How to run server-start only if not already running?

[Reuben Thomas]

Sometimes, normally by error, I start a second Emacs. Since my .emacs runs 
server-start, this overrides the server I run in my normally-running Emacs. 
After quitting the erroneously-started Emacs, I no longer have a server and 
need manually to restart it. Is there some way to run server-start in my 
.emacs only if there's no server currently? It'd be nice to make this easy!

Possibly alternatively, it'd be nice to enable emacsclient to start a server 
process if there's already a running Emacs but no server running in it.

--
http://rrt.sc3d.org/ | dumb blonde, n. susbt. phr.  peroxymoron