This is a Git pre-commit hook I'm developing to make sure local submodule changes are pushed before committing. This would probably be better as a pre-push hook, but there does not appear to be a facility for that.

pre-commit

#!/bin/bash
function git_submodule_unchanged () {
	SUB_MODULE=$1
	GSC_RC=0
	
	pushd $SUB_MODULE > /dev/null
	SUB_BRANCH=$(git branch | grep '*' | cut -d' ' -f 2)
	if [[ "$(git log --pretty=oneline origin/${SUB_BRANCH}..${SUB_BRANCH})" != "" ]]; then
		GSC_RC=1
	fi
	popd > /dev/null
	return $GSC_RC
}

RETURN_CODE=0
SUPERPROJECT_PWD="$(pwd)/"

for MODULE in $(git submodule foreach --recursive --quiet pwd)
do
	for FILE_INDEX in $(git diff --cached --name-only)
	do
		if [[ "${MODULE##$SUPERPROJECT_PWD}" == "$FILE_INDEX" ]]; then
			if ! git_submodule_unchanged $MODULE; then
				echo "There are local only changes in submodule '$FILE_INDEX'."
				echo "Please push these changes before committing the superproject."
				RETURN_CODE=1
			fi
		fi
	done
done

exit $RETURN_CODE