#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int handlerEnabled = 1;         // global variable for controlling
                                // exit handler behaviour

void handler1(void);

int
main(int argc, char *argv[])
{
    atexit(handler1);

    if (argc == 2 && strcmp(argv[1], "-d") == 0)
        handlerEnabled = 0;

    if (handlerEnabled)
        fprintf(stderr, "disable exit handler with -d.\n");
    exit(EXIT_SUCCESS);
}

void
handler1(void)
{
    if (handlerEnabled)
        printf("exit handler 1\n");
}