下面以现实场景作为情境。

基础知识，理解git中的几个区域

本地代码已经add，未commit

修改本地工作目录中的readme.md,添加文字"第一次修改"

然后查看下状态

➜  experimentation git:(master) ✗ git status

On branch master

Your branch is up-to-date with 'origin/master'.

Changes not staged for commit:

  (use "git add <file>..." to update what will be committed)

  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

进行Add操作,并查看状态

➜  experimentation git:(master) ✗ git add README.md

➜  experimentation git:(master) ✗ git status

On branch master

Your branch is up-to-date with 'origin/master'.

Changes to be committed:

  (use "git reset HEAD <file>..." to unstage)

        modified:   README.md

➜  experimentation git:(master) ✗

这时候，变动进入了缓存区(Index)

但是我们突然发现我们改动错了，其实我是想改动experimentation.txt文件。

方法一：我们当然可以再次修改experimentation和readme文件（删除readme中的修改，给experimentation中添加“第一次修改”），然后再Add

方法二：我们想的可能是撤回之前的add操作，然后给experimentation中添加“第一次修改”，然后再次Add,那这样的话，我们如何操作呢？

• 撤销某个add文件:git reset HEAD <filename>

• 撤销全部add文件:git reset HEAD .

➜  experimentation git:(master) ✗ git reset HEAD README.md

Unstaged changes after reset:

M       README.md

➜  experimentation git:(master) ✗ git status

On branch master

Your branch is up-to-date with 'origin/master'.

Changes not staged for commit:

  (use "git add <file>..." to update what will be committed)

  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

本地代码已经add，已commit

将本地代码多commit几次,再来看下我们的提交log

• 方法一(推荐)：执行git revert <commitId>

撤回到指定的版本，包括文件和状态。

• 方法二：执行git reset <commitId>

➜  experimentation git:(master) git reset 2a6c701

Unstaged changes after reset:

M       experimentation.txt

➜  experimentation git:(master) ✗ git status

On branch master

Your branch and 'origin/master' have diverged,

and have 4 and 6 different commits each, respectively.

  (use "git pull" to merge the remote branch into yours)

Changes not staged for commit:

  (use "git add <file>..." to update what will be committed)

  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   experimentation.txt

no changes added to commit (use "git add" and/or "git commit -a")

回退至指定的版本，区别如下