text: #include <stdio.h>
  #include <unistd.h>
  int main(int argc, char ** argv )
  {
      int pid = fork();
      if(pid == -1) 
      {
          printf("error!\n");
      } 
      else if(pid ==0) 
      {
          printf("This is the child process!\n");
          getchar();
      } 
      else 
      {
          printf("This is the parent process! child process id = %d\n", pid);
          getchar();
          wait(NULL);
      }
      return 0;
  }