为子模块选择分支的唯一效果是，每当你在git子模块更新命令行中传递——remote选项时，git将以分离HEAD模式(如果选择默认的——checkout行为)检出所选远程分支的最新提交。

You must be particularly careful when using this remote branch tracking feature for Git submodules if you work with shallow clones of submodules. The branch you choose for this purpose in submodule settings IS NOT the one that will be cloned during git submodule update --remote. If you pass also the --depth parameter and you do not instruct Git about which branch you want to clone -- and actually you cannot in the git submodule update command line!! -- , it will implicitly behave like explained in the git-clone(1) documentation for git clone --single-branch when the explicit --branch parameter is missing, and therefore it will clone the primary branch only.

毫无疑问，在git子模块update命令执行克隆阶段之后，它最终将尝试检出之前为子模块设置的远程分支的最新提交，如果这不是主分支，那么它就不是本地浅克隆的一部分，因此它将失败

致命的:需要一次修改 无法在子模块路径“mySubmodule”中找到当前的origin/NotThePrimaryBranch修订

为了切换子模块的分支(假设你已经将子模块作为存储库的一部分):

CD到包含子模块的存储库的根目录 打开.gitmodules进行编辑 在path =…url =…对于每个子模块，它说branch = your-branch;保存文件。gitmodules。 然后在不改变目录的情况下执行$ git子模块update——remote

.．.对于这样修改的每个子模块，这应该拉入指定分支上的最新提交。

一个我如何使用Git子模块的例子。

创建一个新的存储库 然后将另一个存储库克隆为子模块 然后让该子模块使用一个名为V3.1.2的标记 然后我们承诺。

它看起来有点像这样:

git init 
vi README
git add README
git commit 
git submodule add git://github.com/XXXXX/xxx.yyyy.git stm32_std_lib
git status

git submodule init
git submodule update

cd stm32_std_lib/
git reset --hard V3.1.2 
cd ..
git commit -a

git submodule status 

也许它有帮助(即使我使用标记而不是分支)?

Git子模块有点奇怪——它们总是处于“分离头”模式——它们不会像你期望的那样更新到分支上的最新提交。

不过，当你仔细思考时，这确实是有道理的。假设我用子模块bar创建了存储库foo。我推送我的更改并告诉您从存储库foo中提交a7402be。

然后想象一下，在您可以克隆之前，有人将更改提交到存储库栏。

当您从存储库foo签出commit a7402be时，您希望得到与我推送的相同的代码。这就是为什么子模块不会更新，直到你显式地告诉它们，然后进行新的提交。

我个人认为子模块是Git中最令人困惑的部分。有很多地方可以比我更好地解释子模块。我推荐Scott Chacon的Pro Git。

Git 1.8.2增加了跟踪分支的可能性。

# add submodule to track branch_name branch
git submodule add -b branch_name URL_to_Git_repo optional_directory_rename

# update your submodule
git submodule update --remote 

参见Git子模块

我想在这里补充一个答案，它实际上只是其他答案的综合，但我认为它可能更完整。

有了这两个东西，就有了Git子模块。

Your .gitmodules has an entry like so: [submodule "SubmoduleTestRepo"] path = SubmoduleTestRepo url = https://github.com/jzaccone/SubmoduleTestRepo.git You have a submodule object (named SubmoduleTestRepo in this example) in your Git repository. GitHub shows these as "submodule" objects. Or do git submodule status from a command line. Git submodule objects are special kinds of Git objects, and they hold the SHA information for a specific commit. Whenever you do a git submodule update, it will populate your submodule with content from the commit. It knows where to find the commit because of the information in the .gitmodules. Now, all the -b does is add one line in your .gitmodules file. So following the same example, it would look like this: [submodule "SubmoduleTestRepo"] path = SubmoduleTestRepo url = https://github.com/jzaccone/SubmoduleTestRepo.git branch = master Note: only branch name is supported in a .gitmodules file, but SHA and TAG are not supported! (instead of that, the branch's commit of each module can be tracked and updated using "git add .", for example like git add ./SubmoduleTestRepo, and you do not need to change the .gitmodules file each time) The submodule object is still pointing at a specific commit. The only thing that the -b option buys you is the ability to add a --remote flag to your update as per Vogella's answer: git submodule update --remote Instead of populating the content of the submodule to the commit pointed to by the submodule, it replaces that commit with the latest commit on the master branch, THEN it populates the submodule with that commit. This can be done in two steps by djacobs7 answer. Since you have now updated the commit the submodule object is pointing to, you have to commit the changed submodule object into your Git repository. git submodule add -b is not some magically way to keep everything up to date with a branch. It is simply adds information about a branch in the .gitmodules file and gives you the option to update the submodule object to the latest commit of a specified branch before populating it.