Bootstrapping virtualenv and virtualenvwrapper on Mac OS X

When I upgraded my iMac to Mac OS X 10.8 Mountain Lion it upgraded Python to 2.7.2, which is nice, but also lost my site-specific changes—such as the installation of pip, virtualenv and virtualenvwrapper. These three basic tools allow me to create isolated Python installations and install packages in to them. So it was time to try to work out the neatest way to get things set up again.

Here’s the cribsheet for installing virtualenvwrapper (where $ is standing in for your shell prompt):

$ curl | sudo python
$ curl | sudo python
$ sudo pip install virtualenv virtualenvwrapper

Now, if I had not already done this, I would need to wire virtualenvwrapper in to my shell as follows:

$ mkdir ~/virtualenvs
$ cat >> ~/.profile
export WORKON_HOME=~/virtualenvs
. /usr/local/bin/

The cat command is a substitute for editing your .profile file by hand to add those two lines. Very important to type >> rather than > if you actually use this command.

I want to use the latest version of Python so I also need to do this (having previously installed HomeBrew):

$ brew install python
$ brew link python

Now to create a virtual environment for a project called, say, creosoteelephant, I would do

$ mkvirtualenv --python=/usr/local/bin/python2.7 --distribute creosoteelephant
$ echo cd ~/Projects/creosoteelephant >> ~/virtualenvs/creosoteelephant/bin/postactivate

The second line assumes my arrangement, which is to have a Projects folder in my home directory containing all my projects.