14. Submodules

Submodules let you embed one Git repo inside another — useful for shared libraries or vendor code.

# Add a submodule
git submodule add https://github.com/org/lib.git libs/lib

# Clone a repo that has submodules
git clone --recurse-submodules <url>

# If you already cloned without --recurse-submodules
git submodule init
git submodule update

# Update submodule to latest remote commit
git submodule update --remote libs/lib

# Remove a submodule
git submodule deinit libs/lib
git rm libs/lib
rm -rf .git/modules/libs/lib

Warning: Submodules add complexity. Consider alternatives:

• Package managers (npm, pip, cargo) for dependencies
• Git subtree for simpler vendoring

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