Regular Expression Pocket Reference, 2nd Edition

Shell Tools

awk, sed, and egrep are a related set of Unix shell tools for text processing. awk uses a DFA match engine, egrep switches between a DFA and NFA match engine, depending on which features are being used, and sed uses an NFA engine. For an explanation of the rules behind these engines, see "Introduction to Regexes and Pattern Matching.”

This reference covers GNU egrep 2.4.2, a program for searching lines of text; GNU sed 3.02, a tool for scripting editing commands; and GNU awk 3.1, a programming language for text processing.