Virtualenv - Python虚拟环境

$ pip install virtualenv
$ virtualenv --help

$ cd [venv_root]
# 建立虚拟环境
$ virtualenv myweb
# 启动虚拟环境
$ myweb/Scripts/activate
$ python
...
import flask
...
# 在虚拟环境中安装包
$ pip install flask
$ python
...
import flask
...
$ pip list
# 推出虚拟环境
$ deactivate

$ cd [venv_root]
$ virtualenv mydeep
$ mydeep/Scripts/activate
$ pip list
$ pip install numpy
$ python
...
import numpy
...
$ deactivate

$ cd [venv_root]
$ pip list
$ pip freeze > requirements.txt
$ type requirements.txt
$ virtualenv mydev
$ mydev/Scripts/activate
$ pip list
$ pip install -r requirements.txt
$ pip list
$ deactivate