#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>

/* #define DEBUG 1 */
/* #define SLOW 1 */

int main()
  {
    pid_t pid;

    /* fork a child process */
    pid = fork();

    if( pid < 0 )
      {
	/* error occurred */
	fprintf(stderr, "Fork failed!\n");
	return 1;
      }
    else if( pid == 0 )
      {
	/* child process */
#ifdef SLOW
        sleep(2);
#endif
#ifdef DEBUG
	printf("I am the child! Here I go...\n");
#endif
#ifdef SLOW
        sleep(3);
#endif
	execlp("/bin/ls", "ls", NULL);
	printf("That was fun! What next?\n");
      }
    else
      {
	/* parent process */
#ifdef DEBUG
	printf("I am the parent! Waiting...\n");
#endif
#ifdef SLOW
        sleep(1);
#endif
	wait(NULL);
#ifdef DEBUG
	printf("Child complete now\n");
#endif
      }
  }