If you have tried to install psycopg2 (Postgresql support for python) which is used by the popular sqlalchemy framework under virtualenv you will end up with something like this (python-keygrabber-env)goshawk@cacserver:~/python-keygrabber-env/aranciulla/keygrabber$ pip install psycopg2 Downloading/unpacking psycopg2 Running setup.py egg_info for package psycopg2 Error: pg_config executable not fou