git-submodule

Git repo inside another.
Make every command submodule aware

git config submodule.recurse true

Add

git submodule add <url>

Clone a project with submodule

git clone <url> --recurse-submodule

Update changes from submodule after pulling from repository

git submodule update --init

Rename a submodule locally

git mv <submodule> <subnew>

Remove a submodule

git submodule deinit <path_to_submodule>  
git rm <path_to_submodule>  
git commit-m ""  
rm -rf .git/modules/<path_to_submodule>

Submodule Repo
The git command will work at the current directory, if it in the submodule directory, then that repo will be modified. In the submodule repo, commit and push everything normally.

Main Repo
The main repo only stores the submodule information and commit hashes. This is the information needed to identify the submodule and the contents.
Every time when a commit/push occurs in the submodule, the main repo also needs to be updated.

• it will update .gitmodules file with the new commit hash
• the changes will be reflected on the main repo by git pull and git submodule update