Change source of pip

Some times,we need to change source of pip.We can just get it by:

[global]
index-url = https://pypi.tuna.tsinghua.edu.cn/simple

Where [global] means apply source to any action(such as install) of pip.Then add this to /user/.pip/pip.conf,the corresponding user can use the source. So,if you run sudo pip you need add .pip/pip.conf to root dir.