The Grep Plugin uses a specialized markup that requires some familiarity with how wiki pages are stored and also familiarity with regular expression searches in order to use the plugin to its fullest.
The plugin documentation includes many samples of useful searches that can be used without writing new markup.
# Markup
The plugin is configured with commands, one per line, that describe where on a page to look and then what text is to be found.
Say __ITEM__ _type_ to look in story items of that type.
Say __ACTION__ _type_ to look in journal actions of that type.
Item types are the plugin name in lower case. Action types are create, add, delete, edit, move and fork.
If no type is specified then all items or all actions are searched. Without an ITEM or ACTION command only the title of pages will be searched.
Without further markup the plugin will find all pages with the type of items or actions specified. To be more selective apply a pattern match to text within the objects.
Say __TEXT__ _pattern_ to match the item's text.
Say __SITE__ _pattern_ to match the action's remote site.
Say __TITLE__ _pattern_ to match the page's title.
Say __ID__ _pattern_ to match the item's or action's id.
Say __ALIAS__ _pattern_ to match the item's aliased id.
Say __JSON__ _pattern_ to match any part's formatted json.
The pattern is formed by ordinary characters to be matched along with some special characters that add more options to the search.
^ . ? * [ ] ( ) { } | \ $
Avoid these characters for a simple search. Learn more about regular expression matching for more complicated searches. wikipedia 