Python isolated virtualenv scripts

pve.sh

function pve() {
    local pd=~/.python
    local env_name=$1
    if [[ -z ${env_name} ]]; then
        if [[ -z ${VIRTUAL_ENV} ]]; then
            echo "usage: pve{2,3} <envname>"
            return 1
        else
            deactivate
            return 0
        fi
    fi
    if [[ ! -e ${pd} ]]; then
        echo "${pd} not found"
        return 1
    fi
    local system_python=$2
    if [[ ! -f "${system_python}" ]]; then
        echo "no system python found"
        return 1
    fi
    pushd ${pd}
    if [[ ! -f virtualenv.py ]]; then
        curl -L -O https://raw.github.com/pypa/virtualenv/master/virtualenv.py
    fi
    if [[ ! -d ${env_name} ]]; then
        echo "installing virtualenv"
        ${system_python} virtualenv.py ${env_name} --no-setuptools
        if [[ ! -f get-pip.py ]]; then
            curl -L -O https://raw.github.com/pypa/pip/master/contrib/get-pip.py
        fi
        ${env_name}/bin/python ./get-pip.py
    fi
    echo "switching to existing Python environment ${env_name}"
    source "${env_name}/bin/activate"
    popd
}

function pve2() {
    local system_python
    if [[ -f `which python2` ]]; then
        system_python=`which python2`
    elif [[ -f `which python2.7` ]]; then
        system_python=`which python2.7`
    elif [[ -f `which python2.6` ]]; then
        system_python=`which python2.6`
    else
        echo "no system python2 found"
        return 1
    fi
    pve "$1" "${system_python}"
}

function pve3() {
    local system_python
    if [[ -f `which python3` ]]; then
        system_python=`which python3`
    elif [[ -f `which python3.5` ]]; then
        system_python=`which python3.5`
    else
        echo "no system python3 found"
        return 1
    fi
    pve "$1" "${system_python}"
}

Copy these functions into your shell startup script: .zshrc or .bash_profile.