Somehow my PYTHONPATH environment variable got emptied, and now I can't import some downloaded modules. I've tried running the following command to reinstall all Python packages, but it didn't set the variable back to its original value: dpkg-query -W -f '${package}\n' | grep python | xargs -I % sudo apt-get install % --reinstall How do I reinstall the packages so that this gets sorted out? The (Vagrant) box is running Ubuntu 12.04.