install virtualenv

$ [sudo] pip install virtualenv

$ mkdir ~/envs

$ virtualenv ~/envs/lsbaws/

$ cd ~/envs/lsbaws/

$ ls

bin  include  lib

$ source bin/activate

(lsbaws) $ pip install pyramid

(lsbaws) $ pip install flask

(lsbaws) $ pip install django

退出当前虚拟环境

deactivate