Not sure what you are after but here goes.
In /etc/passwd use this at the end /sbin/shutdown_now of the shutdown line.
Now in /sbin create a script and add the following.
Contents of /sbin/shutdown_now
Code:
#!/bin/sh
/sbin/shutdown -t 120 -h -F
Run the command ' chmod +x /sbin/shutdown_now ' to make it executable.
Hope this helps
Brian1