Python Virtual Environments

Last updated 2026-08-20 · 3 notes · 3 tags

Tags: python venv packages

A virtual environment (“venv”) is a private folder of Python packages for one project. That way Project A and Project B can use different package versions without breaking each other.

Note: Create the venv inside the project folder. Activate it whenever you work on that project.

Create

From your project folder:

cd ~/projects/your-project
python3 -m venv venv

Activate (Linux / WSL / macOS)

source venv/bin/activate

Your prompt usually shows (venv) when it is active.

Deactivate

deactivate

Install a package

With the venv active:

pip install package-name

Save and reinstall requirements

pip freeze > requirements.txt
pip install -r requirements.txt

Note: Commit requirements.txt to Git so another machine can recreate the same packages. Do not commit the whole venv/ folder (add venv/ to .gitignore).

Why not install everything globally?

Global installs clutter your system Python and make “it works on my machine” problems more likely.

Note: CLI tools you want available everywhere are a better fit for pipx (see WSL on Windows or Native Linux). Libraries for a project belong in that project’s venv.

Common mistakes

If pip install seems to hit the wrong Python, check that the venv is activated.
Each new terminal starts deactivated — run source venv/bin/activate again.
These commands are for Linux / WSL Bash. Windows PowerShell uses a different activate script.

This project captures ideas, decisions, and lessons I’ve learned while building with AI. It aims to help non-technical users understand and use these tools effectively. I also use AI at times to improve or refine the content.

Readers should use the commands and instructions here with care. The creator accepts no responsibility for system damage, data loss or other consequences resulting from their use.

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