Git is_submodule function

submodule.sh

#!/bin/bash

cat >> /dev/null <<"HERE"
Looking good. There is a bug in 

        for line in $submodules; do cd "$parent_git/$line"; \
            if [[ `pwd` = $_git_dir ]]; then return 0; fi; \
        done

because it won't cd back (so it would only work if the first submodule
is a match). I'd check without changing directories, or do the `cd` in a
subshell.

I don't know where you get $_git_dir from - I used basename(1) to get that
information (see below).

I also suggest you trap errors (either with 'set -e', 'trap "return 1"
ERR' or similar)

There was also a problem with submodules containing a space in the name. There
is still a problem with newlines in submodule names left, but I don't care
enough to fix that :)

finally declaring all the vars local fixes potential problems when using this
inside other scripts
HERE

function is_submodule() {
	local git_dir parent_git module_name path
    # Find the root of this git repo, then check if its parent dir is also a repo
	git_dir="$(git rev-parse --show-toplevel)"
	module_name="$(basename "$git_dir")"
	parent_git="$(cd "$git_dir/.." && git rev-parse --show-toplevel 2> /dev/null)"
    if [[ -n $parent_git ]]; then
        # List all the submodule paths for the parent repo
		while read path
		do
			if [[ "$path" != "$module_name" ]]; then continue; fi
			if [[ -d "$git_dir/../$path" ]];    then return 0; fi
		done < <(cd $parent_git && git submodule --quiet foreach 'echo $path' 2> /dev/null)
		#return 1
    fi
    return 1
}

# Usage
if is_submodule; then
    echo "In a submodule!"
else
    echo "Not in a submodule"
fi