From - Thu Dec 3 11:38:12 1998 Xref: news.muni.cz comp.os.linux.announce:6560 Path: news.muni.cz!rhino.cis.vutbr.cz!news.cesnet.cz!news-feed1.eu.concert.net!newsfeed.cwix.com!199.0.154.52!news-a.ais.net!ais.net!holonet!colossus.holonet.net!world!nntprelay.mathworks.com!newsfeed1.swip.net!swipnet!masternews.telia.net!news-feed.inet.tele.dk!bofh.vszbr.cz!newsfeed1.telenordia.se!newsfeed1.funet.fi!news.helsinki.fi!not-for-mail From: kiesling@terracom.net Newsgroups: comp.os.linux.announce Subject: Linux Frequently Asked Questions with Answers (Part 1 of 3) Followup-To: poster Date: Mon, 23 Nov 1998 20:42:34 GMT Organization: ISPNews http://ispnews.com Lines: 2034 Approved: linux-announce@news.ornl.gov (Mikko Rauhala) Message-ID: NNTP-Posting-Host: revelation.bak.helsinki.fi Old-Date: 31 Aug 1998 02:22:58 GMT X-No-Archive: yes X-Auth: PGPMoose V1.1 PGP comp.os.linux.announce iQCVAgUBNlnI2lrUI/eHXJZ5AQEVQAQAg+SLoExyGb4XeUvAz6e3x5S2QwQLmq+g U+gvyNE9DPhtDpPQ2zEKpuFaUsnOdRPayRRC/kLvnhQQibCQtd13suw29E2+QCyA H8dhN8jSb0bZKARBc0megWrfynWTMktBQH+KGz3u1VrqxRtveMHk8Fcf/qq7kwje 6u13LYBEwXQ= =LP86 -----BEGIN PGP SIGNED MESSAGE----- Archive-Name: linux/faq/part1 Posting-Frequency: weekly Linux Frequently Asked Questions with Answers August 30, 1998 This is the list of Frequently Asked Questions about Linux, the free Unix for just about every computer hardware platform on the planet. Originally written for 386/486/586 Intel/ISA bus machines, versions are available for Alpha, MIPS, ARM, 680x0 and PPC processors, and many others. (See the question, "What is Linux?" below.) This document should be read in conjunction with the Linux Documentation Project's HOWTO series. ("Where can I get Linux material by FTP?" and "Where can I get the HOWTOs and other documentation?") The INFO-SHEET and META-FAQ, which are found in the same place, also list sources of Linux information. Please look at these documents, and "You still haven't answered my question!" before posting your question to a news group. See "Formats in which this FAQ is available." for details of where to get the PostScript, HTML, and plain ASCII versions of this document. 1. Introduction and General Information * 1.1 What is Linux? * 1.2 Where do I start? * 1.3 What software does Linux support? * 1.4 Does Linux run on my computer? What hardware is supported? * 1.5 What ports to other processors are there? * 1.6 How much hard disk space does Linux need? * 1.7 How much memory does Linux need? * 1.8 How much memory can Linux use? * 1.9 Is Linux public domain? Copyrighted? 2. Network sources and resources. * 2.1 Where can I get the HOWTOs and other documentation? * 2.2 Where should I look on the World Wide Web for Linux stuff? * 2.3 What newsgroups are there for Linux? * 2.4 Where can I find out about Linux and the Millennium (Y2K) bug? * 2.5 Where can I get Linux material by FTP? * 2.6 I don't have FTP access. Where do I get Linux? * 2.7 I don't have Usenet access. Where do I get information? * 2.8 What mailing lists are there? * 2.9 Are the newsgroups archived anywhere? 3. Compatibility with other operating systems. * 3.1 Can Linux share my disk with DOS? OS/2? 386BSD? Win95? * 3.2 How do I access files on my DOS partition or floppy? * 3.3 Does Linux support compressed ext2 file systems? * 3.4 Can I use my Stacked/DBLSPC/etc. DOS drive? * 3.5 Can I access OS/2 HPFS partitions from Linux? * 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 Mac file systems? * 3.10 Can I run Microsoft Windows programs under Linux? * 3.11 How can I boot Linux from OS/2's Boot Manager? * 3.12 How can I share a swap partition between Linux and MS Windows? 4. Linux's handling of file systems, disks, and drives * 4.1 How can I get Linux to work with my disk? * 4.2 How can I undelete files? * 4.3 Is there a defragmenter for ext2fs etc.? * 4.4 How do I format and create a file system on a floppy? * 4.5 I get nasty messages about inodes, blocks, and the suchlike. * 4.6 My swap area isn't working. * 4.7 How do I remove LILO so my system boots DOS again? * 4.8 Why can't I use fdformat except as root? * 4.9 My ext2fs partitions are checked each time I reboot. * 4.10 My root file system is read-only! * 4.11 I have a huge /proc/kcore! Can I delete it? * 4.12 My AHA1542C doesn't work with Linux. 5. Porting, compiling and obtaining programs * 5.1 How do I port XXX to Linux? * 5.2 What is ld.so and where do I get it? * 5.3 Has anyone ported / compiled / written XXX for Linux? * 5.4 Can I use code or a compiler compiled for a 486 on my 386? * 5.5 What does gcc -O6 do? * 5.6 Where are linux/*.h and asm/*.h? * 5.7 I get errors when I try to compile the kernel. * 5.8 How do I make a shared library? * 5.9 My executables are (very) large. * 5.10 Does Linux support threads or lightweight processes? * 5.11 Where can I get `lint' for Linux? * 5.12 Where can I find kermit for Linux? 6. Solutions to common miscellaneous problems. * 6.1 free dumps core. * 6.2 My clock is very wrong. * 6.3 Setuid scripts don't seem to work. * 6.4 Free memory as reported by free keeps shrinking. * 6.5 When I add more memory, the system slows to a crawl. * 6.6 Some programs (e.g. xdm) won't let me log in. * 6.7 Some programs let me log in with no password. * 6.8 My machine runs very slowly when I run GCC / X / ... * 6.9 I can only log in as root. * 6.10 My screen is all full of weird characters instead of letters. * 6.11 I have screwed up my system and can't log in to fix it. * 6.12 I've discovered a huge security hole in rm! * 6.13 lpr(1) and/or lpd(8) don't work. * 6.14 Timestamps on files on msdos partitions are set incorrectly. * 6.15 How do I get LILO to boot the vmlinux file? 7. How do I do this or find out that ... ? * 7.1 How can I get scrollback in text mode? * 7.2 How do I switch virtual consoles? How do I enable them? * 7.3 How do I set the time zone? * 7.4 What version of Linux and what machine name am I using? * 7.5 How can I enable or disable core dumps? * 7.6 How do I upgrade/recompile my kernel? * 7.7 Can I have more than 3 serial ports by sharing interrupts? * 7.8 How do I make a bootable floppy? * 7.9 How do I remap my keyboard to UK, French, etc.? * 7.10 How do I get NUM LOCK to default to on? * 7.11 How can I have more than 128Mb of swap? * 7.12 Miscellaneous information and questions answered. * 7.13 How do I program XYZ under Linux? * 7.14 What's all this about ELF? * 7.15 What is a .gz file ? And a .tgz ? And ... ? * 7.16 What does VFS stand for? * 7.17 What is a BogoMip? * 7.18 What is the Linux Journal and where can I get it? * 7.19 How many people use Linux? * 7.20 How should I pronounce Linux? 8. Frequently encountered error messages. * 8.1 Unknown terminal type linux and similar. * 8.2 lp1 on fire * 8.3 INET: Warning: old style ioctl... called! * 8.4 ld: unrecognized option '-m486' * 8.5 GCC says Internal compiler error. * 8.6 make says Error 139 * 8.7 shell-init: permission denied when I log in. * 8.8 No utmp entry. You must exec ... when I log in. * 8.9 Warning--bdflush not running. * 8.10 Warning: obsolete routing request made. * 8.11 EXT2-fs: warning: mounting unchecked file system. * 8.12 EXT2-fs warning: maximal count reached. * 8.13 EXT2-fs warning: checktime reached. * 8.14 df says Cannot read table of mounted file systems. * 8.15 fdisk says Partition X has different physical/logical ... * 8.16 fdisk: Partition 1 does not start on cylinder boundary * 8.17 fdisk says partition n has an odd number of sectors. * 8.18 mtools says cannot initialize drive XYZ * 8.19 At the start of booting: Memory tight * 8.20 My syslog says `end_request: I/O error, ...'. * 8.21 You don't exist. Go away. 9. The X Window System. * 9.1 Does Linux support X Windows? * 9.2 Where can I get an XF86Config for my system? * 9.3 xterm logins show up strangely in who, finger. * 9.4 I can't get X Windows to work right. 10. Questions applicable to very out-of-date software. * 10.1 fdisk says cannot use nnn sectors of this partition. * 10.2 GCC sometimes uses huge amounts of virtual memory and thrashes. 11. How to get further assistance. * 11.1 You still haven't answered my question! * 11.2 What to put in a request for help. * 11.3 I want to mail someone about my problem. 12. Administrative information and acknowledgements. * 12.1 Feedback is invited. * 12.2 Formats in which this FAQ is available. * 12.3 Authorship and acknowledgements. * 12.4 Disclaimer and Copyright. 1. Introduction and General Information 1.1 What is Linux? Linux is the free Unix written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers from across the Internet. Linux aims towards POSIX compliance, and has all of the features you would expect of a modern, fully-fledged Unix: true multitasking, virtual memory, shared libraries, demand loading, shared, copy-on-write executables, proper memory management, and TCP/IP networking. Linux runs mainly on 386/486/586-based PCs, using the hardware facilities of the 386 processor family (TSS segments, et al.) to implement these features. Ports to other architectures are underway. (See "What ports to other processors are there?") See the Linux INFO-SHEET for more details. (See "Where can I get the HOWTOs and other documentation?") The Linux kernel is distributed under the GNU General Public License. (See, "Is Linux public domain? Copyrighted?") 1.2 Where do I start? There are a handful of different 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://sunsite.unc.edu/LDP. There is also an Installation HOWTO at the LDP Home Page. Most of the distributions are available via anonymous FTP from various Linux archive sites. See "Where can I get Linux material by FTP?" There are also a large number of other releases which are distributed less globally, which suit special local and national needs. 1.3 What software does Linux support? Linux supports GCC, Emacs, the X Window System, all the standard Unix utilities, TCP/IP (including SLIP and PPP), and all the hundreds of programs that people have compiled or ported for it. There is a DOS emulator (available at tsx-11.mit.edu/pub/linux/ALPHA/dosemu) which can run DOS itself and some (but not all) DOS applications. Be sure to look at the README file to determine which version of dosemu you should get. Also, see the DOSEMU-HOWTO (slightly dated at this point--it doesn't cover the most recent version of the program), which is located at sunsite.unc.edu/pub/Linux/docs/HOWTO. Work has been progressing on an emulator for Microsoft Windows binaries. (See "Can I run Microsoft Windows programs under Linux?") 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. See the file tsx-11.mit.edu/pub/linux/BETA/ibcs2/README. For more information see the INFO-SHEET, which is one of the the HOWTOs (See "Where can I get the HOWTOs and other documentation?" See also "How do I port XXX to Linux?" Some companies have commercial software available, including Motif. They announce their availability in comp.os.linux.announce--try searching the archives. (See "Are the newsgroups archived anywhere?") 1.4 Does Linux run on my computer? What hardware is supported? You need a 386, 486 or 586, with at least 2Mb of RAM and a single floppy, to try Linux. To do anything useful, more RAM is needed. (" How much memory does Linux need?") VESA Local Bus and PCI 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://glycerine.itsmm.uni.edu/mca. Linux runs on 386 family based laptops, with X on most of them. There is a relevant Web page at http://www.cs.utexas.edu/users/kharker/linux-laptop/. For details of exactly which PC's, video cards, disk controllers, etc. work see the INFO-SHEET and the Hardware-HOWTO. (See "Where can I get the HOWTOs and other documentation?") There is a port of Linux to the 8086, known as the Embeddable Linux Kernel Subset (ELKS). This is a 16-bit subset of the Linux kernel which will mainly be used for embedded systems. See http://www.linux.org.uk/Linux8086.html for more information. Linux will never run fully on an 8086 or '286, because it requires task-switching and memory management facilities not found on these processors. Linux supports multiprocessing with Intel MP architecture. See the file Documentation/smp.tex in the Linux kernel source code distribution. See the next question for a (probably incomplete) list of hardware platforms that Linux has been ported to. 1.5 What ports to other processors are there? There is a reasonably complete list of Linux ports at http://www.ctv.es/USERS/xose/linux/linux_ports.html, and at http://www.linuxhq.com/dist-index.html. A project has been underway for a while to port Linux to suitable 68000-series based systems such as Amigas and Ataris. The Linux/m68K FAQ is located at www.clark.net/pub/lawrencc/linux/faq/faq.html. The URL of the Linux/m68k home page is www.linux-m68k. There is a linux-680x0 mailing list. (See "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. There are mailing lists for all of these platforms. See http://www.debian.org/MailingLists/subscribe. One of the Linux-PPC project pages has moved recently. Its location is http://www.linuxppc.org, and the archive site is ftp.linuxppc.org/linuxppc. There is a Linux-PPC support page at www.cs.nmt.edu/~linuxppc/. There you will find the kernel that is distributed with Linux. Apple now supports MkLinux development on Power Macs, based on OSF and the Mach microkernel. See http://www.mklinux.apple.com. A port to the 64-bit DEC Alpha/AXP is at http://www.azstarnet.com/~axplinux/. There is a mailing list at vger.rutgers.edu. (See "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.fnet.fr/linux-mips and ftp://ftp.linux.sgi.com/pub/mips-linux. Interested people may mail their questions and offers of assistance to linux@waldorf-gmbh.de. There is also a MIPS channel on the Linux Activists mailserver and a linux-mips mailing list. (See "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, watch 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 available from Jim Mintha's Linux for SPARC Processors page, http://www.geog.ubc.ca/sparclinux.html. The SPARC/Linux archives are at vger.rutgers.edu/pub/linux/Sparc. There is also a port ("Hardhat") to SGI/Indy machines. The URL is http://www.linux.sgi.com. 1.6 How much hard disk space does Linux need? About 10Mb for a very minimal installation, suitable for trying it out and not much else. You can squeeze a more complete installation including X, into 80Mb. Installing almost all of Debian GNU/Linux takes around 500Mb, including kernel source code, some space for user files, and spool areas. 1.7 How much memory does Linux need? At least 4MB, and then you will need to use special installation procedures. Linux will run comfortably in 4MB of RAM, although X Windows Apps will run slowly because they need to swap out to disk. Some recent applications, like Netscape, require 64MB of physical memory. 1.8 How much memory can Linux use? A number of people have asked how to address more than 64 MB of memory, which is the default upper limit. Place the following in your lilo.conf file: append="mem=XXM" Where "XX" is the amount of memory, specified as megabytes, for example, '128M'. For further details see the lilo manual page. 1.9 Is Linux public domain? Copyrighted? The Linux kernel copyright belongs to Linus Torvalds. He has placed it 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. This is not the same as Public Domain. See the Copyright FAQ, rtfm.mit.edu/pub/usenet/news.answers/law/copyright, 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 gnu.misc.discuss and not to the comp.os.linux groups. 2. Network sources and resources. 2.1 Where can I get the HOWTOs and other documentation? Look in the following places, and the sites that mirror them. * ftp.funet.fi : /pub/OS/Linux/doc/HOWTO * tsx-11.mit.edu : /pub/linux/docs/HOWTO * sunsite.unc.edu : /pub/Linux/docs/HOWTO For a complete list of Linux FTP sites, "Where can I get Linux material by FTP?" If you don't have access to FTP, try the FTP-by-mail servers at ftpmail@decwrl.dec.com, ftpmail@doc.ic.ac.uk or ftp-mailer@informatik.tu-muenchen.de.. A complete list of HOWTO's and Mini-HOWTO's is available in the file HOWTO.INDEX in the docs/HOWTO directory at the FTP sites, or on the Web at http://sunsite.unc.edu/LDP/HOWTO/HOWTO-INDEX.html, but here is a (possibly incomplete) list: AX25-HOWTO Access-HOWTO Assembly-HOWTO Benchmarking-HOWTO BootPrompt-HOWTO Bootdisk-HOWTO CD-Writing-HOWTO CDROM-HOWTO Chinese-HOWTO Commercial-HOWTO Consultants-HOWTO Cyrillic-HOWTO DNS-HOWTO DOS-to-Linux-HOWTO DOSEMU-HOWTO Danish-HOWTO Distribution-HOWTO ELF-HOWTO Emacspeak-HOWTO Ethernet-HOWTO Finnish-HOWTO Firewall-HOWTO Ftape-HOWTO GCC-HOWTO German-HOWTO HAM-HOWTO HOWTO-INDEX Hardware-HOWTO Hebrew-HOWTO IPX-HOWTO ISP-Hookup-HOWTO Installation-HOWTO Intranet-Server-HOWTO Italian-HOWTO Java-CGI-HOWTO Kernel-HOWTO Keyboard-and-Console-HOWTO MGR-HOWTO MILO-HOWTO Mail-HOWTO NET-3-HOWTO NFS-HOWTO NIS-HOWTO News-HOWTO Optical-Disk-HOWTO PCI-HOWTO PCMCIA-HOWTO PPP-HOWTO Pilot-HOWTO Polish-HOWTO Printing-HOWTO Printing-Usage-HOWTO RPM-HOWTO Reading-List-HOWTO SCSI-HOWTO SCSI-Programming-HOWTO SMB-HOWTO Serial-HOWTO Serial-Programming-HOWTO Shadow-Password-HOWTO Slovenian-HOWTO Sound-HOWTO Sound-Playing-HOWTO Spanish-HOWTO TeTeX-HOWTO Thai-HOWTO Tips-HOWTO UMSDOS-HOWTO UPS-HOWTO UUCP-HOWTO User-Group-HOWTO VAR-HOWTO VMS-to-Linux-HOWTO XFree86-HOWTO XFree86-Video-Timings-HOWTO 3-Button-Mouse The following Mini-HOWTO's are available from http://sunsite.unc.edu/pub/Linux/HOWTO/mini: ADSM-Backup AI-Alife Advocacy Backup-With-MSDOS Battery-Powered Boca BogoMips Bridge Bridge+Firewall Clock Colour-ls Comeau-C++ DHCPd Dial-On-Demand Diald Dip+SLiRP+CSLIP Diskless Dynamic-IP-Hacks Ext2fs-Undeletion GTEK-BBS-550 HTML-Validation IO-Port-Programming IP-Alias IP-Masquerade IP-Subnetworking JE Jaz-Drive Kerneld Key-Setup LBX Large-Disk Linux+DOS+Win95 Linux+DOS+Win95+OS2 Linux+NT-Loader Linux+OS2+DOS Linux+Win95 Loadlin+Win95 Locales MIDI+SB Mail-Queue Mail2News Man-Page Multiple-Disks-Layout Multiple-Ethernet NFS-Root NFS-Root-Client Netscape+Proxy Offline-Mailing Online-Support PLIP PPP-over-minicom Pager Partition Print2Win Process-Accounting Proxy-ARP Public-Web-Browser Qmail+MH Quota RCS Remote-Boot Remote-X-Apps SLIP+proxyARP SLIP-PPP-Emulator Sendmail+UUCP Software-Building Software-RAID Soundblaster-16 Soundblaster-AWE64 StarOffice Swap-Space Term-Firewall Tiny-News Token-Ring Upgrade VPN Virtual-wu-ftpd Visual-Bell Win95+Win+Linux Windows-Modem-Sharing WordPerfect X-Big-Cursor XFree86-XInside Xterm-Title Xterminal ZIP-Drive ZIP-Install In addition, translations of the HOWTO's are available from sunsite.unc.edu/pub/Linux/docs/HOWTO/translations and mirrors worldwide. Translations in the following languages are available: Chinese (zh) French (fr) German (de) Hellenic (el) Indonesian (id) Italian (it) Japanese (jp) Korean (ko) Polish (pl) Spanish (es) Slovenian (sl) Polish (sv) Turkish (tr) The HOWTO's are also on the Web, at the Linux Documentation Project's home page, http://sunsite.unc./edu/LDP. More of these documents are always in preparation. Please get in touch with Greg Hankins, gregh@cc.gatech.edu, the HOWTO coordinator, if you are interested in writing one. The file sunsite.unc.edu/pub/Linux/HOWTO/HOWTO-INDEX contains guidelines for writing a HOWTO. The Guide Series produced by the Linux Documentation Project is available from http://sunsite.unc.edu/LDP. Please read them if you are new to Unix and Linux. Here is a list of those available so far: * The Linux Documentation Project Manifesto, by Matt Welsh. * Installation and Getting Started Guide, by Matt Welsh. * The Linux Kernel, by David Rusling. * The Network Administrator's Guide, by Olaf Kirch. * The Linux Programmer's Guide, by Sven Goldt, Sven van der Meer, Scott Burkett, and Matt Welsh. * The Linux System Administrator's Guide, Version 0.5, by Lars Wirzenius. * Text Processing with Linux, by Robert Kiesling. 2.2 Where should I look on the World Wide Web for Linux stuff? Two Web pages in particular provide 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. Greg Hankins, gregh@cc.gatech.edu, maintains the Linux Documentation Project Home Page, at http://sunsite.unc.edu/LDP. This page refers to all the FAQs and HOWTOs, both those which are available in HTML (WWW) format, and those which aren't. 2.3 What newsgroups are there for Linux? There are a number of international Usenet newsgroups devoted to Linux. comp.os.linux.announce is the moderated announcements group; you should read this if you intend to use Linux: 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 emailed to linux-announce@news.ornl.gov. comp.os.linux.answers contains all the FAQs, HOWTOs and other important documentation. You should subscribe to this group also. Axel Boldt, axel@uni-paderborn.de, noted that comp.os.linux.announce is NOT archived on Dejanews or Altavista. The only archive for the news group seems to be www.iki.fi/mjr/linux/cola.html. Also worth reading are the other groups in the comp.os.linux.* hierarchy--you may find that many common problems are too recent to find in this FAQ but are answered in the newsgroups. These groups are comp.os.linux.setup comp.os.linux.hardware comp.os.linux.networking comp.os.linux.x comp.os.linux.development.apps comp.os.linux.development.system comp.os.linux.advocacy comp.os.linux.misc Remember that since Linux is POSIX compatible, most all of the material in comp.unix.* and comp.windows.x.* groups will be relevant. Apart from hardware considerations, and some obscure or very technical low-level issues, you'll find that these groups are a good place to start. Please read "You still haven't answered my question!" before posting. Crossposting 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 "I don't have Usenet access. Where do I get information?" Other regional and local newsgroups also exist--you may find the traffic more manageable there. The French Linux newsgroup is fr.comp.os.linux. The German one is de.comp.os.linux. In Australia, try aus.computers.linux. In Croatia there is the moderated group hr.comp.linux.m. In Italy, there is it.comp.linux. 2.4 Where can I find out about Linux and the Millennium (Y2K) bug? The Debian/GNU Linux people have a statement on their Web site at http://www.debian.org Essentially, Linux uses libraries that store dates as 32-bit integers, which count the seconds since 1970. This counter will not overflow until the year 2038, by which time the library programmers will (hopefully) have upgraded the system software to store dates as 64-bit integers. This, of course, does not mean that applications are not susceptible to the millennium bug, if they do not use the standard library routines. The Free Software Foundation has a webpage about Y2K issues in GNU software at http://www.fsf.org/software/year2000.html There is also a Usenet newsgroup, comp.software.year-2000, for general discussion of Y2K issues. 2.5 Where can I get Linux material by FTP? There are three main archive sites for Linux: * ftp.funet.fi (Finland) : /pub/OS/Linux * sunsite.unc.edu (US) : /pub/Linux * tsx-11.mit.edu (US) : /pub/linux The best place to get the Linux kernel is ftp.cs.helsinki.fi/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.debian.org/pub/debian. Red Hat Linux's home site is ftp.redhat.com, and Slackware's is ftp.cdrom.com. The contents of these sites is mirrored (copied, usually approximately daily) by a number of other sites. Please use one close to you--that will be faster for you and easier on the network. * ftp.sun.ac.za/pub/linux/sunsite/ (South Africa) * ftp.is.co.za/linux/sunsite/ (South Africa) * ftp.cs.cuhk.hk/pub/Linux/ (Hong Kong) * ftp.cs.cuhk.hk/pub/Linux/ (Hong Kong) * ftp.spin.ad.jp/pub/linux/sunsite.unc.edu/ (Japan) * ftp.nuri.net/pub/Linux/ (Korea) * ftp.jaring.my/pub/Linux/ (Malaysia) * ftp.nus.sg/pub/unix/Linux/ (Singapore) * ftp.nectec.or.th/pub/mirrors/linux/ (Thailand) * mirror.aarnet.edu.au/pub/linux/ (Australia) * sunsite.anu.edu.au/pub/linux/ (Australia) * ftp.monash.edu.au/pub/linux/ (Australia) * ftp.univie.ac.at/systems/linux/sunsite/ (Austria) * ftp.fi.muni.cz/pub/UNIX/linux/ (Czech Republic) * ftp://sunsite.fri.uni-lj.si/pub/linux/ (Slovenia) * ftp.funet.fi/pub/Linux/sunsite/ (Finland) * ftp.univ-angers.fr/pub/Linux/ (France) * ftp.iut-bm.univ-fcomte.fr (France) * ftp.ibp.fr/pub/linux/sunsite/ (France) * ftp.loria.fr/pub/linux/sunsite/ (France) * ftp.dfv.rwth-aachen.de/pub/linux/sunsite/ (Germany) * ftp.germany.eu.net/pub/os/Linux/Mirror.SunSITE/ (Germany) * ftp.tu-dresden.de/pub/Linux/sunsite/ (Germany) * ftp.uni-erlangen.de/pub/Linux/MIRROR.sunsite/ (Germany) * ftp.gwdg.de/pub/linux/mirrors/sunsite/ (Germany) * ftp.rz.uni-karlsruhe.de/pub/linux/mirror.sunsite/ (Germany) * ftp.ba-mannheim.de/pub/linux/mirror.sunsite/ (Germany) * ftp.uni-paderborn.de/pub/Mirrors/sunsite.unc.edu/ (Germany) * ftp.uni-rostock.de/Linux/sunsite/ (Germany) * tp.rus.uni-stuttgart.de/pub/unix/systems/linux/MIRROR.sunsite/ (Germany) * ftp.uni-tuebingen.de/pub/linux/Mirror.sunsite/ (Germany) * ftp.rz.uni-ulm.de/pub/mirrors/linux/sunsite/ (Germany) * ftp.kfki.hu/pub/linux/ (Hungary) * linux.italnet.it/pub/Linux/ (Italy) * ftp.unina.it/pub/linux/sunsite/ (Italy) * giotto.unipd.it/pub/unix/Linux/ (Italy) * cnuce-arch.cnr.it/pub/Linux/ (Italy) * ftp.flashnet.it/mirror2/sunsite.unc.edu/ (Italy) * ftp.nijenrode.nl/pub/linux/sunsite.unc-mirror/ (Netherlands) * ftp.LeidenUniv.nl/pub/linux/sunsite/ (Netherlands) * ftp.nvg.unit.no/pub/linux/sunsite/ (Norway) * ftp://sunsite.icm.edu.pl/pub/Linux/sunsite.unc.edu/ (Poland) * ftp.rediris.es/software/os/linux/sunsite/ (Spain) * sunsite.rediris.es/software/linux/ (Spain) * ftp.cs.us.es/pub/Linux/sunsite-mirror/ (Spain) * ftp.etse.urv.es/pub/mirror/linux/ (Spain) * ftp.etsimo.uniovi.es/pub/linux/ (Spain) * ftp.luna.gui.es/pub/linux.new/ (Spain) * ftp.switch.ch/mirror/linux/ (Switzerland) * ftp.metu.edu.tr/pub/linux/sunsite/ (Turkey) * unix.hensa.ac.uk/mirrors/sunsite/pub/Linux/ (UK) * ftp.maths.warwick.ac.uk/mirrors/linux/sunsite.unc-mirror/ (UK) * ftp.idiscover.co.uk/pub/Linux/sunsite.unc-mirror/ (UK) * sunsite.doc.ic.ac.uk/packages/linux/sunsite.unc-mirror/ (UK) * ftp.dungeon.com/pub/linux/sunsite-mirror/ (UK) * ftp.io.org/pub/mirrors/linux/sunsite/ (Canada) * ftp.cc.gatech.edu/pub/linux/ (US) * ftp.cdrom.com/pub/linux/sunsite/ (US) * ftp.siriuscc.com/pub/Linux/Sunsite/ (US) * ftp.engr.uark.edu/pub/linux/sunsite/ (US) * ftp.infomagic.com/pub/mirrors/linux/sunsite/ (US) * linux.if.usp.br/pub/mirror/sunsite.unc.edu/pub/Linux/ (Brazil) * farofa.ime.usp.br/pub/linux/ (Brazil) Not all of these mirror all of the other `source' sites, and some have material not available on the `source' sites. 2.6 I don't have FTP access. Where do I get Linux? The easiest thing is probably to find a friend with FTP access. If there is a Linux 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 ftpmail@ftp.sunet.se, ftpmail@garbo.uwasa.fi or ftpmail@ftp.uni-stuttgart.de. Linux is also available via traditional mail on CD-ROM. The file sunsite.unc.edu/pub/Linux/docs/HOWTO/Installation-HOWTO, and the file sunsite.unc.edu/pub/Linux/docs/distributions/Distribution-HOWTO contain information on these distributions. 2.7 I don't have Usenet access. Where do I get information? A digest of comp.os.linux.announce is available by mailing the word "subscribe" (without the quotes) as the body of a message to linux-announce-REQUEST@news-digests.mit.edu. Subscribe 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 subscription and unsubscription messages; mail to the other address is posted to the newsgroup! 2.8 What mailing lists are there? The Linux developers now mainly use the Majordomo server at majordomo@vger.rutgers.edu. 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 which lists instructions for subscribing and unsubscribing to the lists. Most of the lists are used by the developers of Linux to talk about technical issues and future developments. These are not intended for new users' questions. There is a linux-newbie list where "no question is too stupid." Unfortunately, it seems that few of the experienced users read that channel. It does have very low volume. 2.9 Are the newsgroups archived anywhere? The Usenet Linux news groups are archived at http://www.dejanews.com, http://www.reference.com and http://altavista.digital.com sunsite.unc.edu//pub/Linux/docs/linux-announce.archive contains archives of comp.os.linux.announce. These are mirrored from src.doc.ic.ac.uk/usenet, which also archives comp.os.linux, comp.os.linux.development.apps, and comp.os.linux.development.system. There is an "easy to access" archive of comp.os.linux.announce on the World Wide Web at http://www.leo.org/archiv/linux/archiv/ann_index.html. It supports searching and browsing. 3. Compatibility with other operating systems. 3.1 Can Linux share my disk with DOS? OS/2? 386BSD? Win95? Yes. Linux uses the standard MS-DOS partitioning scheme, so it can share your disk with other operating systems. Note, however, that many of these other operating systems are rather picky. 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 like these 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., 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. For information about FAT32 partition support, see http://bmrc.berkeley.edu/people/chaffee/fat32.html. "What software does Linux support?" for details and status of the emulators for DOS, MS Windows, and System V programs. See, "Can Linux access Amiga file systems?" and, "Can Linux access Mac file systems?" "Can Linux access BSD, SysV, etc., UFS?" "Can Linux access SMB file systems?" There are said to be NTFS drivers under development, which should support compression as a standard feature. There is also supposedly a Win95 driver that allows read-only access to Linux file systems, although I don't know the URL. Call Microsoft technical support. 3.2 How do I access files on my DOS partition or floppy? Use the DOS file system; i.e., type, for example: $ mkdir /dos $ mount -t msdos -o conv=text,umask=022,uid=100,gid=100 /dev/hda3 /dos If it's a floppy, don't forget to umount it before ejecting it! You can use the conv=text/binary/auto, umask=nnn, uid=nnn, and gid=nnn options to control the automatic line-ending conversion, permissions and ownerships of the files in the DOS 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 can I get Linux material by FTP?". 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? As of recently, it does. Information about them is located at http://www.netspace.net.au/~reiter/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/ This is according to Roderich Schupp, who adds somewhat cryptically, "There is a program called Zlibc ..." Zlibc is actually a program that allows existing applications to read compressed (GNU gzip'ed) files as if they were not compressed. Look on sunsite.unc.edu in /pub/Linux/libs. The author is Alain.Knuff@imag.fr. There is also a compressing block device driver that can provide on the fly disk compression in the kernel. It is called, "DouBle" and is written by Jean-Marc Verbavatz. The source-only distribution is located on sunsite.unc.edu in the directory /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 compressed executables compressed and only uncompress them temporarily when in use. It is located on sunsite.unc.edu in the directory /pub/Linux/utils/compress/. 3.4 Can I use my Stacked/DBLSPC/etc. DOS drive? 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, which 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 available in the archives on ftp://sunsite.unc.edu/pub/Linux/system/Filesystem/dosfs. There is a module available for the Linux kernel which can do read-only access of the compressed volume. Look in sunsite.unc.edu/pub/Linux/system/filesystems/dosfs for this package. 3.5 Can I access OS/2 HPFS partitions from Linux? 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 do I upgrade/recompile my 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 do I upgrade/recompile my kernel?". Linux supports AFFS hard-drive partitions only, though: 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 do I upgrade/recompile my 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 do I upgrade/recompile my kernel?" in this FAQ. 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 sunsite.unc.edu/pub/Linux/system/network/samba. There is a SMB web site at samba.canberra.edu.au/pub/samba. 3.9 Can Linux access Mac file systems? There is a set of user-level programs that read and write the Macintosh Hierarchical File System (HFS). It is available at sunsite.unc.edu/pub/Linux/utils/disk-management. 3.10 Can I run Microsoft Windows programs under Linux? 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. A commercial, working product known as WABI is said to provide full MS Windows emulation under Linux. It was written by Sunsoft, Inc. The Linux version is available from Caldera. There is also a FAQ, compiled by P. David Gardner, at sunsite.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 bootloader, can boot one of several operating systems from a menu. See the LILO documentation for details. Also, LOADLIN (a DOS program to load a Linux, or other OS, kernel is a handy way to make Linux co-exist with DOS. LOADLIN 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 load 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 in it with a copy of your kernel, and use that. LOADLIN is a VCPI compliant program. Win '95 will want to, "shutdown into DOS mode," to run it (as it would with certain other DOS protected-mode programs). Earlier versions of LOADLIN sometimes required a package called REALBIOS.COM, which required a boot procedure on an (almost) blank floppy to map the REALBIOS 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). (Much thanks to Jim Dennis for this information.) 3.11 How can I boot Linux 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 config 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 on the LDP Home Page, http://sunssite.unc.edu/LDP/. 3.12 How can I share a swap partition between Linux and MS Windows? See the Mini-HOWTO on the subject by H. Peter Anvin, hpa@yggdrasil.com. It is available at sunsite.unc.edu/pub/Linux/docs/HOWTO/mini/Swap-Space. 4. Linux's handling of file systems, disks, and drives 4.1 How can I get Linux to work with my 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. DOS will usually not be able to access partitions which extend beyond 1024 logical cylinders, and will make booting a Linux kernel from such partitions using LILO problematic at best. You can still use such partitions for Linux or other operating systems that access the controller directly. 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 gottent the straight scoop on them--but they are becoming a very common problem and the SVLUG installfests. When you can get 8 to 12 Gig drives for $200 to $300 it's no wonder. (Much thanks to Jim Dennis for this information.) 4.2 How can I undelete files? In general, this is very hard to do on Unices because of their multitasking nature. Undelete functionality for the ext2fs 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. 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. 4.3 Is there a defragmenter for ext2fs etc.? Yes. There is defrag, a Linux file system defragmenter for ext2, minix and old-style ext file systems. It is available at sunsite.unc.edu/pub/Linux/system/filesystems/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. 4.4 How do I format and 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. (See "Where can I get the HOWTOs and other documentation?") A more detailed and technical description is Linux Allocated Devices by H. Peter Anvin, hpa@zytor.com, 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. 4.5 I get nasty messages about inodes, blocks, and the suchlike. 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 reinitialize 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. 4.6 My swap area isn't working. When you boot (or enable swapping manually) you should see Adding Swap: NNNNk swap-space If you don't see any messages at all you are probably missing swapon -av (the command to enable swapping) in your /etc/rc.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 Check the Installation HOWTO for detailed instructions of how to set up a swap area. 4.7 How do I remove LILO so my system boots DOS again? Using DOS (MS-DOS 5.0 or later, or OS/2), type FDISK /MBR (which is not documented). This will restore a standard MS-DOS Master Boot Record. If you have DR-DOS 6.0, go into FDISK in the normal way and then select the `Re-write Master Boot Record' option. If you don't have 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 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. 4.8 Why can't I use fdformat except as root? 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. 4.9 My ext2fs partitions are checked each time I reboot. See "EXT2-fs: warning: mounting unchecked file system.". 4.10 My root file system is read-only! Remount it. If /etc/fstab is correct, you can simply mount -n -o remount /. If /etc/fstab is wrong you must give the device name and posibly 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." 4.11 I have a huge /proc/kcore! Can I delete it? None of the files in /proc are really there--they're all "pretend" files made up by the kernel, to give you information about the system, and don't take up any hard disk space. /proc/kcore is like an "alias" for the memory in your computer; its size is the same as the amount of RAM you have, and if you ask to read it as a file the kernel does memory reads. 4.12 My AHA1542C doesn't work with Linux. The option to allow disks with more than 1024 cylinders is only required as a workaround for a DOS misfeature and should be turned `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. 5. Porting, compiling and obtaining programs 5.1 How do I port XXX to Linux? In general, Unix programs need very little porting. Simply follow the installation instructions. If you don't know--and don't know how to find out--the answers to some of the questions asked during 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. 5.2 What is ld.so and where do I 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 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. 5.3 Has anyone ported / compiled / written XXX for Linux? First, look in the Linux Software Map--it's at sunsite.unc.edu/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/. Check the FTP sites "Where can I get Linux material by FTP?" first--search the ls-lR or INDEX files for appropriate strings. Also look at the Linux Projects Map, ftp.ix.de/pub/ix/Linux/docs/Projects-Map.gz. There's a search engine for Linux FTP archives at http://lfw.linuxhq.com/ Also check out the Freshmeat Web site http://www.freshmeat.org, which is really cool. If you don't find anything, you could either download the sources to the program yourself and compile them. See "How do I port XXX to Linux?" If it's a large package which 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 linux-announce@news.ornl.gov). If you're looking for an application program, the chances are that someone has already written a free verson. The comp.sources.wanted FAQ has instructions for finding the source code. 5.4 Can I use code or a compiler compiled for a 486 on my 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 which 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 will use 486- or Pentium-specific instructions if configured for a 486 or Pentium, thus making it unusable on a 386. GCC can be configured for a 386 or 486; the only difference is that configuring it for a 386 makes -m386 the default and configuring for a 486 makes -m486 the default; in either case these can be overriden on a per-compilation basis or by editing /usr/lib/gcc-lib/i*-linux/n.n.n/specs. There is an Alpha version of GCC which knows how to do optimisation well for the 586, but it is quite unreliable, especially at high optimisation settings. The Pentium GCC can be found on tsx-11.mit.edu in /pub/linux/ALPHA/pentium-gcc. I'd recommend using the ordinary 486 GCC instead; word has it that using -m386 produces code that's better for the Pentium, or at least slightly smaller. 5.5 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 currently does the same thing. The Makefiles of newer kernels use -O2, and you should probably do the same. 5.6 Where are linux/*.h and asm/*.h? These are in the directories /usr/include/linux and /usr/include/asm. However, they should be symbolic links to your kernel sources in /usr/src/linux, not actual directories. If you don't have the kernel sources, download them--see, "How do I upgrade/recompile my kernel?" Then, use rm to remove any garbage, and ln to create the links: rm -rf /usr/include/linux /usr/include/asm ln -sf /usr/src/linux/include/linux /usr/include/linux ln -sf /usr/src/linux/include/asm /usr/include/asm /usr/src/linux/include/asm is a symbolic link to an architecture-specific asm-arch directory--if you have a freshly unpacked kernel source tree you must use make symlinks. You'll also find that you may need to do make config in a newly-unpacked kernel source tree, to create linux/autoconf.h. 5.7 I get errors when I try 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: unrecognised 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. 5.8 How do I 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, in /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 sunsite.unc.edu/pub/Linux/docs/HOWTO/ 5.9 My executables are (very) large. With an ELF compiler (see Q8.2 `What's all this about ELF ?') 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 (see, "What's all this about ELF?") 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, i.e. one which includes a copy of the C library instead of using a dynamically linked copy. Other things worth investigating are -O and -O2 which enable optimisation (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. 5.10 Does Linux support threads or lightweight processes? As well as the Unix multiprocessing model involving heavyweight processes, which is of course part of the standard Linux kernel, there are several implementations of lightweight processes or threads, most of which are generic packages for any Unix: * In sipb.mit.edu:/pub/pthread or ftp.ibp.fr:/pub/unix/threads/pthreads. 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 libcs contain the pthreads source; the GNU Ada compiler on sunsite.unc.edu in /pub/Linux/devel/lang/ada/gnat-3.01-linux+elf.tar.gz contains binaries made from that source code. * In 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 as /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.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. 5.11 Where can I get `lint' for Linux? Roughly equivalent functionality is built into the GNU C compiler (gcc) which is used by Linux systems. Use the -Wall option to turn on most of the useful extra warnings. Check the GCC manual for more details (type control-h followed by 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 larch.lcs.mit.edu in /pub/Larch/lclint; on the World Wide Web look at http://larch-www.lcs.mit.edu:8001/larch/lclint.html. 5.12 Where can I 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 kermit.columbia.edu. The WWW Home Page of the Columbia University Kermit project is http://www.columbia.edu/kermit. 6. Solutions to common miscellaneous problems. 6.1 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 sunsite.unc.edu in /pub/Linux/system/Status/ps/procps-0.99.tgz. 6.2 My clock is very wrong. There are two clocks in your computer. The hardware (CMOS) clock runs even when the computer is off and is used to when the system starts up and by DOS (if you use it). The ordinary system time, shown and set by 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 program--see "man 8 clock." To set the time zone, some programs recognize the TZ environment variable. The manual page for tzset describes setting the time zone. Recent, POSIX-correct systems have the time zone info in /usr/lib/zoneinfo/. The soft link localtime points to the zone information file for your time zone. The soft link posixrules points to localtime. There are various other programs that can correct either or both clocks for systematic drift or transfer time across the network. Some of them may already be installed on your system. Try looking at or for adjtimex (corrects for drift), netdate and getdate (simply get the time from the network) or xntp (accurate fully-featured network time daemon). 6.3 Setuid scripts don't seem to work. That's right. This feature has been deliberately disabled in the Linux kernel because setuid scripts are almost always a security hole. If you want to know why read the FAQ for comp.unix.questions. 6.4 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 and the contents get cached. It will stabilize after a while. 6.5 When I add more memory, the system slows to a crawl. This is quite a common symptom of a failure to cache the additional memory. The exact problem depends on your motherboard. Sometimes you have to enable caching of certain regions in your BIOS setup. Look in the CMOS setup and see if there is an option to cache the new memory area which is currently switched off. This is apparently most common on a 486. Sometimes the RAM has to be in certain sockets to be cached. Sometimes you have to set jumpers to enable the caching. Some motherboards don't cache all the RAM if you have more RAM per amount of cache than they expect. Usually a full 256K cache will solve this problem. If in doubt, check your motherboard manual. If you still can't fix it because the documentation is inadequate you might like to post a message to comp.os.linux.hardware giving *all* the details - make, model number, date code, etc. so that other Linux users can avoid it. 6.6 Some programs (e.g. xdm) won't let me log in. You are probably using non-shadow password programs but are using shadow passwords. If so, you have to get or compile a shadow password version of the program(s) in question. The shadow password suite can be found in (amongst other places): tsx-11.mit.edu:/pub/linux/sources/usr.bin/shadow-* This is the source code; you will probably find the binaries in .../linux/binaries/usr.bin. 6.7 Some programs let me log in with no password. You probably have the same problem as in "Some programs (e.g. xdm) won't let me log in.", with an added wrinkle: If you are using shadow passords 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. 6.8 My machine runs very slowly when I run 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 to buy more memory. You can also reclaim some memory by compiling and using a kernel with less options configured. See "How do I upgrade/recompile my kernel?". You can tell how much memory and/or swap you're using by using the free command, or by typing cat /proc/meminfo If your kernel is configured with a ramdisk this is probably wasted space and will cause things to go slowly. Use LILO or rdev to tell the kernel not to allocate a ramdisk (see the LILO documentation or type man rdev). 6.9 I can only log in as root. You probably have some permission problems, or you have a file /etc/nologin. If the latter, 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 containing these files all the way up the tree, up to and including the root directory. 6.10 My 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. 6.11 I have screwed up my system and can't log in to fix it. Reboot from an emergency floppy or floppy pair, for example, the Slackware boot and root disk pair in the install subdirectory of the Slackware distributions. There are also two do-it-yourself rescue disk creation packages in sunsite.unc.edu/pub/Linux/system/Recovery. These are better because as they have your own kernel on them, so that you don't run the risk of missing devices, file systems, and so forth. 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 back down to / first, or it will say it's busy). 6.12 I've discovered a huge security hole in rm! No you haven't. You are obviously new to Unix and need to read a good book on it to find out how things work. Clue: ability to delete files under Unix depends on permission to write the directory they are in. 6.13 lpr(1) and/or lpd(8) 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 board. You should be able to dump a file directly to the printer; e.g.: $ 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. If your machine has a network-aware lpd, like the one that comes with LPRng, make sure that the lpd.perms file is configured correctly. Also look at the Printing-HOWTO "Where can I get the HOWTOs and other documentation?". 6.14 Timestamps on files on msdos partitions are set incorrectly. There is a bug in the program clock(8) (often found in /sbin)--it miscounts a time zone offset, confusing seconds with minutes or some such. Get a new version of it. 6.15 How do I get LILO to boot the vmlinux file? In kernel versions 1.1.80 and later, the compressed kernel image, which is what LILO needs to find, has been moved to arch/i386/boot/zImage. The vmlinux file in the root directory is the uncompressed kernel, and you shouldn't try to boot it. This change has been made to make it easier to build the versions for several different processors from the same source tree. 7. How do I do this or find out that ... ? 7.1 How can I get scrollback in text mode? With the default US keymap you can use Shift with the PageUp and PageDown keys (NB: these must be the grey ones, not the ones on the numeric keypad!). With other keymaps check the maps in /usr/lib/keytables; you can remap the ScrollUp and ScrollDown keys to be whatever you like--for example, in order to remap them to keys that exist on an 84-key AT keyboard. You can't increase the amount of scrollback, because of the way it is implemented using the video memory to store the scrollback text, though you may be able to get more scrollback in each virtual console by reducing the total number of VC's--see linux/tty.h. 7.2 How do I switch virtual consoles? How do I enable them? In text mode, press Left Alt-F1 to Alt-F12 to select the consoles tty1 to tty12; Right Alt-F1 gives tty13 and so on. To switch out of X windows you must press Ctrl-Alt-F1, etc; Alt-F5 or whatever will switch back. If you want to use a VC for ordinary login you need to list it in /etc/inittab, which controls which terminals and virtual consoles have login prompts. NB: X needs at least one free VC in order to start. Kernels earlier than around 1.1.59 have a compiled-in limit on the number of consoles, for which the default is 8. See NR_CONSOLES in linux/include/linux/tty.h. Newer kernels allocate them dynamically, up to a maximum of 63. 7.3 How do I set the time zone? Change directory to /usr/lib/zoneinfo; get the timezone package if you don't have this directory. The source is available as sunsite.unc.edu/pub/Linux/system/admin/time/timesrc-1.2.tar.gz. 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(1). Don't try to use the TZ variable--leave it unset. 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 universal time is displayed. 7.4 What version of Linux and what machine name am I using? Type: uname -a 7.5 How can I enable or disable core dumps? By using the ulimit(1) command in bash(1), the limit command in tcsh(1), or the rlimit command in ksh(1). See the appropriate manual page for details. This setting affects all programs run from that shell (directly or indirectly), not the whole system. If you wish to enable or disable coredumping for all processes by default, you can change the default setting in linux/sched.h--see the definition of INIT_TASK, and look also in linux/resource.h. 7.6 How do I upgrade/recompile my kernel? See the Kernel HOWTO or the README files which comes with the kernel release on ftp.cs.helsinki.fi, in /pub/Software/Linux/Kernel and mirrors. (See "Where can I get Linux material by FTP?") You may already have a version of the kernel source code installed on your system, but if you got it as part of a standard distribution it is likely to be somewhat out of date (this is not a problem if you only want a custom-configured kernel, but it probably is if you need to upgrade.) Remember that to make the new kernel boot you must run LILO after copying the kernel into your root partition--the Makefile in recent kernels has a special zlilo target for this; try make zlilo. Kernel version numbers with an odd minor version (ie, 1.1.x, 1.3.x) are the testing releases; stable production kernels have even minor versions (1.0.x, 1.2.x). If you want to try the testing kernels you should probably subscribe to the linux-kernel mailing list. (See " What mailing lists are there?.") 7.7 Can I have more than 3 serial ports by sharing interrupts? Yes, but you won't be able to use simultaneously two ordinary ports which share an interrupt (without some trickery). This is a limitation of the ISA bus architecture. See the Serial HOWTO for information about possible solutions to and workarounds for this problem. 7.8 How do I make a bootable 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 ramdisk the same size as the floppy the ramdisk will be loaded at boot-time and mounted as root in place of the floppy. See the Bootdisk HOWTO. 7.9 How do I remap my keyboard to UK, French, etc.? For recent kernels, get /pub/Linux/system/Keyboards/kbd-0.90.tar.gz from sunsite.unc.edu. Make sure you get the appropriate version; you have to use the right keyboard-mapping package to go with your kernel version. 0.90 should work with kernel versions from 1.0. 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 keystroke and console HOWTO, by Andries Brouwer, at sunsite.unc.edu/pub/Linux/docs/HOWTO 7.10 How do I 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 (see Q7.9 `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. 7.11 How can I have more than 128Mb of swap? Use several swap partitions or swap files--Linux supports up to 16 swap areas, each of up to 128Mb. Very old kernels only supported swap area sizes up to 16Mb. Peter Moulder says that Linux on machines with 8MB, paging like Alpha and Sparc64, support a swap partition up to 512MB. He says that the 128MB limitation comes from PAGE_SIZE*BITSPERBYTE on machines with 4MB paging, but is 512MB on machines with 8MB paging. The file mm/swapfile.c has all of the gory details. 7.12 Miscellaneous information and questions answered. 7.13 How do I program XYZ under Linux? Read the manuals, or a good book on Unix. Manual pages (type "man man") are usually a good source of reference information on exactly how to use a particular command or function. There is also a lot of GNU Info documentation, which is often more useful as a tutorial. Run Emacs and type C-h i, or type info info if you don't have or don't like Emacs. Note that the Emacs libc node doesn't exactly describe the Linux libc (which is more like a traditional Unix libc, not having some of the GNU oddities), but it's close enough to make a fair tutorial in Unix C programming. The latest release of the Linux manual pages, a collection of useful GNU Info documentation, and various other information related to programming Linux can be found on sunsite.unc.edu in /pub/Linux/docs/man-pages. 7.14 What's all this about ELF? See the ELF HOWTO by Daniel Barlow--note, 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'). This will have many advantages, including better support for shared libraries and dynamic linking. Both a.out and ELF binaries can coexist on a system. However, they use different shared C libraries, both of which will have to be installed to do this. If you want to find out whether your system can run ELF binaries, look in /lib for a filename libc.so.5. If this exists it probably can. 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 tsx-11.mit.edu in /pub/packages/GCC. You do not need the patch merely to run ELF binaries. 1.3.x and later do not need a patch at all. 7.15 What is a .gz file ? And a .tgz ? And ... ? .gz (and .z) files have been compressed using GNU gzip. You need to use gunzip (which is as a symlink to the gzip command which comes with most Linux installations) to unpack the file. .taz and .tz are tarfiles (made with Unix tar) compressed using standard Unix compress. .tgz (or .tpz) is a tarfile compressed with gzip. .lsm is a Linux Software Map entry, in the form of a short text file. Details about the LSM and the LSM itself are available in the docs subdirectory on sunsite.unc.edu. .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.debian.org). .rpm is a Red Hat RPM package, which is used in the Red Hat distribution. These can be found on ftp.redhat.com. The "file" command can often tell you what a file is. If you find that gzip complains when you try to uncompress a gzipped file you probably downloaded it in ASCII mode by mistake. You must download most things in binary mode - remember to type binary as a command in FTP before using get to get the file. 7.16 What does VFS stand for? Virtual File System. It's the abstraction layer between the user and real file systems like ext2, minix and msdos. 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 7.17 What is a BogoMip? `BogoMips' is a contraction of `Bogus MIPS'. MIPS stands for (depending who you listen to) Millions of Instructions per Second, or Meaningless Indication of Processor Speed. The number printed at boot-time is the result of a kernel timing calibration, used for very short delay loops by some device drivers. As a very rough guide the BogoMips will be approximately: 386SX clock * 0.14 386DX clock * 0.18 486Cyrix/IBM clock * 0.33 486SX/DX/DX2 clock * 0.50 586 clock * 0.39 If the number you're seeing is wildly lower than this you may have the Turbo button or CPU speed set incorrectly, or have some kind of caching problem (as described in Q6.5 `When I add more memory it slows to a crawl.'.) - -- Robert Kiesling kiesling@terracom.net ...No writing gig too small...