# File lib/lumberjack/device/rolling_log_file.rb, line 94
    def cleanup_files!
      if keep
        files = Dir.glob("#{path}.*").collect{|f| [f, File.ctime(f)]}.sort{|a,b| b.last <=> a.last}.collect{|a| a.first}
        if files.size > keep
          files[keep, files.length].each do |f|
            File.delete(f)
          end
        end
      end
    end