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Subject: Linux Frequently Asked Questions with Answers (FAQ: 1/2) Newsgroups: comp.os.linux.announce,comp.os.linux.help,comp.answers,news.answers From: ijackson@nyx.cs.du.edu (Ian Jackson) Date: Sun, 30 Oct 1994 16:24:24 GMT Archive-Name: linux/faq/part1 Last-Modified: 30 Oct 1994 -----BEGIN PGP SIGNED MESSAGE----- This is the list of Frequently Asked Questions about Linux, the free Unix for 386/486/586 [see Q1.1 `What is Linux ?' for more details]. It should be read in conjunction with the HOWTO documents, which are available in * ftp.funet.fi (128.214.6.100) : /pub/OS/Linux/doc/HOWTO * tsx-11.mit.edu (18.172.1.2) : /pub/linux/docs/HOWTO * sunsite.unc.edu (152.2.22.81) : /pub/Linux/docs/HOWTO and mirror sites thereof -- see Q2.5 `Where can I get Linux material by FTP ?'. See Q2.1 `Where can I get the HOWTOs and other documentation ?' for a list of the HOWTOs and more information. The INFO-SHEET and META-FAQ, found in the same place, also list other sources of Linux information. The Linux Documentation Project documentation is available on sunsite.unc.edu in /pub/Linux/docs/LDP. These documents (more are in preparation) are invaluable to the newcomer or for use as a reference work. Please check out these documents and this FAQ, especially Q12.1 `You still haven't answered my question !', before posting your question to the newsgroup comp.os.linux.help. See Q13.2 `Formats in which this FAQ is available' for details of where to get the PostScript, Emacs Info, HTML (WWW) and plain ASCII versions of this document. You can skip to a particular question by searching for `Question n.n'. Note that this posting has been split into two parts because of its size. A new version of this document appears approximately monthly. If this copy is more than a month old it may be out of date. =============================================================================== Index Section 1. Introduction and General Information Q1.1 What is Linux ? Q1.2 What software does it support ? Q1.3 Does it run on my computer ? What hardware is supported ? Q1.4 What ports to other processors are there ? Q1.5 How much hard disk space does Linux need ? Q1.6 Is Linux PD ? Copyrighted ? Section 2. Network sources and resources Q2.1 Where can I get the HOWTOs and other documentation ? Q2.2 Where should I look on the World Wide Web for Linux stuff ? Q2.3 What newsgroups are there for Linux ? Q2.4 How do I install Linux ? Q2.5 Where can I get Linux material by FTP ? Q2.6 I don't have FTP access. Where do I get Linux ? Q2.7 I don't have Usenet access. Where do I get information ? Q2.8 What's this mailing list thing at niksula.hut.fi ? Q2.9 Are the newsgroups archived anywhere ? Section 3. Compatibility with other operating systems Q3.1 Can Linux coexist with DOS ? OS/2 ? 386BSD ? Minix ? Q3.2 How do I access files on my DOS partition or floppy ? Q3.3 Can I use my Stacked/DBLSPC/etc. DOS drive ? Q3.4 Can I access OS/2 HPFS partitions from Linux ? Q3.5 Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ? Q3.6 Can I run Microsoft Windows programs under Linux ? Q3.7 How can I boot Linux from OS/2's Boot Manager ? Q3.8 How can I share a swap partition between Linux and MS Windows ? Section 4. Linux's handling of filesystems, disks and drives Q4.1 How can I undelete files ? Q4.2 Is there a defragmenter for ext2fs etc. ? Q4.3 How do I format and create a filesystem on a floppy ? Q4.4 I get nasty messages about inodes, blocks, and the suchlike Q4.5 My swap area isn't working. Q4.6 How do I remove LILO so my system boots DOS again ? Q4.7 Why can't I use fdformat except as root ? Q4.8 Is there something like Stacker or Doublespace for Linux ? Q4.9 My ext2fs partitions are checked each time I reboot. Q4.10 I have a huge /proc/kcore ! Can I delete it ? Q4.11 My AHA1542C doesn't work with Linux. Section 5. Porting, compiling and obtaining programs Q5.1 What is ld.so and where do I get it ? Q5.2 Has anyone ported / compiled / written XXX for Linux ? Q5.3 How do I port XXX to Linux ? Q5.4 Can I use code or a compiler compiled for a 486 on my 386 ? Q5.5 What does gcc -O6 do ? Q5.6 Where are <linux/*.h> and <asm/*.h> ? Q5.7 I get errors when I try to compile the kernel. Q5.8 How do I make a shared library ? Q5.9 How do I make my executables smaller ? Section 6. Solutions to common miscellaneous problems Q6.1 Setuid scripts don't seem to work. Q6.2 Free memory as reported by free keeps shrinking. Q6.3 When I add more memory it slows to a crawl. Q6.4 Some programs (e.g. xdm) won't let me log in. Q6.5 Some programs let me log in with no password. Q6.6 My machine runs very slowly when I run GCC / X / ... Q6.7 I can only log in as root. Q6.8 My screen is all full of weird characters instead of letters. Q6.9 I have screwed up my system and can't log in to fix it. Q6.10 Emacs just dumps core. Q6.11 I've discovered a huge security hole in rm ! Q6.12 lpr and/or lpd aren't working. Section 7. How do I do this or find out that ... ? Q7.1 How can I get scrollback in text mode ? Q7.2 How do I switch virtual consoles ? How do I enable them ? Q7.3 How do I set the timezone ? Q7.4 What version of Linux and what machine name am I using ? Q7.5 How can I enable or disable core dumps ? Q7.6 How do I upgrade/recompile my kernel ? Q7.7 Can I have more than 3 serial ports by sharing interrupts ? Q7.8 How do I make a bootable floppy ? Q7.9 How do I remap my keyboard to UK, French, etc. ? Q7.10 How do I get NUM LOCK to default to on ? Section 8. Miscellaneous information and questions answered Q8.1 What is a .gz file ? And a .tgz ? And ... ? Q8.2 What does VFS stand for ? Q8.3 What is a BogoMip ? Q8.4 What is the Linux Journal and where can I get it ? Q8.5 How many people use Linux ? Q8.6 How should I pronounce Linux ? Section 9. Frequently encountered error messages Q9.1 During linking I get Undefined symbol _mcount Q9.2 lp1 on fire Q9.3 INET: Warning: old style ioctl(IP_SET_DEV) called! Q9.4 ld: unrecognized option '-m486' Q9.5 GCC says Internal compiler error Q9.6 make says Error 139 Q9.7 shell-init: permission denied when I log in. Q9.8 No utmp entry. You must exec ... when I log in. Q9.9 Warning - bdflush not running Q9.10 Warning: obsolete routing request made. Q9.11 EXT2-fs: warning: mounting unchecked filesystem Q9.12 EXT2-fs warning: maximal count reached Q9.13 EXT2-fs warning: checktime reached Q9.14 df says Cannot read table of mounted filesystems Q9.15 fdisk says Partition X has different physical/logical ... Q9.16 fdisk: Partition 1 does not start on cylinder boundary Q9.17 fdisk says cannot use nnn sectors of this partition Q9.18 fdisk says partition n has an odd number of sectors Q9.19 mtools says cannot initialise drive XYZ Section 10. The X Window System Q10.1 Does Linux support X Windows ? Q10.2 Where can I get an Xconfig for my video card and monitor ? Q10.3 xterm logins show up strangely in who, finger Q10.4 I can't get X Windows to work right. Section 11. Questions applicable to very out-of-date software Q11.1 How can I have more than 16Mb of swap ? Q11.2 GCC sometimes uses huge amounts of virtual memory and thrashes Q11.3 My keyboard goes all funny after I switch VC's. Section 12. How to get further assistance Q12.1 You still haven't answered my question ! Q12.2 What to put in a posting to comp.os.linux.help Section 13. Administrative information and acknowledgements Q13.1 Feedback is invited Q13.2 Formats in which this FAQ is available Q13.3 Authorship and acknowledgements Q13.4 Disclaimer and Copyright =============================================================================== Section 1. Introduction and General Information Q1.1 What is Linux ? Q1.2 What software does it support ? Q1.3 Does it run on my computer ? What hardware is supported ? Q1.4 What ports to other processors are there ? Q1.5 How much hard disk space does Linux need ? Q1.6 Is Linux PD ? Copyrighted ? - ----------------------------------------------------------------------------- Question 1.1. What is Linux ? Linux is a Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX compliance. It has all the features you would expect in a modern fully-fledged Unix, including true multitasking, virtual memory, shared libraries, demand loading, shared copy-on-write executables, proper memory management and TCP/IP networking. It runs mainly on 386/486/586-based PCs, using the hardware facilities of the 386 processor family (TSS segments et al) to implement these features. Ports to other architectures are underway [Q1.4 `What ports to other processors are there ?']. See the Linux INFO-SHEET [Q2.1 `Where can I get the HOWTOs and other documentation ?'] for more details. The Linux kernel is distributed under the GNU General Public License - see Q1.6 `Is Linux PD ? Copyrighted ?' for more details. - ----------------------------------------------------------------------------- Question 1.2. What software does it support ? Linux has GCC, Emacs, X-Windows, all the standard Unix utilities, TCP/IP (including SLIP and PPP) and all the hundreds of programs that people have compiled or ported for it. There is a DOS emulator [Q3.1 `Can Linux coexist with DOS ? OS/2 ? 386BSD ? Minix ?']. Work is progressing on an iBCS2 (Intel Binary Compatibility Standard) emulator for SVR4 ELF and SVR3.2 COFF binaries and an emulator for Microsoft Windows binaries [Q3.6 `Can I run Microsoft Windows programs under Linux ?']. For more information see the INFO-SHEET, which is one of the the HOWTOs [Q2.1 `Where can I get the HOWTOs and other documentation ?']. See also Q5.3 `How do I port XXX to Linux ?'. Some companies have commercial software available, including Motif. They announce their availability in comp.os.linux.announce --- try searching the archives [Q2.9 `Are the newsgroups archived anywhere ?']. - ----------------------------------------------------------------------------- Question 1.3. Does it run on my computer ? What hardware is supported ? You need a 386, 486 or 586, with at least 2Mb of RAM and a single floppy, to try it out. To do anything useful more RAM and a hard disk are required. VESA local bus and PCI are both supported. A driver for the NCR SCSI chip in many PCI machines is included in current alpha test release kernels. There are problems with machines using MCA (IBM's proprietary bus), mainly to do with the hard disk controller. There is a developers' release for PS/2 ESDI drives on invaders.dcrl.nd.edu in /pub/misc/linux. Certain kinds of SCSI controllers also work, I understand. Work is in progress to create a suitable version of the Slackware distribution. I'm afraid I don't have any further details; you could try asking Arindam Banerji <axb@defender.dcrl.nd.edu>. Linux is reported to run on 386 family based laptops, with X on most of them. For details of exactly which PC's, video cards, disk controllers, etc. work see the INFO-SHEET and the Hardware HOWTO [Q2.1 `Where can I get the HOWTOs and other documentation ?']. Linux will never run on a 286, because it uses task-switching and memory management facilities only found on 386 family processors. - ----------------------------------------------------------------------------- Question 1.4. What ports to other processors are there ? A project has been underway for around two years to port Linux to suitable 68000-series based systems such as Amigas and Ataris. This has now reached beta test quality, but still lacks networking support and an X server. There is a 680X0 channel on the Linux Activists mailserver [Q2.8 `What's this mailing list thing at niksula.hut.fi ?']. Work has just been started on a port to the PowerPC. Currently this will be based on the PowerMAC architecture. Again, don't post asking about it unless you have experience to offer, and don't hold your breath. Jim Paradis <paradis@sousa.amt.ako.dec.com> or <jrp@world.std.com> is working on a port to the 64-bit DEC AXP (the Alpha). This can currently boot from a floppy disk or disk image loaded into a ramdisk at boot time. Disk drivers are not yet available. Please email him of you have access to an ISA or EISA-based Alpha AXP and wish to contribute to the project, or have access to another class of Alpha and are willing to write drivers. Ralf Baechle is working on a port to the MIPS, initially for the R4600 on Deskstation Tyne machines. The Linux/MIPS FAQ is available on the WWW and in the MIPS port area on ftp.waldorf-gmbh.de in /pub/linux/mips. There is also a MIPS channel on the Linux Activists mailserver. Interested people may mail their questions and offers of assistance to <linux@waldorf-gmbh.de>. None of these ports will be capable of running Linux/386 binaries. - ----------------------------------------------------------------------------- Question 1.5. How much hard disk space does Linux need ? 10Mb for a very minimal installation, suitable for trying it out and not much else. You can squeeze a more complete installation including X Windows into 80Mb. Installating the whole of Slackware 1.2 takes around 200Mb, including some space for user files and spool areas. - ----------------------------------------------------------------------------- Question 1.6. Is Linux PD ? Copyrighted ? The Linux kernel copyright belongs to Linus Torvalds. He has placed it under the GNU General Public Licence, which basically means that you may freely copy, change and distribute it, but that you may not impose any restrictions on further distribution, and that you must make the source code available. Full details are in the file COPYING in the Linux kernel sources (probably in /usr/src/linux on your system). The licences of the utilities and programs which come with the installations vary; much of the code is from the GNU Project at the Free Software Foundation, and is also under the GPL. Note that discussion about the merits or otherwise of the GPL should be posted to gnu.misc.discuss and not to the comp.os.linux groups. =============================================================================== Section 2. Network sources and resources Q2.1 Where can I get the HOWTOs and other documentation ? Q2.2 Where should I look on the World Wide Web for Linux stuff ? Q2.3 What newsgroups are there for Linux ? Q2.4 How do I install Linux ? Q2.5 Where can I get Linux material by FTP ? Q2.6 I don't have FTP access. Where do I get Linux ? Q2.7 I don't have Usenet access. Where do I get information ? Q2.8 What's this mailing list thing at niksula.hut.fi ? Q2.9 Are the newsgroups archived anywhere ? - ----------------------------------------------------------------------------- Question 2.1. Where can I get the HOWTOs and other documentation ? Look in the following places, and on sites that mirror them. * ftp.funet.fi (128.214.6.100) : /pub/OS/Linux/doc/HOWTO * tsx-11.mit.edu (18.172.1.2) : /pub/linux/docs/HOWTO * sunsite.unc.edu (152.2.22.81) : /pub/Linux/docs/HOWTO For a complete list of Linux FTP sites see Q2.5 `Where can I get Linux material by FTP ?'. If you don't have access to FTP try using 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 is available in the file HOWTO.INDEX in the docs/HOWTO directory at the FTP sites, but here is a (possibly incomplete) list: Linux INFO-SHEET Linux META-FAQ BUPS HOWTO (regarding the Back UPS). Busmouse HOWTO CDROM HOWTO Distribution HOWTO DOSEMU HOWTO Ethernet HOWTO Ftape HOWTO Hardware HOWTO Installation HOWTO Japanese Extensions HOWTO Keystroke HOWTO Mail HOWTO MGR HOWTO NET-2 HOWTO News HOWTO Printing HOWTO SCSI HOWTO Sound HOWTO Term HOWTO Tips HOWTO UUCP HOWTO XFree86 HOWTO More of these documents are always in preparation. You should check in nearby directories on the FTP sites if you can't find the answer in one of the HOWTOs. There are also a few mini-HOWTOs on sunsite.unc.edu in the /pub/Linux/docs/HOWTO/mini directory. The HOWTO.INDEX also contains information on how to write a new HOWTO. The HOWTOs are coordinated by Matt Welsh, <mdw@sunsite.unc.edu>. The `books' produced by the Linux Documentation Project are available in /pub/Linux/docs/LDP on sunsite.unc.edu. Please read them if you are new to Unix and Linux. Here is a list of those released so far: * The Linux Documentation Project manifesto * Installation and Getting Started Guide * The Kernel Hacker's Guide * Network Administration Guide * Linux System Administrator's Guide - ----------------------------------------------------------------------------- Question 2.2. Where should I look on the World Wide Web for Linux stuff ? Matt Welsh maintains the Linux Documentation Project Home Page, at http://sunsite.unc.edu/mdw/linux.html. This page refers to all the FAQs and HOWTOs, both those which are available in HTML (WWW) format, like this FAQ, and those which aren't. - ----------------------------------------------------------------------------- Question 2.3. What newsgroups are there for Linux ? There are five international Usenet newsgroups devoted to Linux. comp.os.linux.announce is the moderated announcements group; you should read this if you intend to use Linux. Submissions for that group should be emailed to linux-announce@tc.cornell.edu. comp.os.linux.help, comp.os.linux.development, comp.os.linux.admin and comp.os.linux.misc are also worth reading -- you may find that many common problems are too recent to find in this FAQ but are answered in the newsgroups. Remember that since Linux is a Unix clone, most all of the material in comp.unix.* and comp.windows.x.* groups will be relevant. Apart from hardware considerations, and some obscure or very technical low-level issues, you'll find that these groups are the right place to start. Please read Q12.1 `You still haven't answered my question !' before posting, and make sure you post to the right newsgroup. Crossposting is rarely a good idea. See also Q2.7 `I don't have Usenet access. Where do I get information ?'. Other regional and local newsgroups also exist - you may find the traffic more manageable there. The French Linux newsgroup is fr.comp.os.linux; The German one is de.comp.os.linux. In Australia, try aus.computers.linux. There may well be Linux groups local to your institution or area - check there first. - ----------------------------------------------------------------------------- Question 2.4. How do I install Linux ? There are several pre-packaged releases of Linux available, including the MCC-Interim release, the TAMU release and the Slackware release. Each contains the software you need to run Linux, ready to install and use. The exact details of which software is included and how to install them vary from release to release. You should read the Installation HOWTO for more details on how to go about installing Slackware. If you prefer a small, clean distribution to one with everything but the kitchen sink you might like to try the MCC-Interim release. All of those releases are available via anonymous FTP from the Linux archive sites [Q2.5 `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 requirements (for example, better internationalisation support). - ----------------------------------------------------------------------------- Question 2.5. Where can I get Linux material by FTP ? There are three main archive sites for Linux: * ftp.funet.fi (Finland, 128.214.6.100) : /pub/OS/Linux * sunsite.unc.edu (US, 152.2.22.81) : /pub/Linux * tsx-11.mit.edu (US, 18.172.1.2) : /pub/linux The MCC-Interim release is available from ftp.mcc.ac.uk (US, 130.88.200.7) in /pub/linux; the TAMU release is available from net.tamu.edu (US, 128.194.177.1) in /pub/linux. The contents of these sites is mirrored (copied, usually approximately daily) by a number of other sites. Please use one close to you -- that will be faster for you and easier on the network. * src.doc.ic.ac.uk : /packages/Linux (UK) * sunacm.swan.ac.uk : /pub/Linux (UK) * ftp.ibp.fr : /pub/linux (France) * wuarchive.wustl.edu : /systems/linux (US) * mrcnext.cso.uiuc.edu : /pub/linux (US) * ftp.informatik.tu-muenchen.de : /pub/comp/os/linux (Germany) * ftp.ibr.cs.tu-bs.de : /pub/os/linux (Germany) * ftp.dfv.rwth-aachen.de : /pub/linux (Germany) * ftp.informatik.rwth-aachen.de : /pub/Linux (Germany) * bond.edu.au : /pub/OS/Linux (Australia) * monu1.cc.monash.edu.au : /pub/linux (Australia) * ftp.sun.ac.za : /pub/linux (South Africa) Not all of these mirror all of the other `source' sites, and some have material not available on the `source' sites. - ----------------------------------------------------------------------------- Question 2.6. I don't have FTP access. Where do I get Linux ? The easiest thing is probably to find a friend with FTP access. If there is a Linux users group near you they may be able to help. If you have a reasonably good email connection you could try the FTP-by-mail servers at ftpmail@decwrl.dec.com, ftpmail@doc.ic.ac.uk or ftp-mailer@informatik.tu-muenchen.de. Linux is also available via traditional mail on diskette, CD-ROM and tape. The Installation HOWTO, and the file /pub/Linux/docs/distributions on sunsite.unc.edu, contain information on these distributions. You could also try Zane Healy <healyzh@holonet.net>'s list of Linux BBS's, which is posted regularly (1st and 15th of each month) to comp.os.linux.announce and occasionally to the Fidonet and RIME UNIX echoes. - ----------------------------------------------------------------------------- Question 2.7. I don't have Usenet access. Where do I get information ? Digests of postings to the comp.os.linux.* groups are available by subscribing to the bidirectional gateway at linux-*-request@news-digests.mit.edu, where * is one of announce, development, help, misc or admin. You are strongly advised to subscribe to at least linux-announce-request@news-digests.mit.edu, as this carries important information and documentation about Linux. Please remember to use the -request addresses for your subscription and unsubscription messages; mail to the other address is posted to the newsgroup ! - ----------------------------------------------------------------------------- Question 2.8. What's this mailing list thing at niksula.hut.fi ? It's a multi-channel mailing list, mainly used by the developers of Linux to talk about technical issues and future developments. Most of the channels are not intended for new users to ask their questions on. The ANNOUNCE channel is a digest of postings to comp.os.linux.announce, for the benefit of those without Usenet access. However since niksula.hut.fi is slow and overloaded I'd recommend subscribing to the MIT digestifier instead [Q2.7 `I don't have Usenet access. Where do I get information ?']. There is also a NEWBIE channel where `no question is too stupid'; unfortunately it seems that few of the experienced users read that channel, probably because of all the `stupid' questions ! If you want to subscribe to one or more of the channels at the multi-channel list, send an empty mail message to linux-activists-request@niksula.hut.fi and you'll receive the instructions for operating the list subscription software. If you want to unsubscribe send a mail message like this From: you@domain.org To: linux-activists-request@niksula.hut.fi Subject: irrelevant X-Mn-Admin: leave CHANNEL to leave a channel called CHANNEL. Do *not* put an X-Mn-Key line in your message - that will cause it to be posted to the list. Note that you *must* remember to unsubscribe *before* you change your email address, as due to a design flaw in the list server it is virtually impossible to get yourself unsubscribed after such a change. - ----------------------------------------------------------------------------- Question 2.9. Are the newsgroups archived anywhere ? Yes. ftp.funet.fi and tsx-11.mit.edu contain archives of both comp.os.linux.announce and the old group comp.os.linux, in their Linux areas. The comp.os.linux.announce archives are mirrored from /usenet on src.doc.ic.ac.uk (which also contains another archive of comp.os.linux). =============================================================================== Section 3. Compatibility with other operating systems Q3.1 Can Linux coexist with DOS ? OS/2 ? 386BSD ? Minix ? Q3.2 How do I access files on my DOS partition or floppy ? Q3.3 Can I use my Stacked/DBLSPC/etc. DOS drive ? Q3.4 Can I access OS/2 HPFS partitions from Linux ? Q3.5 Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ? Q3.6 Can I run Microsoft Windows programs under Linux ? Q3.7 How can I boot Linux from OS/2's Boot Manager ? Q3.8 How can I share a swap partition between Linux and MS Windows ? - ----------------------------------------------------------------------------- Question 3.1. Can Linux coexist with DOS ? OS/2 ? 386BSD ? Minix ? Yes. Linux uses the standard PC partitioning scheme, so it can share your disk with other operating systems. Linux can read and write the files on your DOS and OS/2 FAT partitions and floppies using either the DOS filesystem type built into the kernel or mtools. There is a DOS emulator (look on tsx-11.mit.edu in /pub/linux/ALPHA/dosemu) which can run DOS itself and some (but not all) DOS applications. Linux can also access Minix and System V UFS filesystems, and can read (but not yet write) OS/2 HPFS and Amiga filesystems. - ----------------------------------------------------------------------------- Question 3.2. How do I access files on my DOS partition or floppy ? Use the DOS filesystem, i.e. type, for example: mkdir /dos mount -t msdos -o conv=text,umask=022,uid=100,gid=100 /dev/hda3 /dos If it's a floppy, don't forget to umount it before ejecting it ! You can use the conv=text/binary/auto, umask=nnn, uid=nnn and gid=nnn options to control the automatic line-ending conversion, permissions and ownerships of the files in the DOS filesystem as they appear under Linux. If you mount your DOS filesystem by putting it in your /etc/fstab you can record the options (comma-separated) there, instead of defaults. Alternatively you can use `mtools', available in both binary and source form on the FTP sites -- see Q2.5 `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. - ----------------------------------------------------------------------------- Question 3.3. Can I use my Stacked/DBLSPC/etc. DOS drive ? Not easily. You can access them from within the DOS emulator [Q3.1 `Can Linux coexist with DOS ? OS/2 ? 386BSD ? Minix ?'], but not as a normal filesystem under Linux or using mtools. - ----------------------------------------------------------------------------- Question 3.4. Can I access OS/2 HPFS partitions from Linux ? Yes, but it's only read-only at the moment. To use it you must compile a kernel with support for it enabled [Q7.6 `How do I upgrade/recompile my kernel ?']. Then you can mount it using the mount command, for example: mkdir /hpfs mount -t hpfs /dev/hda5 /hpfs - ----------------------------------------------------------------------------- Question 3.5. Can I access BSD FFS, SysV UFS, Mac, Amiga, etc filesystems ? I'm told that there is an alpha test read-only Amiga filesystem on sunsite.unc.edu, probably in /pub/Linux/kernel/misc-patches/ffs-patch. Work may well be progressing on upgrading this to read-write for the 680x0 Linux project. The 1.1.x alpha test kernel series contains support for the UFS filesystem used by System V and Coherent. There is no support for the rest of those yet; I have not heard of any recent work on providing some. - ----------------------------------------------------------------------------- Question 3.6. Can I run Microsoft Windows programs under Linux ? Not yet. There is a project, known as WINE, to build an MS Windows emulator for Linux, but it is not ready for users yet. Don't ask about it unless you think you can contribute; look out for the status reports in comp.emulators.ms-windows.wine. In the meantime if you need to run MS Windows programs your best bet is probably to reboot when you want to switch environments. LILO (the Linux bootloader) has the facility for a boot menu --- see its documentation for more details. - ----------------------------------------------------------------------------- Question 3.7. How can I boot Linux from OS/2's Boot Manager ? 1. Create a partition using OS/2's FDISK (Not Linux's fdisk). 2. Format the partition under OS/2, either with FAT or HPFS. This is so that OS/2 knows about the partition being formatted. 3. Add the partition to the Boot Manager. 4. Boot Linux, and create a filesystem on the partition using mkfs -t ext2 or mke2fs. At this point you may, if you like, use Linux's fdisk to change the partition type code of the new partition to type 83 (Linux Native) -- this may help some automated installation scripts find the right partition to use. 5. Install Linux on the partition. 6. Install LILO on the Linux partition -- NOT on the master boot record of the hard drive. This installs LILO as a second-stage boot loader on the Linux partition itself, to start up the kernel specified in the LILO config file. To do this you should put boot = /dev/hda2 (where /dev/hda2 is the *partition* you want to boot off) in your /etc/lilo/config or /etc/lilo.config file. 7. Make sure that it is the Boot Manager partition that is marked active, so that you can use Boot Manager to choose what to boot. - ----------------------------------------------------------------------------- Question 3.8. How can I share a swap partition between Linux and MS Windows ? See the Mini-HOWTO on the subject by H. Peter Anvin, <hpa@eecs.nwu.edu>. It is available on sunsite.unc.edu in /pub/Linux/docs. =============================================================================== Section 4. Linux's handling of filesystems, disks and drives Q4.1 How can I undelete files ? Q4.2 Is there a defragmenter for ext2fs etc. ? Q4.3 How do I format and create a filesystem on a floppy ? Q4.4 I get nasty messages about inodes, blocks, and the suchlike Q4.5 My swap area isn't working. Q4.6 How do I remove LILO so my system boots DOS again ? Q4.7 Why can't I use fdformat except as root ? Q4.8 Is there something like Stacker or Doublespace for Linux ? Q4.9 My ext2fs partitions are checked each time I reboot. Q4.10 I have a huge /proc/kcore ! Can I delete it ? Q4.11 My AHA1542C doesn't work with Linux. - ----------------------------------------------------------------------------- Question 4.1. How can I undelete files ? In general, this is very hard to do on Unices because of their multitasking nature. Undelete functionality for the ext2fs is being worked on, but don't hold your breath. There are a number of packages available that work by providing new commands for deletion and sometimes copying that move deleted files into a `wastebasket' directory instead; they can then be recovered until cleaned out automatically by background processing. Alternatively you can search the raw disk device which holds the filesystem in question. This is hard work, and you will need to be root to do this. - ----------------------------------------------------------------------------- Question 4.2. Is there a defragmenter for ext2fs etc. ? Yes. There is a Linux filesystem defragmenter for minix, old-style, ext2, and xia filesystems available on sunsite.unc.edu in system/Filesystems/defrag-0.6.tar.gz. Users of the ext2 filesystem can probably do without defrag since ext2 contains extra code to keep fragmentation reduced even in very full filesystems. - ----------------------------------------------------------------------------- Question 4.3. How do I format and create a filesystem on a floppy ? For a 3.5 inch high density floppy: fdformat /dev/fd0H1440 mkfs -t ext2 -m 0 /dev/fd0H1440 1440 For a 5.25 inch floppy use fd0h1200 and 1200 as appropriate. For the `B' drive use fd1 instead of fd0. Full details of which floppy devices do what can be found in the Linux Device List [Q2.1 `Where can I get the HOWTOs and other documentation ?']. If you don't have the fsutils package you'll have to run mke2fs instead of mkfs -t ext2. The -m 0 option tells mkfs.ext2 not to reserve any space on the disk for the superuser --- usually the last 10% is reserved for root. The first command low-level formats the floppy; the second creates an empty filesystem on it. After doing this you can mount the floppy like a hard disk partition and simply cp and mv files, etc. - ----------------------------------------------------------------------------- Question 4.4. I get nasty messages about inodes, blocks, and the suchlike You probably have a corrupted filesystem, probably caused by not shutting Linux down properly before turning off the power or resetting. You need to use a recent shutdown program to do this --- for example, the one included in the 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 fsutils package) will be able to repair your filesystem; if you're unlucky the filesystem is trashed and you'll have to reinitialise it with mkfs (or mke2fs, mkxfs etc.) it and restore from a backup. NB don't try to check a filesystem that's mounted read-write - this includes the root partition if you don't see VFS: mounted root ... read-only at boot time. - ----------------------------------------------------------------------------- Question 4.5. My swap area isn't working. When you boot (or enable swapping manually) you should see Adding Swap: NNNNk swap-space If you don't see any messages at all you are probably missing swapon -av (the command to enable swapping) in your /etc/rc or /etc/rc.local (the system startup scripts), or have forgotten to make the right entry in /etc/fstab: /dev/hda2 none swap sw for example. If you see Unable to find swap-space signature you have forgotten to run mkswap. See the manpage for details; it works much like mkfs. Check the Installation HOWTO for detailed instructions of how to set up a swap area. - ----------------------------------------------------------------------------- Question 4.6. How do I remove LILO so my system boots DOS again ? Using DOS (MS-DOS 5.0 or later, or OS/2), type FDISK /MBR. This will restore a standard MS-DOS Master Boot Record. If you have DR-DOS 6.0, go into FDISK in the normal way and then select the `Re-write Master Boot Record' option. If you don't have DOS 5 or DR-DOS you need to have the boot sector that LILO saved when you first installed it. You did keep that file, didn't you ? It's probably called boot.0301 or some such. Type dd if=boot.0301 of=/dev/hda bs=445 count=1 (or sda if you're using a SCSI disk). This may also wipe out your partition table, so beware ! If you're desperate, you could use dd if=/dev/zero of=/dev/hda bs=512 count=1 which will erase your partition table and boot sector completely: you can then reformat the disk using your favourite software; however this will render the contents of your disk inaccessible --- you'll lose it all unless you're an expert. Note that the DOS MBR boots whichever (single!) partition is flagged as `active'; you may need to use fdisk to set and clear the active flags on partitions appropriately. - ----------------------------------------------------------------------------- Question 4.7. Why can't I use fdformat except as root ? The system call to format a floppy may only be done as root, regardless of the permissions of /dev/fd0*. If you want any user to be able to format a floppy try getting the fdformat2 program; this works around the problems by being setuid to root. - ----------------------------------------------------------------------------- Question 4.8. Is there something like Stacker or Doublespace for Linux ? Currently none of the Linux filesystems can do compression in the filesystem. There is a transparently uncompressing C library, which is a drop-in replacement for the standard C library. It allows programs to read compressed (ie, GNU zipped) files as if they were not compressed. You install it, and then you can compress files using gzip and have programs still find them. Look on sunsite.unc.edu in /pub/Linux/libs. The author is Alain Knaff <Alain.Knaff@imag.fr>. There is a compressing block device driver that can provide filesystem-independant on the fly disk compression in the kernel. It is called `DouBle'. There is a source only distribution on sunsite.unc.edu in /pub/Linux/utils/compress; the auther is Jean-Marc Verbavatz <jmv@receptor.mgh.harvard.edu>. Note that since this compresses inodes (administrative information) and directories as well as file contents any corruption is quite likely to be serious. There is also a package available called tcx (Transparently Compressed Executables) which allows you to keep infrequently used executables compressed and only uncompress them temporarily while you use them. You'll find it on the Linux FTP sites [Q2.5 `Where can I get Linux material by FTP ?']; it was also announced in comp.os.linux.announce. Note - this is not the same as gzexe, which is an inferior implementation of the same concept. - ----------------------------------------------------------------------------- Question 4.9. My ext2fs partitions are checked each time I reboot. See Q9.11 `EXT2-fs: warning: mounting unchecked filesystem'. - ----------------------------------------------------------------------------- Question 4.10. I have a huge /proc/kcore ! Can I delete it ? None of the files in /proc are really there - they're all "pretend" files made up by the kernel, to give you information about the system, and don't take up any hard disk space. /proc/kcore is like an "alias" for the memory in your computer; its size is the same as the amount of RAM you have, and if you ask to read it as a file the kernel does memory reads. - ----------------------------------------------------------------------------- Question 4.11. 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. =============================================================================== Section 5. Porting, compiling and obtaining programs Q5.1 What is ld.so and where do I get it ? Q5.2 Has anyone ported / compiled / written XXX for Linux ? Q5.3 How do I port XXX to Linux ? Q5.4 Can I use code or a compiler compiled for a 486 on my 386 ? Q5.5 What does gcc -O6 do ? Q5.6 Where are <linux/*.h> and <asm/*.h> ? Q5.7 I get errors when I try to compile the kernel. Q5.8 How do I make a shared library ? Q5.9 How do I make my executables smaller ? - ----------------------------------------------------------------------------- Question 5.1. What is ld.so and where do I get it ? ld.so is the new dynamic library loader. Each binary using shared libraries used to have about 3K of start-up code to find and load the shared libraries. Now that code has been put in a special shared library, /lib/ld.so, where all binaries can look for it, so that it wastes less disk space, and can be upgraded more easily. It can be obtained from tsx-11.mit.edu in /pub/linux/packages/GCC and mirror sites thereof. The latest version at the time of writing is ld.so.1.4.4.tar.gz. - ----------------------------------------------------------------------------- Question 5.2. Has anyone ported / compiled / written XXX for Linux ? First, look in the Linux Software Map (LSM) --- it's in the docs directory on sunsite.unc.edu, and on the other FTP sties. Check the FTP sites (see Q2.5 `Where can I get Linux material by FTP ?') first --- search the find-ls or INDEX files for appropriate strings. Check the Linux Projects Map (LPM), on ftp.ix.de in /pub/Linux/docs/Projects-Map.gz. If you don't find anything, you could either download the sources to the program yourself and compile them -- see Q5.3 `How do I port XXX to Linux ?' -- or, if it's a large package which may require some porting, post a message to the newsgroup. If you compile a largeish program please upload it to one or more of the FTP sites and post a message to comp.os.linux.announce (submit your posting to <linux-announce@tc.cornell.edu>). If you're looking for an application-type program the chances are someone has already written a free verson. Try reading the FAQ in comp.sources.wanted for instructions on how to find sources. You should also check the Projects-FAQ, available in /pub/Linux/docs/faqs/Projects-FAQ on sunsite.unc.edu. - ----------------------------------------------------------------------------- Question 5.3. How do I port XXX to Linux ? In general Unix programs need very little porting. Simply follow the installation instructions. If you don't know and don't know how to find out the answers to some of the questions asked during or by the installation procedure you can guess, but this tends to produce buggy programs. In this case you're probably better off asking someone else to do the port. If you have a BSD-ish program you should try using -I/usr/include/bsd and - -lbsd on the appropriate parts of the compilation lines. - ----------------------------------------------------------------------------- Question 5.4. Can I use code or a compiler compiled for a 486 on my 386 ? Yes. The -m486 option to GCC, which is used to compile binaries for 486 machines, merely changes certain optimisations. This makes for slightly larger binaries which run somewhat faster on a 486. They still work fine on a 386, though, with little performance hit. GCC can be configured for a 386 or 486; the only difference is that configuring it for a 386 makes -m386 the default and configuring for a 486 makes -m486 the default; in either case these can be overriden on a per-compilation basis or by editing /usr/lib/gcc-lib/i*-linux/n.n.n/specs. GCC does not currently know how to do optimisation well for the 586, because Intel won't release the necessary information except under nondisclosure. Don't buy a Pentium or wait for people to reverse-engineer the required optimisations. - ----------------------------------------------------------------------------- Question 5.5. What does gcc -O6 do ? Currently the same as -O2; any number greater than 2 currently works just like 2. The Makefiles of newer kernels use -O2, and so should you. GCC 2.6 adds optimisation level -O3. However, GCC 2.6.0 and several of the following versions are known to have some problems with Linux, though these will hopefully be solved soon. In any case you should not use -O3 on a program until you're sure it doesn't create any problems. - ----------------------------------------------------------------------------- Question 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 and not real directories. If you don't have the kernel sources download them --- see Q7.6 `How do I upgrade/recompile my kernel ?'. Then use rm to remove any garbage, and ln to create the links: rm -rf /usr/include/linux /usr/include/asm ln -sf /usr/src/linux/include/linux /usr/include/linux ln -sf /usr/src/linux/include/asm /usr/include/asm - ----------------------------------------------------------------------------- Question 5.7. I get errors when I try to compile the kernel. Make sure that /usr/include/linux and /usr/include/asm aren't actual directories but instead symbolic links to /usr/src/linux/include/linux and /usr/src/linux/include/asm respectively. If necessary, delete them using rm and then use ln -s to make the links as in Q5.6 `Where are <linux/*.h> and <asm/*.h> ?'. Remember that when you apply a patch to the kernel you must use the -p0 or - -p1 option: otherwise the patch may be misapplied. See the manpage for patch for details. If you're using a kernel more recent than 1.1.44 you should find that there are new directories /usr/src/linux/include/asm-i386. The directory asm there should be removed, as should the directory asm. The symlinks Makefile target will make these be symbolic links to asm-i36 and arch/i386/boot respectively. The easiest way to make sure all this gets done is not to try to patch 1.1.44 to make 1.1.45, but to download linux-1.1.45.tar.gz instead. ld: unrecognised option `-qmagic' means you should get a newer linker, from tsx-11.mit.edu in /pub/linux/packages/GCC. - ----------------------------------------------------------------------------- Question 5.8. How do I make a shared library ? Get tools-n.nn.tar.gz from tsx-11.mit.edu, in /pub/linux/packages/GCC/src. It comes with documentation that will tell you what to do. - ----------------------------------------------------------------------------- Question 5.9. How do I make my executables smaller ? The most common cause of large executables is the -g compiler flag. This produces (as well as debugging information in the output file) a program which is statically linked, i.e. one which includes a copy of the C library instead of using a dynamically linked copy. Other things that are worth investigating are -O and -O2 which enable optimisation (check the GCC documentation) and -s which strips the symbol information from the resulting binary (making debugging totally impossible). You may wish to use -N on very small executables (less than 8K with the - -N), but you shouldn't do this unless you understand its performance implications, and definitely never with daemons. Using QMAGIC binaries also can reduce the size of binaries, especially small ones. Don't worry about this unless you know what QMAGIC is; Linux is moving to QMAGIC as a default. =============================================================================== The remainder of the FAQ is in the next part ... -----BEGIN PGP SIGNATURE----- Version: 2.6 iQCVAgUBLrPJhMMWjroj9a3bAQHWjQP/TH4lgiCnzdpl/guA/aExxwyZk/yuYRBi 6tZU8CNSnduoBucAR4MBhtsuXP6BuqxchkrQnvEJ+a+KTtK8dH6DV38Jlkln0Tk+ aOaFFOYPmdyu2TxU3TVPov5hDR/uTIfMwqyworscTrsIwVzSmaofDdcMP21gI7hZ 2u+8mjjdT5I= =Gtgy -----END PGP SIGNATURE----- -- Ian Jackson, at home. ijackson@nyx.cs.du.edu or iwj10@cus.cam.ac.uk +44 1223 575512 Escoerea on IRC. http://www.cl.cam.ac.uk/users/iwj10/ 2 Lexington Close, Cambridge, CB4 3LS, England. Urgent: iwj@cam-orl.co.uk