Full Search (q)
Definition (defs)
Symbol (refs)
File Path (path)
History (hist)

A Query is a series of clauses. A clause may be prefixed by:

A clause may be either: Wildcard, Fuzzy, Proximity & Range Searches: Escaping special characters:

Opengrok supports escaping special characters that are part of the query syntax. The current list special characters are:
+ - && || ! ( ) { } [ ] ^ " ~ * ? : \
To escape these character use the \ before the character. For example to search for (1+1):2 use the query: \(1\+1\)\:2

valid FIELDs are
                            full: Full text search.
                            defs: Only finds symbol definitions.
                            refs: Only finds symbols.
                            path: path of the source file.
                            hist: History log comments

the term(phrases) can be boosted(making it more relevant) using a caret ^ , e.g. help^4 opengrok - will make term help boosted

                            To find where setResourceMonitors is defined
                            To find files that use sprintf in usr/src/cmd/cmd-inet/usr.sbin/
                            refs:sprintf path:usr/src/cmd/cmd-inet/usr.sbin
                            To find assignments to variable Asign
                            To find Makefiles where pstack binary is being built
                            pstack path:Makefile
                            to search for phrase "Bill Joy":
                            "Bill Joy"
                            To find perl files that do not use /usr/bin/perl but something else, 
                            -"/usr/bin/perl" +"/bin/perl"

Opengrok search is powered by lucene, for more detail on query syntax refer to lucene docs.