Recoll

is a personal full text search tool for Unix/Linux?.

​http://www.lesbonscomptes.com/recoll/

Xapian = is an Open Source Search Engine Library, released under the GPL. It's written in C++, with bindings to allow use from Perl, Python, PHP, Java, Tcl, C#, Ruby and Lua (so far!)

​http://xapian.org/