Restore grub

How to restore grub

When you use dual boot computer there is a risk that reinstalling windows destroy your grub. It happeend to me several times.

Here is a simple How to reinstall grub :

You need a live whatever (Live CD, Live USB-key). Personnaly I used a live arch USB-key.

Restoring your grub is really easy with a few commands:

First of all we mount the partition in order to reinstall grub:

sudo mount /dev/sdXY /mnt

Now bind the directories that grub needs access to to detect other operating systems, like so:

sudo mount --bind /dev /mnt/dev && sudo mount --bind /dev/pts /mnt/dev/pts
&& sudo mount --bind /proc /mnt/proc && sudo mount --bind /sys /mnt/sys

We chroot the partition:

sudo chroot /mnt

Install check and update grub:

grub-install /dev/sdX
grub-install --recheck /dev/sdX
update-grub

Exit chroot environnment and unmount everything:

exit && sudo umount /mnt/dev && sudo umount /mnt/dev/pts && sudo umount
/mnt/proc && sudo umount /mnt/sys && sudo umount /mnt