git的使用（二）git冲突解决和版本回退
版本回退
git reset——回溯历史版本
回到创建feature-A分支之前的master分支，创建一个名为fix-B的分支
首先查看当前分支图表
$ git log --graph
* commit a4dc01ab44706349cc7661e7b1c4315d1b6fd405 (HEAD -> master)
|\ Merge: 6ab6d6b 64aa165
| | Author: kingram <kingram@163.com>
| | Date: Wed Jul 28 18:55:42 2021 +0800
| |
| | Merge branch 'feature-A'
| |
| * commit 64aa16533ca53ae652aca4f6ce8227b7aabc4ad4 (feature-A)
|/ Author: kingram <kingram@163.com>
| Date: Wed Jul 28 18:44:46 2021 +0800
|
| add feature-A
|
* commit 6ab6d6b65bc4d28be5b571dbc01df81e2231effa
| Author: kingram <kingram@163.com>
| Date: Wed Jul 28 18:23:10 2021 +0800
|
| add index
|
* commit 7419956521d4a00e4fa35ec754946f6cdfce10cf
Author: kingram <kingram@163.com>
Date: Wed Jul 28 17:40:54 2021 +0800
first commit
通过这个命令可以看到创建feature-A分支前的时间点的hash值为6ab6d6b65bc4d28be5b571dbc01df81e2231effa，只要执行git reset --hard +hash就可以回到该hash对应的时间点
$ git reset --hard 6ab6d6b65bc4d28be5b571dbc01df81e2231effa
HEAD is now at 6ab6d6b add index
查看下README.md，还没有新建分支
$ cat README.md
# GIT测试
创建分支fix-B
$ git switch -c fix-B
Switched to a new branch 'fix-B'
$ git branch
feature-A
* fix-B
master
修改README.md，增加一行
# GIT测试
- fix-B
提交
$ git add README.md
$ git commit -m "fix B"
[fix-B 8d19107] fix B
1 file changed, 1 insertion(+)
查看下当前版本库的分支图表
$ git log --graph
* commit 8d191079fac23089ae61d916956dee27faaa4bc2 (HEAD -> fix-B)
| Author: kingram <kingram@163.com>
| Date: Wed Jul 28 20:05:25 2021 +0800
|
| fix B
|
* commit 6ab6d6b65bc4d28be5b571dbc01df81e2231effa (master)
| Author: kingram <kingram@163.com>
| Date: Wed Jul 28 18:23:10 2021 +0800
|
| add index
|
* commit 7419956521d4a00e4fa35ec754946f6cdfce10cf
Author: kingram <kingram@163.com>
Date: Wed Jul 28 17:40:54 2021 +0800
first commit
现在要做的就是将fix-B合并到master中，如图中红线标记。注意不是在当前状态直接合并，当前状态切换到master再合并fix-B就没有feature-A分支修改的内容了。
此时在历史记录中，版本库在创建feature-A前的时间点产生了两个分支，一个是feature-A的线，一个是fix-B的线，两条线其实是平行空间的，feature-A的线已经和master合并了，而fix-B的线还没有合并。
使用git reflog命令查看仓库操作日志，找到合并feature-A分支后的时间点的hash值
$ git reflog
8d19107 (HEAD -> fix-B) HEAD@{0}: commit: fix B
6ab6d6b (master) HEAD@{1}: checkout: moving from master to fix-B
6ab6d6b (master) HEAD@{2}: reset: moving to 6ab6d6b65bc4d28be5b571dbc01df81e2231effa
a4dc01a HEAD@{3}: merge feature-A: Merge made by the 'recursive' strategy.
6ab6d6b (master) HEAD@{4}: checkout: moving from feature-A to master
64aa165 (feature-A) HEAD@{5}: checkout: moving from master to feature-A
6ab6d6b (master) HEAD@{6}: checkout: moving from feature-A to master
64aa165 (feature-A) HEAD@{7}: commit: add feature-A
6ab6d6b (master) HEAD@{8}: checkout: moving from master to feature-A
6ab6d6b (master) HEAD@{9}: commit: add index
7419956 HEAD@{10}: commit (initial): first commit
可以看到merge feature-A的时间点的hash值为a4dc01a
先切换到master分支，再回退到a4dc01a时间点
$ git switch master
Switched to branch 'master'
$ git reset --hard a4dc01a
HEAD is now at a4dc01a Merge branch 'feature-A'
此时状态如图所示：
现在只要合并fix-B分支到master分支，就完成任务了，但是我们在feature-A分支中也是修改了README.md文件的，所以合并会产生冲突。
$ git merge fix-B
Auto-merging README.md
CONFLICT (content): Merge conflict in README.md
Automatic merge failed; fix conflicts and then commit the result.
CONFLICT中显示README.md文件产生了冲突，查看下文件
$ cat README.md
# GIT测试
<<<<<<< HEAD
- feature-A
=======
- fix-B
>>>>>>> fix-B
=======上面的是当前HEAD内容，下面是要合并的内容。修改如下
$ cat README.md
# GIT测试
- feature-A
- fix-B
解决冲突后提交一下文件
$ git add README.md
$ git commit -m "fixed conflict"
[master d521ac7] fixed conflict
git commit –amend——修改提交信息
上一条提交信息标记了为fix conflict，但其实是fix-B分支的合并，即：Merge branch 'fix-B'
查看git log
commit d521ac7386bc3aebd58d41c6420d29196751127a (HEAD -> master)
Merge: a4dc01a 8d19107
Author: kingram <kingram@163.com>
Date: Thu Jul 29 09:24:12 2021 +0800
fixed conflict
commit 8d191079fac23089ae61d916956dee27faaa4bc2 (fix-B)
Author: kingram <kingram@163.com>
Date: Wed Jul 28 20:05:25 2021 +0800
fix B
commit a4dc01ab44706349cc7661e7b1c4315d1b6fd405
Merge: 6ab6d6b 64aa165
Author: kingram <kingram@163.com>
Date: Wed Jul 28 18:55:42 2021 +0800
Merge branch 'feature-A'
commit 64aa16533ca53ae652aca4f6ce8227b7aabc4ad4 (feature-A)
Author: kingram <kingram@163.com>
Date: Wed Jul 28 18:44:46 2021 +0800
add feature-A
commit 6ab6d6b65bc4d28be5b571dbc01df81e2231effa
Author: kingram <kingram@163.com>
Date: Wed Jul 28 18:23:10 2021 +0800
add index
commit 7419956521d4a00e4fa35ec754946f6cdfce10cf
Author: kingram <kingram@163.com>
Date: Wed Jul 28 17:40:54 2021 +0800
first commit
修改提交信息
git commit --amend
编译器显示
fixed conflict
# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.
#
# Date: Thu Jul 29 09:24:12 2021 +0800
#
# On branch master
# Changes to be committed:
# modified: README.md
#
按下i，修改为Merge branch 'fix-B'，按下:wq保存退出
[master a564645] Merge branch 'fix-B'
Date: Thu Jul 29 09:24:12 2021 +0800
查看当前分支图表
$ git log --graph
* commit a564645c1cc0bb1f57512fe077abaeaa269aad84 (HEAD -> master)
|\ Merge: a4dc01a 8d19107
| | Author: kingram <kingram@163.com>
| | Date: Thu Jul 29 09:24:12 2021 +0800
| |
| | Merge branch 'fix-B'
| |
| * commit 8d191079fac23089ae61d916956dee27faaa4bc2 (fix-B)
| | Author: kingram <kingram@163.com>
| | Date: Wed Jul 28 20:05:25 2021 +0800
| |
| | fix B
| |
* | commit a4dc01ab44706349cc7661e7b1c4315d1b6fd405
|\ \ Merge: 6ab6d6b 64aa165
| |/ Author: kingram <kingram@163.com>
|/| Date: Wed Jul 28 18:55:42 2021 +0800
| |
| | Merge branch 'feature-A'
| |
| * commit 64aa16533ca53ae652aca4f6ce8227b7aabc4ad4 (feature-A)
|/ Author: kingram <kingram@163.com>
| Date: Wed Jul 28 18:44:46 2021 +0800
|
| add feature-A
|
* commit 6ab6d6b65bc4d28be5b571dbc01df81e2231effa
| Author: kingram <kingram@163.com>
| Date: Wed Jul 28 18:23:10 2021 +0800
|
| add index
|
* commit 7419956521d4a00e4fa35ec754946f6cdfce10cf
Author: kingram <kingram@163.com>
Date: Wed Jul 28 17:40:54 2021 +0800
first commit
git rebase -i——压缩历史
在合并特性分支之前，如果发现已提交的内容中有些许拼写错误等，不妨提交一个修改，然后将这个修改包含到前一个提交之中，压缩成一个历史记录。这是个会经常用到的技巧。
$ git switch -c feature-C
Switched to a new branch 'feature-C'
修改README.md文件
# GIT测试
- feature-A
- fix-B
- faeture-C
这里留了个小拼写错误
提交
$ git commit -am "add feature-C"
[feature-C 768f68a] add feature-C
1 file changed, 1 insertion(+), 1 deletion(-)
修改README.md文件拼写错误
修改后查看区别
$ git diff HEAD
diff --git a/README.md b/README.md
index f583f41..4f997d5 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
# GIT测试
- feature-A
- fix-B
-- faeture-C
+- feature-C
提交
$ git commit -am "fix typo"
[feature-C 65dd8a2] fix typo
1 file changed, 1 insertion(+), 1 deletion(-
修改历史
git rebase -i HEAD~2
修改编译器内容
pick 768f68a add feature-C
pick 65dd8a2 fix typo
# Rebase a564645..65dd8a2 onto a564645 (2 commands)
#
# Commands:
# p, pick <commit> = use commit
# r, reword <commit> = use commit, but edit the commit message
# e, edit <commit> = use commit, but stop for amending
# s, squash <commit> = use commit, but meld into previous commit
# f, fixup <commit> = like "squash", but discard this commit's log message
# x, exec <command> = run command (the rest of the line) using shell
# b, break = stop here (continue rebase later with 'git rebase --continue')
# d, drop <commit> = remove commit
# l, label <label> = label current HEAD with a name
# t, reset <label> = reset HEAD to a label
# m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]
# . create a merge commit using the original merge commit's
# . message (or the oneline, if no original merge commit was
# . specified). Use -c <commit> to reword the commit message.
#
# These lines can be re-ordered; they are executed from top to bottom.
#
# If you remove a line here THAT COMMIT WILL BE LOST.
#
# However, if you remove everything, the rebase will be aborted.
按下i将fixtypo的pick改为fixup，按下:wq保存退出
Successfully rebased and updated refs/heads/feature-C.
系统显示rebase成功，将"Fix typo"的内容合并到了上一个提交 “Add feature-C"中，改写成了一个新的提交。这样一来，Fix typo就从历史中被抹去，也就相当于Add feature-C中从来没有出现过拼写错误。这算是一种良性的历史改写。
合并分支
$ git merge feature-C
Updating a564645..cc1fcc4
Fast-forward
README.md | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)