A Python script which is intended to be run as a background process, and listens for + takes action on GPIO button 17, 22, and 23 presses.

gpio-button-listener

#!/usr/bin/env python2.7
# original script by Alex Eames http://RasPi.tv
# http://RasPi.tv/how-to-use-interrupts-with-python-on-the-raspberry-pi-and-rpi-gpio-part-3

# Modified by George Merlocco http://github.com/scar45
# for Adafruit 2.2" LCD Pi Hat tactile button inputs

import RPi.GPIO as GPIO
import time
import sys

# call is used to enable the execution of any external task
from subprocess import call

GPIO.setmode(GPIO.BCM)

GPIO.setup(17, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(22, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(23, GPIO.IN, pull_up_down=GPIO.PUD_UP)

def btn_press_17(channel):
    call(["echo", "GPIO button 17 pressed!"])

def btn_press_22(channel):
    call(["echo", "GPIO button 22 pressed!"])

def btn_press_23(channel):
    call(["echo", "GPIO button 23 pressed!"])

GPIO.add_event_detect(17, GPIO.FALLING, callback=btn_press_17, bouncetime=300)
GPIO.add_event_detect(22, GPIO.FALLING, callback=btn_press_22, bouncetime=300)
GPIO.add_event_detect(23, GPIO.FALLING, callback=btn_press_23, bouncetime=300)

while True:
    try:
        print "Waiting for presses from GPIOs 17, 22, and 23..."
        time.sleep(31536000) # sleep 1 year...zzzzzzzzzzzz...
    except KeyboardInterrupt:
        GPIO.cleanup()       # clean up GPIO on CTRL+C exit
        sys.exit()
GPIO.cleanup()           # clean up GPIO on normal exit
sys.exit()