I am looking for a way on Windows how to set an environment variable dependent on another one. In my case, I want to add the new path to PYTHONPATH. Let's say, that there is an existing environment variable
%INSTALLATION_DIR% = D:\Programs\MyProject
The easiest way to do that would be:
SETX PYTHONPATH "%PYTHONPATH%;%INSTALLATION_DIR%\Utility\Scripts"
But then, %INSTALLATION_DIR% is directly replaced by D:\Programs\MyProject, so PYTHONPATH is not updated if %INSTALLATION_DIR% changes.
Is there a way to write the text %INSTALLATION_DIR% into an environment variable, without evaluating the variable directly?
If possible, I want to do that in an automated way (so using the console, powershell or python), as a want to write a script which adds a list of paths to PYTHONPATH.