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

static int idata = 111;     /*  Allocated in data segment */

int
main(int argc, char *argv[])
{
    int istack = 222;       /* Allocated in stack segment */
    pid_t childPid;

    switch (childPid = fork()) {
    case -1:
        err(EXIT_FAILURE, "fork");
        break;              /* UNREACHABLE */

    case 0:
        idata *= 3;
        istack *= 3;
        break;

    default:
        sleep(3);           /* Give child a chance to execute */
        break;
    }

    /* Both parent and child come here */

    printf("PID=%ld %s idata=%d istack=%d\n", (long) getpid(),
            (childPid == 0) ? "(child)" : "(parent)", idata, istack);

    exit(EXIT_SUCCESS);
}