2.7. GRUB Menu Configuration File
The configuration file (/boot/grub/grub.conf), which is used to create the list of operating systems to boot in GRUB's menu interface, essentially allows the user to select a pre-set group of commands to execute. The commands given in Section 2.6 GRUB Commands can be used, as well as some special commands that are only available in the configuration file.
2.7.1. Special Configuration File Commands
The following commands can only be used in the GRUB menu configuration file:
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 <title-name> — The default entry title name that will be loaded if the menu interface times out.
fallback <title-name> — If used, the entry title name to try if first attempt fails.
hiddenmenu — If used, 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.password <password> — If used, 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> command. In this case, GRUB will restart the second stage boot loader and use the specified alternate configuration file to build the menu. If an alternate menu configuration file is left out of the command, then a user who knows the password is allowed to edit the current configuration file.
timeout — If used, sets the interval, in seconds, before GRUB loads the entry designated by the default command.
splashimage — Specifies the location of the splash screen image to be used when GRUB boots.
title — Sets a title to be used with a particular group of commands used to load an operating system.
The hash mark (#) character can be used at the beginning of a line to place comments in the menu configuration file.
2.7.2. Configuration File Structure
The GRUB menu interface configuration file is /boot/grub/grub.conf. The commands to set the global preferences for the menu interface are placed at the top of the file, followed by the different entries for each of the operating systems or kernels listed in the menu.
The following is a very basic GRUB menu configuration file designed to boot either Red Hat Linux and Microsoft Windows 2000:
default=0
timeout=10
splashimage=(hd0,0)/grub/splash.xpm.gz
# section to load linux
title Red Hat Linux (2.4.18-5.47)
root (hd0,0)
kernel /vmlinuz-2.4.18-5.47 ro root=/dev/sda2
initrd /initrd-2.4.18-5.47.img
# section to load Windows 2000
title windows
rootnoverify (hd0,0)
chainloader +1 |
This file tells GRUB to build a menu with Red Hat Linux as the default operating system and sets it to autoboot after 10 seconds. Two sections are given, one for each operating system entry, with commands specific to the system disk partition table.
 | Note |
|---|---|
Note that the default is specified as a number. This refers to the first title line GRUB comes across. If you want windows to be the default, change the default=0 to default=1. |
Configuring a GRUB menu configuration file to boot multiple operating systems is beyond the scope of this chapter. Please consult Section 2.11 Additional Resources for a list of additional resources.