Chapter 4. Boot Methods

This chapter describes some techniques for booting your Linux system. Depending on your hardware and whether you want to run any other operating systems, you can configure the system to boot Linux automatically or to provide a choice between several operating systems. Choosing between operating systems is generally referred to as dual booting, but you can actually boot more than two.

Once your Linux system is installed, rebooting the system is generally pretty straightforward. But with the wide variety of hardware and software in use, there are many possibilities for configuring your boot process. The most common choices are:

• Boot Linux from a floppy or bootable CD, leaving any other operating system to boot from the hard drive.

• Use the Linux Loader, LILO.^[1] This is the traditional method of booting and lets you boot both Linux and other operating systems.

  ^[1] LILO is a boot program for i386-architecture machines. On the Alpha, the equivalent boot program is called MILO (Mini Loader), and on the SPARC, it is SILO.

• Use the Grand Unified Bootloader (GRUB), the GNU graphical boot loader and command shell. Like LILO, GRUB lets you boot both Linux and other operating systems. For now, GRUB runs only on i386-based systems.

• Run Loadlin, which is an MS-DOS program that boots Linux from within DOS.

Other boot managers that can load Linux are available, but we don't discuss them here. We also won't talk further about booting from a floppy or CD, except to say that whatever method you choose for booting, be sure to have a working boot disk available for emergency use. In particular, don't experiment with the files and options in this chapter unless you have a boot disk, because any error could leave you unable to boot from the hard disk. Note, though, that one of the advantages of using GRUB is that if there is a problem booting from the menu, it drops you down to the command-line interface so you can enter commands directly and try to recover. Also, see Section 4.3.1.1 for information on making a GRUB boot floppy.^[2]

^[2] Unfortunately, there is no standard set of instructions we can provide for making a bootable CD. Your best bet is to use a bootable installation CD for your distribution. Also, instructions and utilities are available online for making bootable CDs.