LILO, Linux Crash Rescue HOW-TO
alavoor[AT?yahoo.comv10.6, 14 March 2002
This document discusses methods to recover from Linux system failures. Various reasons for linux system failures can be - LILO is destroyed, or linux fails to boot, or Master Boot Record (MBR) is damaged or linux fails to boot when another operating system like Windows NT is installed which erases LILO or MBR.
(The latest version of this document is
at
http://www.milkywaygalaxy.freeservers.com. You may
want to check there for changes).
You cannot avoid accidents and if it happens to linux systems then it may damage the master boot record (MBR) or LILO (Linux boot Loader). There may be cases where linux will not boot due to hard disk failures. The LILO may also fail if you accidentally re-partition the hard disk or you install another additional operating system like Windows 98/NT on the linux computer.
This document gives you some ideas, tips and quick guide to recover fast without wading through hundreds of pages of documentation on LILO or Linux.
To recover any Windows 95/NT/2000, OS/2, BeOS or Linux box you may need the tiny linux which fits on a single floppy disk. See the list of tiny floppy linux given below -
Tomsrtbt *
*
* Trinux *
* DLX *
* FloppyFW *
* Linux Router Proejct floppy *
* Tiny Linux distributions *
* TINYLinux *
It is a good idea to backup the important system files like /etc/fstab, /etc/lilo.conf after you login using Tomsrtbt floppy in next section. This can be very handy during crash situation or something happens to system files.
bash# cp /etc/fstab /etc/fstab.orig bash# cp /etc/lilo.conf /etc/lilo.conf.orig bash# cp /etc/hosts /etc/hosts.orig bash# cp /etc/hosts.allow /etc/hosts.allow.orig bash# cp /etc/hosts.deny /etc/hosts.deny.orig bash# cp /etc/inetd.conf /etc/inetd.conf.orig bash# cp /etc/inittab /etc/inittab.orig bash# cp /etc/networks /etc/networks.orig
Follow these steps to recover from LILO or system failures.
Get the tomsrtbt floppy
http://www.toms.net/rb or !MuLinux? floppy
(see also
Tiny Linux).
Boot with tomsrtbt floppy
Use fdisk to find the partitions. Try to recognise the
root and boot partition. Watch out, you may be having the /boot files on
the root partition itself.
The Linux's root partition has the following directories bin, boot, etc, usr.
And the Linux's boot partition has these directories: vmlinuz, boot.b, chain.b, map.
To find out root partition do this :
bash# fdisk /dev/hda Command (m for help): m (Gives you help on commands) Command (m for help): p (Gives you list of partitons) Command (m for help): q bash# mkdir /test bash# mount /dev/hda1 /test bash# ls /test You should see root-partition list like this - bin fd lib mnt proc sbin usr boot dev etc home lost+found opt root tmp var
If this is not a root partition, then try the next partition /dev/hda2. Keep trying hda3, hda4, hda5, etc.. untill you find the root partition. If you do not find root partition in hda device then repeat the above steps for other hard disk devices like hdb, hdc, hdd etc..
Next, you should find the /boot, /usr and /var partitions. The disk locations of these partitions are needed to create the new lilo configuration.
In my case the root partition is /dev/hda4 which is used in the examples below:
bash# mkdir /rootpart bash# mount /dev/hda4 /rootpart bash# cat /rootpart/etc/fstab Read the output of fstab and mount partitions as per fstab file, see below - bash# mount /dev/hda5 /rootpart/boot bash# mount /dev/hda6 /rootpart/usr bash# mount /dev/hda7 /rootpart/var bash# mount /dev/hda8 /rootpart/opt bash# mount /dev/hda9 /rootpart/root bash# mount /dev/hda10 /rootpart/home
In my case, as per fstab file hda5 was boot, hda6 was usr, hda7 was var, hda8 was opt, hda9 was root, hda10 was home and hda11 was windows95 (FAT16 partition).
Edit /etc/fstab (not /rootpart/etc/fstab) and put (sample code given here) -
/dev/hda4 /rootpart ext2 defaults 1 1 /dev/hda5 /rootpart/boot ext2 defaults 1 1 /dev/hda6 /rootpart/usr ext2 defaults 1 1 /dev/hda7 /rootpart/var ext2 defaults 1 1 /dev/hda8 /rootpart/opt ext2 defaults 1 1 /dev/hda9 /rootpart/root ext2 defaults 1 1 /dev/hda10 /rootpart/home ext2 defaults 1 1 /dev/hda11 /rootpart/win95part vfat defaults 1 1 On my computer hda4 contains the linux root partition, hda5 had boot partition and hda11 has windows 95 vfat system. bash# mkdir /rootpart/win95part bash# mount /rootpart/win95part And repair the problem partitions using fsck or e2fsck commands. bash# man fsck bash# man e2fsck
#
Follow scene 1 above, if that fails then follow these steps. After executing steps in scene 1 above, you should have already mounted /rootpart and have created /etc/fstab file.
Note: It is very important to note how chroot command works below. The /sbin/lilo file which chroot uses is actually located in /rootpart/sbin/lilo and NOT in /sbin!! Hence, do not get confused.
bash# mount -a bash# chroot /rootpart /sbin/lilo -q bash# man chroot bash# chroot /rootpart /sbin/lilo
Note: New users of chroot will be confused. If chroot command complains that it cannot find /boot/map file then it actually means it that it cannot find /rootpart/boot/map. Because you gave /rootpart as the first argument to chroot and all references are with respect to /rootpart.
Alternatively, you can directly use /sbin/lilo instead of chroot. The
It is very strongly recommended that you use chroot, instead of lilo -r, as it is more convenient and can catch errors more easily.
bash# man lilo bash# /sbin/lilo -r /rootpart
#
If scene 1 and 2 failes, then
if you made the boot disk with 'mkbootdisk' (during install or
by using 'man mkbootdisk'), boot with it and repair your partitions.
The mkbootdisk is in mkbootdisk*.rpm package, you must install this.
Or get boot disks for Linux/NT/Windows/DOS/Mac are at
http://www.bootdisk.com
Other option is - get a hold of installation Linux-CDROM. Just about every Linux distribution
provides a image of a rescue disk on their CD. Under Linux use
"dd if=/cdrom/disks/rescue of=/dev/fd0" to create a rescue floppy disk. Under DOS
use rawrite.exe (included on Linux CD) and then do "rawrite image-name a:".
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If you have another computer running linux, then login as root and do -
Note: If you compile your own kernel as a bzImage (for instance, bzImage-2.4.4), then you should create a hard link to vmlinuz-2.4.4 as follows (note the the z in name vmlinuz and it is not vmlinux). If you do not do this then mkbootdisk command may fail.
bash# cd /boot bash# ls -l vmlinuz* bash# ln /boot/bzImage-2.4.4 /boot/vmlinuz-2.4.4
Now that you have bzImage and vmlinuz, give these commands -
bash$ man mkbootdisk bash# cp /etc/lilo.conf /etc/lilo-original.conf
Edit the /etc/lilo.conf and put the root partition name as you obtained in 'scene 1' above and insert a blank floppy and give -
bash$ mkbootdisk --device /dev/fd0 2.2.12-20
The mkbootdisk is in mkbootdisk*.rpm package, you must install this. Make sure you move the /etc/lilo-original.conf back to /etc/lilo.conf!! And then take this floppy and goto scene 3
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stage. Scenes from 1 to 4 will take care of majority of cases. But just in case, all the above scenes 1, 2, 3 and 4 fail then -
Step 1: Boot tomsrtbt (see Tiny Linux) and mount the partitions and backup the root partition to another partition having disk space with comamnds -
Edit /etc/fstab and put (sample code given here, you may have to change as per your disk layout) - /dev/hda4 /rootpart ext2 defaults 1 1 /dev/hda11 /b1 vfat defaults 1 1 bash$ mkdir /rootpart; mount /rootpart bash$ mkdir /b1; mount /b1 bash$ cd / bash$ df And see that there is enough disk space in /b1 to tar up the root partition bash$ tar cvf /b1/root-hda4.tar /rootpart
Step 2: Insert Linux cdrom, reboot and install the redhat linux on /dev/hda4 (but DO NOT install any extra packages, you just need to install only the root, boot systems and LILO manager that is, a very bare minimum). This will also install the LILO on hard disk. Boot linux now and login as root and do -
bash$ man mkbootdisk bash# cp /etc/lilo.conf /etc/lilo-original.conf
Note: You MUST remember to copy back lilo-original.conf to lilo.conf!! Edit the /etc/lilo.conf and put the root partition name as you obtained in 'scene 1' above and insert a blank floppy and give -
bash$ mkbootdisk --device /dev/fd0 2.2.12-20 bash# cp /etc/lilo-original.conf /etc/lilo.conf
Test this boot floppy to see that this works and then restore back the all the files which you backedup using tar on /b1/root-hda4.tar as in step 1 above.
#
You should take the following pre-cautionary measures to tackle the problems in future.
make changes to the partition. Insert a blank floppy and do this -
bash$ man mkbootdisk The mkbootdisk is in mkbootdisk*.rpm package, you must install this. bash$ mkbootdisk --help bash$ mkbootdisk --device /dev/fd0 2.2.12-20
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You should also print this out and paste it on the computer box.
bash$ su - root bash# man fdisk bash# fdisk -l /dev/sda > partition_table_backup.txt
Very helpful if you need to repartition the hard disk. From the printout, you would know where your partition starts. During recovery, after repatitioning and formating you can restore data from the backup.
*
http://www.toms.net/rb
(see also
Tiny Linux)
*
http://www.linuxlots.com/fawcett/yard
*
floppy (see also Tiny Linux) and then
bash# vi /etc/fstab And put these lines - /dev/hda1 /a1 vfat defaults 1 1 /dev/hdb1 /b1 vfat defaults 1 1 In my case hda1 had the linux root partition '/' bash# cd / bash# tar cvf /b1/linux-root-partition-hda1.tar a1 bash# tar cvf /b1/linux-boot-partition-hda1.tar a1/boot
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You can replace the boot sector with the DOS boot loader by issuing the DOS command at MS DOS prompt:
FDISK /MBR
where MBR stands for "Master Boot Record".
See also LILO documentation on linux at /usr/doc/lilo* for other methods of uninstalling the LILO. And see also 'man lilo'.
After making changes to /etc/lilo.conf you MUST run lilo to make changes to go in effect. It is a very common mistake committed by newusers. Type -
bash# lilo -v -v -v
Visit following locators which are related to LILO, Rescue Linux, crash recovery -
http://www.linuxdoc.org/HOWTO/mini/LILO.html
*
http://www.metalab.unc.edu/LDP/HOWTO/Bootdisk-HOWTO/index.html
*
http://www.linuxdoc.org/HOWTO/Bootdisk-HOWTO
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http://www.toms.net/rb
and (see also
Tiny Linux)
*
http://www.linuxlots.com/fawcett/yard
*
http://www.linuxdoc.org/HOWTO/!BootPrompt-HOWTO.html
*
http://www.linuxdoc.org/HOWTO/mini/Multiboot-with-LILO.html
*
http://www.linuxdoc.org/HOWTO/mini/Linux+WinNT.html
*
http://www.milkywaygalaxy.freeservers.com
Mirror sites are at -
http://aldev0.webjump.com,
angelfire,
geocities,
virtualave,
50megs,
theglobe,
NBCi,
Terrashare,
Fortunecity,
Freewebsites,
Tripod,
Spree,
Escalix,
Httpcity,
Freeservers.
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http://metalab.unc.edu/LDP/HOWTO/Vim-HOWTO.html
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This document is published in 14 different formats namely - DVI, Postscript, Latex, Adobe Acrobat PDF, LyX, GNU-info, HTML, RTF(Rich Text Format), Plain-text, Unix man pages, single HTML file, SGML (Linuxdoc format), SGML (Docbook format), MS !WinHelp? format.
This howto document is located at -
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http://www.linuxdoc.org and click on HOWTOs and search
for howto document name using CTRL+f or ALT+f within the web-browser.
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You can also find this document at the following mirrors sites -
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http://www.caldera.com/LDP/HOWTO
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http://www.linux.ucla.edu/LDP
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http://www.cc.gatech.edu/linux/LDP
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http://www.redhat.com/mirrors/LDP
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http://www.linuxdoc.org/mirrors.html
select a site and go to directory /LDP/HOWTO/xxxxx-HOWTO.html
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Postscript or SGML formats from -
ftp://www.linuxdoc.org/pub/Linux/docs/HOWTO/other-formats/
and
http://www.linuxdoc.org/docs.html#howto
*
ftp://www.linuxdoc.org/pub/Linux/docs/HOWTO
and
http://www.linuxdoc.org/docs.html#howto
*
http://www.linuxdoc.org/docs.html#howto
Single HTML file can be created with command (see man sgml2html) -
sgml2html -split 0 xxxxhowto.sgml
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Chinese, Japanese are in
ftp://www.linuxdoc.org/pub/Linux/docs/HOWTO
and
http://www.linuxdoc.org/docs.html#howto
Any help from you to translate to other languages is welcome.
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The document is written using a tool called "SGML-Tools" which can be got from -
http://www.sgmltools.org
Compiling the source you will get the following commands like
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PDF file can be generated from postscript file using
either acrobat distill or Ghostscript.
And postscript file is generated
from DVI which in turn is generated from !LaTex? file.
You can download distill software from
http://www.adobe.com. Given below
is a sample session:
bash$ man sgml2latex bash$ sgml2latex filename.sgml bash$ man dvips bash$ dvips -o filename.ps filename.dvi bash$ distill filename.ps bash$ man ghostscript bash$ man ps2pdf bash$ ps2pdf input.ps output.pdf bash$ acroread output.pdf &
Or you can use Ghostscript command ps2pdf. ps2pdf is a work-alike for nearly all the functionality of Adobe's Acrobat Distiller product: it converts !PostScript files to Portable Document Format (PDF) files. ps2pdf is implemented as a very small command script (batch file) that invokes Ghostscript, selecting a special "output device" called pdfwrite. In order to use ps2pdf, the pdfwrite device must be included in the makefile when Ghostscript was compiled; see the documentation on building Ghostscript for details.
This document is written in linuxdoc SGML format. The Docbook SGML format supercedes the linuxdoc format and has lot more features than linuxdoc. The linuxdoc is very simple and is easy to use. To convert linuxdoc SGML file to Docbook SGML use the program ld2db.sh and some perl scripts. The ld2db output is not 100% clean and you need to use the clean_ld2db.pl perl script. You may need to manually correct few lines in the document.
http://www.dcs.gla.ac.uk/rrt/docbook.html
or from
Milkyway Galaxy site
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from Milkyway Galaxy site *
The ld2db.sh is not 100% clean, you will get lots of errors when you run
bash$ ld2db.sh file-linuxdoc.sgml db.sgml bash$ cleanup.pl db.sgml > db_clean.sgml bash$ gvim db_clean.sgml bash$ docbook2html db.sgml
And you may have to manually edit some of the minor errors after running the perl script. For e.g. you may need to put closing tag < /Para> for each < Listitem>
You can convert the SGML howto document to Microsoft Windows Help file, first convert the sgml to html using:
bash$ sgml2html xxxxhowto.sgml (to generate html file) bash$ sgml2html -split 0 xxxxhowto.sgml (to generate a single page html file)
Then use the tool
You can also use sgml2rtf and then use the RTF files for generating winhelp files.
In order to view the document in dvi format, use the xdvi program. The xdvi program is located in tetex-xdvi*.rpm package in Redhat Linux which can be located through !ControlPanel | Applications | Publishing | TeX menu buttons. To read dvi document give the command -
xdvi -geometry 80x90 howto.dvi man xdvi
And resize the window with mouse. To navigate use Arrow keys, Page Up, Page Down keys, also you can use 'f', 'd', 'u', 'c', 'l', 'r', 'p', 'n' letter keys to move up, down, center, next page, previous page etc. To turn off expert menu press 'x'.
You can read postscript file using the program 'gv' (ghostview) or 'ghostscript'. The ghostscript program is in ghostscript*.rpm package and gv program is in gv*.rpm package in Redhat Linux which can be located through !ControlPanel | Applications | Graphics menu buttons. The gv program is much more user friendly than ghostscript. Also ghostscript and gv are available on other platforms like OS/2, Windows 95 and NT, you view this document even on those platforms.
all OSes from
http://www.cs.wisc.edu/ghost
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To read postscript document give the command -
gv howto.ps ghostscript howto.ps
You can read HTML format document using Netscape Navigator, Microsoft Internet explorer, Redhat Baron Web browser or any of the 10 other web browsers.
You can read the latex, LyX output using LyX a X-Windows front end to latex.
Copyright policy is GNU/GPL as per LDP (Linux Documentation project). LDP is a GNU/GPL project. Additional requests are that you retain the author's name, email address and this copyright notice on all the copies. If you make any changes or additions to this document then you please intimate all the authors of this document. Brand names mentioned in this document are property of their respective owners.
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