Linux 重新安裝 Grub

sudo mount -t ext4 /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