Git 1.8.2提供了一个新选项——remote，它将启用这种行为。运行

git submodule update --remote --merge

将从每个子模块的上游获取最新的更改，将它们合并到子模块中，并检出子模块的最新修订。如文档所述:

——远程 此选项仅对update命令有效。与其使用超项目记录的SHA-1来更新子模块，不如使用子模块的远程跟踪分支的状态。

这相当于在每个子模块中运行git pull <remote> <default_branch>(通常是git pull origin master或git pull origin main)，这通常正是你想要的。

如何在repo中更新所有git子模块(两种方法做两种完全不同的事情!)

快速的总结

# Option 1: as a **user** of the outer repo, pull the latest changes of the
# sub-repos as previously specified (pointed to as commit hashes) by developers
# of this outer repo.
# - This recursively updates all git submodules to their commit hash pointers as
#   currently committed in the outer repo.
git submodule update --init --recursive

# Option 2. As a **developer** of the outer repo, update all subrepos to force
# them each to pull the latest changes from their respective upstreams (ex: via
# `git pull origin main` or `git pull origin master`, or similar, for each
# sub-repo). 
git submodule update --init --recursive --remote

# now add and commit these subrepo changes
git add -A
git commit -m "Update all subrepos to their latest upstream changes"

细节

Option 1: as a user of the outer repo, trying to get all submodules into the state intended by the developers of the outer repo: git submodule update --init --recursive Option 2: as a developer of the outer repo, trying to update all submodules to the latest commit pushed to the default branch of each of their remote repos (ie: update all subrepos to the latest state intended by the developers of each subrepo): git submodule update --init --recursive --remote ...in place of using git submodule foreach --recursive git pull origin master or git submodule foreach --recursive git pull origin main.

在我看来，上述两个选项的最佳答案是不要使用我在其他一些答案中看到的——merge和——force选项。

上述选项的解释:

the --init part above initializes the submodule in case you just cloned the repo and haven't done that yet --recursive does this for submodules within submodules, recursively down forever and --remote says to update the submodule to the latest commit on the default branch on the default remote for the submodule. It is like doing git pull origin master or git pull origin main in most cases, for example, for each submodule. If you want to update to the commit specified by the outer-most repo (super repo) instead, leave --remote off.

Git子模块foreach——递归Git pull(不要用这个——它经常失败)vs Git子模块update——递归——远程(用这个!——它总是有效的)

我在这个答案下面留下了以下评论。我认为它们很重要，所以我也把它们放在我的回答中。

Basically, for some situations, git submodule foreach --recursive git pull might work. For others, git submodule foreach --recursive git pull origin master might be what you need instead. For others, git submodule foreach --recursive git pull origin main might be what you need. And for others still, none of those might work! You might need git submodule foreach --recursive git pull upstream develop, for instance. OR, even worse, there might not be any git submodule foreach command which works for your outer repo, as each submodule might require a different command to update itself from its default remote and default branch. In all cases I can find, however, this does work, including for all cases you might use one of the several git submodule foreach commands I just presented above. So, use this instead:

git submodule update --recursive --remote

不管怎样，下面是我对这个答案的一些评论:

(1/4) @DavidZ, a lot of people think that git submodule foreach git pull and git submodule update --remote are the same thing, with the latter simply being the newer command. They aren't the same thing, however. git submodule foreach git pull will fail under multiple circumstances for which git submodule update --remote works just fine! If your submodule points to a commit hash that doesn't have a branch pointing to it, which is frequently the case in real-life development where you want a particular version of the submodule for your outer repo, then that submodule... (2/4)...is in a detached HEAD state. In this case, git submodule foreach git pull fails to run git pull on that submodule since a detached HEAD cannot have an upstream branch. git submodule update --remote, however, works just fine! It appears to call git pull origin main on that submodule if origin is the default remote and main is the default branch on that default remote, or git pull origin master, for instance, if origin is the default remote but master is the default branch. (3/4) Furthemore, git submodule foreach git pull origin master will even fail in many cases where git submodule update --remote works just fine, since many submodules use master as the default branch, and many other submodules use main as the default branch since GitHub changed from master to main recently in order to get away from terms related to slavery in the United States ("master" and "slave"). (4/4) So, I added the explicit remote and branch to make it more clear that they are frequently needed, and to remind people that git pull is frequently not enough, and git pull origin master may not work, and git pull origin main may work when the former doesn't, but also may not even work, and that none of them by themselves are the same as git submodule update --remote, since that latter command is smart enough to just do git pull <default_remote> <default_branch> for you for each submodule, apparently adjusting the remote and branch as necessary for each submodule.

相关，及其他研究

如何找到一个回购的主要分支:https://stackoverflow.com/a/49384283/4561887 如何通过git子模块foreach运行自定义命令来更新每个subrepo <cmd>: https://stackoverflow.com/a/45744725/4561887 Man git子模块-然后搜索foreach，——remote等。

git子模块update命令实际上告诉git，您希望每个子模块都检出在超项目索引中已经指定的提交。如果您希望将子模块更新为远程可用的最新提交，则需要直接在子模块中执行此操作。

总结一下:

# Get the submodule initially
git submodule add ssh://bla submodule_dir
git submodule init

# Time passes, submodule upstream is updated
# and you now want to update

# Change to the submodule directory
cd submodule_dir

# Checkout desired branch
git checkout master

# Update
git pull

# Get back to your project root
cd ..

# Now the submodules are in the state you want, so
git commit -am "Pulled down update to submodule_dir"

或者，如果你是个大忙人:

git submodule foreach git pull origin master

如果你不知道主机分支，这样做:

git submodule foreach git pull origin $(git rev-parse --abbrev-ref HEAD)

它将获得主Git存储库的一个分支，然后为每个子模块提取相同的分支。

@Jason在某种程度上是正确的，但不完全正确。

更新 更新已注册的子模块， 即克隆缺失子模块和 方法中指定的提交 包含存储库的索引。 这将使子模块HEAD为 分离，除非——rebase或——merge是 指定或键 子模块。美元的名字。Update设置为 重组或合并。

因此，git子模块update确实签出，但它是提交到包含存储库的索引中。它根本不知道上游的新提交。所以去你的子模块，获得你想要的提交，并在主存储库中提交更新后的子模块状态，然后更新git子模块。

这适用于我更新到最新的提交

Git子模块更新——递归——远程——初始化