ubuntu grub repair terminal chroot

sudo mount /dev/sdXY /mnt
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
sudo chroot /mnt
grub-install /dev/sdX
grub-install --recheck /dev/sdX
update-grub
exit &&
sudo umount /mnt/sys &&
sudo umount /mnt/proc &&
sudo umount /mnt/dev/pts &&
sudo umount /mnt/dev &&
sudo umount /mnt