#!/usr/bin/python3

import RPi.GPIO as g
from time import sleep
from subprocess import Popen

g.setmode(g.BCM)
g.setup(26,g.IN)

def p26_callback(channel):
  command = ['/usr/bin/sudo','poweroff']
  Popen(command)
  g.remove_event_detect(channel) # we've done it once, stop watching
  return

g.add_event_detect(26, g.FALLING, callback=p26_callback)

try:
    sleep(30)
finally:
    g.cleanup()