chainloader </path/to/file> — Loads the specified file as a chain loader. Replace </path/to/file> with the absolute path to the chain loader. If the file is located on the first sector of the specified partition, use the blocklist notation, +1.
color <normal-color> <selected-color> — Allows specific colors to be used in the menu, where two colors are configured as the foreground and background. Use simple color names such as red/black. For example:
color red/black green/blue
default=<integer> — Replace <integer> with the default entry title number to be loaded if the menu interface times out.
fallback=<integer> — Replace <integer> with the entry title number to try if the first attempt fails.
hiddenmenu — Prevents the GRUB menu interface from being displayed, loading the default entry when the timeout period expires. The user can see the standard GRUB menu by pressing the Esc key.
initrd </path/to/initrd> — Enables users to specify an initial RAM disk to use when booting. Replace </path/to/initrd> with the absolute path to the initial RAM disk.
kernel </path/to/kernel> <option-1> <option-N> — Specifies the kernel file to load when booting the operating system. Replace </path/to/kernel> with an absolute path from the partition specified by the root directive. Multiple options can be passed to the kernel when it is loaded.
These options include:
rhgb (Red Hat graphical boot) — displays an animation during the boot process, rather than lines of text.
quiet — suppresses all but the most important messages in the part of the boot sequence before the Red Hat graphical boot animation begins.
password=<password> — Prevents a user who does not know the password from editing the entries for this menu option.
Optionally, it is possible to specify an alternate menu configuration file after the password=<password> directive. In this case, GRUB restarts the second stage boot loader and uses the specified alternate configuration file to build the menu. If an alternate menu configuration file is left out of the command, a user who knows the password is allowed to edit the current configuration file.
For more information about securing GRUB, refer to the chapter titled Workstation Security in the Red Hat Enterprise Linux Deployment Guide.
map — Swaps the numbers assigned to two hard drives. For example:
map (hd0) (hd3)
map (hd3) (hd0)
assigns the number 0 to the fourth hard drive, and the number 3 to the first hard drive. This option is especially useful if you configure your system with an option to boot a Windows operating system, becausehe Windows boot loader must find the Windows installation on the first hard drive.
For example, if your Windows installation is on the fourth hard drive, the following entry in grub.conf will allow the Windows boot loader to load Windows correctly:
title Windows
map (hd0) (hd3)
map (hd3) (hd0)
rootnoverify (hd3,0)
chainloader +1
root (<device-type><device-number>,<partition>) — Configures the root partition for GRUB, such as (hd0,0), and mounts the partition.
rootnoverify (<device-type><device-number>,<partition>) — Configures the root partition for GRUB, just like the root command, but does not mount the partition.
timeout=<integer> — Specifies the interval, in seconds, that GRUB waits before loading the entry designated in the default command.
splashimage=<path-to-image> — Specifies the location of the splash screen image to be used when GRUB boots.
title group-title — Specifies a title to be used with a particular group of commands used to load a kernel or operating system.
