gf -server[=port]

You can now specify which port the HTTP server should run on in server mode.
The default is 41296.

src/compiler/GF.hs

@@ -45,5 +45,5 @@ mainOpts opts files =
       ModeHelp        -> putStrLn helpMessage
       ModeInteractive -> mainGFI opts files
       ModeRun         -> mainRunGFI opts files
-      ModeServer      -> mainServerGFI opts files
+      ModeServer port -> mainServerGFI opts port files
       ModeCompiler    -> mainGFC opts files