Check if running in Windows Subsystem for Linux

These examples for C, C++, Fortran, and Python show how to detect if a program is running under Windows Subsystem for Linux (WSL).

There is one header file "is_wsl.h" that works for C and C++ under include/.

The Python example has a function "wsl_available()" that checks if WSL is available and working on the computer.

Build C, C++, Fortran examples

cmake -Bbuild
cmake --build build

Optionally, run the examples:

ctest --test-dir build

Heuristic

The method is to check the kernel name string to see if it contains:

• "-Microsoft " (WSLv1)
• "microsoft-standard-WSL" (WSLv2)

Human check

Manually see relevant info:

# from Windows PowerShell or Command Prompt
wsl.exe -l -v

from WSL Terminal:

uname -a

CI Notes

Our GitHub Workflow gives an example of WSLv1 on GitHub Actions.

There is not currently a way to run WSLv2 directly on GitHub Actions or AppVeyor. One can run WSLv2 in CI using an image or a custom GitHub Action.