<p>Gitolite provides an admin a centralised interface, in the form of a configuration file, to make managing users, user permissions, repos, and user and repo groups easy. It abstracts Git users from UNIX users by defining a user by public keys, and manages permissions down to the branch-level. And better yet, it is itself managed over Git.
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Proper documentation is available on <a href="https://gitolite.com">Gitolite.com</a></p>