How to Properly Initialize Environment Variables with vcvarsall.bat in Python

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The Problem

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After executing this code, you might check your environment variables and find that they haven’t changed as expected. This leads to confusion: why are the variables not sticking?

The Solution: Proper Environment Initialization

It’s essential to understand that when you run a subprocess using Python, the environment set up by that subprocess is separate from the parent process. Here’s a more detailed breakdown of why that’s the case and how you can set up your environment correctly.

Why Environment Changes Don’t Persist

Isolated Subprocesses:

OS Behavior:

This behavior is intentional in operating systems to prevent scripts from unintentionally altering the environment of executing applications and the terminal.

Recommended Approach

Step 1: Set Up the Environment First

Step 2: Verify the Environment Variables

After running the batch file, you can verify if the environment variables have been set correctly by checking them in the command prompt:

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This will show the updated PATH with necessary Visual Studio paths included.

Step 3: Execute Your Python Script

Conclusion

By following these guidelines, you'll be able to leverage the full power of Visual Studio in your Python applications seamlessly. Happy coding!