pip安装后virtualenvwrapper.sh在哪里？

I'm trying to setup virtualenvwrapper on OSX, and all the instructions and tutorials I've found tell me to add a source command to .profile, pointing towards virtualenvwrapper.sh. I've checked all the python and site-packages directories, and I can't find any virtualenvwrapper.sh. Is this something I need to download separately? Is pip not installing correctly?I'm trying to setup virtualenvwrapper on OSX, a