This command searches Drupal 8 core for FieldType plugins and prints them as HTML <li>
items, with links to the Drupal API documentation for the containing files.
$ find core -path '*/Plugin/Field/FieldType/*' | \
grep -v tests | \
xargs fgrep 'id = "' | \
sed -e 's#/#%21#g' | \
sed -e 's#\(core.*.php\)[^"]*"\([^"]*\)",#<li><a href="https://api.drupal.org/api/drupal/\1/8.0.x">\2</a></li>#'