# Regular Expressions/Glossary

This is a glossary of the book.

## \A

    In some flavors, the beginning of a string but not of a line in the string

## \b

    In some flavors, a word boundary

## \B

    In some flavors, a complement to \b

## BRE

    Basic regular expressions

## \d

    In some flavors, a digit

## \D

    In some flavors, a complement to \d

## Emacs

    A scriptable text editor with support for regular expressions

## ERE

    Extended regular expressions

## GNU

    A project to create a free-as-in-freedom operating system, which provides extensions to regular expressions used in tools such as Grep or Sed

## Greedy

    Of an operator, matching as much as it can

## Grep

    A command-line tool for finding lines in a text files that match a regular expression

## Java

    A byte-compiled programming language with support for regular expressions in its standard library since version 1.4

## JavaScript

    A scripting languages for the web supported by web browsers, with built-in support for regular expressions

## Metacharacter

    A character or sequence of characters with a special meaning, such as "." or "\+".

## PCRE

    Perl compatible regular expressions

## Perl

    An interpreted scripting language noted for its regular expressions

## PHP

    An interpreted scripting language with support for regular expressions

## Regex

    A regular expression

## Regular expression

    A string containing special characters indicating patterns, intended to match literal strings

## \s

    In some flavors, a whitespace character: space, tab, newline, form feed

## \s-

    In Emacs, a whitespace character

## \S

    In some flavors, a complement to \s

## Sed

    A non-interactive editor or command-line tool noted for its "s" command substituting strings that match a regular expression with other strings

## \u13F

    In some flavors, the character with the hexadecimal Unicode value of 13F.

## Vim

    A scriptable text editor with support for regular expressions

## \w

    In some flavors, an alphanumeric character, including "_"

## \W

    In some flavors, a complement to \w

## \xF7

    In some flavors, the character with the hexadecimal ASCII value of F7.

## \x{13F}

    In some flavors, the character with the hexadecimal Unicode value of 13F.

## \Z

    In some flavors, the end of a string but not of a line in the string
    In some flavors, an empty string before the beginning of a word
    In some flavors, an empty string after the end of a word
    The beginning of a line
    The end of a line
    Any single character, but possibly not a newline
    The opening of a character class
    The closing of a character class
    In some flavors, the opening of a group
    In some flavors, the closing of a group
    In some flavors, the opening of a group
    In some flavors, the closing of a group
    In some flavors, the opening of a match-count iterator
    In some flavors, the closing of a match-count iterator
    In some flavors, the opening of a match-count iterator
    In some flavors, the closing of a match-count iterator
    In some flavors, a marking of an alternative
    In some flavors, a marking of an alternative

## \1

    In some flavors, a backreference to the 1st group

## \2

    In some flavors, a backreference to the 2nd group
    Any number of the previous
    In some flavors, one or more of the previous
    In some flavors, one or more of the previous
    In some flavors, one or none of the previous
    In some flavors, one or none of the previous
    In some flavors, a non-greedy version of *
    In some flavors, a non-greedy version of +
    In some flavors, a non-greedy version of }