How to REINSTALL GRUB with LiveCD

How to REINSTALL GRUB with LiveCD F10


When the busted system is in a single ext3 root partition (say, /dev/sda5)...

mkdir /mnt/temp
mount /dev/sda5 /mnt/temp
grub-install --root-directory=/mnt/temp /dev/sda

When the busted system has separate ext3 boot and root partitions (say, /dev/sda5 and /dev/sda6)...

mkdir -p /mnt/temp/boot
mount /dev/sda5 /mnt/temp/boot
mount /dev/sda6 /mnt/temp
grub-install --root-directory=/mnt/temp /dev/sda

When the busted system has a separate ext3 boot partition (say, /dev/sda5), and the root partition is a logical volume (say, /dev/VolGroup00/LogVol00 according to lvdisplay)...

mkdir -p /mnt/temp/boot
vgchange -a y
lvdisplay
mount /dev/sda5 /mnt/temp/boot
mount /dev/VolGroup00/LogVol00 /mnt/temp
grub-install --root-directory=/mnt/temp /dev/sda

If grub-install fails with a read error or the boot loader still doesn't work, always try the GRUB shell (and vice versa). They both accomplish the same thing, but different things occur in the background. It's not necessary to mount partitions when using the GRUB shell commands in the LiveCD. Change x & y in the example to the busted system's boot partition...

/sbin/grub
grub> root (hdx,y)
grub> setup (hd0)