One way to issue a system command when someone pushes a button connected to the gpio

gpio2command.py

"""
Some references:

https://sourceforge.net/p/raspberry-gpio-python/wiki/BasicUsage/

https://stackoverflow.com/questions/89228/calling-an-external-command-in-python
"""
import RPi.GPIO as GPIO
import signal
import time
import sys
from subprocess import call

# first look for sigint so we can release the buttons if the script exits. 
def signal_handler(signal, frame):
	GPIO.cleanup()
	sys.exit(0)

signal.signal(signal.SIGINT, signal_handler) # keep an eye our for SIGINT (ctrl-c)

# setup gpio (according to hersh's orignal script)

def keyPressed(key):
	if key == 11:
		# do 11 stuff like halt the pi
		call(["sudo", "halt"])
		
	if key == 13:
		# do 13 stuff
# etc etc



GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, GPIO.IN)
GPIO.add_event_detect(11, GPIO.RISING, callback=keyPressed)
GPIO.setup(13, GPIO.IN)
GPIO.add_event_detect(13, GPIO.RISING, callback=keyPressed)
GPIO.setup(15, GPIO.IN)
GPIO.add_event_detect(15, GPIO.RISING, callback=keyPressed)
GPIO.setup(16, GPIO.IN)
GPIO.add_event_detect(16, GPIO.RISING, callback=keyPressed)
GPIO.setup(7, GPIO.IN)
GPIO.add_event_detect(17, GPIO.RISING, callback=keyPressed)

while True:
    time.sleep(1) # sleep for a second while the system does other stuff.