GRUB Commands

GRUB allows a number of useful commands in its command line interface.
Some of the commands 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
Loads the specified file as a chain loader. If the file is located 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
It 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
It enables users to specify an initial RAM disk to use when booting. 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 pconfig-file
  • Installs GRUB to the system MBR.

Signifies a device, partition, and file where the first boot loader image can be
found, such as (hd0,0)/grub/stage1.


Specifies the disk where the stage 1 boot loader should be installed, such as
(hd0).


Passes the stage 2 boot loader location to the stage 1 boot loader, such as
(hd0,0)/grub/stage2.

  • p
This option tells the install command to look for the menu configuration file
specified by , such as (hd0,0)/grub/grub.conf.

Warning

The install command overwrites any information already located on the MBR

kernel
It specifies the kernel file to load when booting the operating system. Replace
with an absolute path from the partition specified by the root

command. Replace with options for the Linux kernel, such as
root=/dev/VolGroup00/LogVol00 to specify the device on which the root
partition for the system is located. Multiple options can be passed to the kernel in
a space separated list. The following is an example kernel command:

  • kernel /vmlinuz-2.6.8-1.523 ro root=/dev/VolGroup00/LogVol00
The option in the previous example specifies that the root file system for Linux
is located on the hda5 partition.

  • root (,)
Configures the root partition for GRUB, such as (hd0,0), and mounts the
partition. The following is an example root command:

  • root (hd0,0)
rootnoverify (,)
It configures the root partition for GRUB, just like the root command, but does
not mount the partition.

Other commands are also available; type help --all for a full list of commands.
For a description of all GRUB commands, refer to the documentation available
online at http://www.gnu.org/software/grub/manual/.

Comments

Post a Comment

Popular posts from this blog

A-Z Index of the Apple OS X command line

The tcsh command shell of Darwin (the open source core of OSX) alias Create an alias alloc List used and free memory awk Find and Replace text within file(s) basename Convert a full pathname to just a folder path bash Bourne-Again SHell (Linux) bless Set volume bootability and startup disk options. break Exit from a loop cal Display a calendar case Conditionally perform a command cat Display the contents of a file cd Change Directory chflags Change a file or folder's flags. chgrp Change group ownership chmod Change access permissions chown Change file owner and group chroot Run a command with a different root directory cksum Print CRC checksum and byte counts clear Clear terminal screen cmp Compare two files comm Compare two sorted files line by line complete Edit a command completion [word/pattern/list] continue Resume the next iteration of a loop cp ...
Read more

Archiving File Systems With ACLs

Warning The tar and dump commands do not backup ACLs. The star utility is similar to the tar utility in that it can be used to generate archives of files. The star package is required to use this utility. The command line options for Star are as follows
Read more

A-Z Index of the Linux BASH command line

alias Create an alias apropos Search Help manual pages (man -k) awk Find and Replace text, database sort/validate/index break Exit from a loop builtin Run a shell builtin bzip2 Compress or decompress named file(s) cal Display a calendar case Conditionally perform a command cat Display the contents of a file cd Change Directory cfdisk Partition table manipulator for Linux chgrp Change group ownership chmod Change access permissions chown Change file owner and group chroot Run a command with a different root directory cksum Print CRC checksum and byte counts clear Clear terminal screen cmp Compare two files comm Compare two sorted files line by line command Run a command - ignoring shell functions continue Resume the next iteration of a loop cp Copy one or more files to another location cron Daemon to execute scheduled commands crontab Schedule a command to run at a later time c...
Read more