I want to know if my server is running Subversion 1.5.
How can I find that out?
Also would be nice to know my SVN client version number. svn help         
        
For Subversion 1.7 and above, the server doesn't provide a footer that indicates the server version. But you can run the following command to gain the version from the response headers
$ curl -s -D - http://svn.server.net/svn/repository
HTTP/1.1 401 Authorization Required
Date: Wed, 09 Jan 2013 03:01:43 GMT
Server: Apache/2.2.9 (Unix) DAV/2 SVN/1.7.4
Note that this also works on Subversion servers where you don't have authorization to access.