The way I read the OP, the problem is not sending the Ctrl-C or its effect on the child, the problem is to avoid killing the parent along with the child. According to the OP, setting $SIG{INT} to "IGNORE" used to accomplish that task in 5.6.1, but it doesn't anymore. That's what I addressed in my top level post. Do you see it differently? The OP wasn't all that clear.