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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.

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