Use in place of `workon`. Put it in ~/bin.

inve

#!/bin/sh
ENV="$1"
shift 1

VIRTUAL_ENV="${WORKON_HOME}/${ENV}"
if [ ! -f "${VIRTUAL_ENV}/bin/python" ]; then
    echo "No virtualenv named '$ENV'."
    exit 2
fi

# Activate
export VIRTUAL_ENV="$VIRTUAL_ENV"
export PATH="$VIRTUAL_ENV/bin:$PATH"
unset PYTHON_HOME
exec "${@:-$SHELL}"