signal.c:709
void
Init_signal()
{
#ifndef MACOS_UNUSE_SIGNAL
    VALUE mSignal = rb_define_module("Signal");

    rb_define_global_function("trap", sig_trap, -1);
    rb_define_module_function(mSignal, "trap", sig_trap, -1);
    rb_define_module_function(mSignal, "list", sig_list, 0);

    install_sighandler(SIGINT, sighandler);
#ifdef SIGHUP
    install_sighandler(SIGHUP, sighandler);
#endif
#ifdef SIGQUIT
    install_sighandler(SIGQUIT, sighandler);
#endif
#ifdef SIGALRM
    install_sighandler(SIGALRM, sighandler);
#endif
#ifdef SIGUSR1
    install_sighandler(SIGUSR1, sighandler);
#endif
#ifdef SIGUSR2
    install_sighandler(SIGUSR2, sighandler);
#endif

#ifdef SIGBUS
    install_sighandler(SIGBUS, sigbus);
#endif
#ifdef SIGSEGV
    install_sighandler(SIGSEGV, sigsegv);
#endif
#ifdef SIGPIPE
    install_sighandler(SIGPIPE, sigpipe);
#endif
#endif /* MACOS_UNUSE_SIGNAL */
}
