check_URL_for_updates.py

#!/usr/bin/env python3

import sys
import time
import urllib.request
import hashlib
import subprocess

url = sys.argv[1]

def make_hash():
    return hashlib.md5(urllib.request.urlopen(url).read()).digest()

hash = make_hash()

while True:
    time.sleep(5)
    if hash != make_hash():
        subprocess.call(["zenity", "--notification", "--text=URL has been updated!"])