Skip to main content

1.2 Setup and Virtual Environments

A reliable Python setup starts with a local interpreter and a project-scoped virtual environment.

Install and verify Python​

Use an official Python 3 installation, then verify from terminal:

python3 --version

Create a virtual environment​

Official command:

python3 -m venv .venv

This creates an isolated environment containing:

  • pyvenv.cfg
  • interpreter binaries (bin/ on POSIX, Scripts/ on Windows)
  • local site-packages

Activate and use​

source .venv/bin/activate
python --version

You can also run without activation by calling the interpreter directly:

./.venv/bin/python script.py

Install packages​

python -m pip install <package>
python -m pip freeze > requirements.txt

Key official guidance​

  • Virtual environments are disposable and should be recreated when moved.
  • They should not be committed to source control.
  • Use sys.prefix != sys.base_prefix to detect active venv runtime.

Official references​