git pull之后，执行“ git submoudle update”是否会更新子模块？

Question

I am newbie to git submodule and I am really confused by the documentation available regarding git submodules. My question is pretty straight forward

I have been away for 2 months and I want to update my local repo code. My repo which has submodules in it. I do
git pull origin master (It updates the code in my local repo.)
Now I want to update the submodules

So for that, is doing

git submodule update enough?

I also see the command

git submodule foreach git pull origin master
in the text of updating the submodules.

This command, in my opinion, is doing git pull for each submodule. But in my repo, every submodule is in detached head state. When I go in their subdirectory and do git branch, it says (no branch) which I think means that it is in detach head state. So if it is not in any branch, then where with pulled code be placed.

So what is the right way for me to ensure that my repo is in update state.

Answer 1

The command git submodule update is enough to get all registered submodules. If you want to update submodules of submodules then you'd need git submodule update --recursive .

Note that submodules are usually checked out to a specific commit and thus having two months pass between updates won't change the commit associated with the submodule. However, if you did your submodule configuration to use branches, then if those branches have in fact evolved in two months, then you will get the changes.