#!/usr/bin/env bash

case "$1" in
   on)
      set -x
      mount --bind /proc    /ro/proc
      mount --bind /sys     /ro/sys
      mount --bind /dev     /ro/dev
      mount --bind /dev/pts /ro/dev/pts
   ;;
   off)
      set -x
      umount /ro/dev/pts
      umount /ro/dev
      umount /ro/sys
      umount /ro/proc
   ;;
   *)
      echo "Use: $0 (on|off)"
esac