Using python to run another program?

Question

I have a program that I run from the command line that looks like this:

$ program a.txt b.txt

The program requires two text files as arguments. I am trying to write a Python 3.2 script to run the above program. How can I do this? Currently, I am trying to use the subprocess module like this:

import subprocess

with open("a.txt", mode="r") as file_1:
    with open("b.txt", mode="r") as file_2:
        cmd = ['/Users/me/src/program', file_1, file_2]
        process = subprocess.Popen(cmd, stdout=subprocess.PIPE)
        for line in process.stdout:
            print(line)

I read this post and the post here, which seem to describe similar solutions to my problem. Unfortunately, after reading these posts, I still can't seem to make my Python code run my program.

Can anyone help? Thanks in advance!

user_10212631 · Answer

Using subprocess.wait() with stdout=subprocess.PIPE is not recommended.

with subprocess.Popen(cmd, stdout=subprocess.PIPE) as proc:
    print(proc.stdout.read())

You don't have to call subprocess.wait(). This will print realtime stdout of proc and parent process will wait the termination of proc.

Check these urls for more information.

Using python to run another program?

4 Answers