/usr/src/usr.sbin/update/update.c
daemon(0, 0);
sa.sa_handler = mysync;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
if (sigaction(SIGALRM, &sa, (struct sigaction *)0) < 0)
err(1, "sigaction");
These errors get written to /dev/null.