a simple timer :D

timer.py

#!/usr/bin/env python
"""
usage: 
    $ python timer.py -t 00:01:20
"""
import sys
import time
import math 
import datetime 


def timer(period=(0, 1, 0), err=0.01):
    start = time.time()
    duration = sum(map(lambda (i, v): v*60**(2-i), enumerate(period)))
    end = start + duration
 
    if start > end: 
        raise Exception, "waaat ??"

    sleep_time = err/2.
    last = start
        
    while last < end:
        curtime = time.time()
        acc = curtime - last
        if acc > err:
            sys.stdout.write("\r%s" % str(datetime.timedelta(0, end-curtime)))
            sys.stdout.flush()
            last = curtime
        else:
            time.sleep(err-acc)


if __name__ == '__main__':
    flags = sys.argv[1:]
    t = flags[flags.index('-t') + 1]
    t = tuple([int(i) for i in t.split(':')])
    try:
        timer(period=t)
    except KeyboardInterrupt:
        sys.stdout.flush()
        sys.stdout.write("\r[X] terminated\r\n")
    sys.stdout.flush()
    sys.stdout.write("\r[+] FINISHED\r\n")