When working with git submodules the worst part is dealing with missed commits. That usually happens when you make changes to the submodule, but forget to push it to its remote repository before merging/pushing the parent repository.

There are many posts regarding this

• http://codingkilledthecat.wordpress.com/2012/04/28/why-your-company-shouldnt-use-git-submodules/
• http://stackoverflow.com/questions/12075809/git-submodules-workflow-issues
• http://allgood38.io/how-to-break-your-git-submodules.html

The goal of this script is to help avoid this issue by comparing the local commits for each submodule against their corresponding commits on the remotes. If there's a mismatch, then the commit is aborted.

Copy this pre-commit script to .git/hooks folder on the repository you want to monitor. Now, everytime you try to commit the parent repository, the script will run and check the commit SHAs for each submodule to make sure you have the latest copy and you did not miss any push.

If all goes well, this is what you should see and commit will succeed:

user@mac ~/Work/MyClonedRepo (master)$ git commit -am "pushing parent and submodule is good" 
Checking submodules...
  Submodule [Vendor/lib_1] ... OK
  Submodule [Vendor/lib_2] ... OK
  Submodule [Vendor/lib_3] ... OK
returning state 0
[master 73ba08d] pushing parent and submodule is good
 1 file changed, 1 insertion(+)
user@mac ~/Work/MyClonedRepo (master)$ 

Otherwise, an error message is displayed and it lists the SHAs to help you resolve the issues:

user@mac ~/Work/MyClonedRepo (master)$ git commit -am "pushing parent and submodule is wrong"
Checking submodules...
  Submodule [Library/SampleLib] ... FAILED
 
Stop! Pre-commit condition failed.
Did you forget to push submodule [Library/SampleLib] to remote?
Cannot proceed until you do so.
Remote HASH: 12f8c095710278aadf18f04e3ca026ac7cdd7e72
Local HASH.: 3281d051f138bcd8c48d431ecdbdc54c2c6987db

user@mac ~/Work/MyClonedRepo (master)$ 

• Script was tested with Mavericks 10.9.2
• submodules of submodules are not checked