How to run executable from python and pass it arguments asked for?

Question

I can't figure out how to run executable from python and after that pass it commands which is asking for one by one. All examples I found here are made through passing arguments directly when calling executable. But the executable I have needs "user input". It asks for values one by one.

Example:

subprocess.call(grid.exe)
>What grid you want create?: grid.grd
>Is it nice grid?: yes
>Is it really nice grid?: not really
>Grid created

Answer 1

You can use subprocess and the Popen.communicate method:

import subprocess

def create_grid(*commands):
    process = subprocess.Popen(
        ['grid.exe'],
        stdout=subprocess.PIPE,
        stdin=subprocess.PIPE,
        stderr=subprocess.PIPE)

    process.communicate('\n'.join(commands) + '\n')

if __name__ == '__main__':
    create_grid('grid.grd', 'yes', 'not really')

The "communicate" method essentially passes in input, as if you were typing it in. Make sure to end each line of input with the newline character.

If you want the output from grid.exe to show up on the console, modify create_grid to look like the following:

def create_grid(*commands):
    process = subprocess.Popen(
        ['grid.exe'],
        stdin=subprocess.PIPE)

    process.communicate('\n'.join(commands) + '\n')

Caveat: I haven't fully tested my solutions, so can't confirm they work in every case.