Python Virtual Environments (venv) on Windows and Linux (2026)

Python Virtual Environments

If you install Python packages globally, things break sooner or later. One project needs a newer version, another needs an older one, and you end up fighting pip instead of writing code. Virtual environments solve this by keeping dependencies local to each project.

This post shows how to set one up and use it in a way that won’t get in your way later.

Install Python and venv

Make sure Python, pip, and the venv module are installed.

Linux (Debian/Ubuntu)

sudo apt update
sudo apt install python3 python3-venv python3-pip -y

Most systems already have Python, but python3-venv is sometimes missing.

Windows

Download and install Python from https://www.python.org/downloads/

During installation:

• Check “Add Python to PATH”
• Leave the rest as defaults

Verify installation:

python --versionpip --version

Create a project directory

Keep each project in its own folder. Put the virtual environment inside it.

mkdir -p ~/my_python_project
cd ~/my_python_project

Windows equivalent

mkdir my_python_project
cd my_python_project

The name doesn’t matter. The structure does.

Create the virtual environment

Create a virtual environment called venv:

python3 -m venv venv

Windows

python -m venv venv

This creates a venv/ directory with its own Python and pip. Anything installed here stays here.

Activate the environment

Linux / macOS

source venv/bin/activate

Windows (PowerShell)

venv\Scripts\Activate.ps1

Windows (Command Prompt)

venv\Scripts\activate.bat

You’ll see (venv) in your shell prompt. That’s how you know it’s active.

From this point on, pip install only affects this project.

Install packages

pip install --upgrade pip
pip install flask requests

Install whatever your project needs. It won’t touch system Python.

If you already have a requirements file:

pip install -r requirements.txt

Deactivate when you’re done

deactivate

That’s it. You’re back to the system environment.

Saving dependencies

When the project is in a good state, save the package list:

pip freeze > requirements.txt

To rebuild the environment later:

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

Windows rebuild

python -m venv venv
venv\Scripts\Activate.ps1
pip install -r requirements.txt

This works the same on another machine or server.

Important note (Windows only)

If PowerShell blocks activation scripts, run once as admin:

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser