Virtual environments are really useful for maintaining different packages and for separating different environments without getting your system messy. In this post I will go over some of the various virtual environment tricks that I seem to always forget if I haven’t worked with Python in awhile.
This post is meant to be mostly a reference for remembering commands and syntax and other helpful notes. I’d also like to mention that these steps were all tested on OSX, I haven’t tried on Windows so don’t know if it is any different.
Working with virtual environments
There are a few pieces in order to get to get started. First, the default version of Python that ships with OSX is 2.7, which is slowly moving towards extinction. Unfortunately, it isn’t exactly obvious how to replace this version of Python on OSX.
Just doing a “brew install python” won’t actually point the system at the newly installed version. In order to get Python 3.x working correctly, you need to update the system path and place Python3 there.
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
You will want to put the above line into your bashrc or zshrc (or whatever shell profile you use) to get the brew installed Python onto your system path by default.
Another thing I discovered – in Python 3 there is a built in command for creating virtual environments, which alleviates the need to install the virtualenv package.
Here is the command in Python 3 the command to create a new virtual environment.
python -m venv test
Once the environment has been created, it is very similar to virtualenv. To use the environment, just source it.
source test/bin/activate
To deactivate the environment just use the “deactivate” command, like you would in virutalenv.
The virtualenv package
If you like the old school way of doing virtual environments you can still use the virtualenv package for managing your environments.
Once you have the correct version of Python, you will want to install the virtualenv package on your system globally in order to work with virtual environments.
sudo pip install virtualenvwrapper
You can check to see if the package was installed correctly by running virtualenv -h. There are a number of useful virtualenv commands listed below for working with the environments.
Make a new virtual env
mkvirtualenv test-env
Work on a virtual env
workon test-env
Stop working on a virtual env
(when env is actiave) deactive
List environments
lsvirtualenv
Remove a virtual environment
rmvirtualenv test-env
Create virtualenv with specific version of python
mkvirtualenv -p $(which pypy) test2-env
Look at where environments are stored
ls ~/.virtualenvs
I’ll leave it here for now. The commands and tricks I (re)discovered were enough to get me back to being productive with virtual environments. If you have some other tips or tricks feel free to let me know. I will update this post if I find anything else that is noteworthy.
