Grub

Postup obnovy přes chroot

mkdir /media/mnt
mount /dev/sda2 /media/mnt/
mount -o bind /dev/ /media/mnt/dev
chroot /media/mnt

=> now you are on the destination disk, so you can install grub.
grub-install /dev/sda

Grub2

sudo update-grub2

Nastavit default OS

sudo gedit /etc/default/grub


GRUB_DEFAULT=0
to
GRUB_DEFAULT=4


sudo update-grub