Git is a powerful version control system that is widely used by developers to manage and track code changes. Two commands that often cause confusion are `git submodule update --remote` and `git pull`. Both are used to update code, but they serve distinct purposes and operate differently, particularly when working with submodules in a git repository.

Git Submodules

Before delving into the specifics of `git submodule update --remote` and `git pull`, it is important to understand what submodules are in Git. Submodules allow you to keep a Git repository as a subdirectory of another Git repository. This is useful when you need to track and incorporate external repositories into your project without manually integrating these changes.

Adding a Submodule

To add a git submodule to your existing repository, you would use the following command:

• The command updates each submodule to the latest commit on the specified branch of the submodule repository, rather than sticking to the commit recorded in the main repository.
• Primarily, it fetches and checks out the latest changes from the remote branch configured in your submodules.
• Scope: `git pull` operates on the main repository and updates based on its local branch; `git submodule update --remote` operates specifically on submodules.
• Integration Workflow: `git pull` integrates changes automatically; `git submodule update --remote` merely updates to the latest commit on a submodule branch, requiring separate commit actions in the main repository.
• Purpose: Use `git pull` for updating your branch's content; use `git submodule update --remote` to fetch new content within submodules.
• Detached Head: Using `git submodule update --remote` can put your submodule in a detached head state. Always check whether the updates are on the intended branch or detached.
• Manual Commits Needed: Unlike `git pull`, submodule updates require manual committing back in the main repo to record the new commit states.
• Consistency: Regularly update and test submodules so they do not diverge too far from the main project.
• Explicit Tracking: Always specify the branch you want each submodule to track to avoid accidental updates from unintended branches.