Egrep Metacharacter Summary

정규식과 관련된 기본적인 메타케릭터 설명이다. Egrep을 기준으로 작성된거지만 대부분의 표준 정규식에서 지원된다.

Metachracter		Matches
.	dot	Matches any one character
[…]	character class	Matches any one character listed
[^…]	negated character class	Matches any one character not listed
\char	escape character	When char is a metacharacter,or the escaped combination is not otherwise special, matches the literal character

Items Appended to Provide "Counting" :The Quantifers

Metachracter		Matches
?	question	One allowed, but it is optional
*	start	Any number allowed, but all are optional
+	plus	At least one required; additional are optional
{min,max}	specified range	Min required, max allowed

Items That Match a Position

Metachracter		Matches
^	caret	Matches the position at the start of the line
$	dollar	Matches the position at the end of the line
\<	word boundary*	Matches the position at the start of a word
\>	word boundary*	Matches the position at the end of a word

Other

Metachracter		Matches
|	alternation	Matches either expression it separates
(…)	parentheses	Limits scope of alternation, provides grouping for the quantifiers, and "captures" for backreferences
\1,\2..	backreference*	Matches text previously matched within first, second, etc., set of parentheses.

※ 참고자료
O'Reilly - Mastering Regular Expressions 2nd Edition

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