# File lib/FileCache.rb, line 76
  def file_system_image_urls_in_cache
    if @@file_system_image_urls.nil? then
      make_file_system_image_list unless File.exists?(@url_cache_list)
      @@file_system_image_urls=File.open(@url_cache_list,"r").readlines.collect{|url| url.chomp}
    end
    @@file_system_image_urls
  end