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

static int count = 0;
static struct itimerval oldtv;

void set_timer()
{
    struct itimerval itv;//結構體的定義在Timer.h
    itv.it_interval.tv_sec = 1;
    itv.it_interval.tv_usec = 0
 
;
    itv.it_value.tv_sec = 1;
    itv.it_value.tv_usec = 0;
    setitimer(ITIMER_REAL, &itv, &oldtv);//向核心註冊一個timer訊號
}

void signal_handler(int m)
{
    count ++;
    printf("%d\n", count);
}

int main()
{
/*核心收到setitemer時觸發的訊號,會啟用SIGALRM
signal這個函式是訊號量註冊,只要收到SIGALRM就會呼叫signal_handler
*/
    signal(SIGALRM, signal_handler);
    set_timer();
    while
 
(count < 10000);
    exit(0);
    return 1;
}