signal.c

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

#ifdef _WIN32
#include <Windows.h>
#else
#include <unistd.h>
#endif

#define BUFSIZE 128

static pid_t pid;

void intHandler(int dummy) {
    printf("INT\n");
    kill(pid, SIGINT);
}

int main(void) {
    pid = fork();
    if (pid == -1) {
        return -1;
    } else if (pid == 0) {
        return 0;
    }
    printf("pid=%d\n", pid);

    char *cmd = "ping 192.168.11.1 -c 10";    

    char buf[BUFSIZE];
    FILE *fp;

    if ((fp = popen(cmd, "r")) == NULL) {
        printf("Error opening pipe!\n");
        return -1;
    }

    signal(SIGINT, intHandler);

    while (fgets(buf, BUFSIZE, fp) != NULL) {
        printf("OUTPUT: %s", buf);
    }

    if(pclose(fp))  {
        printf("Command not found or exited with error status\n");
        return -1;
    }
    return 0;
}