#!/usr/bin/env python


    import RPi.GPIO as GPIO
    import subprocess

    GPIO.setmode(GPIO.BCM)
    GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)
    GPIO.wait_for_edge(21, GPIO.FALLING)

    subprocess.call(['shutdown', '-h', 'now'], shell=False)

#! /bin/sh

    ### BEGIN INIT INFO
    # Provides:          shutdown.py
    # Required-Start:    $remote_fs $syslog
    # Required-Stop:     $remote_fs $syslog
    # Default-Start:     2 3 4 5
    # Default-Stop:      0 1 6
    ### END INIT INFO

    # If you want a command to always run, put it here

    # Carry out specific functions when asked to by the system
    case "$1" in
      start)
        echo "Starting shutdown.py"
        /usr/local/bin/shutdown.py &
        ;;
      stop)
        echo "Stopping shutdown.py"
        pkill -f /usr/local/bin/shutdown.py
        ;;
      *)
        echo "Usage: /etc/init.d/shutdown.sh {start|stop}"
        exit 1
        ;;
    esac

exit 0