Inspects, updates and manages submodules.
# To install a repository's specified submodules:
git submodule update --init --recursive
# To add a git repository as a submodule:
git submodule add <repository_url>
# To add a git repository as a submodule at the specified directory:
git submodule add <repository_url> <path/to/directory>
# To update every submodule to its latest commit:
git submodule foreach git pull