git submodules.

Is there any documentation about how those work?

What I need is this, I have a already existing git repository, that have a subdir that could be seen as submodule (by this I mean that he is related, but could have a different commit tree). The git repository already exists and has many commits that apply to either the submodule or the main module (I would say that there is no commit that touch both). So is it possible to separate them easily? Would it keep my older commits?

bellow is a shell script that samples my setup: 

=========================== cut here ================================= #!/bin/bash

gitdir=git_submodules_dir

if [[ -d $gitdir ]]; then 
	rm -rf $gitdir;
fi

mkdir $gitdir

cd $gitdir

git init

echo "testing 1 2 3" > file_a.txt git add file_a.txt git commit -m "initial setup"

mkdir submodule

echo "submodule file" > submodule/file_b.txt git add submodule/file_b.txt git commit -m "submodule file"

echo "updated main file" >> file_a.txt git commit -a -m "updated file in main module"

echo "updated sumodule file" >> submodule/file_b.txt git commit -a -m "updated file in the submodule" =========================== cut here =================================