Tracking external dependencies with git-subtree

git-subtree(1) provides a nice way to integrate external code and track it over time. For example to add the source code of Hugo under the sub-directory ‘hugo’:

$ git subtree add -P hugo git@github.com:gohugoio/hugo.git v0.79.1 --squash --message="import hugo v0.79.1"

The man-page of git-subtree provides an explanation of available commands.