= R =
regexp /reg'eksp/ n.
[Unix] (alt. `regex' or `reg-ex')
1. Common written and spoken abbreviation for `regular
expression', one of the wildcard patterns used, e.g., by Unix
utilities such as grep(1), sed(1), and awk(1).
These use conventions similar to but more elaborate than those
described under glob. For purposes of this lexicon, it is
sufficient to note that regexps also allow complemented character
sets using ^; thus, one can specify `any non-alphabetic
character' with [^A-Za-z]. 2. Name of a well-known PD
regexp-handling package in portable C, written by revered Usenetter
Henry Spencer <email@example.com>.
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.