daemon.py 文件源码

def write_pid(filename):
    '''Atomically writes a pid file, or fails if the file already exists.'''

    fd = os.open(filename, os.O_CREAT | os.O_EXCL | os.O_RDWR, 0o644)
    os.write(fd, str(os.getpid()))
    os.close(fd)