Homebrew Python and writing to /Library/Python/2.7/site-packages/?

Question

Is there a definitive guide for how to install Homebrew's Python properly, along with pip, virtualenv, virtualenvwrapper etc.?

I've read the following pages:

https://github.com/mxcl/homebrew/wiki/Homebrew-and-Python
http://osxastrotricks.wordpress.com/2012/05/02/python-setup-with-homebrew/
http://skipperkongen.dk/2011/11/13/installing-django-in-virtual-environment-on-mac/
http://www.thisisthegreenroom.com/2011/installing-python-numpy-scipy-matplotlib-and-ipython-on-lion/
http://youshoulddoityourself.blogspot.com.au/2010/11/test.html

I have OSX 10.8 (Mountain Lion) DP3, and I installed the XCode Command Line Tools.

I also installed XQuartz as well, just in case (10.8 doesn't provide it).

I then ran:

brew install python  --universal --framework

I added the following to my ~/.bash_profile :

export PATH="/usr/local/bin:/usr/local/share/python:${PATH}"

I then ran:

sudo easy_install pip

which seemed to work.

I check where pip's installed:

 Victors-MacBook-Pro:~ victorhooi$ which pip
/usr/local/bin/pip

However, when I try to pip install packages, I get an error complaining about not being able to write to /Library/Python/2.7/site-packages:

running install_lib

creating /Library/Python/2.7/site-packages/yolk

error: could not create '/Library/Python/2.7/site-packages/yolk': Permission denied

----------------------------------------
Command /usr/bin/python -c "import  setuptools;__file__='/Users/victorhooi/build/yolk/setup.py';exec(compile(open(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --single-version-externally-managed --record /var/folders/gg/m37t1rkx4zj7z54ls487jfc40000gn/T/pip-ap7LSB-record/install-record.txt failed with error code 1 in /Users/victorhooi/build/yolk
Storing complete log in /Users/victorhooi/Library/Logs/pip.log

My understanding was that Homebrew's Python would install into it's own site-packages, and I wouldn't need to do weird chown's all over the filesystem tree to get things to work?

Cheers, Victor

Answer 1

Meanwhile, homebrew's python has evolved:

• Python installed via brew no longer tries to write to /Library/Python .
• Homebrew's Python now always uses its own site-packages.
• pip (and distribute) is installed automatically.
• The "--framework" option is not needed. Homebrew defaults to it now.
• XQuartz is needed (unfortunately) because the Tk headers link to X11 headers.

Your PATH in the .bashrc is correct (and still needed).

Answer 2

Please, as someone who has been exactly where you are, start using virtual environments first, then pip and the rest. They are awesome, and will solve this and many future problems.

Answer 3

Now that there is Mountain Lion 10.8.2 out and I had a legacy Python 2.7 install from Lion things just didn't work. Whatever I tried, Python wanted to access /Library/.. No good. The easy solution is to brew uninstall python and then brew install python That solves pretty much all Python related problems with homebrew on ML.