/* Test ignoring, raising SIGUSR1, and unignoring. */ #include "signal.h" static void handler(int signum) { (void) signum; int errnum = errno; printf("SIGUSR1\n"); fflush(stdout); errno = errnum; } int main(void) { signal(SIGUSR1, SIG_IGN); raise(SIGUSR1); signal(SIGUSR1, handler); return 0; }