Raspberry Pi Graceful Shutdown with gpiozero

halt.py

#!/usr/bin/python

'''Having a little fun with Raspberry Pi and gpiozero.  Small script that uses
a button and leds to indicate a graceful Linux shutdown.

Module at https://github.com/RPi-Distro/python-gpiozero

Wiring your button
https://github.com/RPi-Distro/python-gpiozero/blob/master/docs/inputs.md

Wiring LED's
https://github.com/RPi-Distro/python-gpiozero/blob/master/docs/outputs.md
'''

import time
import os
from gpiozero import Button
from gpiozero import LED

button = Button(2)
redled = LED(17)
greenled = LED(27)

while True:
    time.sleep(0.02) # prevents killing your cpu
    # Hold button down for 5 seconds. Light turns red and Linux shuts down gracefully
    if button.is_pressed:  
        time.sleep(5)
        if button.is_pressed:
            redled.on()
            cmd = "shutdown -h now"
            os.system(cmd)
    else:
        # On boot light is green.
        greenled.on()