Count down time and notify a message through Notification Center

countdown.py

#!/usr/bin/env python

import sys
import time
import re
import subprocess

if __name__ == '__main__':
    period = sys.argv[1]
    m = re.match('(.*)([smh])', period)
    if m:
        t = float(m.group(1))
        u = m.group(2)
        if u == 'm':
            sec = t * 60
        elif u == 'h':
            sec = t * 60 * 60
        else:
            sec = t
    else:
        sec = float(period)
    t0 = time.time();
    while True:
        r = sec - (time.time() - t0)
        h = r / (60 * 60)
        m = (r % (60 * 60)) / 60
        s = r % 60
        if 0 < r:
            print '\033[2K\033[0G%02d:%02d:%04.1f'%(h,m,s),
            sys.stdout.flush()
            time.sleep(1.0 / 10.0)
        else:
            print '\033[2K\033[0G00:00:00.0'
            break
    title = 'Countdown'
    message = 'Finished.'
    args = 'osascript', '-e', 'display notification "%s" with title "%s"'%(message, title)
    subprocess.Popen(args)

Usage:
countdown.py 3.5h # 3 hours and 30 minutes
countdown.py 3m # 3 minutes
countdown.py 1.5s # 1.5 seconds
countdown.py 1.5 # 1.5 seconds