PCRE — Perl-compatible regular expressions
The full syntax and semantics of the regular expressions that are supported by PCRE are described in the pcrepattern(3) documentation. This document contains just a quick-reference summary of the syntax.
\aalarm, that is, the BEL character (hex 07) \cx"control-x", where x is any character \eescape (hex 1B) \fformfeed (hex 0C) \nnewline (hex 0A) \rcarriage return (hex 0D) \ttab (hex 09) \dddcharacter with octal code ddd, or backreference \xhhcharacter with hex code hh \x{hhh..}character with hex code hhh..
.any character except newline; in dotall mode, any character whatsoever \Cone byte, even in UTF-8 mode (best avoided) \da decimal digit \Da character that is not a decimal digit \ha horizontal whitespace character \Ha character that is not a horizontal whitespace character \p{xx}a character with the xxproperty\P{xx}a character without the xxproperty\Ra newline sequence \sa whitespace character \Sa character that is not a whitespace character \va vertical whitespace character \Va character that is not a vertical whitespace character \wa "word" character \Wa "non-word" character \Xan extended Unicode sequence
In PCRE, \d, \D, \s, \S, \w, and \W recognize only ASCII characters.
COther CcControl CfFormat CnUnassigned CoPrivate use CsSurrogate LLetter LlLower case letter LmModifier letter LoOther letter LtTitle case letter LuUpper case letter L&Ll, Lu, or Lt MMark McSpacing mark MeEnclosing mark MnNon-spacing mark NNumber NdDecimal number NlLetter number NoOther number PPunctuation PcConnector punctuation PdDash punctuation PeClose punctuation PfFinal punctuation PiInitial punctuation PoOther punctuation PsOpen punctuation SSymbol ScCurrency symbol SkModifier symbol SmMathematical symbol SoOther symbol ZSeparator ZlLine separator ZpParagraph separator ZsSpace separator
Arabic, Armenian, Balinese, Bengali, Bopomofo, Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic, Deseret, Devanagari, Ethiopic, Georgian, Glagolitic, Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew, Hiragana, Inherited, Kannada, Katakana, Kayah_Li, Kharoshthi, Khmer, Lao, Latin, Lepcha, Limbu, Linear_B, Lycian, Lydian, Malayalam, Mongolian, Myanmar, New_Tai_Lue, Nko, Ogham, Old_Italic, Old_Persian, Ol_Chiki, Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic, Saurashtra, Shavian, Sinhala, Sudanese, Syloti_Nagri, Syriac, Tagalog, Tagbanwa, Tai_Le, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Vai, Yi.
[...]positive character class [^...]negative character class [x-y]range (can be used for hex characters) [[:xxx:]]positive POSIX named set [[:^xxx:]]negative POSIX named set alnumalphanumeric alphaalphabetic ascii0-127 blankspace or tab cntrlcontrol character digitdecimal digit graphprinting, excluding space lowerlower case letter printing, including space punctprinting, excluding alphanumeric spacewhitespace upperupper case letter wordsame as \w xdigithexadecimal digit
In PCRE, POSIX character set names recognize only ASCII characters. You can use \Q...\E inside a character class.
?0 or 1, greedy ?+0 or 1, possessive ??0 or 1, lazy *0 or more, greedy *+0 or more, possessive *?0 or more, lazy +1 or more, greedy ++1 or more, possessive +?1 or more, lazy {n}exactly n {n,m}at least n, no more than m, greedy {n,m}+at least n, no more than m, possessive {n,m}?at least n, no more than m, lazy {n,}n or more, greedy {n,}+n or more, possessive {n,}?n or more, lazy
\bword boundary (only ASCII letters recognized) \Bnot a word boundary ^start of subject also after internal newline in multiline mode \Astart of subject $end of subject also before newline at end of subject also before internal newline in multiline mode \Zend of subject also before newline at end of subject \zend of subject \Gfirst matching position in subject
(...)capturing group (?<name>...)named capturing group (Perl) (?'name'...)named capturing group (Perl) (?P<name>...)named capturing group (Python) (?:...)non-capturing group (?|...)non-capturing group; reset group numbers for capturing groups in each alternative
(?i)caseless (?J)allow duplicate names (?m)multiline (?s)single line (dotall) (?U)default ungreedy (lazy) (?x)extended (ignore white space) (?-...)unset option(s)
The following is recognized only at the start of a pattern or after one of the newline-setting options with similar syntax:
(*UTF8) set UTF-8 mode
(?=...)positive look ahead (?!...)negative look ahead (?<=...)positive look behind (?<!...)negative look behind
Each top-level branch of a look behind must be of a fixed length.
\nreference by number (can be ambiguous) \gnreference by number \g{n}reference by number \g{-n}relative reference by number \k<name>reference by name (Perl) \k'name'reference by name (Perl) \g{name}reference by name (Perl) \k{name}reference by name (.NET) (?P=name)reference by name (Python)
(?R)recurse whole pattern (?n)call subpattern by absolute number (?+n)call subpattern by relative number (?-n)call subpattern by relative number (?&name)call subpattern by name (Perl) (?P>name)call subpattern by name (Python) \g<name>call subpattern by name (Oniguruma) \g'name'call subpattern by name (Oniguruma) \g<n>call subpattern by absolute number (Oniguruma) \g'n'call subpattern by absolute number (Oniguruma) \g<+n>call subpattern by relative number (PCRE extension) \g'+n'call subpattern by relative number (PCRE extension) \g<-n>call subpattern by relative number (PCRE extension) \g'-n'call subpattern by relative number (PCRE extension)
(?(condition)yes-pattern)(?(condition)yes-pattern|no-pattern)(?(n)...absolute reference condition (?(+n)...relative reference condition (?(-n)...relative reference condition (?(<name>)...named reference condition (Perl) (?('name')...named reference condition (Perl) (?(name)...named reference condition (PCRE) (?(R)...overall recursion condition (?(Rn)...specific group recursion condition (?(R&name)...specific recursion condition (?(DEFINE)...define subpattern for reference (?(assert)...assertion condition
The following act immediately they are reached:
(*ACCEPT)force successful match (*FAIL)force backtrack; synonym (*F)
The following act only when a subsequent match failure causes a backtrack to reach them. They all force a match failure, but they differ in what happens afterwards. Those that advance the start-of-match point do so only if the pattern is not anchored.
(*COMMIT)overall failure, no advance of starting point (*PRUNE)advance to next starting character (*SKIP)advance start to current matching position (*THEN)local failure, backtrack to next alternation
These are recognized only at the very start of the pattern or after a (*BSR_...) or (*UTF8) option.
(*CR)carriage return only (*LF)linefeed only (*CRLF)carriage return followed by linefeed (*ANYCRLF)all three of the above (*ANY)any Unicode newline sequence
These are recognized only at the very start of the pattern or after a (*...) option that sets the newline convention or UTF-8 mode.
(*BSR_ANYCRLF) CR, LF, or CRLF (*BSR_UNICODE) any Unicode newline sequence
Last updated: 11 April 2009 Copyright (c) 1997-2009 University of Cambridge.
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This manual page is taken from the PCRE library, which is distributed under the BSD license. |