awk, sed, and egrep are a related set of Unix shell tools for text processing. awk and egrep use a DFA match engine, and sed uses an NFA engine. For an explanation of the rules behind these engines, see Section 1.2.

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.