Git is a distributed version control system.
Git is free software distributed under the GPL.
Git has a mutable index called stage.
Git tracks changes of files.
Creating a new branch is quick and simple.


learn git by https://liaoxuefeng.com/books/git/introduction/index.html


解决 ssh connect to host github.com port 22 Connection timed out
https://www.cnblogs.com/weiweirui/p/17999855


out git log " q "