The grep command supports perl-flavored regular expression pattern matching. Rather than grepping for specific words, you can use regex with grep to find patterns throughout a text or command output.

Regex and grep can get you far. Source graph gets you further. A lot of today’s AI coding agents still audit and troubleshoot codebases the same way we did quick shell debugging in 2012: grep, regex, ...

Instead of scanning every file, fast-grep builds a sparse n-gram inverted index over your codebase. When you search, it narrows the candidate set to a small fraction of files before running the regex ...