You're still confusing signals generated by the tty/pty (which go to the foreground process _group_) and OOM signals which _don't_ go to the victim process' pro

You're still confusing signals generated by the tty/pty (which go to the foreground process _group_) and OOM signals which _don't_ go to the victim process' process group. You cannot catch a signal that wasn't posted to the process or its process group -- you just cannot. What you can do is notice via the wait syscalls that the child died with `SIGKILL`, and in a sense this is "catching" that that happened, but no signal handler runs (nor could it, since `SIGKILL` is what's used and you cannot set a handler for `SIGKILL`).