/*
 * Sample program for signal system call  - No.48
 *
 * signal - ANSI C signal handling
 *
 * Synopsis
 *     #include <signal.h>
 *
 *     typedef void (*singhandler_t)(int);
 *
 *     signalhandler_t signal(int signum, sighandler_t handlerj);
 *
 * Description
 *     The signal () system call installs a new signal handler for
 *     the signal with number signum. The signal handler is set to
 *     sighandler which may be a user specified function, or either
 *     SIG_IGN or SIG_DFL.
 *
 *     Upon arrival of a signal with number signum the following
 *     happens. If the corresponding handler is set to SIG_IGN,
 *     then the signal is ignored. If the handler is set to SIG_DFL,
 *     then the default action asscociated to the signal (see signal(7))
 *     occurs. Finally, if the handler is reset to SIG_DFL or an
 *     implementation-dependant blocking of the signal is performed
 *     and next sighandler is called wwith argument signum.
 *
 *     Using a signal handler function for a signal is called
 *     "catching the signal". The signals SIGKILL and SIGSTOP
 *     cannot be caught or ignored.
 */

#include <stdio.h>

#define SIGUSER 60

void sig_user()
{
	printf("user defined signal handler is evoked.\n");
}

main()
{
	int pid;

	signal(SIGUSER, sig_user);
	pid = getpid();

	kill(pid, SIGUSER);

	exit(0);
}