Simple init.d script to save all running virtualboxes on host shutdown or reboot

save-running-virtualboxes

#!/bin/bash
### BEGIN INIT INFO
# Provides:          save-running-virtualboxes
# Required-Start:    
# Required-Stop:     $network
# Default-Start:     
# Default-Stop:      0 1 6
# Short-Description: Stops all running virtualboxes
# Description:       Stops all running virtualboxes of all users
### END INIT INFO


case "$1" in
  stop)
    echo "Saving all running virtualboxes ..."
    for user in $(ps -ouser= -C VBoxHeadless,VirtualBox | sort -u); do
      for vm_name in $(su -c '/usr/bin/VBoxManage list runningvms | cut -d " " -f 1' $user); do
        echo "Saving box '$vm_name' of user '$user'"
        su -c "/usr/bin/VBoxManage controlvm $vm_name savestate" $user
      done
    done
    echo "Done."
    ;;
  *)
    echo "Usage: /etc/init.d/save-running-virtualboxes stop"
    exit 1
    ;;
esac

exit 0

Have to same issue und same idea but doesnt work for me. When i will reboot my System it idles still on 'waiting for vboxnet0 to become free'