A regular expression is a pattern that can match various text strings; for example, `l[0-9]+' matches `l' followed by one or more digits @xref{Regexps}
A regular expression is a pattern that can match various text strings; for example, `l[0-9]+' matches `l' followed by one or more digits See section Syntax of Regular Expressions
(n ) A pattern representing a class of character strings For example, grep interprets the regular expression h t as any three-character string beginning with h and ending with t
a text pattern consisting of alphanumeric characters and special characters, known as metacharacters In vi, ex, and ed, a character string that specifies one or more lines of the file by matching its contents in various ways Search patterns are regular expressions
A regular expression is a pattern that can match various text strings; for example, `a[0-9]+' matches `a' followed by one or more digits See section K 5 Syntax of Regular Expressions
wild card pattern used by Unix utilities; any pattern containing symbols and three operators; class of strings that can be recognized by a finite-state automaton
a string following the rules of a regular language, used to describe a class of strings (that can be recognized by an FSA), allowing alternatives, specifying a sequence, and indicating number of occurrences (0, 1, any number, at least one)
(1) A mechanism to select specific strings from a set of character strings (2) A set of characters, metacharacters, and operators that define a string or group of strings in a search pattern (3) A string containing wildcard characters and operations that define a set of one or more possible strings
Often abbreviated as a regexp, this is a method of specifing a pattern to match in text Both very simple and very complex patterns can be easily matched using this method For information on how to understand and construct regular expressions the best source is the grep manual or info page
Regular sets and expressions derive from a very formal decomposition of language structure In the mmCIF dictionary, a regular expression notation is used to define the patterns which must be matched by values of a data item For instance, a calendar date in the mmCIF dictionary must match a pattern like yyyy-mm-dd, which can be defined by the regular expression [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]
A shorthand for expressing patterns of text An expression which generates a language from the operations union (alternation), concatenation, and concatenation closure
A way of describing a pattern in text - for example, "all the words that begin with the letter A" or "every 10-digit phone number" or even "Every sentence with two commas in it, and no capital letter Q" Regular expressions are useful in Apache because they let you apply certain attributes against collections of files or resources in very flexible ways - for example, all gif and jpg files under any "images" directory could be written as "/images/ *(jpg|gif)$" Apache uses Perl Compatible Regular Expressions provided by the PCRE library