signal 예제

http://www.manpagez.com/man/3/Signal/
 void (* signal(int sig, void (*func)(int)))(int);


signal.c

#include <stdio.h>
#include <signal.h>

static void sig_usr(int);

int main(void) {
    printf("1");
    if (signal(SIGUSR1, sig_usr) == SIG_ERR) {
        perror("can not catch SIGUSR1");
        return -1;
    }

    printf("2");
    if (signal(SIGUSR2, sig_usr) == SIG_ERR) {
        perror("can not catch SIGUSR1");
        return -1;
    }

    printf("3");
    if (signal(SIGINT, sig_usr) == SIG_ERR) {
        perror("can not catch SIGUSR1");
        return -1;
    }

    printf("4");
    for ( ; ; ) {
        pause();
    }

    return 1;
}

    static void sig_usr(int signo) {
        if (signo == SIGUSR1) {
            printf("received SIGUSR1\n");
        } else if (signo == SIGUSR2) {
            printf("received SIGUSR2\n");
        } else {
            fprintf(stderr, "received signal %d\n", signo);
        }
        return;

    }

./signal.o &
  9771
kill -USR1 9771
  received SIGUSR1
kill -USR2 9771
   received SIGUSR2

좋은 자료

[Signal]
http://teamblog.joinc.co.kr/yundream/405
http://www.joinc.co.kr/modules/moniwiki/wiki.php/Site/system_programing/Signal/SignalHow

[Signal 관련 function]
http://www.joinc.co.kr/modules/moniwiki/wiki.php/Site/system_programing/Signal/SignalHow2

[원리]
http://studyfoss.egloos.com/5182475