old_sighup = signal(SIGHUP, normal_stop_handler);
old_sigterm = signal(SIGTERM, normal_stop_handler);
old_sigusr1 = signal(SIGUSR1, normal_stop_handler);
old_sighup = signal(SIGHUP, normal_stop_handler);
old_sigterm = signal(SIGTERM, normal_stop_handler);
old_sigusr1 = signal(SIGUSR1, normal_stop_handler);