Interact with process: Send data to stdin and close it. Read data from stdout and stderr, until end-of-file is reached. Wait for process to terminate. The optional "input" argument should be data to be sent to the child process, or None, if no data should be sent to the child. communicate() returns a tuple (stdout, stderr). By default, all communication is in bytes, and therefore any "input" should be bytes, and the (stdout, stderr) will be bytes. If in text mode (indicated by self.text_mode), any "input" should be a string, and (stdout, stderr) will be strings decoded according to locale encoding, or by "encoding" if set. Text mode is triggered by setting any of text, encoding, errors or universal_newlines.