run from /etc/rc.local on Raspberry Pi connected to Prusa i3 3D printer for homemade power button

printer_switch.py

# printer_switch.py
#
# controls power for a 3D printer that is connected to a Raspberry Pi (optionally running Octoprint)
#
# Copyright 2016 by dayt0n

import RPi.GPIO as GPIO
import time
import os
import subprocess

GPIO.setmode(GPIO.BCM)

upcmd = "sudo hub-ctrl -h 0 -P 2 -p 1\n"
downcmd = "sudo hub-ctrl -h 0 -P 2 -p 0\n"
# not used in this version since this part was still a little buggy
# powercmd = 'export PWRIF=$("sh -c checkit | grep Off")'
offcmd = "expect -f /usr/bin/offit"
oncmd = "expect -f/usr/bin/onit"

GPIO.setup(18, GPIO.IN, pull_up_down=GPIO.PUD_UP)
printpwr = "ON"

while True:
	input_state = GPIO.input(18)
	if input_state == False:
		print('Button Presed')
		if printpwr == "ON":
			printpwr = "OFF"
			process = subprocess.Popen(downcmd.split(), stdout=subprocess.PIPE)
			process.wait()
			print("Turned off USB")
			processthree = subprocess.Popen(offcmd.split(),stdout=subprocess.PIPE)
			process.wait()
			print("Turning power off")
		else:
			printpwr = "ON"
			process = subprocess.Popen(upcmd.split(), stdout=subprocess.PIPE)
			print("Turned on USB")
			processthree = subprocess.Popen(oncmd.split(), stdout=subprocess.PIPE)
			print("Turned power on")
		time.sleep(0.2)

# expect scripts look like this: 
#
# spawn telnet 10.0.1.47
# sleep 2
# expect -re "User> "
# send "*username here*\r"
# expect -re "Password> "
# send "*password here*\r"
# expect -re "iBoot> "
# send "set outlet on (or off) \r\r"
# expect -re "iBoot> "
# send "logout\r"
# expect eof