title: git operations on remote repository without local clone
body: <p>What kind of read-only operations are possible on a remote git repository using the standard git command line tool without having a local clone?</p>
  
  <ul>
  <li>Is there some way to list refs (in particular tags and branches) on the remote repo?</li>
  <li>Is there a way to list the content of a given directory in a given revision?</li>
  <li>Is it possible to retrieve the content of a given file at a given revision?</li>
  </ul>
  
  <p>I guess that doing this without a local clone might involve some low level primitive operations, and I guess that making this usable might best be accomplished by some short shell script. That would still be within the scope of this question.</p>