代码合并的时候，有时候合并后发现合并错了，需要回滚或重置
回滚merge其实有两种方式，一种是
revert
，一种是
reset
环境准备
构造一个已经merge的分支，并准备撤销/回滚刚才的merge
mkdir git-revert-merge-commit
cd git-revert-merge-commit
git init
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echo 'file1' > file1
git add . && git commit -m 'commit 1'
echo 'file2' > file2
git add . && git commit -m 'commit 2'
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从master创建分支feature并提交两个新的commit
git checkout -b feature
echo 'file3' > file3
git add . && git commit -m 'feature - commit 1'
echo 'file4' > file4
git add . && git commit -m 'feature - commit 2'
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切换回master后再提交两个commit，这时候master和feature是不能fast-forword了
git checkout master
echo 'file5' > file5
git add . && git commit -m 'commit 3'
echo 'file6' > file6
git add . && git commit -m 'commit 4'
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git checkout master
git merge feature
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假如这个时候发现合并错误，想撤销/回滚，下面就分别看一下revert和reset怎么操作 *
revert
revert的原理实际上就是提交一个反向变更，低消之前的变更。revert会保留所有的操作记录，历史变更和revert变更都会保存在历史中，可以从git log中看到
➜ git-revert-merge-commit git:(master) git revert d904008
error: commit d904008ec11d364b674a720a9755bd5e247903fe is a merge but no -m option was given.
fatal: revert failed
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回滚失败
no -m option was given
，这是因为merge是把两个分支合并到一起，回滚的话，就必须告诉git需要回滚到哪个个分支
commit d904008ec11d364b674a720a9755bd5e247903fe (HEAD -> master)
Merge: dd542b2 18b2194
Author: timxia <timxia@tencent.com>
Date: Wed Jun 9 13:29:10 2021 +0800
Merge branch 'feature'
commit dd542b2a254a27d1704fe4f9317fef7e3d99b2cb
Author: timxia <timxia@tencent.com>
Date: Tue Jun 8 20:01:41 2021 +0800
commit 4
commit 99acb1f6ddfbd2cdc2bb4a9e1073176c4d1a55e2
Author: timxia <timxia@tencent.com>
Date: Tue Jun 8 20:01:41 2021 +0800
commit 3
commit 18b2194719103f2917960268683b4d052b2eeec3 (feature)
Author: timxia <timxia@tencent.com>
Date: Tue Jun 8 20:01:37 2021 +0800
feature - commit 2
#省略了其他的commit...
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从log(
Merge: dd542b2 18b2194
）中可以看出来，dd542b2(master)是1，18b2194(feature)是2
所以回滚到master的-m参数值是1，命令是
git revert d904008 -m 1
➜ git-revert-merge-commit git:(master) git revert d904008 -m 1
Removing file4
Removing file3
[master 2c32c27] Revert "Merge branch 'feature'"
2 files changed, 2 deletions(-)
delete mode 100644 file3
delete mode 100644 file4
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git log --pretty=oneline
## 结果如下
2c32c27231cdceee676286038e3551913d324a04 (HEAD -> master) Revert "Merge branch 'feature'"
d904008ec11d364b674a720a9755bd5e247903fe Merge branch 'feature'
dd542b2a254a27d1704fe4f9317fef7e3d99b2cb commit 4
99acb1f6ddfbd2cdc2bb4a9e1073176c4d1a55e2 commit 3
18b2194719103f2917960268683b4d052b2eeec3 (feature) feature - commit 2
1203202401c84cdc2defd589e958355ef0574662 feature - commit 1
759fb3f3c740764563ab11a03fdf5a3ad13ed9b9 commit 2
d7757c8fb1c65449d4e436b1c9bc575f79a01ce5 commit 1
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日志中可以看出来，虽然合并进来的分支内容都退回了，但是提交记录以及回滚记录都在
reset
是重置代码到历史某一个提交点
查看提交历史，可以看到merge和feature上的commit都没有了（这种方式一般感觉更加好一点，没有引入一些没有意义的提交）
git log --pretty=oneline
## 执行结果如下，可以看出来，合并的commit都没有了
dd542b2a254a27d1704fe4f9317fef7e3d99b2cb (HEAD -> master) commit 4
99acb1f6ddfbd2cdc2bb4a9e1073176c4d1a55e2 commit 3
