replwrap - Control read-eval-print-loops

Generic wrapper for read-eval-print-loops, a.k.a. interactive shells

New in version 3.3.

class pexpect.replwrap.REPLWrapper(cmd_or_spawn, orig_prompt, prompt_change, new_prompt='[PEXPECT_PROMPT>', continuation_prompt='[PEXPECT_PROMPT+', extra_init_cmd=None)[source]

Wrapper for a REPL.

  • cmd_or_spawn – This can either be an instance of pexpect.spawn in which a REPL has already been started, or a str command to start a new REPL process.
  • orig_prompt (str) – The prompt to expect at first.
  • prompt_change (str) – A command to change the prompt to something more unique. If this is None, the prompt will not be changed. This will be formatted with the new and continuation prompts as positional parameters, so you can use {} style formatting to insert them into the command.
  • new_prompt (str) – The more unique prompt to expect after the change.
  • extra_init_cmd (str) – Commands to do extra initialisation, such as disabling pagers.
run_command(command, timeout=-1, async_=False)[source]

Send a command to the REPL, wait for and return output.

  • command (str) – The command to send. Trailing newlines are not needed. This should be a complete block of input that will trigger execution; if a continuation prompt is found after sending input, ValueError will be raised.
  • timeout (int) – How long to wait for the next prompt. -1 means the default from the pexpect.spawn object (default 30 seconds). None means to wait indefinitely.
  • async (bool) – On Python 3.4, or Python 3.3 with asyncio installed, passing async_=True will make this return an asyncio Future, which you can yield from to get the same result that this method would normally give directly.

A string that can be used as a prompt, and is unlikely to be found in output.

Using the objects above, it is easy to wrap a REPL. For instance, to use a Python shell:

py = REPLWrapper("python", ">>> ", "import sys; sys.ps1={!r}; sys.ps2={!r}")

Convenience functions are provided for Python and bash shells:


Start a Python shell and return a REPLWrapper object.


Start a bash shell and return a REPLWrapper object.