PID lock/release

pid.py

ducovar = dict()

pid = str(os.getpid())

def pid_exists():
    return os.path.isfile(ducovar["PID_FILE"])

def write_pid():
    if len(ducovar["PID_FILE"]) == 0:
        print "Error: invalid pid file [%s]" % ducovar["PID_FILE"]
    file(ducovar["PID_FILE"], 'w').write(pid)

def delete_pid():
    if len(ducovar["PID_FILE"]) > 0:
        os.unlink(ducovar["PID_FILE"])