Learning Red Hat Linux, Second Edition

The GRUB Loader

Most PCs can be booted from a floppy drive or hard drive; many recently manufactured computers can be booted from a CD-ROM drive. The first sector of a disk, diskette, or partition is known as the boot sector. The boot sector associated with a disk or diskette (the first sector of the disk or diskette) is known as the Master Boot Recor d (MBR). In order for a diskette or disk to be bootable, it must contain a boot loader, which can reside in:

• The boot sector of the floppy diskette

• The MBR of the first hard disk or the first CD-ROM drive, if the PC supports booting from a CD-ROM

• The boot sector of a Linux filesystem partition on the first hard disk

• The boot sector of an extended partition on the first hard disk

GRUB is a sophisticated boot loader that can load Linux, Microsoft Windows 3.x and 9x, and other popular operating systems. Most users install GRUB on the MBR of their system’s first hard disk. That way, when the system is started, it boots GRUB, which can be used to load Linux, Microsoft Windows, or another operating system.

Unless you direct otherwise, the Red Hat Linux installation procedure automatically installs GRUB. So you don’t need to install GRUB; you just need to configure it.

Similarly, when you boot by using GRUB, you can also boot parameters to control the boot process; you can specify GRUB’s boot parameters by selecting an operating system from GRUB’s menu and pressing e. In response, GRUB displays an editor screen that shows the commands ...