daemon.py 文件源码

def daemonize(double_fork=True):
    '''Puts process in the background using usual UNIX best practices.'''

    try:
        os.umask(0o22)
    except Exception as e:
        raise Exception("Unable to change file creation mask: %s" % e)

    os.chdir('/')

    # First fork
    if double_fork:
        try:
            pid = os.fork()
            if pid > 0:
                os._exit(0)
        except OSError as e:
            raise Exception("Error on first fork: [%d] %s" % (e.errno, e.strerr,))

    os.setsid()

    # Second fork
    try:
        pid = os.fork()
        if pid > 0:
            os._exit(0)
    except OSError as e:
        raise Exception("Error on second fork: [%d] %s" % (e.errno, e.strerr,))

    close_open_files()
    os.dup2(os.open(os.devnull, os.O_RDWR), sys.stdin.fileno())
    os.dup2(os.open(os.devnull, os.O_RDWR), sys.stdout.fileno())
    os.dup2(os.open(os.devnull, os.O_RDWR), sys.stderr.fileno())