Specifically, the exec() functions change the disposition of any signals being caught to their default action and leave the status of all other signals alone.
the "status of all other signals" refers to the signals which are not being caught, e.g, they are being ignored (
If your program has added a handler for a signal, the program could catch that signal (except of course for
SIGSTOP which cannot be caught). When you call an
exec() function, none of those signal handlers apply to the program after calling the
If your program did not add a signal handler for a given signal, then calling an
exec() function does not change the way that signal affects your program.
Signal handlers can be established with