A Unix command used to search files for the occurrence of a string of characters that matches a specified pattern.

A regular expression, also referred to as regex or regexp, is a concise and flexible method for matching strings of text, such as particular characters, words, or patterns of characters. A regular expression is written in a formal language that can be interpreted by a regular expression processor, a program that either serves as a parser generator or examines text and identifies parts that match the provided specification.

Grep is a command line text search utility originally written for Unix. The name comes from the “ed” editor command, g/re/p (global / regular expression / print). The grep command searches files or standard input globally for lines matching a given regular expression, and prints them to the program’s standard output.

Regular Expressions quickly became, and still remain, the fastest way to manipulate huge amounts of text. Regular Expression support in PERL popularized the use, and combined with CGI made the web dynamic.

In most software, InDesign included, you can search using Wildcards and Regular Expressions (grep). A wildcard character can be used to substitute for any other character or characters in a string. Regular Expressions are like wildcards on steroids! They can make you experience, joy, pain, frustration, and exhilaration, and some emotions that you didn’t even know existed. But, believe me, it’s worth it!