Error message for virtualenvwrapper on OS X Lion

Question

I've used homebrew to install python on a new Mac Lion installation, and have been trying to install virtualenv and virtualenvwrapper with pip, but when I start a new terminal session, I get this traceback:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: No module named virtualenvwrapper.hook_loader
virtualenvwrapper.sh: There was a problem running the initialization hooks. 

If Python could not import the module virtualenvwrapper.hook_loader,
check that virtualenv has been installed for
VIRTUALENVWRAPPER_PYTHON=/usr/bin/python and that PATH is
set properly.

The python and pip used are from homebrew, but it seems to want me to use Apple's default python. I get the following

~$ which python | xargs ls -l
lrwxr-xr-x  1 beard  admin  33 Jun 24 16:11 /usr/local/bin/python -> ../Cellar/python/2.7.3/bin/python
~$ echo $VIRTUALENVWRAPPER_PYTHON
/usr/local/bin/python
~$ which pip | xargs ls -l
-rwxr-xr-x  1 beard  admin  301 Jun 24 16:18 /usr/local/share/python/pip
~$ which virtualenvwrapper.sh | xargs ls -l
-rwxr-xr-x  1 beard  admin  32227 Jun 24 16:19 /usr/local/share/python/virtualenvwrapper.sh

However, it seems to think that I've installed pip (and virtualenv) with the system python in /usr/bin/python

Edit: In my bashrc--

export WORKON_HOME="$HOME/py-env"
export VIRTUALENVWRAPPER_LOG_DIR="$HOME/py-env"
export VIRTUALENVWRAPPER_HOOK_DIR="$HOME/py-env"
source /usr/local/share/python/virtualenvwrapper.sh
export VIRTUALENVWRAPPER_PYTHON="/usr/local/bin/python"

Answer 1

Since you have your own version of python, have you tried overriding VIRTUALENVWRAPPER_PYTHON? (It looks like you want export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python) The virtualenvwrapper docs suggest setting that envvar to the desired python before sourcing virtualenvwrapper.sh. Their example has:

export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python
export VIRTUALENVWRAPPER_VIRTUALENV=/usr/local/bin/virtualenv
source /usr/local/bin/virtualenvwrapper.sh

Answer 2

Add or change path into ~/.bash_profile for virtualenvwrapper.sh to /usr/local/share/python/virtualenvwrapper.sh

it should look like

export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python
export WORKON_HOME=$HOME/.virtualenvs

source /usr/local/share/python/virtualenvwrapper.sh

Answer 3

I ran into similar problems with Hombrew-installed Python conflicting with the system-installed Python under OS X Lion. I was never able to correct the problem using Homebrew. However, when I switched to using pythonbrew (https://github.com/utahta/pythonbrew) to manage my installed Pythons (instead of Homebrew), I was able to run virtualenvwrapper successfully.

Answer 4

If your using PythonBrew & VirtualEnvBurrito with ZSH shell, make sure you check out your .zprofile - this contains some commands to execute the VirtualEnvBurrito startup script. As .zprofile is loaded before .zshrc the Python version is the system one. This will also throw up this error.