如何在 git 中恢复已删除的分支？

How do I get the deleted-branch back in git?

提问by Edison Chuang

I'm trying to use git for our software development. I found that if I delete a branch in git, I could lose my code forever. That surprised me. I thought as a version control system, it should be able to let me do anything (even stupid one) without worry about harming my work.

我正在尝试使用 git 进行我们的软件开发。我发现如果我在 git 中删除一个分支，我可能会永远丢失我的代码。这让我很惊讶。我认为作为一个版本控制系统，它应该能够让我做任何事情（甚至是愚蠢的）而不必担心损害我的工作。

The steps below are what I did:

下面的步骤是我所做的：

1. Initialize a git repository.
2. commit several changes to repository.
3. switch/checkout current working directory to first commit.
4. delete master branch.
5. then I lost all of my works and I can't believe what I saw. Is it real? If I am drunk while coding. I could lose the code in git.

1. 初始化一个 git 存储库。
2. 向存储库提交一些更改。
3. 切换/检出当前工作目录以首次提交。
4. 删除主分支。
5. 然后我失去了我所有的作品，我无法相信我所看到的。这是真的吗？如果我在编码时喝醉了。我可能会丢失 git 中的代码。

The question is how can I roll back the action of deleting a branch? Or, How can I get all history in git, even something which has disappeared in log?

问题是如何回滚删除分支的动作？或者，我怎样才能在 git 中获取所有历史记录，甚至是在日志中消失的东西？

回答by VonC

To avoid the issue in the first place, Jefromiadvices in the comments:

为了首先避免这个问题，Jefromi在评论中提出建议：

Another tip: only use git branch -d, not git branch -D.
You'll be warned if you're about to delete something that might make you lose work, then you can take a second to think before using -D.
(Or, you can go delete from gitkso you really see what you're deleting.)

另一个提示：只使用git branch -d，而不使用git branch -D。
如果您要删除可能使您失去工作的内容，您会收到警告，然后您可以在使用-D.
（或者，您可以从中删除，gitk以便您真正了解要删除的内容。）

-d

Delete a branch.
The branch must be fully merged in its upstream branch, or in HEADif no upstream was set with --trackor --set-upstream.

删除一个分支。
该分支必须在其上游分支中完全合并，或者HEAD如果没有使用--track或设置上游分支--set-upstream。

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But if you did "lose" your work, see one of the many blogsabout reflog(as James Kyburzsuggests in the comments):

但是，如果您确实“丢失”了您的工作，请参阅有关 reflog的众多博客之一（正如James Kyburz在评论中所建议的那样）：

Git reflog to the rescue:

Git reflog 来救援：

back to list Git reflog to the rescue September 09, 2010 — written by Chris Sloan | 0 comments ?

返回列表 Git reflog 来救援 2010 年 9 月 9 日 — 克里斯·斯隆 (Chris Sloan) 撰写 | 0 条评论？

The other day, I was working on a feature for Real Travel using our current branching strategy in that each release we do is a separate branch.
Not sure if it was a cause of lack of sleep from late hours pulled, but I accidentally deleted my local and remote copy of the branch before I merged it back into the master branch for release.
After a quick state of shock and thoughts running through my head of losing hours of work, I calmed down and relied on my Git knowledge.
Reading your full commit history:

There are two ways to read the commit history in git. The first way shows a list of details commits while the other shows the log in reference to the current HEAD.

前几天，我正在使用我们当前的分支策略为 Real Travel 开发一个功能，因为我们所做的每个版本都是一个单独的分支。
不确定这是否是由于拉到深夜导致睡眠不足的原因，但在将其合并回 master 分支以进行发布之前，我不小心删除了该分支的本地和远程副本。
在短暂的震惊和失去工作时间的想法在我脑海中闪过之后，我冷静下来并依靠我的 Git 知识。
阅读完整的提交历史记录：

有两种方法可以在 git 中读取提交历史。第一种方式显示提交细节的列表，而另一种方式显示引用当前HEAD.

// log of detailed commits by users
$> git log

// reference log compared to the current HEAD
$> git reflog

Using the reflogcommand, I was able to find out exactly where the last reference to my deleted branch was.
An example output of the reflogmight look like this:

使用该reflog命令，我能够准确地找出对已删除分支的最后一个引用的位置。
的示例输出reflog可能如下所示：

c7f3d98 HEAD@{0}: commit: Merged in some code
f5716c8 HEAD@{1}: pull : Fast-forward
d93c27b HEAD@{2}: commit: Added some items to project
...

Now the reflog will not show exactly where the branch was deleted, but if you remember your last commit to that branch and have a detailed enough message, it should be easy to find and restore.

Restoring your branch is straight forward by checking out the HEAD you want to a new branch.

现在 reflog 不会准确显示分支被删除的位置，但是如果你记得你最后一次提交到那个分支并且有足够详细的消息，应该很容易找到和恢复。

通过检查你想要一个新分支的 HEAD 来恢复你的分支是直接的。

$> git checkout -b my_new_branch HEAD@{5}

You can also use the hash too to checkout the new branch.

您也可以使用散列来签出新分支。

$> git checkout -b my_new_branch d93c27b

Simple enough and now I can move on with actually merging the branch in before deletion.

足够简单，现在我可以继续在删除之前实际合并分支。