NSTask/Process and exec

gistfile1.txt

I am writing a command line tool which is using Process/NSTask 
to launch $x. Internally $x is actually a bash script which 
is using exec to execute $y.

Now the user sends SIGINT (ctrl+c in Terminal.app), my process
exits but $y is still running and writes stuff to stdout. 
How can I properly handle this case? Usually I would have 
just killed/interrupted/terminated $x (which I do) but this 
seemingly does nothing. d'oh.😢😪