“Regular expressions are endemic to UNIX. It is possible to
use and administer UNIX without knowing what they are, but you
aren’t using the full power of UNIX if you don’t understand how to
use them.“
“Even experienced UNIX users can benefit from a
regular-expression review. There are some aspects of the
expressions, as implemented under UNIX, which are used infrequently
and rarely discussed. This month we will review the basics and
discuss some of the more-powerful and less-used notations.”
“Regular expressions date back to the 1950s, when a
mathematician named Stephen Kleene came up with a notation to
describe a mathematical construct called finite automata. Computer
scientists saw the usefulness of this notation for describing
lexical analyzers in compilers.”