How can I make python 2.6 my default in Mac OS X Lion?

Question

I just upgraded to lion and with it came Python 2.7. I need to use 2.6 as my default python as the project I primarily work on uses 2.6.

Answer 1

Apple has provided two very simple ways to change the default python on OS X 10.6 Snow Leopard and 10.7 Lion. It's all detailed in the Apple man page for python(1):

$ man python
$ which python
/usr/bin/python
$ python -V
Python 2.7.1
#
# temporarily change version
#
$ export VERSIONER_PYTHON_VERSION=2.6
$ python -V
Python 2.6.6
$ unset VERSIONER_PYTHON_VERSION
$ python -V
Python 2.7.1
#
# persistently change version
#
$ defaults write com.apple.versioner.python Version 2.6
$ python -V
Python 2.6.6

Answer 2

After running the following:

defaults write com.apple.versioner.python Version 2.6

To make sure the packages you install with 'sudo' are installed for the correct Python version, also set the versioner option as a superuser:

sudo su
# Enter password
defaults write com.apple.versioner.python Version 2.6
exit