Question

A git submodule is currently on a branch, and I’m not sure not if it’s at the tip. How do I get the commit ID of the branch’s tip so that I can pull up the submodule if necessary?

Answer 1

If you’re on a branch foo in the submodule, then by definition you’re at the tip of that branch. Perhaps what you want is to find out what commit the submodule should be at, according to the version committed in the “supermodule”? To do that you can do:

$ git rev-parse HEAD:mysubmodule
1b6577014983eb68c56025e6d3b95c8b9b7fc511

… and then compare that to:

$ cd mysubmodule
$ git rev-parse HEAD
4dd9ac74b6dc1d0df8de5029656663bd879a4773

However, you can see this more easily just be looking at the output of git status:

# Changes not staged for commit:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#   (commit or discard the untracked or modified content in submodules)
#
#   modified:   mysubmodule (new commits)

The “new commits” indicates that your submodule is behind the committed version, and should be updated with git submodule update mysubmodule.

You can also see this from the output of git submodule, where the line corresponding to your submodule will begin with + if the submodule needs to be updated.

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Another interpretation of your question is that your submodule is on the branch foo, but you want to know where the tip of the branch foo is in the remote repository. To do that you can do:

$ cd mysubmodule
$ git fetch origin
$ git rev-parse origin/foo