OpiumSmoke OpiumSmoke - 1 month ago 9
Git Question

Python script to determine if a directory is a git repository

I have just started with Python and my first assignment is to write a script to determine if a directory where it is ran is a git repository. A co-student suggested this code:

#! /usr/bin/env python

from subprocess import Popen, PIPE, STDOUT
if Popen(("git", "branch"), stderr=STDOUT, stdout=PIPE).returncode != 0:
print("Nope!")
else:
print("Yup!")


It should print an output depending on what the returncode of console command "git branch" is. However, the script did not work in the repository.

In any case, I would be grateful for any piece of advice regarding this.

The assignment also includes:


  • being able to use same script on Windows

  • eventual passing of the path to determine to the script without having to copy it to the target directory



Many thanks!

Answer

Close! Popen is a more complicated object that starts a process but requires other interaction to get information. In your case, you need to call wait() so that the Popen object waits for the program completes to get the return code. You also risk the program hanging if the command returns too much information to fit in the pipe. Try 'call' (it calls wait for you) and send the command output to the bit bucket.

#! /usr/bin/env python

from subprocess import call, STDOUT
import os
if call(["git", "branch"], stderr=STDOUT, stdout=open(os.devnull, 'w')) != 0:
    print("Nope!")
else:
    print("Yup!")
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