signal example for C

main.c

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



static void sig_usr(int);

int main(void) {
    //printf("program start\n");
    signal(SIGUSR1, sig_usr);
    signal(SIGUSR2, sig_usr);

    for (;;) pause();
}

static void sig_usr(int signo) { /* argument is signal number */
    if (signo == SIGUSR1)
        printf("절전모드\n");
    else if (signo == SIGUSR2)
        printf("일반모드\n");
    else {
        printf("received signal %d\n", signo);
        exit(signo);
    }
    return;
}

sender.c

#include <sys/types.h>
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
    int save_mode = 10;
    int common_mode = 12;

    pid_t target_pid = atoi(argv[1]);
    printf("target pid: %d\n", target_pid);

    while (1) {
        kill(target_pid, save_mode);
        sleep(1);
        kill(target_pid, common_mode);
        sleep(1);
    }
}