main()
 {
    int pid;
    int status;
    pid = fork();
    /* if parent, use wait to suspend execution until child finishes */
    if(pid > 0){
       wait(&status);
       printf("ls completed\n");
       exit(0);
    }
    /* if child then exec ls */
    if(pid == 0){
       execl("/bin/ls", "ls", "-l", &status);
       perror("execl failed\n");
       exit(1);
    }
    prinft("fork failed\n");
    exit(1);
 }