sig_handler
nsa.sa_handler = sig_handler;
osa.sa_handler != sig_handler)
static void sig_handler(int);
sa.sa_handler = sig_handler;
sa.sa_handler = sig_handler;
sa.sa_handler = sig_handler;
sa.sa_handler = sig_handler;
signals.sa_handler = sig_handler;
signal(SIGINT, sig_handler);
signal(SIGTERM, sig_handler);
signal(SIGHUP, sig_handler);
signal(SIGPIPE, sig_handler);
static void sig_handler(int);
signal(SIGINT, sig_handler);
signal(SIGTERM, sig_handler);
signal(SIGPIPE, sig_handler);
__dead static void sig_handler(int);