Command to get/clone a fetch/pull/read -only copy of a git repository?

The question is a bit misleading. There's not really such a thing as a "read-only copy" of a git repository. You can clone an existing repository with:

git clone git://example.com/path/to/repo.git

But unlike Subversion, every "copy" in git is itself a completely new repository. Since you can commit to your own repository, it's certainly not read-only in that sense.

git clone git://github.com/Fudge/gltail.git