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 }