Python Scripting: How can I obtain the output from async_send_text?

[Eric G]

I can send a command to a session by doing:

await currentSession.async_send_text( 'ls\r' )

and I would like to obtain the output of that command. I thought I might be able to determine the position of the old prompt and the new prompt, but couldn't get that to work. I figure I may be able to get all of the output in the session via async_get_screen_contents and then start parsing to get what I am looking for.

What is the standard way of doing that?

[George Nachman]

It’s a little more complex than I would like. Here’s how I would write it:

#!/usr/bin/env python3.10

import asyncio

import iterm2

async def wait_for_prompt(connection, my_session):

    """Block until the running command terminates."""

    modes = [iterm2.PromptMonitor.Mode.COMMAND_END]

    async with iterm2.PromptMonitor(connection, my_session.session_id, modes) as prompt_monitor:

        while True:

            type, value = await prompt_monitor.async_get()

            if type == iterm2.PromptMonitor.Mode.COMMAND_END:

                return

async def string_in_lines(my_session, start_y, end_y):

    """Returns a string with the content in a range of lines."""

    contents = await my_session.async_get_contents(start_y, end_y - start_y)

    result = ""

    for line in contents:

        result += line.string

        if line.hard_eol:

            result += "\n"

    return result

async def run_command(connection, my_session, command):

    """Run a command and return its output. Requires shell integration."""

    # Atomically get the last prompt, send a command, and begin watching for the end of the command.

    async with iterm2.Transaction(connection):

        prompt = await iterm2.async_get_last_prompt(connection, my_session.session_id)

        await my_session.async_send_text(command + "\r")

        task = asyncio.create_task(wait_for_prompt(connection, my_session))

    # Wait for the command to end.

    await task

    # Re-fetch the prompt for the command we sent to get the current output range.

    async with iterm2.Transaction(connection):

        prompt = await iterm2.async_get_prompt_by_id(connection, my_session.session_id, prompt.unique_id)

        range = prompt.output_range

        start_y = range.start.y

        end_y = range.end.y

        # Fetch the content in that range and return it

        content = await string_in_lines(my_session, start_y, end_y)

    return content

async def main(connection):

    """Demonstrate how to use run_command"""

    app = await iterm2.async_get_app(connection)

    if app.current_terminal_window:

        my_session = app.current_terminal_window.current_tab.current_session

        print(await run_command(connection, my_session, "seq 150"))

iterm2.run_until_complete(main)

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[Eric Gorr]

Thank you for that. I would have been hard pressed to figure that out for myself.

It may be worthwhile adding a convenience function like async_send_text_with_output which returns the output from the command...

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[Eric Gorr]

Based on behavior I am seeing, if there is already a prompt for the user to enter something, 

await prompt_monitor.async_get() 

will never terminate. So, is there a way for me to see if there is a prompt waiting? 

[George Nachman]

You can use async_get_last_prompt. Here is a REPl session where s is a Session object. 

Initially, we are at the command prompt:

>>> p = await iterm2.async_get_last_prompt(connection, s.session_id)

>>> p.state

<PromptState.EDITING: 0>

I run cat and do it again:

>>> p = await iterm2.async_get_last_prompt(connection, s.session_id)

>>> p.state

<PromptState.RUNNING: 1>

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