[Regex] Regular Expressions Cheat Sheet

참조: https://remram44.github.io/regex-cheatsheet/regex.html

 

 

 

Regex cheatsheet

Many programs use regular expression to find & replace text. However, they tend to come with their own different flavor.

You can probably expect most modern software and programming languages to be using some variation of the Perl flavor, "PCRE"; however command-line tools (grep, less, ...) will often use the POSIX flavor (sometimes with an extended variant, e.g. egrep or sed -r). Vim also comes with its own syntax (a superset of what Vi accepts).

This cheatsheet lists the respective syntax of each flavor, and the software that uses it.

If you spot errors or missing data, or just want to make this prettier/more accurate, don't hesitate to open an issue or a pull request.

Syntax

WhatPerl/PCREPython's rePOSIX (BRE)POSIX extended (ERE)VimBasicsCharacter classesZero-width assertionsCaptures and groupsLook-aroundMultiplicityOther

Custom character class	[...]	[...]	[...]	[...]	[...]
Negated custom character class	[^...]	[^...]	[^...]	[^...]	[^...]
\ special in class?	yes	yes	no, ] escaped if comes first	no, ] escaped if comes first	yes
Ranges	[a-z], - escaped if first or last	[a-z], - escaped if first or last	[a-z], - escaped if first or last	[a-z], - escaped if first or last	[a-z], - escaped if first or last
Alternation	|	|	\|	|	\| \& (low precedence)
Escaped character	\033 \x1B \x{1234} \N{name} \N{U+263D}	\x12			\%d123 \%x2A \%u1234 \%U1234ABCD
Any character (except newline)	.	.	.	.	.
Any character (including newline)					\_.
Match a "word" character (alphanumeric plus _)	\w [[:word:]]	\w	\w	\w	\w
Case	[[:upper:]] / [[:lower:]]		[[:upper:]] / [[:lower:]]	[[:upper:]] / [[:lower:]]	\u [[:upper:]] / \l [[:lower:]]
Match a non-"word" character	\W	\W			\W
Match a whitespace character (except newline)			\s [[:space:]]	\s [[:space:]]	\s [[:space:]]
Whitespace including newline	\s [[:space:]]	\s			\_s
Match a non-whitespace character	\S	\S	[^[:space:]]	[^[:space:]]	\S [^[:space:]]
Match a digit character	\d [[:digit:]]	\d	[[:digit:]]	[[:digit:]]	\d [[:digit:]]
Match a non-digit character	\D	\D	[^[:digit:]]	[^[:digit:]]	\D [^[:digit:]]
Any hexadecimal digit	[[:xdigit:]]		[[:xdigit:]]	[[:xdigit:]]	\x [[:xdigit:]]
Any octal digit					\o
Any graphical character excluding "word" characters	[[:punct:]]		[[:punct:]]	[[:punct:]]	[[:punct:]]
Any alphabetical character	[[:alpha:]]		[[:alpha:]]	[[:alpha:]]	\a [[:alpha:]]
Non-alphabetical character			[^[:alpha:]]	[^[:alpha:]]	\A [^[:alpha:]]
Any alphanumerical character	[[:alnum:]]		[[:alnum:]]	[[:alnum:]]	[[:alnum:]]
ASCII	[[:ascii:]]
Character equivalents (e = é = è) (as per locale)			[[=e=]]	[[=e=]]	[[=e=]]
Word boundary	\b	\b	\b / \< (start) / \> (end)	\b / \< (start) / \> (end)	\< (start) / \> (end)
Anywhere but word boundary	\B	\B	\B	\B
Beginning of line/string	^ / \A	^ / \A	^	^	^ (beginning of pattern ) \_^
End of line/string	$ / \Z	$ / \Z	$	$	$ (end of pattern) \_$
Capturing group	(...) (?<name>...)	(...) (?P<name>...)	\(...\)	(...)	\(...\)
Non-capturing group	(?:...)	(?:...)			\%(...\)
Backreference to a specific group.	\1 \g1 \g{-1}	\1	\1	\1 non-official	\1
Named backreference	\g{name} \k<name>	(?P=name)
Positive look-ahead	(?=...)	(?=...)			\(...\)\@=
Negative look-ahead	(?!...)	(?!...)			\(...\)\@!
Positive look-behind	(?<=...)	(?<=...)			\(...\)\@<=
Negative look-behind	(?<!...)	(?<!...)			\(...\)\@<!
0 or 1	?	?	\?	?	\?
0 or more	*	*	*	*	*
1 or more	+	+		+	\+
Specific number	{n} {n,m} {n,}	{n} {n,m} {n,}	\{n\} \{n,m\} \{n,\}	{n} {n,m} {n,}	\{n} \{n,m} \{n,}
0 or 1, non-greedy	??	??
0 or more, non-greedy	*?	*?			\{-}
1 or more, non-greedy	+?	+?
Specific number, non-greedy	{n,m}? {n,}?	{n,m}? {n,}?			\{-n,m} \{-n,}
0 or 1, don't give back on backtrack	?+
0 or more, don't give back on backtrack	*+
1 or more, don't give back on backtrack	++
Specific number, don't give back on backtrack	{n,m}+ {n,}+
Independent non-backtracking pattern	(?>...)				\(...\)\@>
Make case-sensitive/insensitive	(?i) / (?-i)	(?i) / (?-i)			\c / \C

Programs

WhatSyntaxComments/gotchasProgramming languagesText editorsCommand-line tools

Perl	PCRE	PCRE is actually a separate implementation from Perl's, with slight differences
Python's re standard lib	Python's own syntax (Perl-inspired)
Ruby	Ruby's own syntax (Perl-inspired)
Java's java.util.regex	Almost PCRE
Boost.Regex	PCRE
Eclipse	PCRE
Emacs	?
Netbeans	PCRE
Notepad++	PCRE (Boost.Regex)
PyCharm	PCRE	Perl-inspired
Sublime Text	?
UltraEdit	PCRE
Vim	Vim	In "magic" mode (default)
awk	ERE	might depend on the implementation
grep	BRE, egrep for ERE, grep -P for PCRE (optional)
less	ERE	usually; man page says "regular expression library supplied by your system"
screen	plain text
sed	BRE, -E switches to ERE