学校做网站方案,网站功能项目报价,百度云搜索引擎入口百度网盘,免费制作企业网站平台文章目录 一、分离头指针二、创建分支三、比较commit内容四、总结 一、分离头指针
正常情况下#xff0c;在通过git checkout命令切换分支时#xff0c;在命令后面跟着的是分支名#xff08;例如master、temp等#xff09;或分支名对应commit的哈希值。
非正常情况下在通过git checkout命令切换分支时在命令后面跟着的是分支名例如master、temp等或分支名对应commit的哈希值。
非正常情况下git checkout切换分支时后面跟了一个非分支对应commit的哈希值此时就会产生分离头指针问题。
例如项目的版本历史中有如下3次commit其中两个分别是temp分支和master分支此时将分支切换到第三个commit也就是非temp、master分支上就会出现detached HEAD提示即分离头指针问题。
git log
commit e5d60c7d913d427b2e2161f717dff97249dd1f9b (HEAD - temp)
Author: xxx xxx163.com
Date: Thu Nov 9 10:22:51 2023 0800add temp_testcommit 01df9fd5e046f104312468746168b027f4285c5c (master)
Author: xxx xxx163.com
Date: Thu Nov 9 10:22:04 2023 0800add file1commit db2d096bf27e4e8f4ca42e8b185e973b05e186df
Author: xxx xxx163.com
Date: Thu Nov 9 10:21:31 2023 0800add readme切换到非分支的commit上git就会提示当前处在detached HEAD分离头指针状态
git checkout db2d096bf27e4e
Note: switching to db2d096bf27e4e.You are in detached HEAD state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:git switch -c new-branch-nameOr undo this operation with:git switch -Turn off this advice by setting config variable advice.detachedHead to falseHEAD is now at db2d096 add readme此时HEAD指针并未在某个分支旁边即头指针与分支分离了
git log --all
commit e5d60c7d913d427b2e2161f717dff97249dd1f9b (temp)
Author: xxx xxx163.com
Date: Thu Nov 9 10:22:51 2023 0800add temp_testcommit 01df9fd5e046f104312468746168b027f4285c5c (master)
Author: xxx xxx163.com
Date: Thu Nov 9 10:22:04 2023 0800add file1commit db2d096bf27e4e8f4ca42e8b185e973b05e186df (HEAD)
Author: xxx xxx163.com
Date: Thu Nov 9 10:21:31 2023 0800add readme
二、创建分支
当切换到某个commit时git会提示已进入到分离头指针状态并显示在该状态下可进行的操作 a可在该HEADcommit中进行测试、提交或取消更改当切回到分支时不会影响到分支但此前在此commit上做的所有操作都会丢失 b若想保留在该commit上的变动可通过git switch -c branch_name进行分支添加 分离头指针指向某个commit后若再切换回master分支或其他分支时没有为该commit新建分支则所有在该commit上做的操作都将丢失。 1在commit上进行修改操作并进行commit提交
vi readmegit status
HEAD detached at db2d096
Changes not staged for commit:(use git add file... to update what will be committed)(use git restore file... to discard changes in working directory)modified: readmeno changes added to commit (use git add and/or git commit -a)git add readme
warning: LF will be replaced by CRLF in readme.
The file will have its original line endings in your working directorygit commit -m detach modify file
[detached HEAD 69cde78] detach modify file1 file changed, 1 insertion()git log
commit 69cde788edb4184538f2155ea5e062f5649e8781 (HEAD)
Author: xxx xxx163.com
Date: Thu Nov 9 15:56:42 2023 0800detach modify filecommit db2d096bf27e4e8f4ca42e8b185e973b05e186df
Author: xxx xxx163.com
Date: Thu Nov 9 10:21:31 2023 0800add readme2当再切回到master分支时git提示有一个commit未被连接到任意branch分支上可通过git branch来创建新分支。
git checkout master
Warning: you are leaving 1 commit behind, not connected to
any of your branches:69cde78 detach modify fileIf you want to keep it by creating a new branch, this may be a good time
to do so with:git branch new-branch-name 69cde78Switched to branch master3在未把分离头指针对应的commit创建新branch时git log中是看不到它的信息的。
git log --all --graph # gitk --all 可调出图形界面
* commit e5d60c7d913d427b2e2161f717dff97249dd1f9b (temp)
| Author: xxx xxx163.com
| Date: Thu Nov 9 10:22:51 2023 0800
|
| add temp_test
|
* commit 01df9fd5e046f104312468746168b027f4285c5c (HEAD - master)
| Author: xxx xxx163.com
| Date: Thu Nov 9 10:22:04 2023 0800
|
| add file1
|
* commit db2d096bf27e4e8f4ca42e8b185e973b05e186dfAuthor: xxx xxx163.comDate: Thu Nov 9 10:21:31 2023 0800add readme
4为detach区域建立分支。
git branch detach_branch 69cde78 # 复制前面git提示的命令语句添加分支名称即可git log --all --graph # 此时版本历史中就能看到detach分支的信息
* commit 69cde788edb4184538f2155ea5e062f5649e8781 (detach_branch)
| Author: xxx xxx163.com
| Date: Thu Nov 9 15:56:42 2023 0800
|
| detach modify file
|
| * commit e5d60c7d913d427b2e2161f717dff97249dd1f9b (temp)
| | Author: xxx xxx163.com
| | Date: Thu Nov 9 10:22:51 2023 0800
| |
| | add temp_test
| |
| * commit 01df9fd5e046f104312468746168b027f4285c5c (HEAD - master)
|/ Author: xxx xxx163.com
| Date: Thu Nov 9 10:22:04 2023 0800
|
| add file1
|
* commit db2d096bf27e4e8f4ca42e8b185e973b05e186dfAuthor: xxx xxx163.comDate: Thu Nov 9 10:21:31 2023 0800add readme5图形化界面看版本历史 gitk --all
三、比较commit内容
可通过git diff命令来比较两个commit之间的内容差异。
git log --all --oneline
69cde78 (detach_branch) detach modify file
e5d60c7 (temp) add temp_test
01df9fd (HEAD - master) add file1
db2d096 add readmegit diff 69cde78 e5d60c7 # 后跟两个commit哈希值
diff --git a/file1 b/file1
new file mode 100644
index 0000000..e69de29
diff --git a/readme b/readme
index 9fa5398..e69de29 100644
--- a/readmeb/readme-1 0,0
-test detach
diff --git a/temp_test b/temp_test
new file mode 100644
index 0000000..e69de29git diff后面也可以跟HEAD这样的指针名称以及用^和~1来表示父类
git diff HEAD HEAD^ # HEAD^ 表示HEAD指针对应commit的父commit
diff --git a/file1 b/file1
deleted file mode 100644
index e69de29..0000000git diff HEAD HEAD^^ # HEAD^^ 父亲的父亲
fatal: ambiguous argument HEAD^^: unknown revision or path not in the working tree.
Use -- to separate paths from revisions, like this:
git command [revision...] -- [file...]git diff HEAD HEAD~1 # HEAD~1 HEAD^
diff --git a/file1 b/file1
deleted file mode 100644
index e69de29..0000000git diff HEAD HEAD~2 # HEAD~2 HEAD^^
fatal: ambiguous argument HEAD~2: unknown revision or path not in the working tree.
Use -- to separate paths from revisions, like this:
git command [revision...] -- [file...]
四、总结
一般情况下我们切换分支只在已有的几个分支名称之间来回切换但遇到切换到某个commit的情况时即出现分离头指针问题时要懂得该问题是如何产生的并通过什么样的操作步骤可以去解决它而不影响到现有分支。此外分离头指针现象也可以便于我们进行相关的测试在不影响现有生产的前提下。
