Bash

To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@ubuntu:~$ sudo mount /dev/sda1 /mnt
ubuntu@ubuntu:~$ mount --rbind /proc /mnt/proc
mount: only root can use "--rbind" option
ubuntu@ubuntu:~$ sudo mount --rbind /proc /mnt/proc
ubuntu@ubuntu:~$ sudo mount --rbind /sys /mnt/sys
ubuntu@ubuntu:~$ sudo mount --rbind /dev /mnt/dev
ubuntu@ubuntu:~$ chroot /mnt
chroot: cannot change root directory to '/mnt': Operation not permitted
ubuntu@ubuntu:~$ sudo chroot /mnt
root@ubuntu:/# mount -a
root@ubuntu:/# cd /boot
root@ubuntu:/boot# ls /lib/modules
4.4.0-57-generic  4.4.0-59-generic
root@ubuntu:/boot# update-initramfs -c -k 4.4.0-57-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-57-generic
root@ubuntu:/boot#