Code/text so rtmpdump will rename file

Code/text so rtmpdump will rename file

 

Hi can anyone please tell me as basically a they can what piece of text i need to use in my rtmpdump command so that if i manually need to restart pressing up to start capture again the file name will change to lets say e.g from "my stream" to "my stream2", Is there a type of ++ command I can use?, thanks in advance.