grub 2 with chroot from live stick

install-grub.sh

sudo mkdir /foo
sudo mount /dev/sda1 /foo # system partition
sudo mount /dev/sda2 /foo/boot/efi # EFI System Partition
sudo mount -o bind /dev /foo/dev
sudo mount -o bind /sys /foo/sys
sudo mount -t proc /proc /foo/proc
sudo cp /proc/mounts /foo/etc/mtab
sudo chroot /foo /bin/bash

# in root shell:
grub-install /dev/sda
update-grub