Regular expression
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A regular expression, sometimes referred to as a rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms
Stephen Cole Kleene, who introduced the concept
Sed
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sed is a utility that transforms text via a script written in a relatively simple and compact programming language. It was developed from 1973 to 1974 by Lee E. McMahon of Bell Labs, and is available
Regular expression
…Regular expressions are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis. Regular expressions are supported in many programming languages. Library implementations are often called an "engine…
An excerpt from GNU sed's man page