1.Install
Arch 下默认是 python3, 而如果强制用软链接改为 python2 的话，一些程序会有问题的，之前都是小脚本，所以手动把第一行改为 #!/usr/bin/env python2 或者 #!/usr/bin/python2 就行，现在要做 GAE 发现手动改了好多还是不行，于是便有了 Python virtualenv 等。
Install virtualenv virtualenvwrapper and pip
# pacman -S python2-virtualenv
# pacman -S python2-virtualenvwrapper
# pacman -S python2-pip
2.Configure
Add the following lines to the ~/.bashrc or ~/.zshrc
export WORKON_HOME=~/.virtualenvs
source /usr/bin/virtualenvwrapper.sh
Then run
mkdir $WORKON_HOME
source ~/.zshrc # or ~/.bashrc
Or manually perform the following operation
export WORKON_HOME=~/.virtualenvs
mkdir $WORKON_HOME
source /usr/bin/virtualenvwrapper.sh
3.Basic Usage
Create a virtualenv:
mkvirtualenv -p python2.7 --no-site-packages hello
We can see:
Running virtualenv with interpreter /usr/bin/python2.7
New python executable in hello/bin/python2.7
Also creating executable in hello/bin/python
Installing setuptools............................done.
Installing pip...............done.
We can see them in ~/.virtualenvs/hello
and find (hello) in the Prompt. It means we already activate the virtualenv.
Then we could do something we want, like install some package inside the virtualenv (like, Django):
(hello)$ pip install django
We could use deactivate to leave the virtualenv.
But we also could virtualenv any directory you want, for instance:
cd ~/gae
mkdir test
virtualenv2 -p python2.7 --no-site-packages test
then we could activate the virtualenv.
cd test
source bin/activate
then we could do something we want, like install some package inside the virtualenv (like, Django):
(hello)$ pip install django
Finally, we could similarly use deactivate to leave the virtualenv.
4.Virtualenvwrapper
We could use Virtualenvwrapper activate a virtualenv:
$ workon hello
The hello is a virtualenv directory in the $WORKON_HOME(~/.virtualenvs).
所以我们可以在 $WORKON_HOME(~/.virtualenvs) 中做个软链接，然后就能用 workon 命令激活
cd ~/.virtualenvs
ln -s ~/gae/test .
workon test
如果频繁切换，容易搞混的话，可以用下面命令来查看自己所处的环境
which pip
which python
which python2
which python3 # and so on
5.Summary
一般来说，一个虚拟环境就放在 $WORKON_HOME 就好了，不要和要做的项目工程的源码放在一起，配置好之后就相当于一个稳定的环境了，用的时候切换过去就行了。