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Xref: bloom-picayune.mit.edu comp.os.linux:18318 news.answers:4214 Path: bloom-picayune.mit.edu!enterpoop.mit.edu!usc!zaphod.mps.ohio-state.edu!cs.utexas.edu!uunet!mcsun!julienas!corton!geocub!labri.greco-prog.fr!corsini From: corsini@labri.greco-prog.fr Newsgroups: comp.os.linux,news.answers Subject: Linux Frequently Asked Questions 2/4 [monthly posted] Summary: Linux, a small and free unix for 386-AT computers. Message-ID: <PART2_722647309@geocub.greco-prog.fr> Date: 24 Nov 92 23:22:02 GMT Expires: Sat, 19 Dec 1992 23:00:00 GMT References: <PART1_722647309@geocub.greco-prog.fr> Sender: corsini@greco-prog.fr (Marc-Michel CORSINI) Reply-To: linux@numero6.greco-prog.fr Followup-To: poster Organization: Greco Prog. CNRS & LaBRI, Bordeaux France Lines: 1132 Approved: news-answers-request@MIT.Edu Supersedes: <PART2_722567366@geocub.greco-prog.fr> Archive-name: linux-faq/part2 Last-Modified: 92/11/20 Version: 1.11 ********************************************************* * * * Answers to Frequently asked questions about Linux * * * ********************************************************* This post contains Part 2 of the Linux FAQ (4 parts). It must be read *after* the first part. ================================8<=====8<============================== CONTENTS (of this part) IV. LINUX and DOS (part2) V. SOME CLASSICAL PROBLEMS (part2) VI. MISCELLANEOUS HINTS (part2) VII. MORE HINTS (part2) ===================================8<====>8============================ IV. LINUX and DOS ================= *** This section is co-written by Mark Komarinski, A. V. Le Blanc and *** MM. Corsini. The official maintainer is Mark, if you have *any* *** questions, critics \ldots, mail him at komarimf@craft.camp.clarkson.edu *** Last Update 15.11.92 QUESTION: Is is possible to access DOS from Linux? ANSWER: Yes. (1) The mtools package allows you to access DOS files; it emulates the DOS commands CD, COPY, DEL, DIR, TYPE, and others. (2) Since approximately version 0.97 of the kernel, you can mount DOS file systems as part of your Linux directory tree, providing you have an appropriate mount command. (3) A DOS emulator is in alpha test, which will allow some DOS programs and utilities to run under Linux. QUESTION: Why use mtools if you can just mount a drive? ANSWER: Mtools is good if you want to do something quickly. For example, if you want to get directories on a bunch of floppies. The mount procedure requires you to mount the drive, get a directory, then umount it. Mtools lets you get the directory with one command. (Dirk Hohndel:) Mtools is really fast when copying disks. I mount the SLS directory of my SUN to my linux box and use mcopy to get the files on the disks. 3 times faster than using xcopy under DOS QUESTION: How do I get the mtools package set up correctly? ANSWER: The mtools package is available in source form on most Linux ftp sites. The most recent version (As of Sept 1992) is mtools.n2, and there are linked binaries and library (.a) files available as well (for example, as part of MCC interim releases of Linux). In the n2 release of mtools, there is only one executable binary which works differently depending on its name: you can create hard or symbolic links to it named mcopy, mdel, mdir, mtype, etc; this is how the Makefile in version n2 of mtools does it, and it saves several hundred kilobytes of disk space. Finally, you need the correct information in the file /etc/mtools, which is described below. QUESTION: What is the format of the file /etc/mtools? ANSWER: A complete entry in the file /etc/mtools contains the following fields: drive, device, fat, cylinders, heads, sectors, offset. Two examples of entries from /etc/mtools are A /dev/fd0 12 80 2 15 C /dev/hda1 16 0 0 0 which defines the DOS disk A: as accessible through the device /dev/fd0, having a 12-bit FAT, 80 cylinders, 2 heads, and 15 sectors per track; DOS disk C: is accessible through the device /dev/hda1, has a 16-bit FAT, and its geometry is simply that of the hard disk where it lives. The last three numbers can be 0 if you wish; this allows mtools to try to figure out the disk's geometry itself, and perhaps to fail. A 12-bit FAT is common for floppies, but may occur in small hard disk partitions. A 16-bit FAT is common for hard disks. This is an extract of my /etc/mtools file: A /dev/fd0 12 0 0 0 # 3.5 1.4 Meg (autodetect) B /dev/fd1 12 0 0 0 # 5.25 1.2 Meg (autodetect) C /dev/hda1 16 0 0 0 # 1st partition of my Disk QUESTION: Where can I find out more about mtools? ANSWER: There are two detailed README files in the mtools.n2 distribu- tion. These files treat compiling and using mtools. There is a file README.mtools which treats only using mtools, which is a part of the MCC interim version of Linux. QUESTION: How do I use the DOS file system? ANSWER: The DOS file system is part of the kernel. If you have a kernel of level 97.1 or above, and an appropriate mount command, type mount -t msdos [-o conv=text] /dev/hda1 /dos to mount the partition /dev/hda1 as an MS/DOS file system on the directory /dos. You'll need a recent mount command, from at least release 97 or later of the root disk. Recent mount commands also accept the options conv=binary|text|auto (default is binary) to specify that text end-of-lines in DOS files are to be converted to UNIX end-of-lines (by omitting carriage return characters) in no cases (binary) or in all cases (text) or in cases that don't have 'well- known binary extensions' (e.g., .EXE or .COM) (auto). QUESTION: I want to use the DOS file system with either conv=binary or conv=auto, but I want to convert text files from DOS to UNIX format, or from UNIX to DOS format. ANSWER: Use the utility todos/fromdos which comes as part of the dosfs package, currently (Sept 92) in released in version 8, or use the flip utility by Rahul Dhesi. QUESTION: Where can I find out more about the DOS file system? ANSWER: There is a README file included in dosfs.XX.tar.Z (the current value of XX is 8), and an abbreviated version of this in the MCC interim package. QUESTION: Whenever I use mtools to read a 720K in an 1.44MB drive, I get a long sequence of reset-floppy-errors, why? ANSWER: This is what happens if you use the /dev/PS0 device (b 2 28), to read a 720k floppy you have to use another device, for example /dev/fd0. Or you may use the setfdprm utility. QUESTION: This sounds me like a chicken and eggs problem, how can I install the mtools package at the very beginning. ANSWER: You have to use the rawrite stuff or the mount procedure. QUESTION: Could someone explain how to use rawrite? ANSWER: Well, rawrite is a DOS util, which write sequential sector of a formatted disk/floppy. When a floppy has been rawritten, you can (under Linux) untar it (use x, v, z and f flags). As an example: a) under Dos use rawrite rawrite source: kermit.z destination: a b) boot under Linux, and perform a tar tar zxvf /dev/fd0 tar zxvp < /dev/fd0 You DO NOT NEED TO MOUNT a rawritten disk QUESTION: What is as86.tar.Z ? ANSWER: It's the port of Bruce Evans' minix assembler, you need it to be able to recompile Linux at your convenience. In fact this is ONLY used for boot/setup.S and boot/bootsect.S they create 80x86 REAL mode code. QUESTION: Turbo (Microsoft) Assembler won't compile the Linux boot code. In fact, some of the opcodes in these files look completely unfamiliar. Why? ANSWER: The Linux boot codes are written in Bruce Evans' minix assembler, which has the same opcodes as the original minix assembler ported to linux get as86.tar.Z Anyway there are a few differences between these and normal DOS assemblers. QUESTION: What about the dos emulator (dosemu)? ANSWER: Dosemu is in alpha testing now, so it is very unstable and crashes easily. Some programs (such as earlier versions of Turbo Pascal; TP 5.5 too) seem to work fine, but other programs such as dir /p will crash the emulator. Look in your favorite FTP site for the dosemu kit. V. SOME CLASSICAL PROBLEMS ========================== QUESTION: While running du I get "Kernel panic: free_inode: bit already cleared". Also, du produces a ENOENT error for all the files in certain of my directories. What's going on? ANSWER: These are both consistent with a bad file-system. That's relatively easy to produce by not syncing before rebooting, as linux usually has 1.5MB of buffer space held in memory (unless you have <=4M RAM, in which case the buffers are only about 0.5MB). Also linux doesn't do anything special about the bit-map blocks, and as they are used often, those are the thing most likely to be in memory. If you reboot, and they haven't been written to disk ... Just do an fsck on the device, the -a flag might repair it otherwise, the only thing to do is to reinstall the filesystem from the Images. A sync is done only every 30 seconds normally (standard unix practice), so do one by hand (some people think you should do 3 syncs after each other, but that's superstition), or by logging out from the startup-shell, which automatically syncs the system. Unmounting a filesystem also syncs it (but of course you can never unmount root). Another (sad) possibility is that you have bad blocks on your disk. Not very probable, as they would have to be in the inode-tables, just a couple of blocks in size. Again there aren't programs available to read a disk for bad sectors and put them in some kind of "bad-sector-file". On IDE drives this is no problem (bad sectors are automatically mapped away). QUESTION: How can I partition my hard-drive to use Linux? ANSWER: There are (at least) two ways to answer this. The easy way is probably to use a program which will do it for you, such as the MS-DOS fdisk, Minix fdisk, Xenix/Unix fdisk, or programs such as edpart.exe or part.exe. With the 0.95a distribution, there is pfdisk. To use it have a look in the beginner's guide written by I. Reid, it's clear and it had worked for me like a charm. In the mcc-interim release ther is also fdisk, which runs under Linux and manages partition tables (it also creates extended partitions). On the other hand, you can use a disk editor and modify the contents of the partition table directly. This has been already done, and an extensive explanatory note can be found in the mailing-list archives (25th Jan. 92). You must also edit the bpb on the Dos partition you are shrinking, otherwise Dos will step on Linux. BTW It might be useful to set three (3) separated partitions for Linux, one for the root, another one for the usr and a third one for swap, as an illustration, my root partition is 10Meg, the usr is 22Meg and instead of a swap partition I use a swap file. As an experience I have used MS-DOS fdisk to partition my two hd and got no peculiar difficulties. You can, as long as you stay within the 64MB per filesystem limit (Minix-filesystem limitation), have swap, root, etc, ... all on there. QUESTION: I heard something about repartition a hard disk without deleting everything on it, any clue? ANSWER: It's not a program but a partition procedure which requires a) a partitionning program b) a sector editor The procedure itself can be found (at least) in digest#132 Vol2. QUESTION: What must I do to mkfs a floppy? ANSWER: blocks are of size 1K so 1.44 floppy is 1440 blocks. The floppy has to be formatted before this will work (e.g., fdformat can do this from within Linux). QUESTION: I have some trouble with tar/untar; any clue ? ANSWER: The tar provided on .96 and latter is Pax (don't know for .98) which do not accept the z flag. You can download the GNU tar at tsx-11 in /pub/linux/binaries/usr.bin QUESTION: I can do this as root but not as non-root, is it a bug? ANSWER: Except for an early make utility, the problem is caused by an incorrect permission flag. The most common problems are about /tmp which should be 1777 and /dev/ttys? which might be 766. So as root do chmod 1777 /tmp ; chmod 766 /dev/ttys? QUESTION: "du" reports twice the size showed with "ls -l", is it a bug? ANSWER: No it is not, the report is 512 bytes multiple (due to POSIX requirement), for KB you just add the -k flag. You can add a du function in your .profile which does this automatically, something like du(){ /usr/bin/du -k $* } QUESTION: Sometimes, I get "mount can't open lock file"; what does this means? ANSWER: This can happened for two reasons: A) You try to mount something as non-root. In that case you can either retry as root, or set the setuid bit to mount as follows: - be sure that mount belongs to root, if not do 'chown root /bin/mount' - set the setuid bit with 'chmod u+s /bin/mount' BTW you have to do the same with umount (in order to be able to unmount) Remark that it is NOT safe to allow anyone to perform mount/umount, you should rather write a small utility that will make any user able to mount/unmount a (and ONLY a) *floppy* B) You are root. mount wants to open /etc/mtab and /etc/mtab~ - the first one for reading, the second as lock file. If there is already a mtab~ remove it. This can happen if you used once gnuemacs on mtab. To forbid that case, just add the following entry in your /etc/rc file: rm -f /etc/mtab QUESTION: When I try "mount /dev/hd?? /user", I get error 2. ANSWER: Be sure, that your mount point /user does exist; if not perform a "mkdir /user". BTW the error numbering is explained in /usr/include/errno.h QUESTION: Since I have upgrade my Linux kernel, ps won't work anymore, why? ANSWER: Each time you upgrade (or re-compile the kernel), you should perform a 'ps -U' (-U is for update the /etc/psdatabase). Every time you boot a new kernel you have to do a 'ps U' to update the psdatabase, after doing this you can remove the system file or do a make clean. The pathname to the system binary [/usr/src/linux/tools/system] is stored in the psdatabase, so you only have to specify it if you have moved your source tree or if you are creating the psdatabase for the first time. The psdatabase is always '/etc/psdatabase'. The system file is obtained in compiling the linux kernel (which I assume is rooted in /usr/src/linux). BTW: sometimes a patch makes recompiling ps necessary. Sometimes you even have to patch the ps-suite. QUESTION: Since Linux 0.96b I have a lot of core file all over my disk. How can I sweep them away ? ANSWER: Use the following command find / -name core -exec rm {} \; BTW: think twice before using this command, there might be a John Core user on your system; this command will erase his mail :) (Rick) If you never want to see another core file, put this line into your /etc/rc file: ulimit -c 0 provided you are a bash user :)) QUESTION: I can only log-in as "root", is it normal ? ANSWER: No, add "rm -f /etc/nologin" in your /etc/rc.local file VI. MISCELLANEOUS HINTS ======================= *** This section is maintained by Matt Welsh (mdw@tc.cornell.edu). Please *** mail me if you have any changes/updates/questions. Thanks -mdw Special gcc information are located in section IX. A special section is devoted to it since it's *the* compiler of Linux. I have subsectionned this part in 3 subsections: Misc/Device Major-Minor/Serial Information. VI.A. Misc information ~~~~~~~~~~~~~~~~~~~~~~ QUESTION: It seems that $#@! ported on linux don't run correctly, what do I do about reporting bugs? ANSWER: (Matt Welsh) It's possible that either the program itself has a bug or that Linux has a problem that this program brings out. :) But first check that the size of the file(s) corresponds that of the files(s) on the FTP sites where it's available. If they're different, either you downloaded them incorrectly (i.e. you forgot to turn on "bin") or whoever put them on the FTP site uploaded them incorrectly. If that's not the problem, then post to comp.os.linux asking about the program, to verify that it is a bug. PLEASE: when posting possible "bug reports" include all error and output information from running/compiling the program. Just saying "it doesn't work" isn't very helpful. Also mention your specific setup, Linux version, GCC version, etc. Some of these things depend on running under certain versions and you may have missed that information. Note that my "ml-linux-bugs@dg-rtp.dg.com" bug reporting list has been phased out. It turns out that Linux has so few bugs, most of which are resolved on the newsgroup or through Linus before I can accumulate them and post. :) In short: if there's a bug in Linux or in Linux-ported software, it will usually be fixed in the next patchlevel or version. QUESTION: Has $#@! been ported to Linux? ANSWER: First check out the FTP sites and read the monthly INFO-SHEET, as well as the new "Linux News" and the META-FAQ's (all of which are either available on the FTP sites and/or posted to the newsgroup as they're written). Also check out the "Linux Project Registry" (posted to the newsgroup and on the FTP sites) which lists ongoing/current Linux projects. Also look in the "old" Linux digests and mailing-list archives, kept on tsx-11.mit.edu and nic.funet.fi. Also, see if there's a GNU(*) version of the program you're looking for (which are available everywhere). Since Linux uses GCC as its native compiler, most GNU software ports directly to Linux without problems. If all else fails, ask on the mailing list or newsgroup if the program is ported and where it's available. (*) GNU stands for GNU's Not Unix, which (besides being a recursive acronym) is a project started by the Free Software Foundation (the FSF) to write a freely distributable version of Unix. The GNU kernel is named HURD, and is based on Mach. It is currently being written, and is not yet done. Many of the GNU utilities, however, are completed and are much more functional than the original Unix utilities. Since they are freely available, Linux is using them as well. QUESTION: I've ported $#@! to Linux, what should i do to add it in the standard distribution? ANSWER: (Matt Welsh) First read the previous Q/A, then talk to the maintainers of the various releases (MCC interim, SLS, and so on) about including your program with those releases. The best way to make programs available to the rest of the world is to upload it to one of the Linux FTP sites (such as tsx-11.mit.edu:/pub/incoming or sunsite.unc.edu:/pub/Linux/Incoming). BTW Whenever you submit binaries, please think that if you link them with shared libraries, this might cause problems for those who (gasp!) don't have the shared libraries installed. You can either link them using -static, and if someone wants to build a shared version on their own machine they can get the sources (which you should also make available) and build it themself. Or else provide the shared lib. QUESTION: I want to port $#@! to Linux, what are the flags? ANSWER: Recall that Linux implements subset of SYSV and POSIX, so -DUSG and -DPOSIX work in general. NOTE1: SIGBUS is not there, and can be safely commented out in general. NOTE2: see section related to GCC, in the third part of this FAQ, for more details. VI.B. Major/Minor device number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *** This section is maintained by Rick Miller, any comments, *** suggestions, remarks should be mailed to him at <rick@ee.uwm.edu> *** Last Update: 17 Nov 1992 16:00:20 GMT QUESTION: What are the device minor/major numbers? ANSWER: Here's a preliminary listing from Rick Miller <rick@ee.uwm.edu>: The Linux Device List published by rick@ee.uwm.edu (Rick Miller, Linux Device Registrar) Many thanks to richard@stat.tamu.edu and Jim Winstead Jr. Majors: 0. Unnamed . (unknown) .... for proc-fs, NFS clients, etc. 1. Memory .. (character) .. ram, mem, kmem, null, port, zero 2. Floppy .. (block) ...... fd[01][dhDH]{360,720,1200,1440} or fd[01] 3. Hard Disk (block) ...... hd[ab] or hd[ab][1-?] (Extended>4) 4. Tty ..... (character) .. tty{0,1-8,63,64-127,128-?} or ttys{0-3,1-4} 5. tty ..... (character) .. special tty: owner of its calling process. 6. Lp ...... (character) .. lp[0-2] or par[0-2] 7. Tape .... (block) ...... t[0-?] (reserved for Non-SCSI tape drives) 8. Scsi Disk (block) ...... sd[0-?] or sd[0-?][0-?] 9. Scsi Tape (block) ...... st[0-?] 10. Bus Mouse (character) .. bm, psaux (mouse) 11. CD-ROM .. (block) ...... scd Breakdown of minors by Majors: ------------------------------ 0. Unnamed . (unknown) .... for proc-fs, NFS clients, etc. Minors??? (Not yet implemented???) 1. Memory .. (character) .. ram, mem, kmem, null, port, zero 0. /dev/ram 1. (block): RAM-Disk (character): /dev/mem 2. /dev/kmem 3. /dev/null 4. /dev/port 5. /dev/zero 2. Floppy .. (block) ...... fd[01][dhDH]{360,720,1200,1440} or fd[01] Minors are [drive + [4 * type]] where drive 0-3 == A:-D: (floppy) and type is: 0: Autodetect 4: 720k in 3.5" 1: 360k in 5.25" 1.2M 5: 360k in 5.25" 1.2M 2: 1.2M in 5.25" 1.2M 6. 720k in 5.25" 1.2M 3: 360k in 3.5" 7. 1.44M in 3.5" 1.44 3. Hard Disk (block) ...... hd[ab] or hd[ab][1-?] (Extended>4) 0. First HD (/dev/hda), whole drive including Master Boot Record. 1-4. Partitions on the first HD. 5-8. Logical partitions within an extended partition on first HD. 64. Second HD (/dev/hdb), whole drive including Master Boot Record. 65-68. Partitions on the second HD. 69-72. Logical partitions within an extended partition on second HD. Notes: BE *VERY* CAREFUL WITH /dev/hda AND /dev/hdb!! These two devices signify the *entire* *drive*, not just one partition. The only things that use /dev/hda or /dev/hdb are things that need to read/change the partition table (like fdisk). The names of the hard drives are not the same as under Minix. Linux doesn't order anything. It perceives partitions in the order in which they appear in the partition table. Thus, /dev/hd?1 may be physically after /dev/hd?2. 4. Tty ..... (character) .. tty{0,1-8,63,64-127,128-?} or ttys{0-3,1-4} 0. /dev/tty0: This is the currently active Virtual Console. 1-63. /dev/tty#: Specific virtual consoles. 64-127. /dev/ttys*: Serial ports. 128-191. /dev/pty[??]: PTY Masters. 192-255. /dev/pty[??]: PTY Slaves. Notes: There are several constants set in the kernel sources which can be changed to compile a more customized kernel. They're found in [/usr/src]/linux/include/linux/tty.h: NR_CONSOLES The number of virtual consoles. NR_SERIALS The number of serial lines. NR_PTYS The number of pty's. 5. tty ..... (character) .. special tty: owner of its calling process. 0. /dev/tty: the tty that owns the process calling it. 6. Lp ...... (character) .. lp[0-2] or par[0-2] 1-3. Parallel (printer) ports. (Increasable in include/linux/lp.h) Notes: The number of line printers is defined by LP_NO which is found in [/usr/src]/linux/include/lp.h. 7. Tape .... (block) ...... t[0-?] (reserved for Non-SCSI tape drives) This one's just getting started. No minor numbers are yet assigned. It's not even in the source code. 8. Scsi Disk (block) ...... sd[0-?] or sd[0-?][0-?] Minors numbers are [[16 * HostID] + partition] Notes: The maximum number of SCSI drives is defined by MAX_SD found in [/usr/src]/linux/kernel/blk_drv/scsi/sd.h. Additional note (Eric Youngdale): In the new scsi drivers there is no set maximum number of scsi disks, hence no need to fiddle with sd.h Everything autoconfigures as the system boots. 9. Scsi Tape (block) ...... st[0-?] Quoting from the source-code: void do_st_request(void) { panic("There is no st driver.\n\r"); } Notes: For future reference, the maximum number of SCSI tapes is defined by MAX_ST which is found in [/usr/src]/linux/kernel/blk_drv/scsi/st.h. (E. Youngdale) The same is true here. There is no longer any need to set MAX_ST, and it would be a bad thing to actually try. Even though there is a MAX_SR in the cdrom code in the 0.98.5 kernel, the new scsi code effectively eliminates this as well. 10. Bus Mouse (character) .. bm, psaux (mouse) (If I recall, X Windows requires that /dev/mouse be linked to one of these...) 0. /dev/bm: (Logitec?) bus mouse 1. /dev/psaux: PS/2 mouse port 2. /dev/bm: MicroSoft bus mouse 3. /dev/bm: ATI XL bus mouse 11. CD-ROM .. (block) ...... scd Minors? From: eric@tantalus.nrl.navy.mil (Eric Youngdale) Date: 17 Nov 92 16:25:40 GMT > For the cdrom, the minors are just the devices > themselves. If you have one cdrom drive, the minor is 0. If you > have two, then the minors are 0 and 1. Not much more to it than that. > For a SCSI tape, each physical device has two minor numbers > that are associated with it. If you have two tape drives, then > minors 0 and 1 will refer to the first and second drives and the > tape will be rewound when the device is closed. Minor numbers 128 > and 129 (i.e. 128+n) also refer to the first and second physical > drives, but the tape will not be rewound after closing the device. > If you have one tape, you could create the devices with the > following commands: > mknod /dev/rmt0 c 9 0 > mknod /dev/nrmt0 c 9 128 NOTE: all the numbers given are in decimal form (the one you can see if you perform ls -l on /dev). QUESTION: Could some one give me indication about the meaning of the IRQ's ? ANSWER: (alawrenc@sobeco.com:) Standard IRQ's : IRQ 0 - Timer IRQ 1 - Keyboard IRQ 2 - Slave 8259 (AT) IRQ 3 - COM 2 / COM 4 IRQ 4 - COM 1 / COM 3 IRQ 5 - (XT) Hard Disk, (AT) LPT2 IRQ 6 - Floppy Disk IRQ 7 - LPT1 AT only IRQ 8 - Real Time Clock IRQ 9 - Re-direct to IRQ 2 IRQ 10 - Not Defined IRQ 11 - Not Defined IRQ 12 - Not Defined IRQ 13 - 80287 IRQ 14 - Hard Disk (AT) IRQ 15 - Not Defined QUESTION: (Chuck Boyer) Could some one clear up the devices meaning? ANSWER: (Jim Winstead Jr) >port This allows programs to access the hardware ports directly. Not something you generally mess around with much. >ptyp0-3 >ptypa...tty These are the pseudo-tty 'master' devices. Each pty connection uses a slave-master set of tty devices. >tty0... tty[1-8] are the virtual consoles associated with Alt-F[1-8]. tty0 is the current virtual console (so writing something to tty0 goes to the current vc). >tty64 I've figured out is the modem connection Yes, that would correspond to COM1 under DOS. However, the tty64 name is obsolete - ttys[1-4] should be used instead. >ttyp0... >ttypa... These are the pseudo-tty 'slave' devices. >ttys1... These are the serial devices. ttys1 corresponds to COM1 under DOS, ttys2 corresponds to COM2, etc. VI.C Special Serial ~~~~~~~~~~~~~~~~~~~ *** This section is maintained by Jim Gifford *** (jgifford@attmail,world.std}.com *** Last update October 1992. Douglas E. Quale: This has come up a couple of times already (including the case of serial mice as well), but for the record stty acts on stdin not stdout. Old stty's (from V7 through BSD4.3) used stdout, but this is suboptimal and doesn't conform to POSIX. The GNU stty you are likely using on Linux uses stdin, as does the stty distributed with BSD Networking Release 2. (Also, ``stty -a'' is more informative about possible parameters, although it's pretty hard for me to remember what 90% of that stuff does without refering to the man page.) Jim Gifford: However, there are a few older (of mysterious origin) stty's that work on stdout(I have one myself!) QUESTION: Is there a list somewhere where I can get help with serial communications under Linux? ANSWER: (Jim Gifford -- jgifford@world.std.com) There is a list for the discussion of serial communications under Linux. It is for problems, drivers, new developments, etc... with the Linux serial devices. The list is: linux-serial@stolaf.edu To join, send mail to linux-serial-request@stolaf.edu I hope that this list will prove beneficial to the improvement of Linux. This list is maintained by Michael K. Johnson as linux-serial-request@stolaf.edu QUESTION: When I run kermit under Linux, I get "Warning, Read access to lock directory denied". What am I doing wrong? ANSWER: Nothing, you just need to create /usr/spool/uucp (kermit 4.6?) or /usr/spool/locks (this is for the kermit5A), which is where kermit like to lock files. QUESTION: What are the major, minor numbers for the serial ports under linux? ANSWER: Major 4, Minor : 64 /dev/ttys0 - com1 65 /dev/ttys1 - com2 66 /dev/ttys2 - com3 67 /dev/ttys3 - com4 QUESTION: can anyone give me a sample /etc/inittab entry for login from a pc attached to serial line /dev/ttys2? ANSWER: "Humberto speaking :), updated by Rick Miller" First set up the modem to turn off echo and enable auto answer, I do this in kermit by connecting to the modem and typing "ate0s0=1" followed by enter (w/o quotes). Then setup inittab to spawn getty on the modem ttys2:vt100:/etc/getty -m 1200 ttys2 (Replace "vt100" with the name of the /etc/termcap entry for the terminal type you will use, or use "dumb" if you don't have one.) Then it should work. Some modems can be permanently set to disable echo and set auto answer, see your manual. Jim Weigand says: disable all messages. This will prevent getty from hanging up your modem. Set For: ATE0 No echo ATQ1 No messages ATS0=2 Answer 2nd ring ATS7=60 1 minute to answer (shorter if 2400 baud) You can use kermit to set these. Do an AT&W to save for power-up. Michael K. Johnson says: If you would rather not save these commands as defaults to come up on power-up, perhaps because you want to use your current modem settings under a DOS communications package, you can also shove these command out ttys? from /etc/rc (or /etc/rc.local) using the command: echo "<modem_settings>" > /dev/ttys? QUESTION: How do I set parameters like parity for serial login? ANSWER: Use stty and redirect input from the serial line. ex: stty parodd < /dev/ttys2 which gives ttys2 odd parity. type stty -a to get an idea of possible parameters. Or 'man stty' as well :) VII. MORE HINTS =============== This part try to keep track of the different information that appeared in comp.os.linux and on the list since beginning of March. I tried to update it for KERENL_VERSION, so there might be some mistakes. Moreover take care to use the correct library and include stuff, and the ad-hoc gcc you use !!! QUESTION: How can I backup my Hd under Linux ? ANSWER: I know at least two ways. One possibility is tar and mtools, another possibility is the diskbackup/diskrestore of Diamano Bolla (digest37 vol. #2) which saves big hd to floppies using the stdin/stdout. These utilities have been uploaded to the major sites in file disksplit.tar.Z. An example usage (Roger Binns) is: tar cvf - bin dev usr etc .. | compress | diskbackup and to restore: diskrestore | uncompress | tar xvf - BTW: if you are on Ethernet you could send your files via tar..|rsh (tar...) or even via NFS to a host which is regularly backed up ! QUESTION: Where is 'which' ? ANSWER: It depends on the sh you are running: in bash 'type -path' in tcsh it's a builtin for rc you can try the following (untested by me) script from Kevin Brown: #!/bin/sh for i in `echo $PATH | sed 's/:/ /g'` ; do for j in ""$@" ; do if test -x "$i/$j" ; then echo "$i/$j" fi done done QUESTION: How to use setterm: for the novice? ANSWER:The setterm utility provides access to most of Virtual Consoles (VCs) functionality. You can set your screen up to blank at 10 minutes using: setterm -blank 10 You can set colors, and clear the screen. For a full list of commands, just type "setterm" with no arguments. There are a few tricks with the screen dumper can really make VCs go a long way. Here are a few of the common ones that I use: setterm dump Dumps the contents of the current VC to screen.dump (in the current dir). setterm dump 4 Dumps the contents of VC 4 to screen.dump setterm -file mydumpfile -dump 4 Dump the contents of VC 4 to the file mydumpfile setterm -file /dev/tty0 -dump 4 Dumps the contents of VC 4 to the current VC. setterm -file /dev/tty4 -dump Dumps the contents of the current VC to VC 4. setterm -file /dev/ttys1 -dump Dumps the contents of the current VC to the serial port. Handy if you are logged on and want to paste a screen full without having to resort to doing a file transfer. setterm -file mydumpfile -append 4 Appends to instead of overwriting the dump file. Useful if you have several screens you wish to concatenate. QUESTION: I've tried clear/reset which exist on most of unix but it doesn't work, have I missed something? ANSWER: setterm -clear or setterm -reset will solve your missing. For clear, you can also write a small script (which use the cl: part of /etc/termcap wrt your TERM), or use bash where ctrl-l will do it for you. QUESTION: I know there are VC, but where is the setterm stuff? ANSWER: It's in the current distribution (i.e. on the images), the source can be found in virtcons.tar.Z at nic. QUESTION: I know there are shared libraries; does there exist an easy way to check an executable for sharing ? ANSWER: (Josh Yelon & HJ Lu) (J.Y.) An executable which shares a library is linked with an (ordinary, non-shared) "stub" version of the library. One of the first thing this stub does (when the executable is run) is to ask the kernel to load the (big) "shared version" of the library (which is usually named /lib/lib.XX.XX) The upshot of this is that in the code for the stub (part of the executable), is the string "/lib/lib.XX.XX"; which can be searched by using 'strings' or 'grep'. (HJ. L.) if you have gcc2.11a or later the shared image is changed to /lib/libxxxx_vyy_zzz. And you should better use nm to find "__shared_lib" (nm failed on stripped executable). You can also write a function for "file", which can even check the version number .... (Claude Morin:) There exists at tsx-11 ldd.tar.Z If you follow the instructions, you will be able to type "ldd <executable>" to List the Dynamic Dependencies of the executables. In other words 'ldd' prints the name of the shared libraries needed by the executable, nothing appears for static one. QUESTION: What is the rdev program provided in the images? ANSWER: It's a program from Werner Almesberger of ETH. With no argument it prints the first line of /etc/mtab. With one argument, a boot-image, it prints the device configured as the root device, and with two arguments, a boot image and a device, it sets the device as default root in the specified image. QUESTION: How to start Linux from drive B? ANSWER: There is a DOS utility called boot_b.exe (look at DOS ftp). Another simple way is to open the box and invert the cables. QUESTION: The program boot_b works fine /but/ once the first disk is read the system go back to the first drive, any hints? ANSWER: Yes, change the bootimage in just the same way that you change it to boot on the hard drive, execept that the major/minor pair is different. All these information are in the file INSTALL-0.10. Remember that if you use a sun or other endian machine, you will need to reverse the byte order when you run the filter program (also in the same file). QUESTION: How can I get Linux to boot directly from the harddisk? ANSWER: (Rick) The best option right now is LILO version ALPHA.6. It has been generally agreed that the days of using "shoelace" are at an end. QUESTION: I use shoelace, but I want to change my root partition, what is the process to get rid of it? ANSWER: With Norton utility you can put back a standard boot sector. Another possibility is to restore the old boot sector (the one you should have backup *before* installing shoelace). QUESTION: Sometimes, when I want to remove a directory, I get an error message, is it a (known) bug? ANSWER: No, There is no bug at all, you probaly have another shell on another VC whose working directory is either the one you try to remove, either a subdirectory of it. QUESTION: I'm looking for init, getty, login, passwd stuff, where can I find them? ANSWER: You should find it in shadow.tar.Z (only sources), at least at tsx in the usr.bin directory. Many people have reported some troubles with the *OLD* shadow-passwd (shadow-bin.tar.Z and shadow-src.tar.Z, so do not use them anymore); an alternative might be the mcc-interim which contains standard passwd binary. There is also the Peter Orbaek's admutil-1.?.tar.Z and poeigl-1.?.tar.Z which contains source for shutdown, su, chsh, passwd and a system V init compatible. QUESTION: How can I setup a user account other than root ? ANSWER: You can either use the adduser program, either do it manually. In the later case, you have to: a) edit /etc/passwd as root and add a line of the following format: user:passwd:uid:gid:user name:home directory:login shell user is the login name; uid is the numeric user id, it should be unique; gid is the numeric group id, this number should correspond to an entry in /etc/group. The passwd field should be left blank 'cause it is stored in an encrypted form [to set this field just use the passwd program]. example faq::200:5:Marc-Michel:/home/faq:/bin/sh b) Still as root, you shoud now create the home directory and set the correct ownership. mkdir /home/faq chown faq /home/faq chgrp 5 /home/faq QUESTION: I've been trying to get Linux to run on my [3/4]86 box. It can't even boot. Any suggestions? ANSWER: The most common error/problem is writing the bootimage to a low density disk. It fits, but the bootstrap code will only recognize high density disk. So try to format explicitely disk as high density: - for 3.5", 'format a: /n:18 /t:80 ' - for 5.25", 'format a: /n:15 /t:80 ' QUESTION: Does there exist games, languages (other than C), and anything which make the system more friendly? ANSWER: Yes, among other things there are rogue and yahtzee; TeX; Prolog, Perl.. but in general, if you want some extra tool port it to Linux this is also a good beta-testing exercice. QUESTION: Whenever I use uemacs 3.1X on a symlink, the symlink does not exist anymore, why? ANSWER: (Tristram Mabbs) Since ue3.10, uemacs uses 'safe save' mode, writing the file to a temporary and moving it OVER the original. In the process, this deletes the original. To prevent this just add the following in your emacs '.rc' file: set $ssave FALSE QUESTION: Uemacs doesn't work anymore with 0.95a, whenever I want to save a file; what can I do? ANSWER: ^S and ^Q are used for flow control. One solution is ^X^W followed by the filename, or M-X save-file, try also ^XS it could work for some version (not mine). Another possibility, if you have download the stty.tar.Z file, is to do stty -IXON before you first use uemacs (this can be included in your .profile). And the last is to recompile the Peter Orbaek init-1.2 package. QUESTION: I have an SVGA, but Linux detect an EGAc/EGAm; is it normal? ANSWER: (Jim Winstead) This is correct actually. You have an EGA+ card (SVGA) with a Color/Mono monitor. The only four possibilties are EGAc, EGAm, *MDA and *CGA (according to the code in kernel/chr_drv/console.c). The true test, if Linux detects your video card, is if you press <RETURN> at the "Press <RETURN> to see SVGA- ..." boot-time message. If you have a SVGA recognized card, it will ask you to choose a screen size. If not detected, the default is 80x50 mode. BTW if you have no SVGA, press the <space> and you are in 80x25 mode. If you have dowloaded the kernel, you can automatically skip this query at boot-time if you set the SVGA_MODE variable in the main Makefile before compiling a new bootimage. QUESTION: How can I change the keyboard repeat rate? ANSWER: (Michael K Johnson) In boot/setup.S there are the lines: ! set the keyboard repeat rate to max mov ax,#0x0305 mov bx,0x0000 int 0x16 If you don't want to change the repeat rate at all, just comment out these lines. If you want something in the middle, change the mov bx,0x000 by mov bx,0x??yy where ??yy is determined by (Ralf Brown's interrupt list) bh= delay value (0x00 = 250ms to 0x03= 1000ms (one sec)) this is the delay before the repeat is performed bl= repeat rate (0x00 =30/sec to 0x1f=2/sec; 0x0c=10/sec [default]) QUESTION: I compiled fdformat.c and ran it on 1.44Mb and 1.2Mb, the results are unreadable, any clue? ANSWER: (M. Pereckas) fdformat only low-level formats the disk. to use the fdformatted disk with DOS filesystem, run mformat on the disk. Mformat writes DOS filesystem information but is unable to low-format :). In order to put a Linux filesystem on a (low)formatted disk you have to mkfs it. QUESTION: Is it possible to disable the 3-fingers salute (ctrl-alt-del) ? ANSWER: Yes, in kernel/sys.c you can read the following: /* * this indicates wether you can reboot with ctrl-alt-del: the deault is yes */ static int C_A_D = 1; there is also a small utility written by Linus in digest242 vol#2 QUESTION: Could some one explain the information provided at boot-time? ANSWER: (Jim Winstead Jr) > serial port at 0x03f8 is a 16450 > serial port at 0x02f8 is a 16450 (what's that the uart chip?) Right, the last number should either be 8250, 16450, 16550, or 16550a, and on the two 16550 models, it will report that FIFO's have been disable (16550) or enabled (16550a). > 8 virtual consoles (that's how many alt-F's I can get going? > but only F1-4 actually work) You can get sessions running on Alt-F[1-8], but the 'standard' /etc/inittab only runs getty/login on Alt-F[1-4]. You can start sessions on the other consoles by using 'doshell' or adding lines to /etc/inittab. > 4 pty's (are these the consoles F1-4?) No, those are 'pseudo' ttys, which programs like MGR use to simulate tty connections. That's probably a gross over-simplification, but it gives you the general idea, I think. :) > p_init: lp1 exists (0) (is that the (l)ine (p)rinter?) Right. QUESTION: What is the meaning of files ended by .T.Z (or .taz) ? ANSWER: The suffix Z is for compressed files (to uncompress them use the command `uncompress file.Z`). The suffix T indicates a "tar file" the usual suffix is tar but, the 14 chars filename limit of the Minix filesystem makes it cumbersome to use .tar.Z (to untar a file ended by .T, use the command `tar options file.T` (see the man page for more details). For the .taz file, change them as .T.Z and go-ahead. QUESTION: I have upgraded the kernel from XX to YY (XX > YY), however the login screen still says YY. ANSWER: Just change the message in one of these files: /etc/issue and /etc/motd. The former contains the message before the login, the later is the one after you are logged in. QUESTION: What is doshell good for ? ANSWER: It's an old program provided in the early Linux version (0.12) when the getty was not already there, it spawns a shell on any tty's. (Mattew Gream): I do this quite often ( getty on tty1, 2, 3 and my rc.local spawns a shell on tty4 as follows '/usr/bin/doshell /dev/tty4 /bin/tcsh &' QUESTION: I don't have the kernel sources, how can I change the keyboard language? ANSWER: You can use the fixkbd program written by laurentj@hpgnse2.grenoble.hp.com. Its purpose is to fix the keyboard map used in your kernel image. It works more or less a la "rootdev" (or rdev). -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ # LaBRI | # # 351 cours de la Liberation | e-mail: corsini@labri.greco-prog.fr # # 33405 Talence Cedex | # # | # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- There will be some sig, once our local net will be reliable. Right now I rather stay anonymous.