signal.c

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/**
 * signal.c
 *
 * Demonstrates signal handling. During normal operation this program counts up
 * each second, starting from 1. Upon receiving SIGINT, the final count will be
 * printed and the program will exit. Many programs use this type of signal
 * handling to clean up and gracefully exit when the user presses Ctrl+C.
 *
 * Compile: gcc -g -Wall signal.c -o signal
 * Run: ./signal
 */

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

unsigned long count = 0;

void sigint_handler(int signo) {
    printf("\n");
    printf("Final count is: %ld\n", count);
    printf("Goodbye!\n");
    exit(0);
}

int main(void) {

    printf("Starting up. My PID = %d\n", getpid());

    /* Set up our signal handler. SIGINT can be sent via Ctrl+C */
    signal(SIGINT, sigint_handler);




    /* NOTE: You should NOT modify below this line!!!! ----------------------*/
    /* Instead, use signal handlers to accomplish what you have to do.       */
    while (true) {
        count++;
        printf("Count: %ld\n", count);
        sleep(1);
    }
    /* ----------------------------------------------------------------------*/

    return 0;

}