Python Virtual Environment Mangement

First, two packages:

pip3 install virtualenv
pip3 install virtualenvwrapper

virtualenv makes one can create new virtual environment conveniently, like:

virtualenv new_env

and a new directory named new_env will be created under the current directory.

virtualenvwrapper is a wrapper of virtualenv, which allows one to manage virtual environments.

It supplies some commands:

• mkvirtualenv: create a new virtual env
• rmvirtualenv: remove a certain virtual env
• workon: active or switch virtual env
• deactivate: deactivate or exit the virtual env
• lsvirtualenv: list all available virtual env

To enjoy the wrapper, put

export WORKON_HOME='~/.virtualenvs'
source `which virtualenvwrapper.sh`

into your favorite shell init file, such as .zshrc, .bashrc, and then all virtual environments created would be managed under the ~/.virtualenvs directory.

Sometimes, you should specify which python interpreter is used by

export VIRTUALENVWRAPPER_PYTHON='/usr/bin/python3'

Because the virtualenvwrapper.sh will find your python rather than python3

# Locate the global Python where virtualenvwrapper is installed.
if [ "${VIRTUALENVWRAPPER_PYTHON:-}" = "" ]
then
    VIRTUALENVWRAPPER_PYTHON="$(command \which python)"
fi

But python sometimes refers to python2 or just not exists, such as that on Ubuntu.

Similarly if you want to use the wrapper in python2.