I can't find the answer on this page:
https://nim-lang.org/docs/os.html
This module contains basic operating system facilities like retrieving environment variables, reading command line arguments, working with directories, running shell commands, etc.
Thanks, Mark
I typically use DevDocs or TheIndex to search for such stuff.
The answer is ospaths: https://nim-lang.org/docs/ospaths.html#getEnv,string,string.