private void getfile(long id, OutputStream os)throws IOException
    {
        FS_Function fs_fsi = FS_Function.getInstance();
        if(id != -1L && fs_fsi.getFile(id, os))
            System.out.println((new StringBuilder("File ID:")).append(id).append("Found").toString());
        else
            System.out.println((new StringBuilder("File ID:")).append(id).append("not exist").toString());
    }