runtime.exec()

How do I use runtime.exec() on iSeries? I've read several web articles but I
still don't undertand and can't get it to work.

Let's say I want to do "ls >mylist.txt".

Runtime rt = Runtime.getRuntime();
Process proc = rt.exec("ls >mylist.txt");
int exitVal = proc.waitFor();
System.out.println("Process exitValue: " + exitVal);

This prints out an exit value of zero, but the output file is not created
and a spool file is created with a CEE0020:

Message . . . . :   This job is about to end.

Cause . . . . . :   The job is being terminated because the job is capable
of 
  having multiple threads and the application has issued an exit(), abort()
or
  their equivalent APIs, an exception has occurred and is not being handled,

  or a return from main() has occurred in a program that runs in a *NEW

  Activation Group.


Do I have to tell it to run qshell? I guess what I am asking is whether the
commands I submit to exec() have to be CL commands or qshell commands.

Thanks,
-Marty