# Python VirtualEnv

virtualenv is a Python tool written by Ian Bicking and used to create isolated environments for Python in which you can install packages without interfering with the other virtualenvs nor with the system Python's packages. The present article covers the installation of the virtualenv package and its companion command line utility virtualenvwrapper designed by Doug Hellmann to (greatly) improve your work flow. A quick how-to to help you to begin working inside virtual environment is then provided.

## Virtual Environments at a glance

virtualenv is a tool designated to address the problem of dealing with packages' dependencies while maintaining different versions that suit projects' needs. For example, if you work on two Django web sites, say one that needs Django 1.2 while the other needs the good old 0.96. You have no way to keep both versions if you install them into /usr/lib/python2/site-packages . Thanks to virtualenv it's possible, by creating two isolated environments, to have the two development environment to play along nicely.

vitualenvwrapper takes virtualenv a step further by providing convenient commands you can invoke from your favorite console.

## Virtualenv

virtualenv supports Python 2.6+ and Python 3.x.

### Installation

Simply install from the community repository:

    # pacman -S python2-virtualenv

or

    # pacman -S python-virtualenv

### Basic Usage

An extended tutorial on how use virtualenv for sandboxing can be found here. If the link does not work, try the archive link

The typical use case is:

- Create a folder for the new virtualenv:

    $ mkdir -p ~/.virtualenvs/my_env

- Create the virtualenv:

    $ virtualenv2 ~/.virtualenvs/my_env

- Activate the virtualenv:

    $ source ~/.virtualenvs/my_env/bin/activate

- Install some package inside the virtualenv (say, Django):

    (my_env)$ pip install django

- Do your things
- Leave the virtualenv:

    (my_env)$ deactivate

## Virtualenvwrapper

virtualenvwrapper allows more natural command line interaction with your virtualenvs by exposing several useful commands to create, activate and remove virtualenvs. This package is a wrapper for both python-virtualenv and python2-virtualenv.

### Installation

Install the python-virtualenvwrapper package from the official repositories.

Now add the following lines to your `~/.bashrc`:

    export WORKON_HOME=~/.virtualenvs
    source /usr/bin/virtualenvwrapper.sh

If you are not using python3 by default (check the output of `$ python --version`) you also need to add the following line to your `~/.bashrc` prior sourcing the `virtualenvwrapper.sh` script. The current version of the `virtualenvwrapper-python` package only works with python3. It can create python2 virtualenvs fine though.

    VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3

Re-open your console and create the `WORKON_HOME` folder:

    $ mkdir $WORKON_HOME

### Basic Usage

The main information source on virtualenvwrapper usage (and extension capability) is Doug Hellmann's page.

- Create the virtualenv:

    $ mkvirtualenv -p /usr/bin/python2.7 my_env

- Activate the virtualenv:

    $ workon my_env

- Install some package inside the virtualenv (say, Django):

    $ (my_env)$ pip install django

- Do your things
- Leave the virtualenv:

    (my_env)$ deactivate

## See Also

- virtualenv Pypi page
- Tutorial for virtualenv
- virtualenvwrapper page at Doug Hellmann's

Category:

- Development