftpd are correct, and that you have
installed the /etc/ftpusers and /etc/pam.d/ftp files. Then restart
xinetd with the command: /etc/rc.d/init.d/xinetd restart. The command
should report "OK," and the restart will be noted in the system
message log.
6.2. Free Dumps Core.
In Linux 1.3.57 and later, the format of /proc/meminfo was changed in
a way that the implementation of free doesn't understand. Get the
latest version, from metalab.unc.edu, in
/pub/Linux/system/Status/ps/procps-0.99.tgz.
6.3. Netscape Crashes Frequently.
Netscape shouldn't crash, if it and the network are properly
configured. Some things to check:
* Make sure that the MOZILLA_HOME environment variable is correctly
set. If you installed Netscape under /usr/local/netscape/, for
example, that should be the value of MOZILLA_HOME. Set it from the
command line (e.g, "export MOZILLA_HOME="/usr/local/netscape""
under bash or add it to one your personal or system initialization
files. Refer to the manual page for your shell for details.
* If you have a brand-new version of Netscape, try a previous
version, in case the run-time libraries are slightly incompatible.
For example, if Netscape version 4.75 is installed (type "netscape
--version" at the shell prompt), try installing version 4.7. All
versions are archived at ftp://ftp.netscape.com/.
* Netscape uses its own Motif and Java Runtime Environment
libraries. If a separate version of either is installed on your
system, ensure that they aren't interfering with Netscape's
libraries; e.g., by un-installing them.
* Make sure that Netscape can connect to its default name servers.
The program will appear to freeze and time out after several
minutes if it can't. This indicates a problem with the system's
Internet connection; likely, the system can't connect to other
sites, either.
6.4. FTP or Telnet Server Won't Allow Logins.
This applies to server daemons that respond to clients, but don't
allow logins. On new systems that have Pluggable Authentication
Modules installed, look for a file named, "ftp," or "telnet," in the
directory /etc/pam/ or /etc/pam.d/. If the corresponding
authentication file doesn't exist, the instructions for configuring
FTP and Telnet authentication and other PAM configuration, should be
in /usr/doc/pam-
says: "421 service not available, remote server has closed
connection."."
If it's an FTP server on an older system, make sure that the account
exists in /etc/passwd, especially "anonymous."
This type of problem may also be caused a failure to resolve the host
addresses properly, especially if using Reverse Address Resolution
Protocol (RARP). The simple answer to this is to list all relevant
host names and IP addresses in the /etc/hosts files on each machine. (
Refer to the example /etc/hosts and /etc/resolv.conf files in:
"Sendmail Pauses for Up to a Minute at Each Command..") If the network
has an internal DNS, make sure that each host can resolve network
addresses using it.
If the host machine doesn't respond to FTP or Telnet clients at all,
then the server daemon is not installed correctly, or at all. Refer to
the manual pages: inetd and inetd.conf on older systems, or xinetd and
xinetd.conf, as well as ftpd, and telnetd.
6.5. How To Keep Track of Bookmarks in Netscape?
This probably applies to most other browsers, too. In the
Preferences/Navigator menu, set your home page to Netscape's
bookmarks.html file, which is located in the .netscape (with a leading
period) subdirectory. For example, if your login name is "smith," set
the home page to:
file://home/smith/.netscape/bookmarks.html
Setting up your personal home page like this will present you with a
nicely formatted (albeit possibly long) page of bookmarks when
Netscape starts. And the file is automatically updated whenever you
add, delete, or visit a bookmarked site.
Archive-Name: linux/faq/part4
URL: http://www.mainmatter.com/
Reply-to: [email protected]
Posting-Frequency: weekly
Last-modified: 12/04/2001
6.6. The Computer Has the Wrong Time.
There are two clocks in your computer. The hardware (CMOS) clock runs
even when the computer is turned off, and is used when the system
starts up and by DOS (if you use DOS). The ordinary system time, shown
and set by 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 /sbin/clock (now called hwclock in many distributions).
Refer to: man 8 clock or man 8 hwclock.
There are various other programs that can correct either or both
clocks for system drift or transfer time across the network. Some of
them may already be installed on your system. Try looking for adjtimex
(corrects for drift), Network Time Protocol clients like netdate,
getdate, and xntp, or NTP client-server suite like chrony. Refer to:
"How to Find a Particular Application.."
6.7. Setuid Scripts Don't Seem to Work.
That's right. This feature has been disabled in the Linux kernel on
purpose, because setuid scripts are almost always a security hole.
Sudo and SuidPerl can provide more security than setuid scripts or
binaries, especially if execute permissions are limited to a certain
user ID or group ID.
If you want to know why setuid scripts are a security hole, read the
FAQ for comp.unix.questions.
6.8. Free Memory as Reported by free Keeps Shrinking.
The "free" figure printed by 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 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, the contents get cached. It
will stabilize after a while.
6.9. When Adding More Memory, the System Slows to a Crawl.
This is 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 RAM has to be in certain sockets to be cached.
Sometimes you have to set jumpers to enable caching.
Some motherboards don't cache all of the RAM if you have more RAM per
amount of cache than the hardware expects. Usually a full 256K cache
will solve this problem.
If in doubt, check the manual. If you still can't fix it because the
documentation is inadequate, you might like to post a message to
comp.os.linux.hardware giving all of the details--make, model number,
date code, etc., so other Linux users can avoid it.
6.10. Some Programs (E.g. xdm) Won't Allow Logins.
You are probably using non-shadow password programs and are using
shadow passwords.
If so, you have to get or compile a shadow password version of the
programs in question. The shadow password suite can be found at
ftp://tsx-11.mit.edu:/pub/linux/sources/usr.bin/shadow/. This is the
source code. The binaries are probably in linux/binaries/usr.bin/.
6.11. Some Programs Allow Logins with No Password.
You probably have the same problem as in ("Some Programs (E.g. xdm)
Won't Allow Logins."), with an added wrinkle.
If you are using shadow passwords, you should put a letter `x' or an
asterisk in the password field of /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.
6.12. The Machine Runs Very Slowly with GCC / X / ...
You may have too little real memory. If you have less RAM than all the
programs you're running at once, Linux will swap to your hard disk
instead and thrash horribly. The solution in this case is to not run
so many things at once or buy more memory. You can also reclaim some
memory by compiling and using a kernel with less options configured.
See ("How To Upgrade/Recompile a Kernel.")
You can tell how much memory and swap you're using with the free
command, or by typing:
$ cat /proc/meminfo
If your kernel is configured with a RAM disk, this is probably wasted
space and will cause things to go slowly. Use LILO or rdev to tell the
kernel not to allocate a RAM disk (see the LILO documentation or type
"man rdev").
6.13. System Only Allows Root Logins.
You probably have some permission problems, or you have a file
/etc/nologin.
In the latter case, put "rm -f /etc/nologin" in your /etc/rc.local or
/etc/rc.d/* scripts.
Otherwise, check the permissions on your shell, and any file names
that appear in error messages, and also the directories that contain
these files, up to and including the root directory.
6.14. The Screen Is All Full of Weird Characters Instead of Letters.
You probably sent some binary data to your screen by mistake. Type
echo '/033c' to fix it. Many Linux distributions have a command,
reset, that does this.
If that doesn't help, try a direct screen escape command.
$ echo 'Ctrl-V Ctrl-O'
This resets the default font of a Linux console. Remember to hold down
the Control key and type the letter, instead of, for example, Ctrl,
then V. The sequence
$ echo 'Ctrl-V Esc C'
causes a full screen reset. If there's data left on the shell command
line after typing a binary file, press Ctrl-C a few times to restore
the shell command line.
Another possible command is an alias, "sane," that can work with
generic terminals:
$ alias sane='echo -e "//033c";tput is2; /
> stty sane line 1 rows $LINES columns $COLUMNS'
The alias is enclosed with open quotes (backticks), not single quotes.
The line break is included here for clarity, and is not required.
Make sure that $LINES and $COLUMNS are defined in the environment with
a command similar to this in ~/.cshrc or ~/.bashrc,
$ LINES=25; export $LINES; $COLUMNS=80; export $COLUMNS
using the correct numbers of $LINES and $COLUMNS for the terminal.
Finally, the output of "stty -g" can be used to create a shell script
that will reset the terminal:
1. Save the output of "stty -g" to a file. In this example, the file
is named "termset.":
$ stty -g >termset
The output of "stty -g" (the contents of "termset") will look
something like:
500:5:bd:8a3b:3:1c:7f:15:4:0:1:0:11:13:1a:0:12:f:17:16:0:0:73
2. Edit "termset" to become a shell script; adding an interpreter and
"stty" command:
#!/bin/bash
stty 500:5:bd:8a3b:3:1c:7f:15:4:0:1:0:11:13:1a:0:12:f:17:16:0:0:73
3. Add executable permissions to "termset" and use as a shell script:
$ chmod +x termset
$ ./termset
[Floyd L. Davidson, Bernhard Gabler]
6.15. I Screwed Up the 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 install subdirectory of the
Slackware distribution.
There are also two, do-it-yourself rescue disk creation packages in
ftp://metalab.unc.edu/pub/Linux/system/recovery/. These are better
because they have your own kernel on them, so you don't run the risk
of missing devices and file systems.
Get to a shell prompt and mount your hard disk with something like
$ mount -t ext2 /dev/hda1 /mnt
Then your file system is available under the directory /mnt and you
can fix the problem. Remember to unmount your hard disk before
rebooting (cd somewhere else first, or it will say it's busy).
6.16. I Forgot the root Password.
Note: Incorrectly editing any of the files in the /etc/ directory can
severely screw up a system. Please keep a spare copy of any files in
case you make a mistake.
If your Linux distribution permits, try booting into single-user mode
by typing "single" at the BOOT lilo: prompt. With more recent
distributions, you can boot into single-user mode when prompted by
typing "linux 1," "linux single," or "init=/bin/bash."
If the above doesn't work for you, boot from the installation or
rescue floppy, and switch to another virtual console with Alt-F1 --
Alt-F8, and then mount the root file system on /mnt. Then proceed with
the steps below to determine if your system has standard or shadow
passwords, and how to remove the password.
Using your favorite text editor, edit the root entry of the
/etc/passwd file to remove the password, which is located between the
first and second colons. Do this only if the password field does not
contain an "x," in which case see below.
root:Yhgew13xs:0:0: ...
Change that to:
root::0:0: ...
If the password field contains an "x," then you must remove the
password from the /etc/shadow file, which is in a similar format.
Refer to the manual pages: "man passwd," and "man 5 shadow."
[Paul Colquhuon, Robert Kiesling, Tom Plunket]
6.17. There's a Huge Security Hole in rm!
No there isn't. You are obviously new to unices and need to read a
good book to find out how things work. Clue: the ability to delete
files depends on permission to write in that directory.
6.18. lpr and/or lpd Don't Work.
First make sure that your /dev/lp* port is correctly configured. Its
IRQ (if any) and port address need to match the settings on the
printer card. You should be able to dump a file directly to the
printer:
$ cat the_file >/dev/lp1
If lpr gives you a message like myname@host: host not found" it may
mean that the TCP/IP loopback interface, lo, isn't working properly.
Loopback support is compiled into most distribution kernels. Check
that the interface is configured with the ifconfig command. By
Internet convention, the network number is 127.0.0.0, and the local
host address is 127.0.0.1. If everything is configured correctly, you
should be able to telnet to your own machine and get a login prompt.
Make sure that /etc/hosts.lpd contains the machine's host name.
If your machine has a network-aware lpd, like the one that comes with
LPRng, make sure that /etc/lpd.perms is configured correctly. Also
look at the Printing HOWTO. "Where can I get the HOWTO's and other
documentation? ".
6.19. Timestamps on Files on MS-DOS Partitions Are Set Incorrectly
There is a bug in the program clock (often found in /sbin). It
miscounts a time zone offset, confusing seconds with minutes or
something like that. Get a recent version.
6.20. How To Get LILO to Boot the Kernel Image.
From kernel versions 1.1.80 on, the compressed kernel image, which is
what LILO needs to find, is in arch/i386/boot/zImage, or
arch/i386/boot/bzImage when it is built, and is normally stored in the
/boot/ directory. The /etc/lilo.conf file should refer to the vmlinuz
symbolic link, not the actual kernel image.
This was changed to make it easier to build kernel versions for
several different processors from one source tree.
6.21. How To Make Sure the System Boots after Re-Installing the Operating
System.
This should work whether you're re-installing Linux or some other,
commercial, operating system:
* Insert a blank, formatted floppy in drive A:
* Save a copy of the boot hard drive's Master Boot Record to the
floppy, by executing the command:
#dd if=/dev/hda of=/dev/fd0 count=1
dd is a standard program on Linux systems. A MS-Windows compatible
version is available from ftp://ftp.gnu.org/ , as well as many MS
software archives.
* Test that the floppy boots the system by rebooting with the floppy
in the A: drive.
* Then you should be able to install the other operating system (on
a different hard drive and/or partition, if you don't want to
uninstall Linux).
* After installation, boot Linux again from the floppy, and
re-install the MBR with the command: /sbin/lilo.
[Jacques Guy]
6.22. The PCMCIA Card Doesn't Work after Upgrading the Kernel.
The PCMCIA Card Services modules, which are located in
/lib/modules/version/pcmcia, where version is the version number of
the kernel, use configuration information that is specific to that
kernel image only. The PCMCIA modules on your system will not work
with a different kernel image. You need to upgrade the PCMCIA card
modules when you upgrade the kernel.
When upgrading from older kernels, make sure that you have the most
recent version of the run-time libraries, the modutils package, and so
on. Refer to the file Documentation/Changes in the kernel source tree
for details.
Important: If you use the PCMCIA Card Services, do not enable the
Network device support/Pocket and portable adapters option of the
kernel configuration menu, as this conflicts with the modules in Card
Services.
Knowing the PCMCIA module dependencies of the old kernel is useful.
You need to keep track of them. For example, if your PCMCIA card
depends on the serial port character device being installed as a
module for the old kernel, then you need to ensure that the serial
module is available for the new kernel and PCMCIA modules as well.
The procedure described here is somewhat kludgey, but it is much
easier than re-calculating module dependencies from scratch, and
making sure the upgrade modules get loaded so that both the non-PCMCIA
and PCMCIA are happy. Recent kernel releases contain a myriad of
module options, too many to keep track of easily. These steps use the
existing module dependencies as much as possible, instead of requiring
you to calculate new ones.
However, this procedure does not take into account instances where
module dependencies are incompatible from one kernel version to
another. In these cases, you'll need to load the modules yourself with
insmod, or adjust the module dependencies in the /etc/conf.modules
file. The Documentation/modules.txt file in the kernel source tree
contains a good description of how to use the kernel loadable modules
and the module utilities like insmod, modprobe, and depmod.
Modules.txt also contains a recommended procedure for determining
which features to include in a resident kernel, and which to build as
modules.
Essentially, you need to follow these steps when you install a new
kernel.
* Before building the new kernel, make a record with the lsmod
command of the module dependencies that your system currently
uses. For example, part of the lsmod output might look like this:
Module Pages Used by
memory_cs 2 0
ds 2 [memory_cs] 3
i82365 4 2
pcmcia_core 8 [memory_cs ds i82365] 3
sg 1 0
bsd_comp 1 0
ppp 5 [bsd_comp] 0
slhc 2 [ppp] 0
serial 8 0
psaux 1 0
lp 2 0
This tells you for example that the memory_cs module needs the ds
and pcmcia_core modules loaded first. What it doesn't say is that,
in order to avoid recalculating the module dependencies, you may
also need to have the serial, lp, psaux, and other standard
modules available to prevent errors when installing the pcmcia
routines at boot time with insmod. A glance at the /etc/modules
file will tell you what modules the system currently loads, and in
what order. Save a copy of this file for future reference, until
you have successfully installed the new kernel's modules. Also
save the lsmod output to a file, for example, with the command:
lsmod >lsmod.old-kernel.output.
* Build the new kernel, and install the boot image, either zImage or
bzImage, to a floppy diskette. To do this, change to the
arch/i386/boot directory (substitute the correct architecture
directory if you don't have an Intel machine), and, with a floppy
in the diskette drive, execute the command:
$ dd if=bzImage of=/dev/fd0 bs=512
if you built the kernel with the make bzImage command, and if your
floppy drive is /dev/fd0. This results in a bootable kernel image
being written to the floppy, and allows you to try out the new
kernel without replacing the existing one that LILO boots on the
hard drive.
* Boot the new kernel from the floppy to make sure that it works.
* With the system running the new kernel, compile and install a
current version of the PCMCIA Card Services package, available
from metalab.unc.edu as well as other Linux archives. Before
installing the Card Services utilities, change the names of
/sbin/cardmgr and /sbin/cardctl to /sbin/cardmgr.old and
/sbin/cardctl.old. The old versions of these utilities are not
compatible with the replacement utilities that Card Services
installs. In case something goes awry with the installation, the
old utilities won't be overwritten, and you can revert to the
older versions if necessary. When configuring Card Services with
the "make config" command, make sure that the build scripts know
where to locate the kernel configuration, either by using
information from the running kernel, or telling the build process
where the source tree of the new kernel is. The "make config" step
should complete without errors. Installing the modules from the
Card Services package places them in the directory
/lib/modules/version/pcmcia, where version is the version number
of the new kernel.
* Reboot the system, and note which, if any, of the PCMCIA devices
work. Also make sure that the non-PCMCIA hardware devices are
working. It's likely that some or all of them won't work. Use
lsmod to determine which modules the kernel loaded at boot time,
and compare it with the module listing that the old kernel loaded,
which you saved from the first step of the procedure. (If you
didn't save a listing of the lsmod output, go back and reboot the
old kernel, and make the listing now.)
* When all modules are properly loaded, you can replace the old
kernel image on the hard drive. This will most likely be the file
pointed to by the /vmlinuz symlink. Remember to update the boot
sector by running the lilo command after installing the new kernel
image on the hard drive.
Also look at the questions, How do I upgrade/recompile my kernel? and
Modprobe can't locate module, "XXX," and similar messages.
6.23. How To Remove (or Change) the Colors in the ls Display.
The shell command, "unalias ls," should completely unset the
configuration that some distributions provide as standard. To change
the colors, refer to the ls man page ("man ls").
6.24. Why Won't a Program Work in the Current Directory?
Because the current directory (i.e., ".") is not in the search path,
for security reasons, as well as to insure that the correct program
versions are used. If an intruder is able to write a file to a
world-writable directory, like /tmp, presumably he or she would be
able to execute it if the directory were in the search path. The
solution to this is to include the directory in the command; e.g.,
"./myprog," instead of "myprog." Or add the current directory to your
PATH environment variable; e.g., "export PATH=".:"$PATH" using bash,
although this is discouraged for the reasons mentioned above.
7. How To Do This or Find Out That...
7.1. How To Find Out If a Notebook Runs Linux.
There's no fixed answer to this question, because notebook hardware is
constantly updated, and getting the X display, sound, PCMCIA, modem,
and so forth, working, can take a good deal of effort.
Most notebooks currently on the market, for example, use "Winmodems,"
which often do not work with Linux because of their proprietary
hardware interfaces. Even notebooks which are certified as "Linux
compatible," may not be completely compatible.
Information about installing Winmodems in general is contained in the
Winmodems-and-Linux HOWTO. (Refer to "Where Is the Documentation?")
You can find the most current information, or ask other users about
their notebook experiences, on the linux-laptop mailing list, which is
hosted by the vger.redhat.com server. (Refer to "What Mailing Lists
Are There?")
A mailing list for Linux on IBM Thinkpads has its home page at
http://www.topica.com/lists/linux-thinkpad/.
Another Thinkpad mailing list is hosted by http://www.bm-soft.com/.
Send email with the word "help" in the body of the message to
[email protected].
There is a Web page about Linux on IBM Thinkpads at
http://peipa.essex.ac.uk/tp-linux/.
The Linux Laptop home page is at
http://www.cs.utexas.edu/users/kharker/linux-laptop/.
For information about interfacing peripherals like Zip and CD-ROM
drives through parallel ports, refer to the Linux Parallel Port Home
Page, at http://www.torque.net/linux-pp.html.
If you need the latest version of the PCMCIA Card Services package, it
is (or was) located at ftp://cb-iris.stanford.edu/pub/pcmcia/ , but
that host no longer seems to be available. Recent distributions are on
ftp://metalab.unc.edu/pub/Linux/kernel/pcmcia/. You will also need to
have the kernel source code installed as well. Be sure to read the
PCMCIA-HOWTO, which is included in the distribution.
7.2. Installing Linux Using FTP.
Most distributions are too large and complex to make FTP installation
practical. Installing a basic Linux system that doesn't have a GUI or
major applications is possible with FTP, however. The main
non-commercial distribution in use is Debian GNU/Linux, and this
answer describes an installation of a basic Debian system, to which
you can add other Linux applications and commercial software as
necessary.
This answer describes installation on IBM-compatible machines with an
Intel x86 or Pentium processor. You will need a machine with at least
a 80386 processor, 8 Mb of memory, and about 100 Mb of disk space.
More memory and a larger disk is necessary however, for practical
everyday use.
For other hardware, substitute "-arm," "-ppc," "-m68k," or other
abbreviation in directory names for "-i386."
For detailed and hardware-specific information refer to:
http://www.debian.org/releases/stable/.
* Connect using anonymous FTP to ftp.debian.org and cd to the
pub/debian/dists/stable/main/disks-i386/current/ subdirectory.
* Retrieve the binary image files for the rescue disk, and the
drivers disk. Depending on the floppy drive installed on your
machine, retrieve either the diskette images with "1200" in the
names if you have a 1.2 Mb, 5.25-in. floppy, or the disks with
"1440" in the name if the computer has a 3.25-in., 1.44 Mb floppy.
Then retrieve the base system diskettes. Note that there are 7
base system images in the 1.44-Mb set (which have a "14" in their
names) , and 9 in the 1.2-Mb set of images (which have a "12" in
their names). You will use these to create the basic installation
diskettes. If you have a Linux machine, you can use dd to write
the images to the diskettes. If you are creating the installation
diskettes on a MS-DOS machine, also download the RAWRITE.EXE
MS-DOS utility, which will copy the raw binary images to floppy
disks. Also download the install.en.txt document, which contains
the detailed installation instructions.
* Create the installation disk set on floppies using either dd under
Linux (e.g.: "dd if=resc1440.bin of=/dev/fd0"), or the RAWRITE.EXE
utility under MS-DOS. Be sure to label each installation diskette.
* Insert the rescue diskette into the floppy drive and reboot the
computer. If all goes well, the Linux kernel will boot, and you
will be able start the installation program by pressing Enter at
the boot: prompt.
* Follow the on-screen instructions for partitioning the hard disk,
installing device drivers, the basic system software, and the
Linux kernel. If the machine is connected to a local network,
enter the network information when the system asks for it.
* To install additional software over the Internet, be sure that you
have installed the ppp module during the installation process, and
run (as root) the /usr/sbin/pppconfig utility. You will need to
provide your user name with your ISP, your password, the ISP's
dial-up phone number, the address(es) of the ISP's Domain Name
Service, and the serial port that your modem is connected to,
/dev/ttyS0-/dev/ttyS3. Be sure also to specify the defaultroute
option to the PPP system, so the computer knows to use the PPP
connection for remote Internet addresses.
* You may have to perform additional configuration on the PPP
scripts in the /etc/ppp subdirectory, and in particular, the
ISP-specific script in the /etc/ppp/peers subdirectory. There are
basic instructions in each script. For detailed information, refer
to the Debian/GNU Linux installation instructions that you
downloaded, the pppd manual page (type man pppd), and the PPP
HOWTO from the Linux Documentation project,
http://www.linuxdoc.org/.
* Once you have a PPP connection established with your ISP (it will
be displayed in the output of ifconfig), use the dselect program
to specify which additional software you want to install. Use the
apt [A]ccess option to retrieve packages via anonymous FTP, and
make sure to use the [U]pdate option to retrieve a current list of
packages from the FTP archive.
7.3. Resuming an Interrupted Download.
You can use the "reget" command of the standard ftp client program
after reconnecting to pick up where you left off.
Clients like ncftp support resumed FTP downloads, and wget supports
resumed FTP and HTTP downloads.
7.4. Boot-Time Configuration.
You can configure Linux at the lilo: prompt either by typing the
kernel arguments at the BOOT lilo: prompt, or by adding an "append="
directive to the /etc/lilo.conf file; for example:
# At the LILO prompt (example only):
BOOT lilo: parport=0x3bc,7 parport=0x3bc,none serial=0x3f8,4 serial=0x2f8,3
# Example statement for /etc/lilo.conf:
append="parport=0x3bc,none serial=0x3f8,4 serial=0x2f8,3"
If you modify the /etc/lilo.conf file, be sure to run the lilo command
to install the new configuration.
Configuration notes for specific hardware devices are in the
documentation of the kernel source distribution,
/usr/src/linux/Documentation in most distributions.
Refer to the lilo and /etc/lilo.conf manual pages, as well as the LDP
BootPrompt-HowTo ("Where Is the Documentation?"), and the
documentation in /usr/doc/lilo.
7.5. Formatting Man Pages without man or groff.
The man2html program translates groff text to HTML, which you can view
with a Web browser. The man2html program, and many like it, are
availble on the Web. Look for them with your favorite search engine.
The unformatted manual pages are stored in subdirectories of /usr/man,
/usr/local/man, and elsewhere.
If you want to view text, use nroff and less. Both of these programs
have MSDOS versions with an implementation of the man macro package
available as well. An example would be:
$ nroff -man /usr/man/man1/ls.1 | less
If you know where to find a good implementation of the man macros
without installing groff, please let the FAQ maintainer know.
If the manual page filename ends in ".gz," then you'll need to
uncompress it before formatting it, using gzip -d or gunzip. A
one-line example would be:
$ gzip -dc /usr/man/man1/ls.1.gz | nroff -man | less
7.6. How To Scroll Backwards in Text Mode.
With the default US keymap, you can use Shift with the PgUp and PgDn
keys. (The gray ones, not the ones on the numeric keypad.) With other
keymaps, look in /usr/lib/keytables. You can remap the ScrollUp and
ScrollDown keys to be whatever you like.
The screen program,
http://vector.co.jp/vpack/browse/person/an010455.html provides a
searchable scrollback buffer and the ability to take "snapshots" of
text-mode screens.
Recent kernels that have the VGA Console driver can use dramatically
more memory for scrollback, provided that the video card can actually
handle 64 kb of video memory. Add the line:
#define VGA_CAN_DO_64B
to the start of the file drivers/video/vgacon.c. This feature may
become a standard setting in future kernels. If the video frame buffer
is also enabled in the kernel, this setting may not affect buffering.
In older kernels, the amount of scrollback is fixed, because it is
implemented using the video memory to store the scrollback text. You
may be able to get more scrollback in each virtual console by reducing
the total number of VC's. See linux/tty.h.
[Chris Karakas]
7.7. How To Get Email to Work.
For sending mail via SMTP (Simple Mail Transfer Protocol) and
receiving mail from an ISP's POP (Post Office Protocol) server, you
can use a desktop client like Netscape Communicator or KDE kmail. You
will need to enter the names of the SMTP and POP servers in the
preferences of the respective application, as well as your E-mail
address (username@isp's-domain-name), and your dial-up password. The
same applies to Usenet News. Enter the name of the NNTP (Network News
Transfer Protocol) server in your News client's preferences section.
You may also have to provide the IP addresses of the ISP's primary and
secondary name servers.
If you have a traditional MTA (Mail Transport Agent) like Sendmail,
Smail, qmail, or Exim, you'll need to follow the instructions in each
package. Basically, configuration entails determining which host
machine, either on your local LAN or via dial-up Internet, is the
"Smart Host," if you're using SMTP. If you're using the older UUCP
protocol, then you'll need to consult the directions for configuring
UUCP, and also make sure that your ISP's system is configured to relay
mail to you.
Information about Internet hosting, and News and E-mail in general, is
available on the Usenet News group news.announce.newusers, and those
FAQ's are also archived at ftp://rtfm.mit.edu/pub/usenet/.
7.8. Sendmail Pauses for Up to a Minute at Each Command.
Make sure that Sendmail can resolve your hostname to a valid (i.e.,
parsable) domain address. If you are not connected to the Internet, or
have a dial-up connection with dynamic IP addressing, add the fully
qualified domain name to the /etc/hosts file, in addition to the base
host name; e.g., if the host name is "bilbo" and the domain is
"bag-end.com:"
192.168.0.1 bilbo.bag-end.com bilbo
And make sure that either the /etc/host.conf or /etc/resolv.conf file
contains the line:
order hosts,bind
Caution: Do not change the "localhost" entry in /etc/hosts, because
many programs depend on it for internal message-passing.
Sendmail takes many factors into account when resolving domain
addresses. These factors, collectively, are known as, "rulesets," in
sendmail jargon. The program does not require that a domain address be
canonical, or even appear to be canonical. In the example above,
"bilbo." (note the period) would work just as well as
"bilbo.bag-end.com." This and other modifications apply mainly to
recent versions.
Prior to version 8.7, sendmail required that the FQDN appear first in
the /etc/hosts entry. This is due to changes in the envelope address
masquerade options. Consult the sendmail documents.
If you have a domain name server for only a local subnet, make sure
that "." refers to a SOA record on the server machine, and that
reverse lookups (check by using nslookup) work for all machines on the
subnet.
Finally, FEATURE configuration macro options like nodns,
always_add_domain, and nocanonify, control how sendmail interprets
host names.
The document, Sendmail: Installation and Operation Guide, included in
the doc/ subdirectory of Sendmail source code distributions, discusses
briefly how Sendmail resolves Internet addresses. Sendmail source code
archives are listed at: http://www.sendmail.org/
[Chris Karakas]
7.9. How To Enable and Select Virtual Consoles.
In text mode, press the left Alt-F1 to Alt-F12 to select the consoles
tty1 to tty12; Right Alt-F1 gives tty13 and so on. To switch out of X
you must press Ctrl-Alt-F1, etc; Alt-F5 or whatever will switch back.
However, If you have a non-PC compatible system, please see the note
below.
If you want to use a VC for ordinary login, it must be listed in
/etc/inittab, which controls which terminals and virtual consoles have
login prompts. The X Window System needs at least one free VC in order
to start.
[Note: The key sequence is actually Ctrl--Meta-- FN. On PC compatible
systems, the right and left Alt keys are really synonymous with the
keysymbols Meta_L and Meta_R. If the binding is different, you can
determine what keys produce Meta_L and Meta_R with xkeycaps or a
similar application.]
[David Charlap]
7.10. How To Set the Time Zone.
Change directory to /usr/lib/zoneinfo/. Get the time zone package if
you don't have this directory. The source is available in
ftp://metalab.unc.edu/pub/Linux/system/admin/time/.
Then make a symbolic link named localtime pointing to one of the files
in this directory (or a subdirectory), and one called posixrules
pointing to localtime. For example:
$ ln -sf US/Mountain localtime
$ ln -sf localtime posixrules
This change will take effect immediately--try date.
Archive-Name: linux/faq/part5
URL: http://www.mainmatter.com/
Reply-to: [email protected]
Posting-Frequency: weekly
Last-modified: 12/04/2001
If the system uses Red Hat-style configuration files, the respective
time zone info files are /usr/share/zoneinfo and /etc/localtime.
The manual pages for tzset or tzselect describe setting the time zone.
Some programs recognize the "TZ" environment variable, but this is not
POSIX-correct.
You should also make sure that your Linux kernel clock is set to the
correct GMT time. Type date -u and check that the correct UTC time is
displayed. ("The Computer Has the Wrong Time.")
7.11. Dial-up PPP Configuration.
This information is mainly for people who do not have a wrapper
utility like kppp or pppconfig, or are not able to get those utilities
to work correctly. If you need to manually configure PPP to dial in to
your ISP, you will need the following information:
* The port that your modem is connected to: /dev/ttyS0-/dev/ttyS3,
which correspond to COM1-COM4 under MS-DOS.
* The phone number of your ISP's data connection.
* The user name and password that your ISP gave you.
* The IP addresses of the primary and possibly secondary Domain Name
Service that you will use when dialing in to the ISP. This assumes
that you will not be using a DNS that you installed on your
system.
When you have all of this information, make sure that the programs
pppd and chat, at the very minimum, are installed correctly. In most
current distributions, they are installed in the /usr/sbin/ directory,
and you will need to be logged in as root to use them. In addition,
the following programs are also useful for configuring network
connections, determining network status, and diagnosing problems:
/sbin/ifconfig, /sbin/route, /bin/ping, /usr/sbin/traceroute.
These are the basic steps that you need to follow to configure PPP.
You must be logged in as root.
* Make sure that the serial port and modem are operating correctly.
Using a program like minicomm or kermit, you should be able to
send AT commands to the modem and receive the OK string in
response from the modem.
* Enter the primary and possibly secondary Domain Name Server IP
addresses in the /etc/resolv.conf file, using dotted quad
notation, with the nameserver label. For example:
order hosts,bind
nameserver 196.182.101.103
nameserver 196.182.101.104
The nameserver addresses in the example above are examples only.
They don't correspond to actual network hosts.
The first line, order hosts,bind, tells your networking software,
when it resolves network domain addresses, to first look in the
/etc/hosts file, and then use the bind service; i.e., the DNS
servers, which are specified on the lines that begin with
nameserver.
* Locate the chat script that PPP will use to dial the modem and
connect to your ISP. In many systems, this is either in the
/etc/chatscripts or /etc/ppp directory, and will be called
provider or something similar. You can store a chat script
anywhere, provided that you tell pppd to use it rather than the
default script. Refer to the chat and pppd manual pages, and the
information below, for details. Here is a sample chat script:
ABORT BUSY
ABORT "NO CARRIER"
ABORT VOICE
ABORT "NO DIALTONE"
"" ATDT
ogin
word
This is a chat program for a simple, script based login. The chat
program uses the pair of strings on each line as a match/response
pair. When it starts, it sends the string
"ATDTyour_isp's_phone_number," where you have substituted the
actual phone number of course. It then waits for the string ogin
(a substring of the word login) and sends your user name. It then
waits for word (a substring of password) and sends your password.
If your ISP uses a different login and password prompts, and any
additional prompts, you will need to edit the script accordingly.
Again, refer to the chat manual page for details.
If your ISP uses PAP or CHAP authentication, you will need to edit
the pap-secrets or chap-secrets files in /etc/ppp directory as
well. Refer to the manual pages for these files, as well as the
instruction in the files themselves.
* The configuration of pppd, the program that maintains the actual
connection, is usually contained in two or three separate files.
The first is usually /etc/ppp/options, which contains options that
all of your system's PPP connections will use. (Yes, you can have
more than one; as many as your computer has serial ports,
generally.)
Here is a sample /etc/ppp/options file:
# /etc/ppp/options
asyncmap 0
auth
crtscts
lock
noipx
# ---
The options may be given on one line or each on a separate line.
Many options files are much longer, and come with a description of
each option. Here, the options mean, in order, don't remap any
characters between the PPP client and server; always use password,
PAP, or CHAP authentication when making a connection; use the
modem's hardware handshake lines for flow control; lock the serial
port when in use so no other programs can access it; and do not
use the IPX network protocol.
* For connection set-up on each individual serial port or PPP host,
there will either be an /etc/ppp/options.ttyS1, for example,
options file for /etc/ttyS1, or a file for your ISP in the
/etc/ppp/peers directory. The default is often called
/etc/ppp/peers/provider. Here is a sample of the default provider
file:
noauth
connect "/usr/sbin/chat -v -f /etc/chatscripts/provider"
defaultroute
/dev/ttyS1
38400
persist
There might be an explanation of these and other options in the
/etc/ppp/peers/provider file itself. You can also refer to the
pppd manual page for details. Briefly, they mean: do not use PAP
authentication for this connection; use the chat program and the
/etc/chatscripts/provider script, which is described above, to
dial the phone and log in; set the network default route to the
PPP connection (so when your network software needs to resolve an
network address that is not on your local machine(s), it will use
the PPP connection to the Internet); use /dev/ttyS1 as the serial
port for the connection; set the modem speed to 38400; and keep
the pppd daemon running even if the connection fails.
* That is all of the configuration you need. To actually start and
stop PPP, there are often /usr/bin/pon and /usr/bin/poff scripts
(in Debian), or something similar, and they are usually very
simple, and only contain the command:
$ /usr/sbin/pppd call ${1:-provider}
This will start pppd and use the call option to call the server
that you type on the command line, or the provider given in the
/etc/ppp/peers/provider file if you do not specify a remote
server. After making the call and logging in (about 30 seconds),
you should be able to use the /sbin/ifconfig program to determine
that the connection really did establish a PPP interface (the
first will be ppp0, the second will be ppp1, etc., depending on
how many simultaneous PPP connections you have. If something goes
wrong, you can look at the /var/log/ppp.log file to determine what
happened. You can also view the log as the connection is being
made, by "tailing" it in another window; that is, viewing it as
pppd logs the connection's status information. To do this, use the
command (again, as root):
$ tail -f /var/log/ppp.log
On some systems the PPP output is directed to /var/log/messages,
in which case your system may not have a dedicated PPP log file.
You should be also able to ping one of your ISP's domain names (e.g.,
mail.isp.com) and receive a response.
These are the most basic steps for configuring a PPP connection. You
will also need to take into account what other network connections may
be present (for example, if there's an Ethernet connection that has
already been assigned the default route), as well as various security
measures at your ISP's end. If you're having trouble making the
dial-up connection, usually the best way to determine what may be
going wrong is to use Seyon, minicomm, kermit, or some other program
to dial and log in manually to the ISP, and determine just exactly
what you have to do to log in, then duplicate that in the PPP scripts.
Most Linux documentation also has additional instructions for
configuring PPP connections. Refer to ("Where Are the Linux FTP
Archives?") ("Where Is the Documentation?")
7.12. What Version of Linux and What Machine Name Is This?
Type:
$ uname -a
7.13. What Is a "core" File?
A core file is created when a program terminates unexpectedly, due to
a bug, or a violation of the operating system's or hardware's
protection mechanisms. The operating system kills the program and
creates a core file that programmers can use to figure out what went
wrong. It contains a detailed description of the state that the
program was in when it died.
If would like to determine what program a core file came from, use the
file command, like this:
$ file core
That will tell you the name of the program that produced the core
dump. You may want to write the maintainer(s) of the program, telling
them that their program dumped core.
[Eric Hanchrow]
7.14. How To Enable or Disable Core Dumps.
By using the ulimit command in bash, the limit command in tcsh, or the
rlimit command in ksh. See the appropriate manual page for details.
This setting affects all programs run from the shell (directly or
indirectly), not the whole system.
If you wish to enable or disable core dumping for all processes by
default, you can change the default setting in linux/sched.h. Refer to
definition of INIT_TASK, and look also in linux/resource.h.
PAM support optimizes the system's environment, including the amount
of memory a user is allowed. In some distributions this parameter is
configurable in the /etc/security/limits.conf file. For more
information, refer to the Linux Administrator's Security Guide.
("Where Is the Documentation?")
7.15. How To Upgrade/Recompile a Kernel.
See the Kernel HOWTO or the README files which come with the kernel
release on ftp.cs.helsinki.fi/pub/Software/Linux/Kernel/ and mirrors.
(See "Where Are the Linux FTP Archives?") You may already have a
version of the kernel source code installed on your system, but if it
is 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.)
With newer kernels you can (and should) make all of the following
targets. Don't forget that you can specify multiple targets with one
command.
$ make clean dep install modules modules_install
Also remember to update the module dependencies.
$ depmod -a
This command can be run automatically at boot time. On Debian/GNU
Linux systems, the command is part of the /etc/init.d/modutils script,
and can be linked appropriately in the /etc/rcx.d/ directories. For
more information on depmod, see the manual page.
Make sure you are using the most recent version of the modutils
utilities, as well as all other supporting packages. Refer to the file
Documentation/Changes in the kernel source tree for specifics, and be
sure to consult the README file in the modutils package.
Remember that to make the new kernel boot you must run lilo after
copying the kernel into your root partition. The Makefile in some
kernels have a special zlilo target for this; try:
$ make zlilo
On current systems, however, you can simply copy the zImage or bzImage
file (in arch/i386/boot/ to the /boot/ directory on the root file
system, or to a floppy using the dd command. Refer also to the
question, How do I get LILO to boot the kernel image?
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 linux-kernel mailing list. ("What
Mailing Lists Are There?")
The Web site http://www.kernelnotes.org/ has lots of information and
links to other sites that provide information about Linux kernel
updates.
Also refer to the questions, "The PCMCIA Card Doesn't Work after
Upgrading the Kernel." and "How To Get LILO to Boot the Kernel Image."
7.16. Can Linux Use 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 Serial HOWTO for information about possible solutions and
workarounds for this problem.
7.17. Configuring Emacs's Default Settings.
Create a file in your home directory named .emacs with the Emacs Lisp
commands that you want to run every time Emacs starts up. You won't
see the file in the directory listing. (The leading '.' tells ls not
to display it, unless you use the -a command line switch with ls.)
Any kind of Emacs Lisp statement will work in the .emacs file,
including entire defuns. Emacs uses lisp variables and statements
extensively, and many of the editing functions are written in Emacs
Lisp. For example, to enable word wrapping whenever you edit a file
that ends with .txt, add the following statement. This is from the
Emacs Texinfo help document ( F1-i, then m Emacs Return):
(add-hook text-mode-hook
'(lambda () (auto-fill-mode 1)))
This adds a statement that calls a hook function whenever a text
editing mode is entered for that buffer. The value of text-mode-hook,
which is a variable, to auto-fill-mode, which is a function.
If you want to turn off the menu bar at the top of each Emacs frame,
add this statement:
(menu-bar-mode -1)
And if you want to include an Emacs Lisp program that someone has
written, like msb.el (an enhanced, pop-up buffer menu), make sure the
lisp file is in a directory where Emacs can find it (usually it will
be named Site-lisp), and add these statements in the .emacs file:
(require 'msb)
(msb-mode 1)
Most tasks have several possible solutions in Emacs Lisp. Any task
that can be programmed in Emacs Lisp is valid in the .emacs file. For
more information, consult the Texinfo documentation. There is also a
FAQ list for Emacs (refer to: What other FAQ's are there for Linux? ).
7.18. How To Make a Rescue Floppy.
Make a file system on it with bin, etc, lib and 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
lilo.u.*.ps).
If you build the kernel (or tell LILO to tell the kernel) to have a
RAM disk the same size as the floppy the RAM disk will be loaded at
boot time and mounted as root in place of the floppy.
See the Bootdisk HOWTO.
7.19. How To Remap a Keyboard to UK, French, Etc.?
For recent kernels, get /pub/Linux/system/Keyboards/kbd-0.90.tar.gz
from ftp://metalab.unc.edu/. Make sure you get the appropriate
version; you have to use the right keyboard mapping package for your
kernel version. For older kernels you have to edit the top-level
kernel Makefile, in /usr/src/linux/. You may find more helpful
information in The Linux Keyboard and Console HOWTO, by Andries
Brouwer, at ftp://metalab.unc.edu/pub/Linux/docs/HOWTO/.
7.20. How To Get NUM LOCK to Default to On.
Use the setleds program, for example (in /etc/rc.local or one of the
/etc/rc.d/* files):
for t in 1 2 3 4 5 6 7 8
do
setleds +num < /dev/tty$t > /dev/null
done
setleds is part of the kbd package ("How do I remap my keyboard to UK,
French, etc.? "). Alternatively, patch your kernel. You need to
arrange for KBD_DEFLEDS to be defined to (1 << VC_NUMLOCK) when
compiling drivers/char/keyboard.c.
7.21. How To Set (Or Reset) Initial Terminal Colors.
The following shell script should work for VGA consoles:
for n in 1 2 4 5 6 7 8; do
setterm -fore yellow -bold on -back blue -store > /dev/tty$n
done
Substitute your favorite colors, and use /dev/ttyS$n for serial
terminals.
To make sure they are reset when people log out (if they've been
changed):
Replace the references to getty (or mingetty or uugetty or whatever)
in /etc/inittab with references to /sbin/mygetty.
#!/bin/sh
setterm -fore yellow -bold on -back blue -store > $1
exec /sbin/mingetty $@
[Jim Dennis]
7.22. How To Have More Than 128Mb of Swap.
Use several swap partitions or swap files. Linux kernels before
version 2.2 supported up to 16 swap areas, each of up to 128Mb. Recent
versions do not have this limitation.
Very old kernels only supported swap partition sizes up to 16Mb.
Linux on machines with 8KB paging, like Alpha and Sparc64, support a
swap partition up to 512MB. The 128MB limitation comes from
PAGE_SIZE*BITSPERBYTE on machines with 4KB paging, but is 512KB on
machines with 8KB paging. The limit is due to the use of a single page
allocation map.
The file mm/swapfile.c has all of the gory details.
[Peter Moulder, Gordon Weast]
How To Prevent Errors when Linking Programs with Math Functions.
Older run-time libraries included the math library in the C run-time
library. It was not necessary to specify the math library separately
when compiling. If the compiler generates a message like this when
linking a program that uses math functions:
/tmp/ccDUQM4J.o: In function `main':
/tmp/ccDUQM4J.o(.text+0x19): undefined reference to `sqrt'
collect2: ld returned 1 exit status
You need use the -lm option with GCC to link with the math libraries:
# gcc -o program program.c -lm
Make sure also to use the statement #include
file.
[Florian Schmidt]
8. Miscellaneous Information and Questions Answered
8.1. How To Program XYZ Under Linux.
Read the manuals, or a good book on Unix and the manual pages (type
man man). There is a lot of GNU Info documentation, which is often
more useful as a tutorial. Run Emacs and type F1-i, or type info info
if you don't have or don't like Emacs. Note that the Emacs libc node
may not exactly describe the latest Linux libc, or GNU glibc2. But the
GNU project and LDP are always looking for volunteers to upgrade their
library documentation.
Anyway, between the existing Texinfo documentation, and the manual
pages in sections 2 and 3, should provide enough information to get
started.
As with all free software, the best tutorial is the source code
itself.
The latest release of the Linux manual pages, a collection of useful
GNU Info documentation, and various other information related to
programming Linux, can be found on
metalab.unc.edu/pub/Linux/docs/man-pages/.
8.2. What's All This about ELF? glibc?
See the ELF HOWTO by Daniel Barlow. Note that this is not the file
move-to-elf, which is a blow-by-blow account of how to upgrade to ELF
manually.
Linux has two different formats for executables, object files, and
object code libraries, known as, "ELF." (The old format is called
"a.out.") They have 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 have to be installed.
If you want to find out whether your system can run ELF binaries, look
in /lib for a file named, "libc.so.5." If it's there, you probably
have ELF libraries. If you want to know whether your installation
actually is ELF you can pick a representative program, like ls, and
run file on it:
-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
There is a patch to get 1.2.x to compile using the ELF compilers, and
produce ELF core dumps, at ftp://tsx-11.mit.edu/pub/packages/GCC/. You
do not need the patch merely to run ELF binaries. 1.3.x and later do
not need the patch at all.
The GNU glibc2 libraries are essentially more recent versions of ELF
libraries that follow most of the same processes for dynamic linking
and loading. Upgrade information is contained in ("How To Upgrade the
Libraries without Trashing the System.")
8.3. How To Determine What Packages Are Installed on a System.
For distributions that use RPM format packages, use the command:
$ rpm -qa
You need to be logged in as root. You can save the output to a text
file for future reference, a command like:
$ rpm -qa >installed-packages
For Debian systems, the equivalent command is:
$ dpkg -l
8.4. What Is a .gz File? And a .tgz? And .bz2? And... ?
gz (and .z) files are compressed using GNU gzip. You need to use
gunzip (which is a symlink to the gzip command that comes with most
Linux installations) to unpack the file.
taz, .tar.Z, and .tz are tar files (made with tar) and compressed
using compress. The standard *nix compress is proprietary software,
but free equivalents like ncompress exist.
tgz (or .tpz) is a tar file compressed with gzip.
bz2 is a file compressed by the more recently introduced (and
efficient) bzip2.
lsm is a Linux Software Map entry, in the form of a short text file.
Details about the LSM project and the LSM itself are available in the
subdirectory on ftp://metalab.unc.edu/pub/Linux/docs/.
deb is a Debian Binary Package--the binary package format used by the
Debian GNU/Linux distribution. It is manipulated using dpkg and
dpkg-deb (available on Debian systems and from
ftp://ftp.debian.org//).
rpm is a Red Hat RPM package, which is used in the Red Hat and
similar distributions.
sit is a compressed Macintosh archive made with StuffIt, a commercial
program. Aladdin Systems Inc., the manufacturer of StuffIt, has a free
expander utility that will uncompress these archives. You can download
it at http://www.aladdinsys.com/expander/.
The file command can often tell you what a file is.
If you find that gzip complains when you try to uncompress a file, you
probably downloaded it in ASCII mode by mistake. You must download
most things in binary mode: "get," to download the file.
8.5. What Does VFS Stand For?
Virtual File System. It's the abstraction layer between the user and
real file systems like ext2, Minix and MS-DOS. Among other things, its
job is to flush the read buffer when it detects a disk change on the
floppy disk drive.
VFS: Disk change detected on device 2/0
8.6. What is a BogoMip?
"BogoMips" is a combination of Bogus and Mips. MIPS stands for
(depending on who you ask) 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.
According to the BogoMips mini-HOWTO, the rating for your machine will
be:
Common BogoMips Ratings
Processor BogoMips Comparison
Intel 8088 clock * 0.004 0.02
Intel/AMD 386SX clock * 0.14 0.8
Intel/AMD 386DX clock * 0.18 1 (definition)
Motorola 68030 clock * 0.25 1.4
Cyrix/IBM 486 clock * 0.34 1.8
Intel Pentium clock * 0.40 2.2
Intel 486 clock * 0.50 2.8
AMD 5x86 clock * 0.50 2.8
Mips R4000/R4400 clock * 0.50 2.8
Nexgen Nx586 clock * 0.75 4.2
PowerPC 601 clock * 0.84 4.7
Alpha 21064/21064A clock * 0.99 5.5
Alpha 21066/21066A clock * 0.99 5.5
Alpha 21164/21164A clock * 0.99 5.5
Intel Pentium Pro clock * 0.99 5.5
Cyrix 5x86/6x86 clock * 1.00 5.6
Intel Pentium II/III clock * 1.00 5.6
Intel Celeron clock * 1.00 5.6
Mips R4600 clock * 1.00 5.6
Alpha 21264 clock * 1.99 11.1
AMD K5/K6/K6-2/K6-III clock * 2.00 11.1
UltraSparc II clock * 2.00 11.1
Pentium MMX clock * 2.00 11.1
PowerPC 604/604e/750 clock * 2.00 11.1
Motorola 68060 clock * 2.01 11.2
Motorola 68040 Not enough data (yet).
AMD Athlon Not enough data (yet).
IBM S390 Not enough data (yet).
If the number is wildly lower, you may have the Turbo button or CPU
speed set incorrectly, or have some kind of caching problem (as
described in ("When Adding More Memory, the System Slows to a Crawl.")
For values people have seen with other, rarer, chips, or to calculate
your own BogoMips rating, please refer to the BogoMips Mini-HOWTO, on
ftp://metalab.unc.edu/. ("Where Is the Documentation?")
[Wim van Dorst]
8.7. What Online/Free Periodicals Exist for Linux?
There are a number of recent additions to the list of periodicals
devoted to Linux and free software:
* geek news. http://geeknews.cjb.net/. Headlines for articles about
Linux, like the comp.os.linux.announce and Techweb postings, and
general interest, like Associated Press stories.
* Linux Gazette. http://www.linuxgazette.com/. This is the
longest-running of the on-line periodicals, and the only one that
publishes source code.
* Linux Today. http://www.linuxtoday.com. News and opinion related
to the Linux community, updated daily.
* Linux Weekly News. http://lwn.net. News about the Linux community,
updated weekly.
* Slashdot. http://www.slashdot.org. News about the free software
community and culture.
* Freshmeat. http://www.freshmeat.net/. Notices of new and updated
software for Linux and other free OS's.
Please send additions to this list to the FAQ maintainer.
[Jim Dennis, Robert Kiesling]
8.8. How Many People Use Linux?
Linux is freely available, and no one is required to register with any
central authority, so it is difficult to know. Several businesses
survive solely on selling and supporting Linux. Linux news groups are
some of the most heavily read on Usenet. Accurate numbers are hard to
come by, but the number is almost certainly in the millions.
However, people can register as Linux users at the Linux Counter
project, which has been in existence since 1993. In August, 1998, the
project counted more than 70,000 users.
Visit the Web site at http://counter.li.org/ and fill in the
registration form. If you don't want to use the Web, send E-mail to
[email protected] with the subject line, "I use Linux at home,"
or "I use Linux at work."
The current count is posted monthly to comp.os.linux.misc, and is
always available from the Web site.
[Harald Tveit Alvestrand]
8.9. How Many People Use Linux? (Redux.)
In 1999, International Data Corporation released its first commercial
forecast of Linux sales. The report quantifies Linux vendor sales in
1996, 1997, and 1998, and forecasts through the year 2003.
To obtain the report, contact IDC at [email protected] . Their Web site
is http://www.itresearch.com/.
8.10. What Is the Best (Distribution|SCSI Card|Editor|CD-ROM Drive|....)
The "best" of anything depends on your particular needs. Discussions
like these frequently occur on Usenet. Most often they're flame bait.
Answering is generally a waste of time. Free software licensing is
unrestrictive enough, that, with a little experience, you can perform
your own testing on your own hosts.
A better way to phrase a specific inquiry might be: "Where can I
find...."
8.11. How Does One Pronounce Linux?
This question produces an outrageous amount of heated debate.
If you want to hear Linus himself say how he pronounces it, download
english.au or swedish.au from
ftp.funet.fi/pub/Linux/PEOPLE/Linus/SillySounds/. If you have a sound
card 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 who don't have the equipment or inclination:
Linus pronounces Linux approximately as Leenus, where the "ee" is
pronounced 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).
9. Frequently Encountered Error Messages
9.1. Modprobe Can't Locate Module, XXX, and Similar Messages.
These types of messages mostly occur at boot time or shutdown. If
modprobe, insmod, or rmmod complain about not being able to find a
module, add the following to the /etc/modules.conf or
/etc/modutils/aliases file, whichever is present on your system.
$ alias
And use the name of the module that appears in the error message.
[J.H.M. Dassen]
9.2. Unknown Terminal Type "linux" and Similar.
In early kernels the default console terminal type has changed from
"console" to "linux." You must edit /etc/termcap to change the line
reading:
console|con80x25:/
to
linux|console|con80x25:/
(there may be an additional "dumb" in there--if so it should be
removed.)
To get the editor to work you may need type:
$ TERM=console
(for bash and ksh), or
$ setenv TERM console
for csh or tcsh.
Some programs use /usr/lib/terminfo instead of /etc/termcap. For these
programs you should upgrade your terminfo package, which is part of
ncurses.
The same is true for X terminal displays. If your distribution sets
the TERM to something strange like xterm-24-color, you can simply
reset it to a generic value from the command line:
$ TERM="xterm"; export TERM
9.3. INET: Warning: old style ioctl... called!
You are trying to use the old network configuration utilities. The new
ones can be found on
ftp.linux.org.uk/pub/linux/Networking/PROGRAMS/NetTools/ (source only,
I'm afraid).
Note that they cannot be used just like the old-style programs. See
the NET-2 HOWTO for instructions on how to set up the old-style
networking programs correctly. Even better, see the NET-3 HOWTO and
upgrade your networking software.
9.4. ld: unrecognized option '-m486'
You have an old version of ld. Install a newer binutils package that
contains an updated ld. Look on tsx-11.mit.edu in
Archive-Name: linux/faq/part6
URL: http://www.mainmatter.com/
Reply-to: [email protected]
Posting-Frequency: weekly
Last-modified: 12/04/2001
/pub/linux/packages/GCC/ for binutils-2.6.0.2.bin.tar.gz.
9.5. GCC Says, "Internal compiler error."
If the fault is repeatable (i.e., 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 F1-i in Emacs, and select GCC from the menu) for
details on how to report the error. Make sure you have the latest
version, though.
Note that this is probably not a Linux-specific problem. Unless you
are compiling a program many other Linux users also compile, you
should not post your bug report to any of the comp.os.linux groups.
If the problem is not repeatable, you may be experiencing memory
corruption. Refer to the answer: ("Make Says, "Error 139."")
9.6. Make Says, "Error 139."
Your compiler (GCC) dumped core. You probably have a corrupted, buggy,
or old version of GCC--get the latest release or EGCS. Alternatively,
you may be running out of swap space. Refer to: ("The Machine Runs
Very Slowly with GCC / X / ...")
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 marginal SIMMS, or
a faulty motherboard or hard disk or controller.
Linux is a very good memory tester--much better than MS-DOS based
memory test programs.
Reportedly, some clone x87 math coprocessors can cause problems. Try
compiling a kernel with math emulation ("How To Upgrade/Recompile a
Kernel.") no387 kernel command line flag on the LILO prompt to force
the kernel to use math emulation, or it may be able to work and still
use the '387, with the math emulation compiled in but mainly unused.
More information about this problem is available on the Web at
http://www.bitwizard.nl/sig11/.
9.7. 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 manual page for
chmod or a book on Unix for how to fix the problem.
9.8. No Utmp Entry. You Must Exec ... when Logging In.
Your /var/run/utmp is screwed up. You should have
/var/run/utmp
in your /etc/rc.local or /etc/rc.d/*. See, ("I Screwed Up the System
and Can't Log In to Fix It.") Note that the utmp may also be found in
/var/adm/ or /etc/ on some older systems.
9.9. 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
update program which used to write everything every 30 seconds with a
more subtle daemon (actually a pair), known as bdflush. Get
bdflush-n.n.tar.gz from the same place as the kernel source code ("How
To Upgrade/Recompile a Kernel.") and compile and install it. bdflush
should be started before the usual boot-time file system checks. It
will work fine with older kernels as well, so there's no need to keep
the old update around.
9.10. Warning: obsolete routing request made.
This is nothing to worry about. The message means that your version
route is a little out of date, compared to the kernel. You can make
the message go away by getting a new version of route from the same
place as the kernel source code. ("How To Upgrade/Recompile a
Kernel.")
9.11. EXT2-fs: warning: mounting unchecked file system.
You need to run e2fsck (or fsck -t ext2 if you have the fsck front end
program) with the -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 fsck, umount, and
shutdown commands, available in Rik Faith's util-linux package ("Where
Are the Linux FTP Archives?") You have to make sure that your
/etc/rc*/ scripts use them correctly.
NB: Don't try to check a file system that's mounted read/write. This
includes the root partition if you don't see
VFS: mounted root ... read-only
at boot time. You must arrange to mount the root file system read/only
to start with, check it if necessary, and then remount it read/write.
Almost all distributions do this. If your's doesn't, read the
documentation that comes with util-linux to find out how to do this.
Note that you need to specify the -n option to mount so it won't try
to update /etc/mtab, since the root file system is still read-only,
and this will otherwise cause it to fail.
9.12. EXT2-fs warning: maximal count reached.
This message is issued by the kernel when it mounts a file system
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 (e2fsprogs-0.5b.tar.gz at the
time of writing) from the usual sites. ("Where Are the Linux FTP
Archives?")
The maximal number of mounts value can be examined and changed using
the tune2fs program from this package.
9.13. EXT2-fs warning: checktime reached.
Kernels from 1.0 onwards support checking a file system 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. ("EXT2-fs warning:
maximal count reached.")
9.14. df Says, "Cannot read table of mounted file systems."
There is probably something wrong with your /etc/mtab or /etc/fstab
files. If you have a reasonably new version of mount, /etc/mtab should
be emptied or deleted at boot time (in /etc/rc.local or /etc/rc.d/*),
using something like
$ rm -f /etc/mtab*
Some old Linux distributions have an entry for the root partition in
/etc/mtab made in /etc/rc* by using rdev. That is incorrect--the newer
versions of mount do this automatically.
Some old distributions also have a line in /etc/fstab that looks like:
/dev/sdb1 /root ext2 defaults
The entry for /root should read simply /.
9.15. fdisk Says, "Partition X has different physical/logical..."
If the partition number (X, above) is 1, this is the same problem as
in fdisk: Partition 1 does not start on cylinder boundary. If the
partition begins or ends on a cylinder numbered greater than 1024,
this is because the standard DOS disk geometry information format in
the partition table can't cope with cylinder numbers with more than 10
bits. You should see ("How To Get Linux to Work with a Disk.")
9.16. fdisk: Partition 1 does not start on cylinder boundary.
The version of 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 fdisk, from
Rik Faith's util-linux package (available on all the usual 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.
* Create partition 1 in the normal way. A `p' listing will produce
the mismatch complaint.
* Type u to set sector mode and do p again. Copy down the number
from the End column.
* Delete partition 1.
* While still in sector mode, re-create 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 p output. Set the last
sector to the value you wrote down in the step above.
* Type 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, and they
are not used if you start the first partition in track 2.
9.17. fdisk Says 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.
9.18. Mtools Utilities Say They Cannot Initialize Drive X.
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
(/dev/fd0* and /dev/fd1*) being incorrect. The user running mtools
must have the appropriate access. See the manual page for chmod for
details.
Most versions of mtools distributed with Linux systems (not the
standard GNU version) use the contents of a file /etc/mtools to
determine 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.
For the easiest way to access your MS-DOS files (especially those on a
hard disk partition) see How do I access files on my DOS partition or
floppy? Note--you should never use mtools to access files on an
msdosfs mounted partition or disk!
9.19. At the Start of Booting: Memory tight
This means that you have an extra-large kernel, which 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. ("How To
Upgrade/Recompile a Kernel.")
9.20. The System Log Says, "end_request: I/O error, ...."
This error message, and messages like it, almost always indicate a
hardware error with a hard drive.
This commonly indicates a hard drive defect. The only way to avoid
further data loss is to completely shut own the system. You must also
make sure that whatever data is on the drive is backed up, and restore
it to a non-defective hard drive.
This error message may also indicate a bad connection to the drive,
especially with home brew systems. If you install an IDE drive, always
use new ribbon cables. It's probably is a good idea with SCSI drives,
too.
In one instance, this error also seemed to coincide with a bad ground
between the system board and the chassis. Be sure that all electrical
connections are clean and tight before placing the blame on the hard
drive itself.
[Peter Moulder, Theodore Ts'o]
9.21. "You don't exist. Go away."
This is not a viral infection. It comes from programs like write,
talk, and wall, if your invoking UID doesn't correspond to a valid
user (probably due to /etc/passwd being corrupted), or if the session
(pseudoterminal, specifically) you're using isn't properly registered
in the utmp file (probably because you invoked it in a funny way).
9.22. "Operation not permitted."
One or more of the file's or directory's attribute bits are set
incorrectly. If the "I" bit is set, for example, you won't be able to
change file permissions with chmod.
The solution is to use lsattr to display file and directory
attributes, and chattr to set and unset them. The programs'
documentation is contained in their manual pages.
[Paul Campbell]
9.23. programname: error in loading shared libraries: lib xxx..so. x: cannot
open shared object file: No such file or directory.
A message like this, when the program that you're trying to run uses
shared libraries, usually means one of two things: the program was
either compiled on a machine that had a different set of libraries or
library paths than yours; or you've upgraded your libraries but not
the program.
Executable programs that are linked with dynamic libraries, expect the
full pathname of each of the library files it requires. So do the
shared libraries, if they rely on other libraries. This is so the
shared object dependencies remain as unambiguous as possible, and also
as a security measure.
Short of recompiling the executable file for the libraries on the
system--probably the most desirable alternative in the long run--you
can try to determine which libraries the executable file needs with
the command: "ldd programname." The output will be a list of the
shared libraries on the system that the program needs to run, as well
as the missing libraries. You can then add the library packages, or if
the libraries already exist in a different directory, you can create a
symbolic link so the program can find it. For example, if the program
requires /usr/lib/libncurses.so.2, and your machine has
/lib/libncurses.so.2, you can create a link where the program expects
to find the library; e.g.:
# cd /usr/lib && ln -s /lib/libncurses.so.2 .
You should note, however, that creating library links like these
should be considered a security risk, and the additional links you
create will not be compatible with future upgrades. It's simply a
quick fix for backward compatibility.
Also, it may take some guesswork to determine in exactly which of the
system library directories the program expects to find a shared
library file, because ldd will not list the paths of libraries it
can't find. A program most likely will tell the run-time linker,
/lib/ld.so, to look for shared libraries in /lib, /usr/lib,
/usr/local/lib, or /usr/X11R6/lib, if it's an X client. But that
doesn't mean that libraries can't be installed elsewhere. It helps to
have some idea of the original library configuration before
proceeding.
Also be sure to run ldconfig after creating the symbolic link, so that
ld.so has an updated view of the system's libraries. You should also
make certain that all of the library directories are listed in
/etc/ld.so.conf, and perhaps in the LD_LIBRARY_PATH environment
variable.
9.24. "init: Id "x" respawning too fast: disabled for 5 minutes."
In most distributions this means that the system is booting by default
into runlevel 5, which is supposed to respawn (re-start again after
it's been exited) a graphical login via xdm, kdm, gdm, or whatever,
and the system can't locate the program.
However, "Id" can also indicate the absence or misconfiguration of
another program, like mingetty, if init tries to respawn itself more
than 10 times in 2 minutes.
Id "x" is the number in the leftmost column of the /etc/inittab file:
# Run gettys in standard runlevels
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
4:2345:respawn:/sbin/mingetty tty4
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty tty6
Commenting the offending line out and then fixing the errant program
and testing on the command line will allow you to see any error
messages that go to standard error output (console) if the errors are
not going to the system log file. Uncomment the line and restart init
with "kill -SIGHUP 1" or "telinit q" to cause init to reinitialize and
reread the /etc/inittab file.
Some systems, however, rewrite /etc/inittab when booting. In that
case, refer to the init man page, and/or the settings in
/etc/sysconfig/init.
Refer to the init and /etc/inittab man pages for detailed information.
[Carl King]
9.25. FTP server says: "421 service not available, remote server has closed
connection."
If an FTP server won't allow logins, it is probably configured
correctly, but the problem is probably with authorizing users at
login. FTP servers in current distriubtions often authorize users with
the Pluggable Authentication Modules library, in which case there
should be an authorization file /etc/pam.d/ftp. A generic
authorization file looks like this. (The line break on the first
"auth" line is for readability. The entry is actually a single, long
line).
#%PAM-1.0
auth required /lib/security/pam_listfile.so item=user /
sense=deny file=/etc/ftpusers onerr=succeed
auth required /lib/security/pam_pwdb.so shadow nullok
auth required /lib/security/pam_shells.so
account required /lib/security/pam_pwdb.so
session required /lib/security/pam_pwdb.so
Also, make sure the /etc/ftpusers file, or whatever users file is
named in the first "auth" line, is configured correctly.
Btw, the sample ftp file above is actually theftpd/ftp.pam.sample file
from the ftpd-BSD-0.3.1.tar.gz package. Many thanks to David A. Madore
for this much needed port.
10. The X Window System
10.1. Does Linux Support X?
Yes. Linux uses XFree86 (the current version is 4.0, which is based on
X11R6). You need to have a video card which is supported by XFree86.
See the XFree86 HOWTO for more details. Most Linux distributions
nowadays come with an X installation. However, you can install or
upgrade your own, from "ftp://metalab.unc.edu/pub/Linux/X11/Xfree86-*"
and its mirror sites, or from http://www.xfree86.org/.
10.2. How To Get the X Window System to Work.
The answers to this question can, and do, fill entire books. If the
installation program wasn't able to configure the X server correctly,
Linux will most likely try to start the X display, fail, and drop back
into text-only terminal mode.
First and foremost, make certain that you have provided, as closely as
possible, the correct information to the installation program of your
video hardware: the video card and monitor. Some installation programs
can correctly guess a "least common denominator" screen configuration,
like a 640-by-480 VESA-standard display, but there are many possible
video hardware configurations that may not be able to display this
standard.
The X Window System configuration file is called (usually)
/etc/XF86Config, /etc/X11/XF86Config, or
/usr/X11R6/lib/X11/XF86Config.
If you need to manually configure the X server, there are several
possible methods:
* Try to use the XF86Setup program, which can help identify the
correct X server and monitor timings for the video hardware.
* Make sure that the X server has the correct options. If you log in
as the superuser, you should be able to use X --probeonly to get a
listing of the video card chipset, memory, and any special
graphics features. Also, refer to the manual page for the X
server. (E.g.; man X), and try running the X server and
redirecting the standard error output to a file so you can
determine, after you can view text on the screen again, what error
messages the server is generating; e.g., X 2>x.error.
* With that information, you should be able to safely refer to one
of the references provided by the Linux Documentation Project.
("Where can I get the HOWTO's and other documentation? ") There
are several HOWTO's on the subject, including a HOWTO to calculate
video timings manually if necessary. Also, the Installation and
Getting Started guide has a chapter with a step-by-step guide to
writing a XF86Config file.
Also, make sure that the problem really is an incorrect XF86Config
file, not something else like the window manager failing to start. If
the X server is working correctly, you should be able to move the
mouse cursor on the screen, and pressing Ctrl-Alt-Backspace will shut
down the X server and return to the shell prompt in one of the virtual
terminals.
10.3. Where To Find a Ready-Made XF86Config file.
If you can't seem to get X working using the guidelines above, refer
to the XFree86 HOWTO, recent versions of Installation and Getting
Started, and the instructions for the XF86Setup program. The contents
of the XF86Config file depend on the your exact combination of video
card and monitor. It can either be configured by hand, or using the
XF86Setup utility. Read the instructions that came with XFree86, in
/usr/X11R6/lib/X11/etc. The file you probably need to look at most is
README.Config. You should not use the sample XF86Config.eg file which
is included with newer versions of XFree86 verbatim, because the wrong
video clock settings can damage your monitor. Please don't post to
comp.os.linux.x asking for an XF86Config, and please don't answer such
requests. If you have a laptop, look at the Linux Laptop Web page
("How To Find Out If a Notebook Runs Linux.") Many of the installation
notes also have the XF86Config file for the display. If you have a
desktop machine, there are a few sample XF86Config files at
ftp://metalab.unc.edu/. Refer also to the XFree86 FAQ
http://www.xfree.org/FAQ/ and the monitor timings list
http://www.xfree.org/#resources/ , and in the /usr/X11R6/lib/X11/
directory of your X distribution.
10.4. What Desktop Environments Run on Linux?
Linux with XFree86 supports the KDE, GNOME, and commercial CDE desktop
environments, and extended window managers like WindowMaker. Each uses
a different set of libraries and provides varying degrees of MS
Windows-like look and feel.
Information on KDE is available from http://www.kde.org/. The KDE
environment uses the Qt graphics libraries, available from
http://www.qt.org/. The desktop uses its own window manager, kwm, and
provides a MS Windows-like look and feel.
The GNOME home page is http://www.gnome.org/. The environment uses the
free GTK libraries, available from http://www.gtk.org/ , and window
managers like Enlightenment, http://www.enlightenment.org/ , SawFish,
http://www.sawfish.org/. There's also a Web page for GNOME
installation and upgrade that functions much like Debian's apt-get
utility with a friendly GUI front end. It's at:
http://www.helixcode/com/desktop/.
The commercial CDE environment uses the Motif libraries and a
variation of the Motif mwm window manager, dtwm, and provides a suite
of desktop and session-management utilities. Several vendors have made
the source code of Motif available and provided binary packages for
Linux distributions. As a starting point, download and installation
information is available at http://www.opengroup.org/openmotif/.
A free version of Motif, called LessTiF, is available from
http://www.lesstif.org/.
WindowMaker, http://www.windowmaker.org/ is a window manager that has
many desktop environment-like features. It provides support for
GNUstep, http://www.gnustep.org/ , a clone of the commercial NeXTStep
environment.
10.5. xterm Logins Show Up Strangely in who, finger.
The xterm that comes with XFree86 2.1 and earlier doesn't correctly
understand the format that Linux uses for the /var/adm/utmp file,
where the system records who is logged in. It therefore doesn't set
all the information correctly. The xterms in XFree86 3.1 and later
versions fix this problem.
10.6. How to Start a X Client on Another Display.
To start a X client on another system that has a running X server, use
the following commands:
* Use xhost on the server system to allow the client system use the
display. If the server's IP address is 192.168.20.1, enter the
command:
$ xhost + 192.168.20.1
* On the client system, open a telnet connection to the server
system.
* In the telnet session, start a xterm in the background with the
-display and -e options. For example, if the IP address of the
machine running the server is 192.168.20.1 and the client program
name is named "clientapp," use the following command:
$ xterm -display 192.168.20.1 -e clientapp &
[Pierre Dal Farra]
11. How to Get Further Assistance
11.1. If this Document Still Hasn't Answered Your 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 50,000
people and waste hundreds of hours of their time. Don't you think it's
worth spending some of your time to read and follow these
instructions?
If you think an answer is incomplete or inaccurate, please e-mail
Read the appropriate Linux Documentation Project books. Refer to:
("Where Is the Documentation?")
If you're a Unix or Linux newbie, read the FAQ for
comp.unix.questions, news.announces.newusers, and those for any of the
other comp.unix.* groups that may be relevant.
Linux has so much in common with commercial unices, that almost
everything you read there will apply to Linux. The FAQ's, like all
FAQ's, be found on ftp://rtfm.mit.edu/pub/usenet/ (the
[email protected] can send you these files, if you don't have
FTP access). There are mirrors of rtfm's FAQ archives on various
sites. Check the Introduction to *.answers posting, or look in
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 manual pages (type man man if you
don't know about manual pages. Also try man -k subject and apropos
subject. They often list useful and relevant, but not very obvious,
manual pages.
Check the Info documentation (type F1-i, i.e. the F1 function key
followed by "i" in Emacs). This isn't just for Emacs. For example, the
GCC documentation lives here as well.
There will also often be a README file with a package that gives
installation and/or usage instructions.
Make sure you don't have a corrupted or out-of-date copy of the
program in question. If possible, download it again and re-install
it--you probably made a mistake the first time.
Read comp.os.linux.announce. It often contains very important
information for all Linux users. General X Window System questions
belong in comp.windows.x.i386unix, not in 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 comp.os.linux.* newsgroup. Make sure you read the next
question first. "( What to put in a request for help. )"
11.2. What to Put in a Request for Help.
Please read the following advice carefully about how to write your
posting or E-mail. Making a complete posting will greatly increase the
chances that an expert 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
E-mail sent to experts and fellow users.
Make sure you give full details of the problem, including:
* 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
--version option.
* Which Linux release you're using (Red Hat, Slackware, Debian, or
whatever) and what version of that release.
* The exact and complete text of any error messages printed.
* Exactly what behavior you expected, and exactly what behavior you
observed. A transcript of an example session is a good way to show
this.
* The contents of any configuration files used by the program in
question and any related programs.
* What version of the kernel and shared libraries you have
installed. The kernel version can be found by typing "uname -a,"
and the shared library version by typing "ls -l /lib/libc*."
* Details of what hardware you're running on, if it seems
appropriate.
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 know that.
Save the space for the name of the program, a fragment of an error
message, or summary of the unusual behavior.
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 "Followup-To: poster."
Then, actually post the summary in a few days or a week or so. Don't
just concatenate the replies you got--summarize. Putting the word
"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 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
readers, along with the rest of a boring thread.
You might like to say in your posting that you've read this FAQ and
the appropriate HOWTO's--this may make people less likely to skip your
posting.
Remember that you should not post E-mail sent to you personally
without the sender's permission.
11.3. How To Email Someone about Your Problem.
Try to find the author or developer of whatever program or component
is causing you difficulty. If you have a contact point for your Linux
distribution, you should use it.
Please put everything in your E-mail message 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 E-mailed questions,
you're likely asking for help from unpaid volunteers, so you have no
right to expect an answer.
12. Acknowledgments and Administrivia
12.1. Where To Send Comments.
Contributions to the FAQ may be in any format. Comments and
corrections are gratefully received. Again, that email address is:
If you wish to refer to a question in the FAQ, it's better to do so by
the question heading instead of number. The question numbers are
generated automagically, and I don't see them in the source file.
I prefer comments in English to patch files--context diff is not my
first language.
12.2. Formats in Which This FAQ Is Available.
This document is available as an ASCII text file, an HTML World Wide
Web page, Postscript, PDF, and as a USENET news posting.
Section and item numbers are generated with Perl. HTML is generated
from SGML source using the Jade DSSSL interpreter by James Clark. Text
versions are generated using lynx and edited with sed, which are part
of most Linux distributions.
The Usenet version is posted regularly to news.answers, comp.answers,
and comp.os.linux.misc. It is archived at
ftp://rtfm.mit.edu/pub/usenet-by-hierarchy/comp/os/linux/misc/.
For Postscript and PDF versions, please contact the FAQ maintainer.
If you would like to receive the archived version of the FAQ by
E-mail, send the following in the body of an E-mail message to
[email protected] :
send faqs/linux/faq
Text, HTML, and SGML versions are available from the Linux archives at
metalab.unc.edu, and from http://www.linuxdoc.org/ , but they may be
out of date, owing to lack of time on the LDP maintainers' parts.
The latest text and HTML versions are available at
http://www.mainmatter.com and directly from the FAQ maintainer,
12.3. Authorship and Acknowledgments.
This FAQ is compiled and maintained by Robert Kiesling,
activists all over the world.
Freddy Contreras, [email protected] , designed and GPL'd the
Linux Frequently Asked Questions logos that appear on
www.mainmatter.com.
Special thanks are due to Matt Welsh, who moderated
comp.os.linux.announce and comp.os.linux.answers, coordinated the
HOWTO's and wrote substantial portions of many of them, Greg Hankins
the former Linux Documentation Project HOWTO maintainer, Lars
Wirzenius and Mikko Rauhala, the former and current moderators of
comp.os.linux.announce, Marc-Michel Corsini, who wrote the original
Linux FAQ, and Ian Jackson, the previous FAQ maintainer. Thanks also
to Roman Maurer for his many updates and additions, especially with
European Web sites, translations, and general miscellany.
Last but not least, thanks to Linus Torvalds and the other
contributors to Linux for giving us something to talk about!
12.4. Disclaimer and Copyright.
The GNU Free Documentation License
Copyright (c) 2001 Robert Kiesling. Permission is granted to copy,
distribute and/or modify this document under the terms of the GNU Free
Documentation License, Version 1.1 or any later version published by
the Free Software Foundation; with no Invariant Sections, with no
Front-Cover Texts, and with no Back-Cover Texts. A copy of the license
is included at: http://www.gnu.org/licenses/licenses.html#FDL.
I would be happy to answer any questions regarding the copyright. My
email address is [email protected] .