This is a nutch plugin. It can statistics tags in the html. tags based on user's tags.txt, tags.txt store in your execute script directory. Install put the index-tags and parse-metatags in the apache-nutch/src/plugin direcotory, and update the nutch-default.xml to open these plugin, and edit the apache-nutch/src/plugin/build.xml add plugin ant. You may should search nutch plugin install methods in google to