2021-08-30 17:57:44 +02:00
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.TH PCRE2SYNTAX 3 "30 August 2021" "PCRE2 10.38"
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2014-10-20 18:48:14 +02:00
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.SH NAME
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PCRE2 - Perl-compatible regular expressions (revised API)
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.SH "PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY"
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.rs
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.sp
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The full syntax and semantics of the regular expressions that are supported by
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PCRE2 are described in the
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.\" HREF
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\fBpcre2pattern\fP
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.\"
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documentation. This document contains a quick-reference summary of the syntax.
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.
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.
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.SH "QUOTING"
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.rs
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.sp
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\ex where x is non-alphanumeric is a literal x
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\eQ...\eE treat enclosed characters as literal
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.
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.
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2015-04-23 19:28:39 +02:00
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.SH "ESCAPED CHARACTERS"
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2014-10-20 18:48:14 +02:00
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.rs
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2015-06-13 18:10:14 +02:00
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.sp
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2019-03-04 19:07:04 +01:00
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This table applies to ASCII and Unicode environments. An unrecognized escape
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2019-02-12 18:50:19 +01:00
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sequence causes an error.
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2014-10-20 18:48:14 +02:00
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.sp
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\ea alarm, that is, the BEL character (hex 07)
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2015-06-13 18:10:14 +02:00
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\ecx "control-x", where x is any ASCII printing character
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2014-10-20 18:48:14 +02:00
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\ee escape (hex 1B)
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\ef form feed (hex 0C)
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\en newline (hex 0A)
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\er carriage return (hex 0D)
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\et tab (hex 09)
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\e0dd character with octal code 0dd
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\eddd character with octal code ddd, or backreference
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\eo{ddd..} character with octal code ddd..
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2018-09-02 18:03:27 +02:00
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\eN{U+hh..} character with Unicode code point hh.. (Unicode mode only)
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2015-04-23 19:28:39 +02:00
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\exhh character with hex code hh
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2018-07-27 18:30:40 +02:00
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\ex{hh..} character with hex code hh..
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2014-10-20 18:48:14 +02:00
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.sp
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2019-02-12 18:50:19 +01:00
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If PCRE2_ALT_BSUX or PCRE2_EXTRA_ALT_BSUX is set ("ALT_BSUX mode"), the
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following are also recognized:
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.sp
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\eU the character "U"
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\euhhhh character with hex code hhhh
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\eu{hh..} character with hex code hh.. but only for EXTRA_ALT_BSUX
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.sp
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When \ex is not followed by {, from zero to two hexadecimal digits are read,
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but in ALT_BSUX mode \ex must be followed by two hexadecimal digits to be
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recognized as a hexadecimal escape; otherwise it matches a literal "x".
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2019-03-04 19:07:04 +01:00
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Likewise, if \eu (in ALT_BSUX mode) is not followed by four hexadecimal digits
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2019-02-12 18:50:19 +01:00
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or (in EXTRA_ALT_BSUX mode) a sequence of hex digits in curly brackets, it
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matches a literal "u".
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.P
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2015-04-23 19:28:39 +02:00
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Note that \e0dd is always an octal code. The treatment of backslash followed by
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a non-zero digit is complicated; for details see the section
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.\" HTML <a href="pcre2pattern.html#digitsafterbackslash">
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.\" </a>
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"Non-printing characters"
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.\"
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in the
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.\" HREF
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\fBpcre2pattern\fP
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.\"
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2015-06-18 18:39:25 +02:00
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documentation, where details of escape processing in EBCDIC environments are
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2018-07-27 18:30:40 +02:00
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also given. \eN{U+hh..} is synonymous with \ex{hh..} in PCRE2 but is not
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supported in EBCDIC environments. Note that \eN not followed by an opening
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curly bracket has a different meaning (see below).
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2014-10-20 18:48:14 +02:00
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.
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.
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.SH "CHARACTER TYPES"
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.rs
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.sp
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. any character except newline;
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in dotall mode, any character whatsoever
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2015-04-13 19:29:05 +02:00
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\eC one code unit, even in UTF mode (best avoided)
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2014-10-20 18:48:14 +02:00
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\ed a decimal digit
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\eD a character that is not a decimal digit
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\eh a horizontal white space character
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\eH a character that is not a horizontal white space character
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\eN a character that is not a newline
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\ep{\fIxx\fP} a character with the \fIxx\fP property
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\eP{\fIxx\fP} a character without the \fIxx\fP property
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\eR a newline sequence
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\es a white space character
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\eS a character that is not a white space character
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\ev a vertical white space character
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\eV a character that is not a vertical white space character
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\ew a "word" character
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\eW a "non-word" character
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\eX a Unicode extended grapheme cluster
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.sp
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2015-10-17 15:50:56 +02:00
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\eC is dangerous because it may leave the current matching point in the middle
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of a UTF-8 or UTF-16 character. The application can lock out the use of \eC by
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2015-12-17 19:44:06 +01:00
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setting the PCRE2_NEVER_BACKSLASH_C option. It is also possible to build PCRE2
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2015-10-17 15:50:56 +02:00
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with the use of \eC permanently disabled.
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2015-04-13 19:29:05 +02:00
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.P
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2014-10-20 18:48:14 +02:00
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By default, \ed, \es, and \ew match only ASCII characters, even in UTF-8 mode
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or in the 16-bit and 32-bit libraries. However, if locale-specific matching is
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happening, \es and \ew may also match characters with code points in the range
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128-255. If the PCRE2_UCP option is set, the behaviour of these escape
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sequences is changed to use Unicode properties and they match many more
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characters.
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.
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.
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.SH "GENERAL CATEGORY PROPERTIES FOR \ep and \eP"
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.rs
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.sp
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C Other
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Cc Control
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Cf Format
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Cn Unassigned
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Co Private use
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Cs Surrogate
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.sp
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L Letter
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Ll Lower case letter
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Lm Modifier letter
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Lo Other letter
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Lt Title case letter
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Lu Upper case letter
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L& Ll, Lu, or Lt
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.sp
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M Mark
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Mc Spacing mark
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Me Enclosing mark
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Mn Non-spacing mark
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.sp
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N Number
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Nd Decimal number
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Nl Letter number
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No Other number
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.sp
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P Punctuation
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Pc Connector punctuation
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Pd Dash punctuation
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Pe Close punctuation
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Pf Final punctuation
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Pi Initial punctuation
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Po Other punctuation
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Ps Open punctuation
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.sp
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S Symbol
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Sc Currency symbol
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Sk Modifier symbol
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Sm Mathematical symbol
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So Other symbol
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.sp
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Z Separator
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Zl Line separator
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Zp Paragraph separator
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Zs Space separator
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.
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.SH "PCRE2 SPECIAL CATEGORY PROPERTIES FOR \ep and \eP"
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.rs
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.sp
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Xan Alphanumeric: union of properties L and N
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Xps POSIX space: property Z or tab, NL, VT, FF, CR
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Xsp Perl space: property Z or tab, NL, VT, FF, CR
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Xuc Univerally-named character: one that can be
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represented by a Universal Character Name
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Xwd Perl word: property Xan or underscore
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.sp
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Perl and POSIX space are now the same. Perl added VT to its space character set
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at release 5.18.
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.SH "SCRIPT NAMES FOR \ep AND \eP"
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.rs
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.sp
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2018-07-07 18:10:29 +02:00
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Adlam,
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2015-07-17 17:44:51 +02:00
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Ahom,
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Anatolian_Hieroglyphs,
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2014-10-20 18:48:14 +02:00
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Arabic,
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Armenian,
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Avestan,
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Balinese,
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Bamum,
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Bassa_Vah,
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Batak,
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Bengali,
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2018-07-07 18:10:29 +02:00
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Bhaiksuki,
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2014-10-20 18:48:14 +02:00
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Bopomofo,
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Brahmi,
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Braille,
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Buginese,
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Buhid,
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Canadian_Aboriginal,
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Carian,
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Caucasian_Albanian,
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Chakma,
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Cham,
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Cherokee,
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2020-03-25 18:18:33 +01:00
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Chorasmian,
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2014-10-20 18:48:14 +02:00
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Common,
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Coptic,
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Cuneiform,
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Cypriot,
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Cyrillic,
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Deseret,
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Devanagari,
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2020-03-25 18:18:33 +01:00
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Dives_Akuru,
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2018-07-07 18:10:29 +02:00
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Dogra,
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2014-10-20 18:48:14 +02:00
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Duployan,
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Egyptian_Hieroglyphs,
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Elbasan,
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2019-07-29 17:32:36 +02:00
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Elymaic,
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2014-10-20 18:48:14 +02:00
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Ethiopic,
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Georgian,
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Glagolitic,
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Gothic,
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Grantha,
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Greek,
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Gujarati,
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2018-07-07 18:10:29 +02:00
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Gunjala_Gondi,
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2014-10-20 18:48:14 +02:00
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Gurmukhi,
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Han,
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Hangul,
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2018-07-07 18:10:29 +02:00
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Hanifi_Rohingya,
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2014-10-20 18:48:14 +02:00
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Hanunoo,
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2015-07-17 17:44:51 +02:00
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Hatran,
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2014-10-20 18:48:14 +02:00
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Hebrew,
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Hiragana,
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Imperial_Aramaic,
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Inherited,
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Inscriptional_Pahlavi,
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Inscriptional_Parthian,
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Javanese,
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Kaithi,
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Kannada,
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Katakana,
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Kayah_Li,
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Kharoshthi,
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2020-03-25 18:18:33 +01:00
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Khitan_Small_Script,
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2014-10-20 18:48:14 +02:00
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Khmer,
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Khojki,
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Khudawadi,
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Lao,
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Latin,
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Lepcha,
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Limbu,
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Linear_A,
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Linear_B,
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Lisu,
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Lycian,
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Lydian,
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Mahajani,
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2018-07-07 18:10:29 +02:00
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Makasar,
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2014-10-20 18:48:14 +02:00
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Malayalam,
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Mandaic,
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Manichaean,
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2018-07-07 18:10:29 +02:00
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Marchen,
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Masaram_Gondi,
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Medefaidrin,
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2014-10-20 18:48:14 +02:00
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Meetei_Mayek,
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Mende_Kikakui,
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Meroitic_Cursive,
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Meroitic_Hieroglyphs,
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Miao,
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Modi,
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Mongolian,
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Mro,
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2015-07-17 17:44:51 +02:00
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Multani,
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2014-10-20 18:48:14 +02:00
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Myanmar,
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Nabataean,
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2019-07-29 17:32:36 +02:00
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Nandinagari,
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2014-10-20 18:48:14 +02:00
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New_Tai_Lue,
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2018-07-07 18:10:29 +02:00
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Newa,
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2014-10-20 18:48:14 +02:00
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Nko,
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2018-07-07 18:10:29 +02:00
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Nushu,
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2019-07-29 17:32:36 +02:00
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Nyakeng_Puachue_Hmong,
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2014-10-20 18:48:14 +02:00
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Ogham,
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Ol_Chiki,
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2015-07-17 17:44:51 +02:00
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Old_Hungarian,
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2014-10-20 18:48:14 +02:00
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Old_Italic,
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Old_North_Arabian,
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Old_Permic,
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Old_Persian,
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2018-07-07 18:10:29 +02:00
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Old_Sogdian,
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2014-10-20 18:48:14 +02:00
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Old_South_Arabian,
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Old_Turkic,
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Oriya,
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2018-07-07 18:10:29 +02:00
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Osage,
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2014-10-20 18:48:14 +02:00
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Osmanya,
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Pahawh_Hmong,
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Palmyrene,
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Pau_Cin_Hau,
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Phags_Pa,
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Phoenician,
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Psalter_Pahlavi,
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Rejang,
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Runic,
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Samaritan,
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Saurashtra,
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Sharada,
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Shavian,
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Siddham,
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2015-07-17 17:44:51 +02:00
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SignWriting,
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2014-10-20 18:48:14 +02:00
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Sinhala,
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2018-07-07 18:10:29 +02:00
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Sogdian,
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2014-10-20 18:48:14 +02:00
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Sora_Sompeng,
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2018-07-07 18:10:29 +02:00
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Soyombo,
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2014-10-20 18:48:14 +02:00
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Sundanese,
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Syloti_Nagri,
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Syriac,
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Tagalog,
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Tagbanwa,
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Tai_Le,
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Tai_Tham,
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Tai_Viet,
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Takri,
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Tamil,
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2018-07-07 18:10:29 +02:00
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Tangut,
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2014-10-20 18:48:14 +02:00
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Telugu,
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Thaana,
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Thai,
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Tibetan,
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Tifinagh,
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Tirhuta,
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Ugaritic,
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Vai,
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2019-07-29 17:32:36 +02:00
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Wancho,
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2014-10-20 18:48:14 +02:00
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Warang_Citi,
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2020-03-25 18:18:33 +01:00
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Yezidi,
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2018-07-07 18:10:29 +02:00
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Yi,
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Zanabazar_Square.
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2014-10-20 18:48:14 +02:00
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.
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.
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.SH "CHARACTER CLASSES"
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.rs
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.sp
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[...] positive character class
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[^...] negative character class
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[x-y] range (can be used for hex characters)
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[[:xxx:]] positive POSIX named set
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|
[[:^xxx:]] negative POSIX named set
|
|
|
|
.sp
|
|
|
|
alnum alphanumeric
|
|
|
|
alpha alphabetic
|
|
|
|
ascii 0-127
|
|
|
|
blank space or tab
|
|
|
|
cntrl control character
|
|
|
|
digit decimal digit
|
|
|
|
graph printing, excluding space
|
|
|
|
lower lower case letter
|
|
|
|
print printing, including space
|
|
|
|
punct printing, excluding alphanumeric
|
|
|
|
space white space
|
|
|
|
upper upper case letter
|
|
|
|
word same as \ew
|
|
|
|
xdigit hexadecimal digit
|
|
|
|
.sp
|
|
|
|
In PCRE2, POSIX character set names recognize only ASCII characters by default,
|
|
|
|
but some of them use Unicode properties if PCRE2_UCP is set. You can use
|
|
|
|
\eQ...\eE inside a character class.
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "QUANTIFIERS"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
? 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
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "ANCHORS AND SIMPLE ASSERTIONS"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
\eb word boundary
|
|
|
|
\eB not a word boundary
|
|
|
|
^ start of subject
|
2015-04-22 19:39:25 +02:00
|
|
|
also after an internal newline in multiline mode
|
2015-04-23 19:28:39 +02:00
|
|
|
(after any newline if PCRE2_ALT_CIRCUMFLEX is set)
|
2014-10-20 18:48:14 +02:00
|
|
|
\eA start of subject
|
|
|
|
$ end of subject
|
2015-04-22 19:39:25 +02:00
|
|
|
also before newline at end of subject
|
|
|
|
also before internal newline in multiline mode
|
2014-10-20 18:48:14 +02:00
|
|
|
\eZ end of subject
|
2015-04-22 19:39:25 +02:00
|
|
|
also before newline at end of subject
|
2014-10-20 18:48:14 +02:00
|
|
|
\ez end of subject
|
|
|
|
\eG first matching position in subject
|
|
|
|
.
|
|
|
|
.
|
2018-06-28 18:56:56 +02:00
|
|
|
.SH "REPORTED MATCH POINT SETTING"
|
2014-10-20 18:48:14 +02:00
|
|
|
.rs
|
|
|
|
.sp
|
2018-06-28 18:56:56 +02:00
|
|
|
\eK set reported start of match
|
2014-10-20 18:48:14 +02:00
|
|
|
.sp
|
2021-08-31 18:14:42 +02:00
|
|
|
From release 10.38 \eK is not permitted by default in lookaround assertions,
|
2021-08-30 17:57:44 +02:00
|
|
|
for compatibility with Perl. However, if the PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK
|
|
|
|
option is set, the previous behaviour is re-enabled. When this option is set,
|
2014-10-20 18:48:14 +02:00
|
|
|
\eK is honoured in positive assertions, but ignored in negative ones.
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "ALTERNATION"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
expr|expr|expr...
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "CAPTURING"
|
|
|
|
.rs
|
|
|
|
.sp
|
2019-02-06 19:11:36 +01:00
|
|
|
(...) capture group
|
|
|
|
(?<name>...) named capture group (Perl)
|
|
|
|
(?'name'...) named capture group (Perl)
|
|
|
|
(?P<name>...) named capture group (Python)
|
|
|
|
(?:...) non-capture group
|
|
|
|
(?|...) non-capture group; reset group numbers for
|
|
|
|
capture groups in each alternative
|
|
|
|
.sp
|
|
|
|
In non-UTF modes, names may contain underscores and ASCII letters and digits;
|
|
|
|
in UTF modes, any Unicode letters and Unicode decimal digits are permitted. In
|
|
|
|
both cases, a name must not start with a digit.
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "ATOMIC GROUPS"
|
|
|
|
.rs
|
|
|
|
.sp
|
2019-02-06 19:11:36 +01:00
|
|
|
(?>...) atomic non-capture group
|
|
|
|
(*atomic:...) atomic non-capture group
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "COMMENT"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
(?#....) comment (not nestable)
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "OPTION SETTING"
|
|
|
|
.rs
|
2018-08-13 13:57:09 +02:00
|
|
|
Changes of these options within a group are automatically cancelled at the end
|
2018-08-03 11:38:36 +02:00
|
|
|
of the group.
|
2014-10-20 18:48:14 +02:00
|
|
|
.sp
|
|
|
|
(?i) caseless
|
2019-12-28 15:09:09 +01:00
|
|
|
(?J) allow duplicate named groups
|
2014-10-20 18:48:14 +02:00
|
|
|
(?m) multiline
|
2017-07-19 18:04:15 +02:00
|
|
|
(?n) no auto capture
|
2014-10-20 18:48:14 +02:00
|
|
|
(?s) single line (dotall)
|
|
|
|
(?U) default ungreedy (lazy)
|
2017-04-18 14:32:52 +02:00
|
|
|
(?x) extended: ignore white space except in classes
|
2017-07-19 18:04:15 +02:00
|
|
|
(?xx) as (?x) but also ignore space and tab in classes
|
2014-10-20 18:48:14 +02:00
|
|
|
(?-...) unset option(s)
|
2018-08-13 13:57:09 +02:00
|
|
|
(?^) unset imnsx options
|
2014-10-20 18:48:14 +02:00
|
|
|
.sp
|
2018-07-28 18:23:24 +02:00
|
|
|
Unsetting x or xx unsets both. Several options may be set at once, and a
|
|
|
|
mixture of setting and unsetting such as (?i-x) is allowed, but there may be
|
|
|
|
only one hyphen. Setting (but no unsetting) is allowed after (?^ for example
|
2019-02-06 19:11:36 +01:00
|
|
|
(?^in). An option setting may appear at the start of a non-capture group, for
|
2018-07-28 18:23:24 +02:00
|
|
|
example (?i:...).
|
|
|
|
.P
|
2014-10-20 18:48:14 +02:00
|
|
|
The following are recognized only at the very start of a pattern or after one
|
|
|
|
of the newline or \eR options with similar syntax. More than one of them may
|
2017-06-17 13:40:17 +02:00
|
|
|
appear. For the first three, d is a decimal number.
|
2014-10-20 18:48:14 +02:00
|
|
|
.sp
|
2017-06-17 13:40:17 +02:00
|
|
|
(*LIMIT_DEPTH=d) set the backtracking limit to d
|
2018-06-17 16:13:28 +02:00
|
|
|
(*LIMIT_HEAP=d) set the heap size limit to d * 1024 bytes
|
2017-06-17 13:40:17 +02:00
|
|
|
(*LIMIT_MATCH=d) set the match limit to d
|
|
|
|
(*NOTEMPTY) set PCRE2_NOTEMPTY when matching
|
2014-10-20 19:28:49 +02:00
|
|
|
(*NOTEMPTY_ATSTART) set PCRE2_NOTEMPTY_ATSTART when matching
|
2014-10-20 18:48:14 +02:00
|
|
|
(*NO_AUTO_POSSESS) no auto-possessification (PCRE2_NO_AUTO_POSSESS)
|
2015-01-02 18:09:16 +01:00
|
|
|
(*NO_DOTSTAR_ANCHOR) no .* anchoring (PCRE2_NO_DOTSTAR_ANCHOR)
|
2015-02-20 12:20:40 +01:00
|
|
|
(*NO_JIT) disable JIT optimization
|
2014-10-20 18:48:14 +02:00
|
|
|
(*NO_START_OPT) no start-match optimization (PCRE2_NO_START_OPTIMIZE)
|
|
|
|
(*UTF) set appropriate UTF mode for the library in use
|
|
|
|
(*UCP) set PCRE2_UCP (use Unicode properties for \ed etc)
|
|
|
|
.sp
|
2017-06-17 13:40:17 +02:00
|
|
|
Note that LIMIT_DEPTH, LIMIT_HEAP, and LIMIT_MATCH can only reduce the value of
|
|
|
|
the limits set by the caller of \fBpcre2_match()\fP or \fBpcre2_dfa_match()\fP,
|
|
|
|
not increase them. LIMIT_RECURSION is an obsolete synonym for LIMIT_DEPTH. The
|
2017-03-31 19:06:43 +02:00
|
|
|
application can lock out the use of (*UTF) and (*UCP) by setting the
|
|
|
|
PCRE2_NEVER_UTF or PCRE2_NEVER_UCP options, respectively, at compile time.
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "NEWLINE CONVENTION"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
These are recognized only at the very start of the pattern or after option
|
|
|
|
settings with a similar syntax.
|
|
|
|
.sp
|
|
|
|
(*CR) carriage return only
|
|
|
|
(*LF) linefeed only
|
|
|
|
(*CRLF) carriage return followed by linefeed
|
|
|
|
(*ANYCRLF) all three of the above
|
|
|
|
(*ANY) any Unicode newline sequence
|
2017-05-26 19:14:36 +02:00
|
|
|
(*NUL) the NUL character (binary zero)
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "WHAT \eR MATCHES"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
These are recognized only at the very start of the pattern or after option
|
|
|
|
setting with a similar syntax.
|
|
|
|
.sp
|
|
|
|
(*BSR_ANYCRLF) CR, LF, or CRLF
|
|
|
|
(*BSR_UNICODE) any Unicode newline sequence
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "LOOKAHEAD AND LOOKBEHIND ASSERTIONS"
|
|
|
|
.rs
|
|
|
|
.sp
|
2018-09-24 18:23:53 +02:00
|
|
|
(?=...) )
|
|
|
|
(*pla:...) ) positive lookahead
|
|
|
|
(*positive_lookahead:...) )
|
2014-10-20 18:48:14 +02:00
|
|
|
.sp
|
2018-09-24 18:23:53 +02:00
|
|
|
(?!...) )
|
|
|
|
(*nla:...) ) negative lookahead
|
|
|
|
(*negative_lookahead:...) )
|
|
|
|
.sp
|
|
|
|
(?<=...) )
|
|
|
|
(*plb:...) ) positive lookbehind
|
|
|
|
(*positive_lookbehind:...) )
|
|
|
|
.sp
|
|
|
|
(?<!...) )
|
|
|
|
(*nlb:...) ) negative lookbehind
|
|
|
|
(*negative_lookbehind:...) )
|
|
|
|
.sp
|
|
|
|
Each top-level branch of a lookbehind must be of a fixed length.
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
2019-07-13 13:12:03 +02:00
|
|
|
.SH "NON-ATOMIC LOOKAROUND ASSERTIONS"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
These assertions are specific to PCRE2 and are not Perl-compatible.
|
|
|
|
.sp
|
2019-12-28 14:53:59 +01:00
|
|
|
(?*...) )
|
|
|
|
(*napla:...) ) synonyms
|
|
|
|
(*non_atomic_positive_lookahead:...) )
|
2020-04-15 18:34:36 +02:00
|
|
|
.sp
|
2019-12-28 14:53:59 +01:00
|
|
|
(?<*...) )
|
|
|
|
(*naplb:...) ) synonyms
|
|
|
|
(*non_atomic_positive_lookbehind:...) )
|
2019-07-13 13:12:03 +02:00
|
|
|
.
|
|
|
|
.
|
2018-10-12 19:02:34 +02:00
|
|
|
.SH "SCRIPT RUNS"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
(*script_run:...) ) script run, can be backtracked into
|
|
|
|
(*sr:...) )
|
|
|
|
.sp
|
|
|
|
(*atomic_script_run:...) ) atomic script run
|
|
|
|
(*asr:...) )
|
|
|
|
.
|
|
|
|
.
|
2014-10-20 18:48:14 +02:00
|
|
|
.SH "BACKREFERENCES"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
\en reference by number (can be ambiguous)
|
|
|
|
\egn reference by number
|
|
|
|
\eg{n} reference by number
|
2016-10-02 18:01:01 +02:00
|
|
|
\eg+n relative reference by number (PCRE2 extension)
|
|
|
|
\eg-n relative reference by number
|
2017-01-16 18:40:47 +01:00
|
|
|
\eg{+n} relative reference by number (PCRE2 extension)
|
2014-10-20 18:48:14 +02:00
|
|
|
\eg{-n} relative reference by number
|
|
|
|
\ek<name> reference by name (Perl)
|
|
|
|
\ek'name' reference by name (Perl)
|
|
|
|
\eg{name} reference by name (Perl)
|
|
|
|
\ek{name} reference by name (.NET)
|
|
|
|
(?P=name) reference by name (Python)
|
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
(?R) recurse whole pattern
|
2019-02-06 19:11:36 +01:00
|
|
|
(?n) call subroutine by absolute number
|
|
|
|
(?+n) call subroutine by relative number
|
|
|
|
(?-n) call subroutine by relative number
|
|
|
|
(?&name) call subroutine by name (Perl)
|
|
|
|
(?P>name) call subroutine by name (Python)
|
|
|
|
\eg<name> call subroutine by name (Oniguruma)
|
|
|
|
\eg'name' call subroutine by name (Oniguruma)
|
|
|
|
\eg<n> call subroutine by absolute number (Oniguruma)
|
|
|
|
\eg'n' call subroutine by absolute number (Oniguruma)
|
|
|
|
\eg<+n> call subroutine by relative number (PCRE2 extension)
|
|
|
|
\eg'+n' call subroutine by relative number (PCRE2 extension)
|
|
|
|
\eg<-n> call subroutine by relative number (PCRE2 extension)
|
|
|
|
\eg'-n' call subroutine by relative number (PCRE2 extension)
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "CONDITIONAL PATTERNS"
|
|
|
|
.rs
|
|
|
|
.sp
|
|
|
|
(?(condition)yes-pattern)
|
|
|
|
(?(condition)yes-pattern|no-pattern)
|
|
|
|
.sp
|
2014-11-14 19:41:20 +01:00
|
|
|
(?(n) absolute reference condition
|
|
|
|
(?(+n) relative reference condition
|
|
|
|
(?(-n) relative reference condition
|
|
|
|
(?(<name>) named reference condition (Perl)
|
|
|
|
(?('name') named reference condition (Perl)
|
2016-10-02 18:01:01 +02:00
|
|
|
(?(name) named reference condition (PCRE2, deprecated)
|
2014-11-14 19:41:20 +01:00
|
|
|
(?(R) overall recursion condition
|
2016-10-02 18:01:01 +02:00
|
|
|
(?(Rn) specific numbered group recursion condition
|
|
|
|
(?(R&name) specific named group recursion condition
|
2019-02-06 19:11:36 +01:00
|
|
|
(?(DEFINE) define groups for reference
|
2014-11-14 19:41:20 +01:00
|
|
|
(?(VERSION[>]=n.m) test PCRE2 version
|
|
|
|
(?(assert) assertion condition
|
2016-10-02 18:01:01 +02:00
|
|
|
.sp
|
2017-01-16 18:40:47 +01:00
|
|
|
Note the ambiguity of (?(R) and (?(Rn) which might be named reference
|
2016-10-02 18:01:01 +02:00
|
|
|
conditions or recursion tests. Such a condition is interpreted as a reference
|
|
|
|
condition if the relevant named group exists.
|
2014-10-20 18:48:14 +02:00
|
|
|
.
|
|
|
|
.
|
|
|
|
.SH "BACKTRACKING CONTROL"
|
|
|
|
.rs
|
|
|
|
.sp
|
2018-07-21 16:34:51 +02:00
|
|
|
All backtracking control verbs may be in the form (*VERB:NAME). For (*MARK) the
|
|
|
|
name is mandatory, for the others it is optional. (*SKIP) changes its behaviour
|
|
|
|
if :NAME is present. The others just set a name for passing back to the caller,
|
|
|
|
but this is not a name that (*SKIP) can see. The following act immediately they
|
|
|
|
are reached:
|
2014-10-20 18:48:14 +02:00
|
|
|
.sp
|
|
|
|
(*ACCEPT) force successful match
|
|
|
|
(*FAIL) force backtrack; synonym (*F)
|
|
|
|
(*MARK:NAME) set name to be passed back; synonym (*:NAME)
|
|
|
|
.sp
|
|
|
|
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.
|
|
|
|
.sp
|
|
|
|
(*COMMIT) overall failure, no advance of starting point
|
|
|
|
(*PRUNE) advance to next starting character
|
|
|
|
(*SKIP) advance to current matching position
|
|
|
|
(*SKIP:NAME) advance to position corresponding to an earlier
|
|
|
|
(*MARK:NAME); if not found, the (*SKIP) is ignored
|
|
|
|
(*THEN) local failure, backtrack to next alternation
|
2018-07-21 16:34:51 +02:00
|
|
|
.sp
|
2018-08-13 13:57:09 +02:00
|
|
|
The effect of one of these verbs in a group called as a subroutine is confined
|
|
|
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to the subroutine call.
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2014-10-20 18:48:14 +02:00
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.
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.
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.SH "CALLOUTS"
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.rs
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.sp
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2015-03-15 18:49:03 +01:00
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(?C) callout (assumed number 0)
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(?Cn) callout with numerical data n
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(?C"text") callout with string data
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.sp
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2015-04-23 19:28:39 +02:00
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The allowed string delimiters are ` ' " ^ % # $ (which are the same for the
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start and the end), and the starting delimiter { matched with the ending
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delimiter }. To encode the ending delimiter within the string, double it.
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2014-10-20 18:48:14 +02:00
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.
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.
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.SH "SEE ALSO"
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.rs
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.sp
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\fBpcre2pattern\fP(3), \fBpcre2api\fP(3), \fBpcre2callout\fP(3),
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\fBpcre2matching\fP(3), \fBpcre2\fP(3).
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.
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.
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.SH AUTHOR
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.rs
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.sp
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.nf
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Philip Hazel
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2021-08-30 17:57:44 +02:00
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Retired from University Computing Service
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2014-11-17 17:59:02 +01:00
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Cambridge, England.
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2014-10-20 18:48:14 +02:00
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.fi
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.
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.
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.SH REVISION
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.rs
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.sp
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.nf
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2021-08-30 17:57:44 +02:00
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Last updated: 30 August 2021
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Copyright (c) 1997-2021 University of Cambridge.
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2014-10-20 18:48:14 +02:00
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.fi
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