LILO, Linux Crash Rescue HOW-TO

Al Dev (Alavoor Vasudevan) alavoor@yahoo.com

1. Introduction

• 1.1 Tiny Floppy Linux
• 1.2 Preparation Tips
• 1.3 Quick Steps to recovery
• 1.4 Precautionary measures
• 1.5 Removing LILO
• 1.6 Common mistakes

2. Related URLs

3. Other Formats of this Document

• 3.1 Acrobat PDF format
• 3.2 Convert Linuxdoc to Docbook format
• 3.3 Convert to MS WinHelp format
• 3.4 Reading various formats

4. Copyright

1. Introduction

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.

1.1 Tiny Floppy 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 -

• The best Tomsrtbt
• Second best floppy linux MuLinux
• Trinux
• DLX
• FloppyFW
• Linux Router Proejct floppy
• Tiny Linux distributions
• TINYLinux

1.2 Preparation Tips

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

1.3 Quick Steps to recovery

Follow these steps to recover from LILO or system failures.

1. SCENE 1: If your system does not boot -

   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 partition by doing this -

   ---

   bash# fdisk /dev/hda
   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. Next try hda3, hda4, hda5, etc.. untill you find the root partition. Still not found in hda then repeat the above steps for other devices like hdb, hdc, hdd etc.. Also the /usr, /var, and /boot partition are needed as these are required to create new lilo configuration.

   In my case the root partition is /dev/hda4 which is used in the examples below:

   ---

   bash# mkdir /hda4
   bash# mount /dev/hda4 /hda4
   bash# cat /hda4/etc/fstab
           Read the output of fstab and mount partitions as per fstab file, see below -
   bash# mount /dev/hda5 /hda4/boot
   bash# mount /dev/hda6 /hda4/usr
   bash# mount /dev/hda7 /hda4/var
   bash# mount /dev/hda8 /hda4/opt
   bash# mount /dev/hda9 /hda4/root
   bash# mount /dev/hda10 /hda4/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 directory.

   Edit /etc/fstab (not /hda4/etc/fstab) and put (sample code given here) -

   ---

           /dev/hda4  /hda4           ext2 defaults 1 1
           /dev/hda5  /hda4/boot      ext2 defaults 1 1
           /dev/hda6  /hda4/usr       ext2 defaults 1 1
           /dev/hda7  /hda4/var       ext2 defaults 1 1
           /dev/hda8  /hda4/opt       ext2 defaults 1 1
           /dev/hda9  /hda4/root      ext2 defaults 1 1
           /dev/hda10 /hda4/home      ext2 defaults 1 1
           /dev/hda11 /hda4/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 /hda4/win95part
   bash# mount /hda4/win95part
           And repair the system using fsck or e2fsck commands.
   bash# man fsck
   bash# man e2fsck
   

   ---

2. SCENE 2: If LILO is not working..

   Follow scene 1 above, if that fails then follow these steps. Now you should have already mounted /hda4 and have created /etc/fstab file.

   ---

   bash# mount -a 
   bash# chroot /hda4 /sbin/lilo -q
   bash# man chroot
   bash# chroot /hda4 /sbin/lilo 
   

   ---

   Alternatively, you can directly use /sbin/lilo instead of chroot. The -r option of lilo actually does chroot. 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 /hda4
   

   ---

3. SCENE 3: If LILO is not working..

   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.

4. SCENE 4: If 1, 2 and 3 above fails and you do not have boot disk

   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

5. SCENE 5: This is the worst scenerio and hopefully you will never come to this 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  /hda4        ext2 defaults 1 1
                   /dev/hda11 /b1          vfat defaults 1 1
   bash$ mkdir /hda4; mount /hda4
   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   /hda4
   

   ---

   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.

1.4 Precautionary measures

You should take the following pre-cautionary measures to tackle the problems in future.

• You MUST make emergency boot disk from time to time and whenever you 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
  

  ---

• You must keep the tomsrtbt boot floppy handy. Visit http://www.toms.net/rb (see also Tiny Linux)

• You must keep the Yard rescue and boot floppy disk handy. Visit http://www.croftj.net/~fawcett/yard

• Backup /root and /boot directories. Boot the Tomsrtbt 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
  

  ---

1.5 Removing LILO

You can replace the boot sector with the DOS boot loader by issuing the DOS command at MS DOS prompt:

        FDISK  /MBR

See also LILO documentation on linux at /usr/doc/lilo* for other methods of uninstalling the LILO. And see also 'man lilo'.

1.6 Common mistakes

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

2. Related URLs

Visit following locators which are related to LILO, Rescue Linux, crash recovery -

• Mini Lilo HOWTO at http://www.linuxdoc.org/HOWTO/mini/LILO.html
• Bootdisk-HOWTO at http://www.metalab.unc.edu/LDP/HOWTO/Bootdisk-HOWTO/index.html

• Pre-made boot disks at http://www.linuxdoc.org/HOWTO/Bootdisk-HOWTO
• Tomsrtbt boot floppy disk http://www.toms.net/rb and (see also Tiny Linux)
• Yard rescue and boot floppy disk http://www.croftj.net/~fawcett/yard

• BootPrompt-HOWTO at http://www.linuxdoc.org/HOWTO/BootPrompt-HOWTO.html
• Multiboot with LILO mini HOWTO at http://www.linuxdoc.org/HOWTO/mini/Multiboot-with-LILO.html
• Linux+WinNT mini HOWTO at http://www.linuxdoc.org/HOWTO/mini/Linux+WinNT.html

• Linux goodies main site http://www.aldev.8m.com Mirror sites are at - http://aldev0.webjump.com, angelfire, geocities, virtualave, 50megs, theglobe, NBCi, Terrashare, Fortunecity, Freewebsites, Tripod, Spree, Escalix, Httpcity, Freeservers.
• Vim color text editor for C++, C http://metalab.unc.edu/LDP/HOWTO/Vim-HOWTO.html

3. Other Formats of this Document

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 -

• http://www.linuxdoc.org and click on HOWTOs and search for howto document name using CTRL+f or ALT+f within the web-browser.

You can also find this document at the following mirrors sites -

• http://www.caldera.com/LDP/HOWTO
• http://www.linux.ucla.edu/LDP
• http://www.cc.gatech.edu/linux/LDP
• http://www.redhat.com/mirrors/LDP
• Other mirror sites near you (network-address-wise) can be found at http://www.linuxdoc.org/mirrors.html select a site and go to directory /LDP/HOWTO/xxxxx-HOWTO.html

• You can get this HOWTO document as a single file tar ball in HTML, DVI, Postscript or SGML formats from - ftp://www.linuxdoc.org/pub/Linux/docs/HOWTO/other-formats/ and http://www.linuxdoc.org/docs.html#howto

• Plain text format is in: ftp://www.linuxdoc.org/pub/Linux/docs/HOWTO and http://www.linuxdoc.org/docs.html#howto

• Single HTML file format is in: http://www.linuxdoc.org/docs.html#howto

  Single HTML file can be created with command (see man sgml2html) - sgml2html -split 0 xxxxhowto.sgml

• Translations to other languages like French, German, Spanish, 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.

• sgml2html xxxxhowto.sgml (to generate html file)
• sgml2html -split 0 xxxxhowto.sgml (to generate a single page html file)
• sgml2rtf xxxxhowto.sgml (to generate RTF file)
• sgml2latex xxxxhowto.sgml (to generate latex file)

3.1 Acrobat PDF format

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 &

3.2 Convert Linuxdoc to Docbook format

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.

• Download ld2db program from http://www.dcs.gla.ac.uk/~rrt/docbook.html or from Al Dev site
• Download the cleanup_ld2db.pl perl script from from Al Dev site

        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

3.3 Convert to MS WinHelp format

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)

3.4 Reading various formats

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

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.

• Get ghostscript for Windows 95, OS/2, and for all OSes from http://www.cs.wisc.edu/~ghost

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.

4. Copyright

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.