go的IO读取与写入

func (s *SealosInstaller) appendAPIServer() error {
   etcHostPath := "/etc/hosts"
   etcHostMap := fmt.Sprintf("%s %s", IPFormat(s.Masters[0]), APIServer)
   file, err := os.OpenFile(etcHostPath, os.O_RDWR|os.O_APPEND, 0666)
   if err != nil {
      os.Exit(1)
   }
   defer file.Close()
   reader := bufio.NewReader(file)
   for {
      str, err := reader.ReadString('\n')
      if strings.Contains(str, APIServer) {
         logger.Info("local %s is already exists %s", etcHostPath, APIServer)
         return nil
      }
      if err == io.EOF {
         break
      }
   }
   write := bufio.NewWriter(file)
   _, _ = write.WriteString(etcHostMap)
   return write.Flush()
}