Joseph Herlant
version 1.0.0, 2014-07-04 : Initial version

In GRUB’s configuration file, the (hd0, 0) means to load the bootloader from the partition 0 of the hd0 drive.

In RHEL6, the GRUB version used is 0.97 so you can still edit the /boot/grub/grub.conf manually unlinke GRUB 2.0.

From GRUB’s command line:

  • To find the partition containing GRUB’s conf file: find /grub/grub.conf or simply root

  • To reinstall grub on hd0: setup (hd0)

To boot in maintenance mode (init 1 / telinit 1 equivalent) from the grub menu, just append single to the boot arguments to the "kernel" line.

If you are booting by default on runlevel 5 and that you want to reboot in runlevel 3, just add " 3" at the end of the kernel line at the grub prompt. Tested on Centos.

For UEFI boots, the grub.conf is located at: /boot/efi/EFI/redhat/grub.conf