Code Search is a tool for indexing and then performing regular expression searches over large bodies of source code. It is a set of command-line programs written in Go. Binary downloads are available for those who do not have Go installed.

For background and an overview of the commands, see Regular Expression Matching with a Trigram Index.

Related: Go, RE2, Regular Expression Matching Can Be Simple And Fast

Emacs editor integration: https://github.com/abingham/codesearch.el