I have a script called \'git-export\' which helps me to export a remote repository. It is run like that:
git-export http://host.com/git-repo <-t tag or -b         
        You can use curl for checking if the specific url exists or not for example when i try to hit angularjs existing url
$ curl -I https://github.com/angular/angularjs.org/tree/master/src
**HTTP/1.1 200 OK**
Server: GitHub.com
Date: Mon, 11 Aug 2014 15:22:40 GMT
When I hit on a wrong URL
$ curl -I https://github.com/angular/angularjs.org/tree/master/abcd
**HTTP/1.1 404 Not Found**
Server: GitHub.com
Date: Mon, 11 Aug 2014 15:24:06 GMT
Hope this helps
You're looking for git ls-remote. For example:
$ git ls-remote git://git.kernel.org/pub/scm/git/git.git
4d8b32a2e1758236c4c1b714f179892e3bce982c    HEAD
f75a94048af9e423a3d8cba694531d0d08bd82b4    refs/heads/html
810cae53e0f622d6804f063c04a83dbc3a11b7ca    refs/heads/maint
70b5eebd65f2d47fd69073aed1d3da0f1fd7a017    refs/heads/man
4d8b32a2e1758236c4c1b714f179892e3bce982c    refs/heads/master
b9f1b13437fd0b8b1857ffbdebb9e1adc50481f0    refs/heads/next
83a9d3226b19a683a9a783bde0784c2caf19e9a1    refs/heads/pu
2309986900ed1a5744b3a81c507943593000ce32    refs/heads/todo
d5aef6e4d58cfe1549adef5b436f3ace984e8c86    refs/tags/gitgui-0.10.0
3d654be48f65545c4d3e35f5d3bbed5489820930    refs/tags/gitgui-0.10.0^{}
33682a5e98adfd8ba4ce0e21363c443bd273eb77    refs/tags/gitgui-0.10.1
729ffa50f75a025935623bfc58d0932c65f7de2f    refs/tags/gitgui-0.10.1^{}
...
(git.git has a lot of tags!)
You can limit yourself to branches with the --heads option or tags with the --tags option, or specify a pattern to select refs, for example to see only the git version tags from git.git, git ls-remote <url> refs/tags/v*. Or you might already know exactly what ref you want: git ls-remote <url> HEAD.
You can't run arbitrary commands on arbitrary remotes, though. The transfer protocols don't support that - they're designed to support listing refs and transferring objects (via packs). In particular, you won't be able to do anything analogous to rev-list. You'll be limited to getting SHA1s for commits pointed to by refs.