Getting started¶

This tutorial will teach you the basics of virtualenv through hands-on practice. You’ll create your first virtual environment, install packages, and learn how to manage project dependencies.

Prerequisites¶

Before starting this tutorial, you need:

Python 3.9 or later installed on your system. If you use a version manager like pyenv, mise, or asdf, virtualenv will automatically discover the Python version they manage.
virtualenv installed (see Install virtualenv).

Create your first virtual environment¶

Let’s create a virtual environment called myproject:

$ virtualenv myproject
created virtual environment CPython3.13.2.final.0-64 in 200ms
  creator CPython3Posix(dest=/home/user/myproject, clear=False, no_vcs_ignore=False, global=False)
  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, via=copy, app_data_dir=/home/user/.cache/virtualenv)
  activators BashActivator,CShellActivator,FishActivator,NushellActivator,PowerShellActivator,PythonActivator

This creates a new directory called myproject containing a complete, isolated Python environment with its own copy of Python, pip, and other tools.

The interpreter answers to several names, so a script expecting any of them keeps working inside the environment:

$ ls myproject/bin/python*
myproject/bin/python  myproject/bin/python3  myproject/bin/python3.13

Environment layout lists the full set, which differs on Windows.

Activate the environment¶

To use your virtual environment, you can activate it. The activation command differs by platform:

Linux/macOS

$ source myproject/bin/activate

Windows (PowerShell)

PS> .\myproject\Scripts\Activate.ps1

Windows (CMD)

C:\> .\myproject\Scripts\activate.bat

After activation, your prompt changes to show the active environment:

(myproject) $

You can verify that Python is now running from inside the virtual environment:

Linux/macOS

(myproject) $ which python
/home/user/myproject/bin/python

Windows (PowerShell)

(myproject) PS> where.exe python
C:\Users\user\myproject\Scripts\python.exe

Windows (CMD)

(myproject) C:\> where.exe python
C:\Users\user\myproject\Scripts\python.exe

Install a package¶

With the environment activated, install a package using pip:

(myproject) $ pip install requests
Collecting requests
  Using cached requests-2.32.3-py3-none-any.whl (64 kB)
Installing collected packages: requests
Successfully installed requests-2.32.3

Verify that the package is installed only inside your virtual environment:

(myproject) $ python -c "import requests; print(requests.__file__)"
/home/user/myproject/lib/python3.13/site-packages/requests/__init__.py

The path shows that requests is installed in the virtual environment, not in your system Python.

Deactivate¶

When you’re done working in the virtual environment, deactivate it:

(myproject) $ deactivate
$

The prompt returns to normal, and Python commands now use your system Python again.

Use without activation¶

Activation is a convenience, not a requirement. You can run any executable from the virtual environment directly by using its full path:

Linux/macOS

$ myproject/bin/python -c "import sys; print(sys.prefix)"
/home/user/myproject

$ myproject/bin/pip install httpx

Windows (PowerShell)

PS> .\myproject\Scripts\python.exe -c "import sys; print(sys.prefix)"
C:\Users\user\myproject

PS> .\myproject\Scripts\pip.exe install httpx

Windows (CMD)

C:\> .\myproject\Scripts\python.exe -c "import sys; print(sys.prefix)"
C:\Users\user\myproject

C:\> .\myproject\Scripts\pip.exe install httpx

This is especially useful in scripts, CI pipelines, and automation where modifying the shell environment is unnecessary.

Set up a real project¶

Now let’s apply what you’ve learned to a real project workflow:

$ mkdir myapp && cd myapp
$ virtualenv venv
$ source venv/bin/activate  # or use the appropriate command for your platform
(venv) $ pip install flask requests
(venv) $ pip freeze > requirements.txt

The requirements.txt file now contains your project’s dependencies:

blinker==1.9.0
certifi==2025.1.31
charset-normalizer==3.4.1
click==8.1.8
flask==3.1.0
idna==3.10
itsdangerous==2.2.0
Jinja2==3.1.5
MarkupSafe==3.0.2
requests==2.32.3
urllib3==2.3.0
werkzeug==3.1.3

This file lets you recreate the exact environment later. Let’s test this:

(venv) $ deactivate
$ rm -rf venv
$ virtualenv venv
$ source venv/bin/activate
(venv) $ pip install -r requirements.txt

All packages are reinstalled exactly as before. Here’s the complete workflow:

        graph TD
    A[Create virtual environment] --> B[Activate]
    B --> C[Install packages]
    C --> D[Freeze to requirements.txt]
    D --> E[Deactivate & clean up]
    E --> F[Recreate virtual environment]
    F --> G[Install from requirements.txt]
    G --> H[Ready to work]

    style A fill:#2563eb,stroke:#1d4ed8,color:#fff
    style B fill:#6366f1,stroke:#4f46e5,color:#fff
    style C fill:#6366f1,stroke:#4f46e5,color:#fff
    style D fill:#6366f1,stroke:#4f46e5,color:#fff
    style E fill:#d97706,stroke:#b45309,color:#fff
    style F fill:#6366f1,stroke:#4f46e5,color:#fff
    style G fill:#6366f1,stroke:#4f46e5,color:#fff
    style H fill:#16a34a,stroke:#15803d,color:#fff

What you learned¶

In this tutorial, you learned how to:

Create a virtual environment with virtualenv.
Activate and deactivate virtual environments on different platforms.
Install packages in isolation from your system Python.
Save project dependencies with pip freeze.
Reproduce environments using requirements.txt.

Next steps¶

Now that you understand the basics, explore these topics:

Use virtualenv for selecting specific Python versions, configuring defaults, and advanced usage patterns.
Explanation for understanding how virtualenv works under the hood and how it compares to venv.
Command line for all available command line options and flags.