create a demonize process with python

demonize.py

def daemonize():
    """Performs the necessary dance to become a background daemon."""
    if os.fork():
        os._exit(0)
    os.chdir("/")
    os.umask(022)
    os.setsid()
    os.umask(0)
    if os.fork():
        os._exit(0)
    stdin = open(os.devnull)
    stdout = open(os.devnull, 'w')
    os.dup2(stdin.fileno(), 0)
    os.dup2(stdout.fileno(), 1)
    os.dup2(stdout.fileno(), 2)
    stdin.close()
    stdout.close()
    os.umask(022)
    for fd in xrange(3, 1024):
        try:
            os.close(fd)
        except OSError:  # This FD wasn't opened...
            pass         # ... ignore the exception.

it's just a memo