pulse.py

"""
Sends system's pulse to a watchdog device

Usage:
    python pulse.py <serial device>

Example:
    SLEEP=25 python pulse.py /dev/ttyUSB0
"""

import os
import sys
import time

SLEEP = os.environ.get('SLEEP', 1)


def main(filename):
    with open(filename, 'rw+') as file_obj:
        file_obj.write('y')


if __name__ == '__main__':
    if len(sys.argv) < 2:
        print __doc__
        exit(1)

    filename = sys.argv[1]
    while True:
        main(filename)
        time.sleep(SLEEP)