Gets url as argument and notify user when the website content changes

Site chnges monitor

#!/usr/bin/python

import sys, time, re, urllib2, hashlib, pynotify

def get_site_hash(url):
    opener = urllib2.build_opener()
    opener.addheaders = [('User-agent', 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36')]
    u = opener.open(url)
    data = u.read()
    return  hashlib.sha256(data).hexdigest()

def send_notify(str):
    pynotify.Notification("Site Changes Monitor", str, "dialog-information").show()

def main(args):
    if len(args) == 1: return

    pynotify.init("Site Changes Monitor")

    url = args[1]

    site_hash = get_site_hash(url)
    
    while True:
        new_site_hash = get_site_hash(url)
        if site_hash != new_site_hash:
            send_notify("site changed")
            site_hash = new_site_hash
        time.sleep(5)

if __name__ == "__main__":
    main(sys.argv)