这里有一个很棒的一行代码，可以将所有内容更新到master上的最新版本:

git submodule foreach 'git fetch origin --tags; git checkout master; git pull' && git pull && git submodule update --init --recursive

感谢Mark Jaquith

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

简单地获取子模块:

git submodule update --init --recursive

现在继续将它们更新到最新的主分支(例如):

git submodule foreach git pull origin master

@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。

主项目指向子模块应该所在的特定提交。Git子模块update尝试检查每个已初始化的子模块中的提交。子模块实际上是一个独立的存储库——仅仅在子模块中创建一个新的提交并推送是不够的。您还需要显式地在主项目中添加子模块的新版本。

所以，在你的情况下，你应该在子模块中找到正确的提交-让我们假设这是master的提示:

cd mod
git checkout master
git pull origin master

现在回到主项目，阶段子模块并提交:

cd ..
git add mod
git commit -m "Updating the submodule 'mod' to the latest version"

现在推送你的主项目的新版本:

git push origin master

从这一点开始，如果有人更新了他们的主项目，那么他们的git子模块update将更新子模块，假设它已经初始化。

注意，虽然更新子模块提交的现代形式是:

git submodule update --recursive --remote --force

请参阅Gabriel Staples的另一种回答，不使用“合并”力。

——force选项允许发生签出，即使在包含存储库的索引中指定的提交已经与子模块中签出的提交匹配。

在这种情况下，——merge选项似乎没有必要:“记录在超项目中的提交将被合并到子模块中的当前分支中。”

旧的形式是:

git submodule foreach --quiet git pull --quiet origin

除了……第二种形式并不是真正的“安静”。

参见提交a282f5a (12 Apr 2019) by nguyThái ngeconc Duy (pclouds)。 (由Junio C Hamano—gitster—在commit f1c9f6c中合并，2019年4月25日)

子模块foreach:修复“<命令>—quiet”不被尊重

Robin reported that git submodule foreach --quiet git pull --quiet origin is not really quiet anymore. It should be quiet before fc1b924 (submodule: port submodule subcommand 'foreach' from shell to C, 2018-05-10, Git v2.19.0-rc0) because parseopt can't accidentally eat options then. "git pull" behaves as if --quiet is not given. This happens because parseopt in submodule--helper will try to parse both --quiet options as if they are foreach's options, not git-pull's. The parsed options are removed from the command line. So when we do pull later, we execute just this git pull origin When calling submodule helper, adding "--" in front of "git pull" will stop parseopt for parsing options that do not really belong to submodule--helper foreach. PARSE_OPT_KEEP_UNKNOWN is removed as a safety measure. parseopt should never see unknown options or something has gone wrong. There are also a couple usage string update while I'm looking at them. While at it, I also add "--" to other subcommands that pass "$@" to submodule--helper. "$@" in these cases are paths and less likely to be --something-like-this. But the point still stands, git-submodule has parsed and classified what are options, what are paths. submodule--helper should never consider paths passed by git-submodule to be options even if they look like one.

Git 2.23(2019年Q3)修复了另一个问题:当“——recursive”选项正在使用时，“Git submodule foreach”没有保护传递给命令的命令行选项，以便在每个子模块中正确运行。

参见莫里亚十四行诗(momoson)的commit 30db18b(2019年6月24日)。 (由Junio C Hamano—gitster—在commit 968eecb中合并，2019年7月9日)

子模块foreach:修复选项的递归

Calling: git submodule foreach --recursive <subcommand> --<option> leads to an error stating that the option --<option> is unknown to submodule--helper. That is of course only, when <option> is not a valid option for git submodule foreach. The reason for this is, that above call is internally translated into a call to submodule--helper: git submodule--helper foreach --recursive \ -- <subcommand> --<option> This call starts by executing the subcommand with its option inside the first level submodule and continues by calling the next iteration of the submodule foreach call git --super-prefix <submodulepath> submodule--helper \ foreach --recursive <subcommand> --<option> inside the first level submodule. Note that the double dash in front of the subcommand is missing. This problem starts to arise only recently, as the PARSE_OPT_KEEP_UNKNOWN flag for the argument parsing of git submodule foreach was removed in commit a282f5a. Hence, the unknown option is complained about now, as the argument parsing is not properly ended by the double dash. This commit fixes the problem by adding the double dash in front of the subcommand during the recursion.

请注意，在Git 2.29 (Q4 2020)之前，“Git子模块更新—quiet”(man)并没有压制底层的“rebase”和“pull”命令。

参见Theodore Dubois (tbodt)提交3ad0401(2020年9月30日)。 (由Junio C Hamano - gitster -在commit 300cd14中合并，2020年10月5日)

子模块更新:在merge/rebase下使用"——quiet" 署名:Theodore Dubois

Commands such as $ git pull --rebase --recurse-submodules --quiet produce non-quiet output from the merge or rebase. Pass the --quiet option down when invoking "rebase" and "merge". Also fix the parsing of git submodule update(man) -v. When e84c3cf3 ("git-submodule.sh: accept verbose flag in cmd_update to be non-quiet", 2018-08-14, Git v2.19.0-rc0 -- merge) taught "git submodule update"(man) to take "--quiet", it apparently did not know how ${GIT_QUIET:+--quiet} works, and reviewers seem to have missed that setting the variable to "0", rather than unsetting it, still results in "--quiet" being passed to underlying commands.

在Git 2.38 (Q3 2022)中，Git -submodule.sh已准备好被转换为内置，这意味着存在上述问题的子模块-helper将被淡出。

参见commit 5b893f7, commit 2eec463, commit 8f12108, commit 36d4516, commit 6e556c4, commit 0d68ee7, commit d9c7f69, commit da3aae9, commit 757d092, commit 960fad9, commit 8577525 (28 Jun 2022) by Ævar Arnfjörð Bjarmason (avar)。 参见commit b788fc6(2022年6月28日)，作者Glen Choo (chooglen)。 (由Junio C Hamano—gitster—在commit 361cbe6中合并，2022年7月14日)

git-submodule.sh:使用$quiet，而不是$GIT_QUIET 署名:Ævar Arnfjörð Bjarmason

Remove the use of the "$GIT_QUIET" variable in favor of our own "$quiet", ever since b3c5f5c ("submodule: move core cmd_update() logic to C", 2022-03-15, Git v2.36.0-rc0 -- merge) we have not used the "say" function in git-sh-setup.sh, which is the only thing that's affected by using "GIT_QUIET". We still want to support --quiet for our own use though, but let's use our own variable for that. Now it's obvious that we only care about passing "--quiet" to git submodule--helper, and not to change the output of any "say" invocation.