Virtual environments

Using Python virtual environments

To create a virtual environment that uses a particular Python executable, assuming that Python executable is /usr/bin/python, run:

/usr/bin/python -m venv /path/for/new/venv

To start using it, run:

. /path/for/new/venv/bin/activate

Virtualenv and virtualenvwrapper

Virtualenvwrapper adds some helpful shell aliases, but some of them do assume all your venvs are under one directory, which is ~/.virtualenvs by default. Still, a few of the aliases work anytime a venv has been activated.

Virtualenvwrapper needs virtualenv installed. It’s probably simplest to install both of them using your system packages, e.g. for ubuntu:

sudo apt-get install python3-virtualenv virtualenvwrapper

That puts the files on your system, but there’s one more step to make it work - you need to activate it in your ~/.bashrc:

. /usr/share/virtualenvwrapper/

If when you open a new shell, you get an error like:

/home/dpoirier/.pythonz/pythons/CPython-3.9.0/bin/python: Error while finding module specification for 'virtualenvwrapper.hook_loader'
(ModuleNotFoundError: No module named 'virtualenvwrapper') There was a problem running the initialization hooks.

If Python could not import the module virtualenvwrapper.hook_loader,
check that virtualenvwrapper has been installed for
VIRTUALENVWRAPPER_PYTHON=/home/dpoirier/.pythonz/pythons/CPython-3.9.0/bin/python and that PATH is
set properly.

then before loading, set an env var VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3:

export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3 . /usr/share/virtualenvwrapper/

Aliases that only work for venvs under ~/.virtualenvs

Now if you want to create and activates a new env under ~/.virtualenvs:

mkvirtualenv envname

switch to ~/.virtualenvs/envname2:

workon envname2

List all of the environments:


Show the details for a single virtualenv:


delete a virtual env (must deactivate first):


Aliases that work anytime a venv is active

no longer work with a virtual env:


uninstall all the packages from the current venv: