pty.py 文件源码

def __init__(self, args, *, size=core.STANDARD_SIZE, cmd=None, env=None, callbacks_cls=PtyCallbacks, __os_close=os.close, **kwargs):
        self._master_fd = -1
        super().__init__(size)
        master_fd, slave_fd = os.openpty()
        try:
            self._slave_name = os.ttyname(slave_fd)
            _spawn(cmd, args, env, fds={0: slave_fd, 1: slave_fd, 2: slave_fd}, tty=slave_fd)

            self._master_fd = master_fd
            master_fd = -1
        finally:
            __os_close(slave_fd)
            if master_fd != -1:
                __os_close(master_fd)

        # configure some sensible defaults
        callbacks = callbacks_cls(self, **kwargs)
        self.set_callbacks(callbacks)
        self.callbacks = callbacks