ripgrep is a command line search tool that combines the usability of The Silver Searcher (an ack clone) with the raw speed of GNU grep.
Ack is designed as a standalone (one perl file) replacement for 99% of the uses of grep. ack is intelligent about the files it searches. It knows about certain file types, based on both the extension on the file and, in some cases, the contents of the file.
The awk utility interprets a special-purpose programming language that makes it possible to handle simple data-reformatting jobs with just a few lines of code. Gawk is Gnu's interpreter for the awk language.
UniversalCodeGrep (ucg) is an extremely fast grep-like tool specialized for searching large bodies of source code. It is intended to be largely command-line compatible with Ack, to some extent with ag, and where appropriate with grep.