2. Introduction.

Linux boot disks are useful in a number of situations, such as:

• Testing a new kernel.
• Recovering from a disk failure -- anything from a lost boot sector to a disk head crash.
• Fixing a disabled system. A minor mistake as root can leave your system unusable, and you may have to boot from diskette to fix it.
• Upgrading critical system files, such as libc.so.

There are several ways of obtaining boot disks:

• Use one from a distribution such as Slackware. This will at least allow you to boot.
• Use a rescue package to set up disks designed to be used as rescue disks.
• Learn what is required for each of the types of disk to operate, then build your own.

Some people choose the last option so they can do it themselves. That way, if something breaks, they can work out what to do to fix it. Plus it's a great way to learn about how a Linux system works.

This document assumes some basic familiarity with Linux system administration concepts. For example, you should know about directories, filesystems and floppy diskettes. You should know how to use mount and df. You should know what /etc/passwd and fstab files are for and what they look like. You should know that most of the commands in this HOWTO should be run as root.

Constructing your own bootdisk from scratch can be complicated. If you haven't read the Linux FAQ and related documents, such as the Linux Installation HOWTO and the Linux Install Guide, you should not be trying to build boot diskettes. If you just need a working bootdisk for emergencies, it is much easier to download a prefabricated one. See Appendix Pre-made bootdisks, below, for where to find these.