小众GIT

1、git reflog: 操作记录，找回reset等误操作

2、git rebase --todo

3、git submodule:

参考：https://codewinsarguments.co/2016/05/01/git-submodules-vs-git-subtrees/

a. 解决了什么问题
需要用到公共类库 library
类库特点：业务相关&公用
即有与业务代码一起开发的需要（为什么不用npm：npm包需要频繁发包更新版本），又要在多个项目中可共用

参考：http://www.ayqy.net/blog/%E7%90%86%E8%A7%A3git-submodules/

b. 对比subtree：

简而言之：

• Submodules are easier to push but harder to pull – This is because they are pointers to the original repository
• Subtrees are easier to pull but harder to push – This is because they are copies of the original repository

分开来讲：

• Submodules：
  适用：
  Need to push frequently
  本质：
  a submodule is nothing but a pointer to a specific commit in an external repository
  **issues: **
  1.Changes to the parent could be committed and pushed without having committed and pushed the changes to the submodule. （to commit&push sub+commit&push super）
  2.If a collaborator has modified and pushed changes to a submodule but you haven’t run git submodule update to update the submodule on your machine to their latest version, you may run git add -A and downgrade to your out of date version.( to git submodule update )
  issue eg：

Git commit sub（without push）
git commit&push super
// Clone repo: 
Git pull super
git submodule update

without push subproject
golden rule
Always commit and push the submodule changes first, before then committing the submodule change in the parent repository.
Tips:
If you define an alias which runs git submodule update after every single git pull then you will be safe, but a newbie is unlikely to do this.

• Subtree：
  适用：No need to push ( then why not npm? npm不提供源码细节 )
  注意：there will be nothing in the dir to indicate that the folder ever came from another git repository.
  issues：
  1.So slow in a large repository on Windows
  2.very little documentation