Raspberry PI: Shutdown with momentary switch

Connect N.O. (normally open) momentary switch to pins 39 and 40 on the GPIO pins.

Run commands:

sudo apt update
sudo apt install python3-gpiozero

sudo nano shutdown-press-simple.py

Copy and paste the following text into the file you just created:

#!/usr/bin/env python3

from gpiozero import Button

import os

Button(21).wait_for_press()

os.system("sudo poweroff")

Run commands:

sudo chmod a+x shutdown-press-simple.py

sudo nano /etc/rc.local

Add the following text above "exit 0":

sudo python /home/pi/shutdown-press-simple.py &

Reboot and test the button.