ubuntu@ubuntu:~$ sudo mount /dev/mapper/luks-9f321f75-7bc6-4da9-87d0-71a9d1b73b89 /mnt
ubuntu@ubuntu:~$ sudo mount --bind /dev /mnt/dev
ubuntu@ubuntu:~$ sudo mount --bind /sys /mnt/sys
ubuntu@ubuntu:~$ sudo mount --bind /proc /mnt/proc
ubuntu@ubuntu:~$ sudo mount /dev/sda1 /mnt/boot
ubuntu@ubuntu:~$ sudo chroot /mnt
root@ubuntu:/# sudo update-grub
sudo: unable to resolve host ubuntu: Connection refused
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.4.0-21-generic
Found initrd image: /boot/initrd.img-4.4.0-21-generic
Found memtest86+ image: /memtest86+.elf
Found memtest86+ image: /memtest86+.bin
Found Windows 10 (loader) on /dev/sda2
done
root@ubuntu:/#