Run a single command in a virtualenv (using virtualenvwrapper)

justonce.sh

function justonce(){
    E_BADARGS=65

    if [ $# -lt 2 ]
    then
      echo "Usage: `justonce <envname> <command>`"
      exit $E_BADARGS
    fi
    workon $1
    shift
    $*
    deactivate
}