rpi_shutdown.py

#!/usr/bin/python
import RPi.GPIO as GPIO
import time
import subprocess

BUTTON_PIN = 40
BUTTON_SHUTDOWN_TIMEOUT = 3

# we will use the pin numbering to match the pins on the Pi, instead of the
# GPIO pin outs (makes it easier to keep track of things)
GPIO.setmode(GPIO.BOARD)
# use the same pin that is used for the reset button (one button to rule them all!)
GPIO.setup(BUTTON_PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP)

buttonPressed = False
buttonPressedTime = 0

while True:
    if GPIO.input(BUTTON_PIN) == GPIO.HIGH:
        # button was pushed
        if not buttonPressed:
            # button wasn't pushed before so track state change
            buttonPressed = True
            buttonPressedTime = time.time()
        else:
            # button was pressed, check if it's time to shutdown
            if time.time() - buttonPressedTime >= BUTTON_SHUTDOWN_TIMEOUT:
                subprocess.call("shutdown -h now", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    else:
        buttonPressed = False
        buttonPressedTime = 0

    time.sleep(.1)