use IO::File;
    my $cache= IO::File->new_tmpfile()
      or  die "Can't create temporary file: $!\n";
    print $cache $_
      or  die "Can't append to temporary file: $!\n"
      while  defined( $_= <> );
    seek( $cache, 0, 0 )
      or  die "Can't rewind temporary file: $!\n";
    while(  <$cache>  ) {
        ...
    }
    seek( $cache, 0, 0 )
      or  die "Can't rewind temporary file: $!\n";
    while(  <$cache>  ) {
        ...
    }