glimpse - 4.18.7-10 main

Glimpse, which stands for GLobal IMPlicit SEarch, is a very popular
UNIX indexing and query system that allows you to search through a
large set of files very quickly. Glimpse supports most of agrep's
options (agrep is our powerful version of grep) including approximate
matching (e.g., finding misspelled words), Boolean queries, and even
some limited forms of regular expressions.