starting Mozilla

[Claus Atzenbeck]

I have Mozilla 0.8/Linux.

I want to start it via command line including URL, like:

        mozilla http://www.just-testing.com

It is working. But when I do this twice, I get 2 Mozillas running. I want 
to do this instead:

1) start Mozilla with this URL if it is not running
2) open just a new window with this URL if Mozilla is already running

Is there a way to tell Mozilla what I want or do I have to write a shell 
script by my own?

Thanks for your help!
Claus.