watchdog.py 文件源码

def daemonize():
    # See http://www.steve.org.uk/Reference/Unix/faq_2.html#SEC16
    if os.fork():  # launch child and...
        os._exit(0)  # kill off parent
    os.setsid()
    if os.fork():  # launch child and...
        os._exit(0)  # kill off parent again.
    # some argue that this umask should be 0, but that's annoying.
    os.umask(0o077)
    null = os.open('/dev/null', os.O_RDWR)
    for i in range(3):
        try:
            os.dup2(null, i)
        except OSError as e:
            if e.errno != errno.EBADF:
                raise
    os.close(null)