process.py 文件源码

def check(self):
        """
        Check if the process has exited, and if an error occured.

        Returns None if process hasn't exited, or a CompletedProcess
        object if it has exited without an error. If the process
        has exited with an error, raises a CalledProcessError.

        If process has exited, all available stdout and stderr
        are captured into the returned object or raised exception.
        """
        retcode = self.poll()

        if retcode is not None:
            stdout, stderr = self.communicate(timeout=0)
            completed = subprocess.CompletedProcess(
                args=self.args,
                returncode=retcode,
                stdout=stdout,
                stderr=stderr,
            )
            completed.check_returncode()
            return completed