stop_catcher
stop_catcher(0);
signal(SIGTSTP, stop_catcher);
signal(SIGTSTP, stop_catcher);
static void stop_catcher(int);
sigset(SIGTSTP,stop_catcher); /* unenable the stop */
sigset(SIGTSTP, stop_catcher);
sigset(SIGSTOP, stop_catcher);
void stop_catcher(int sig);
(void)stop_catcher();