text: #include "types.h"
  #include "stat.h"
  #include "user.h"
  
  int
  main (int argc, char* argv[])
  {
      printf(0, "hello world (pid:%d)\n", (int) getpid());
      int status;
      int rc = fork();
      if (rc < 0) {
          exit(1);
      } else if (rc == 0) {
          printf(0, "Hello, I am child (pid:%d)\n", (int) getpid());
          exit(0);
      } else {
          int wc = waitpid(rc, &status, 0);
          printf(0, "hello, I am parent of %d (wc:%d) (pid:%d)\nChild exited with status %d\n",
                  rc, wc, (int) getpid(), status);
          exit(0);
      }
  
      return 0;
  }
  