onsignal
sa.sa_handler = onsignal;
void onsignal(int);
sa.sa_handler = onsignal;
void onsignal(int);
(void)signal(SIGALRM, onsignal);
(void)signal(SIGINT, onsignal);
(void)signal(SIGINFO, onsignal);
(void)signal(SIGALRM, onsignal);
(void)signal(SIGALRM, onsignal);