Update submodules on branch switch

post-checkout

#!/bin/sh

# To skip submodule update:
# 	IGNORE_SUBMODULES=1 git checkout <...>



# Third arg is "1" when doing a branch checkout (as opposed to a file 
# checkout)
if [ "$3" = "1" ] && [ -z "$IGNORE_SUBMODULES" ]; then
	# Only sync submodules if .gitmodules has changed (`git submodule 
	# sync` can be a little slow)
	should_sync="$(git diff --exit-code $1 $2 -- .gitmodules; echo $?)"
	if [ "$should_sync" != "0" ]; then
		git submodule sync --recursive
	fi

	git submodule update --init --recursive
fi

Updates your submodules when switching branches.

To use, put in your repo at: .git/hooks/post-checkout & make it executable