#!/bin/bash
gmessage "Have a nice day ~" -center -title "Take action" -font "Sans bold 10" -default "Cancel" -buttons "_Cancel":1,"_Log out":2,"_Reboot":3,"_Shut down":4 >/dev/null 

case $? in
	1)
		echo "Exit";;
	2)
		killall openbox;;
	3)
		shutdown -r now;;
	4)
		shutdown -h now;;
esac
#By adding suid mode to shutdown command, you are allowing regular user to run shutdown command as root: sudo chmod u+s /sbin/shutdown