Installation guide

Refer to Section 6, “GRUB Commands” for a list of common commands.

5.1. Interfaces Load Order

When GRUB loads its second stage boot loader, it first searches for its configuration file. Once

found, the menu interface bypass screen is displayed. If a key is pressed within three seconds,

GRUB builds a menu list and displays the menu interface. If no key is pressed, the default ker-

nel entry in the GRUB menu is used.

If the configuration file cannot be found, or if the configuration file is unreadable, GRUB loads

the command line interface, allowing the user to type commands to complete the boot process.

If the configuration file is not valid, GRUB prints out the error and asks for input. This helps the

user see precisely where the problem occurred. Pressing any key reloads the menu interface,

where it is then possible to edit the menu option and correct the problem based on the error re-

ported by GRUB. If the correction fails, GRUB reports an error and reloads the menu interface.

6. GRUB Commands

GRUB allows a number of useful commands in its command line interface. Some of the com-

mands accept options after their name; these options should be separated from the command

and other options on that line by space characters.

The following is a list of useful commands:

• boot — Boots the operating system or chain loader that was last loaded.

• chainloader </path/to/file> — Loads the specified file as a chain loader. If the file is loc-

ated on the first sector of the specified partition, use the blocklist notation, +1, instead of the

file name.

The following is an example chainloader command:

chainloader +1

• displaymem — Displays the current use of memory, based on information from the BIOS.

This is useful to determine how much RAM a system has prior to booting it.

• initrd </path/to/initrd> — Enables users to specify an initial RAM disk to use when boot-

ing. An initrd is necessary when the kernel needs certain modules in order to boot properly,

such as when the root partition is formatted with the ext3 file system.

The following is an example initrd command:

initrd /initrd-2.6.8-1.523.img

• install <stage-1><install-disk><stage-2>pconfig-file — Installs GRUB to the system

MBR.

• <stage-1> — Signifies a device, partition, and file where the first boot loader image can

be found, such as (hd0,0)/grub/stage1.

5.1. Interfaces Load Order