pythonwindows-subsystem-for-linuxopenfoam

Run a Linux application on WSL from a Windows python script

In my case the application is OpenFoam, but this happens also with others Linux programs.

I have a py script (run_test.py) wrote with Windows VS Code:

import subprocess

command = "wsl python3 /mnt/wslg/distro/home/j/test.py"
subprocess.Popen(command, shell=True)

that run another script py (test.py) wrote in Linux VS Code in my WSL:

import subprocess

command = "cd $FOAM_RUN/airfopt && foamRun"
process=subprocess.Popen(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
output, error = process.communicate()

if output:
    print("Output:", output.decode())
if error:
    print("Error:", error.decode())

When i start test.py through Linux VS Code everything works fine, but when i run "run_test.py" i get the error /bin/sh: 1: cd: can't cd to /airfopt

Instead $FOAM_RUN/airfopt if i write the full path /mnt/wslg/distro/root/OpenFOAM/root-11/run/airfopt the new error is /bin/sh: 1: foamRun: not found.

I think because run_test.py run test.py under Windows enviroment and not Linux one. I want run test.py from run_test.py but under Linux env.

The same error running an test.sh file too.

It's my first time with WSL because I need OpenFoam Linux (not blueCFD etc) and connect it to a Windows python script. I search on Google, here... and I also asked ChatGPT without getting a good answer.

Solution

  • Short version

    Also see the bottom of this answer for a better method, but it may be overkill here.

    Side-note: /mnt/wslg/distro/home/j/test.py is a bit of an odd path. While it works, it should be the same as the shorter /home/j/test.py. The /mnt/wslg mount is used internally by WSLg and may change in the future (it has already changed many times in the past). There is no guarantee that /mnt/wslg/distro will continue to point to root of the distro in future WSL releases.

    More detail and other options

    Most likely, $FOAM_RUN is defined in your ~/.bashrc or equivalent. This startup config is only sourced when you are starting an interactive shell. When the first Python script runs:

    wsl python3 /mnt/wslg/distro/home/j/test.py

    There's an implicit call to bash -c first (or whatever your default shell is):

    wsl -e bash -c 'python3 /mnt/wslg/distro/home/j/test.py'"

    By default, when executing a commandline with -c, Bash does not run interactively, and so ~/.bashrc is never read. On some distributions, the stock ~/.bashrc even goes further to try to prevent interactive use.

    You don't mention if running the:

    wsl python3 /mnt/wslg/distro/home/j/test.py

    ... works from PowerShell or CMD. If my answer is correct, this should fail with the same message.

    You have a few options: