git 如何创建一个新的（和空的！）“根”分支？
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How to create a new (and empty!) "root" branch?
提问by kjo
I would like to define a new "root" branch in this git repository. By "root" branch I mean a branch that is entirely independent of all the other branches in the repository1.
我想在这个 git 存储库中定义一个新的“根”分支。“根”分支是指完全独立于存储库1中所有其他分支的分支。
Unfortunately, even the commit (let's call it A) at the very base of the repo's commit tree contains a lot of files (this was a repository that was initialized on an already fairly mature project).
不幸的是，即使是Arepo 提交树最基础的提交（我们称之为）也包含很多文件（这是一个在已经相当成熟的项目上初始化的存储库）。
This means that even if I gave Aas the new branch's <start-point>, this new branch would not start from a "clean slate", but rather it would contain all the files that were committed in A.
即使我给这意味着A新科的<start-point>，这个新分支将不会从一个“干净的石板”开始，而是它将包含所有已经提交的文件A。
Is there some way I can create a completely bare branch in this repository, with <start-point>as close to Aas possible?
有什么方法可以在这个存储库中创建一个完全裸露的分支，<start-point>尽可能接近A？
1BTW, this is notequivalent to creating a new repo. Separate repos would be less convenient for a lot of reasons.
1顺便说一句，这不等同于创建一个新的回购。由于很多原因，单独的存储库不太方便。
EDIT: OK, this is what I did, based on vcsjones' answer:
编辑：好的，这就是我所做的，基于vcsjones的回答：
# save rev of the current earliest commit
OLDBASE=$(git rev-list --max-parents=0 HEAD)
# create a new orphan branch and switch to it
git checkout --orphan newbranch
# make sure it's empty
git rm -rf .
# create a new empty commit in the new branch, and
# save its rev in NEWBASE
git commit --allow-empty -m 'base commit (empty)'
NEWBASE=$(git rev-list HEAD)
# specify $NEWBASE as the new parent for $OLDBASE, and
# run filter-branch on the original branch
echo "$OLDBASE $NEWBASE" > .git/info/grafts
git checkout master
git filter-branch
# NOTE: this assumes that the original repo had only one
# branch; if not, a git-filter-branch -f <branch> command
# need to be run for each additional branch.
rm .git/info/grafts
Although this procedure is a bit involved, the end result is an emptybase commit that can serve as the <start-point>for any new "clean-slate branch"; all I'd need to do then is
虽然这个过程有点复杂，但最终的结果是一个空的基础提交，可以作为<start-point>任何新的“clean-slate 分支”的提交；我需要做的就是
git checkout -b cleanslate $(git rev-list --max-parents=0 HEAD)
In the future I will always create new repositories like this:
将来，我将始终创建这样的新存储库：
git init
git commit --allow-empty -m 'base commit (empty)'
...so that the first commit is empty, and always available for starting a new independent branch. (This would be, I know, a very rarely needed facility, but it is quite effortless to make it readily available.)
...这样第一个提交是空的，并且始终可用于启动一个新的独立分支。（我知道，这将是一个很少需要的设施，但要使其随时可用是非常容易的。）
回答by vcsjones
Use the --orphanwhen creating the branch:
--orphan创建分支时使用：
git checkout --orphan YourBranchName
This will create a new branch with zero commits on it, however all of your files will be staged. At that point you could just remove them.
("remove them": A git reset --hardwill empty the index, leaving you with an empty working tree)
这将创建一个零提交的新分支，但是您的所有文件都将被暂存。那时你可以删除它们。
（“删除它们”：Agit reset --hard将清空索引，留下一个空的工作树）
Take a look at the man pagefor checkout for more information on --orphan.
查看手册页以获取有关 --orphan 的更多信息。
回答by Mr_and_Mrs_D
To add to the accepted answer - best practiceto revert to clean state is to create an initial empty commitso you can easily rebase while setting up your branches for posterity. Plus since you want a clean state you probably have committed files that you shouldn't, so you have to remove them from the index. With those in mind you should:
要添加到已接受的答案中 -恢复到干净状态的最佳做法是创建一个初始的空提交，这样您就可以在为后代设置分支时轻松变基。另外，由于您想要一个干净的状态，您可能已经提交了您不应该提交的文件，因此您必须将它们从索引中删除。考虑到这些，您应该：
$ git checkout --orphan dev2
Switched to a new branch 'dev2'
$ git reset # unstage all the files, you probably don't want to commit all of them
$ git commit --allow-empty -m 'Initial empty commit'
[dev2 (root-commit) a515c28] Initial empty commit
回答by Captain Man
If you use git 2.23 or above you may be used to git switchand git restoreinstead of git checkout. If so, the flag is the same as mentioned in this answer.
如果您使用 git 2.23 或更高版本，您可能习惯于使用git switch和git restore而不是git checkout. 如果是这样，标志与此答案中提到的相同。
git switch --orphan YourBranchHere
