system() doesn't give you the output of the executed command: it sends the output to STDOUT.

You can probably* set ALARM, open P,"prog |"; read from P and close. There's lots of documentation and examples in perlipc and perlopentut.

* there seem to be some issues with the safe signal handlers in recent perls. try it out.

Joost.

Update: The executed command will probably not end until it tries to write to its STDOUT, which is bound to the P file-handle in the pseudo-code above. You could try using kill to kill it immediately.