regexps

http://eason982.blogspot.com/2007/10/regexps.html

"Regular expression" is often shortened to regex or regexp (singular), or regexes, regexps, or regexen (plural).

In computing, a regular expression is a string that is used to describe or match a set of strings, according to certain syntax rules.

Regular expressions are used by many text editors, utilities, and programming languages to search and manipulate text based on patterns. For example, Perl and Tcl have a powerful regular expression engine built directly into their syntax --By Wiki