This is based on a very useful post by a chap named Arie.The credit for much of the following goes to him: I’m just reposting a summary to make it more widely discoverable.
The pre-defined variables are contained in /usr/sbin/grub-mkconfig and can be listed using the following command: This file contains basic settings which would be considered normal for the user to configure.
Options include the time the menu is displayed, the default OS to boot, etc.
Starting with Fedora 16, GRUB 2 is the default bootloader on x86 BIOS systems.
For upgrades of BIOS systems the default is also to install GRUB 2, but you can opt to skip bootloader configuration entirely.
Then you need to configure which kernel is initially the one that’s ‘saved’.
GRUB 2's method of building the GRUB menu is vastly different from GRUB 0.97.GRUB 2 has replaced what was formerly known as GRUB (i.e.version 0.9x), which has, in turn, become GRUB Legacy.file is a system file, therefore any editing must be done by a user with 'Administrator/root' privileges.The file is a simple text file and can be edited by any text editor.The bootloader is installed with something like: grub2-mkconfig will create a new configuration based on the currently running system, what is found in /boot, what is set in /etc/default/grub, and the customizable scripts in /etc/grub.d/ .