We currently host multiple sites on the same domain that all live in the same physical directory on the server. Each is database driven and lives at a unique subdomain. For example, site1.example.com, site2.example.com, etc. However, because all of these sites live in the same directory, they share a robots.txt file.
I would like to set up a test/demo site on this same codebase(i.e. demo.example.com), but I do not want it to be indexed by search engines. Is there any way that I can configure robots.txt to disallow an entire subdomain while not affecting other subdomains that live in the same physical location?