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289 lines
12 KiB
Groff
289 lines
12 KiB
Groff
.TH PCRETEST 1
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.SH NAME
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pcretest - a program for testing Perl-compatible regular expressions.
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.SH SYNOPSIS
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.B pcretest "[-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]"
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\fBpcretest\fR was written as a test program for the PCRE regular expression
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library itself, but it can also be used for experimenting with regular
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expressions. This man page describes the features of the test program; for
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details of the regular expressions themselves, see the \fBpcre\fR man page.
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.SH OPTIONS
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.TP 10
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\fB-d\fR
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Behave as if each regex had the \fB/D\fR modifier (see below); the internal
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form is output after compilation.
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.TP 10
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\fB-i\fR
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Behave as if each regex had the \fB/I\fR modifier; information about the
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compiled pattern is given after compilation.
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.TP 10
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\fB-m\fR
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Output the size of each compiled pattern after it has been compiled. This is
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equivalent to adding /M to each regular expression. For compatibility with
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earlier versions of pcretest, \fB-s\fR is a synonym for \fB-m\fR.
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.TP 10
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\fB-o\fR \fIosize\fR
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Set the number of elements in the output vector that is used when calling PCRE
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to be \fIosize\fR. The default value is 45, which is enough for 14 capturing
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subexpressions. The vector size can be changed for individual matching calls by
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including \\O in the data line (see below).
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.TP 10
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\fB-p\fR
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Behave as if each regex has \fB/P\fR modifier; the POSIX wrapper API is used
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to call PCRE. None of the other options has any effect when \fB-p\fR is set.
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.TP 10
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\fB-t\fR
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Run each compile, study, and match many times with a timer, and output
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resulting time per compile or match (in milliseconds). Do not set \fB-t\fR with
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\fB-m\fR, because you will then get the size output 20000 times and the timing
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will be distorted.
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.SH DESCRIPTION
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If \fBpcretest\fR is given two filename arguments, it reads from the first and
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writes to the second. If it is given only one filename argument, it reads from
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that file and writes to stdout. Otherwise, it reads from stdin and writes to
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stdout, and prompts for each line of input, using "re>" to prompt for regular
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expressions, and "data>" to prompt for data lines.
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The program handles any number of sets of input on a single input file. Each
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set starts with a regular expression, and continues with any number of data
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lines to be matched against the pattern.
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Each line is matched separately and independently. If you want to do
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multiple-line matches, you have to use the \\n escape sequence in a single line
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of input to encode the newline characters. The maximum length of data line is
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30,000 characters.
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An empty line signals the end of the data lines, at which point a new regular
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expression is read. The regular expressions are given enclosed in any
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non-alphameric delimiters other than backslash, for example
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/(a|bc)x+yz/
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White space before the initial delimiter is ignored. A regular expression may
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be continued over several input lines, in which case the newline characters are
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included within it. It is possible to include the delimiter within the pattern
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by escaping it, for example
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/abc\\/def/
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If you do so, the escape and the delimiter form part of the pattern, but since
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delimiters are always non-alphameric, this does not affect its interpretation.
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If the terminating delimiter is immediately followed by a backslash, for
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example,
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/abc/\\
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then a backslash is added to the end of the pattern. This is done to provide a
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way of testing the error condition that arises if a pattern finishes with a
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backslash, because
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/abc\\/
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is interpreted as the first line of a pattern that starts with "abc/", causing
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pcretest to read the next line as a continuation of the regular expression.
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.SH PATTERN MODIFIERS
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The pattern may be followed by \fBi\fR, \fBm\fR, \fBs\fR, or \fBx\fR to set the
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PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options,
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respectively. For example:
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/caseless/i
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These modifier letters have the same effect as they do in Perl. There are
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others which set PCRE options that do not correspond to anything in Perl:
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\fB/A\fR, \fB/E\fR, and \fB/X\fR set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and
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PCRE_EXTRA respectively.
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Searching for all possible matches within each subject string can be requested
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by the \fB/g\fR or \fB/G\fR modifier. After finding a match, PCRE is called
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again to search the remainder of the subject string. The difference between
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\fB/g\fR and \fB/G\fR is that the former uses the \fIstartoffset\fR argument to
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\fBpcre_exec()\fR to start searching at a new point within the entire string
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(which is in effect what Perl does), whereas the latter passes over a shortened
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substring. This makes a difference to the matching process if the pattern
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begins with a lookbehind assertion (including \\b or \\B).
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If any call to \fBpcre_exec()\fR in a \fB/g\fR or \fB/G\fR sequence matches an
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empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
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flags set in order to search for another, non-empty, match at the same point.
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If this second match fails, the start offset is advanced by one, and the normal
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match is retried. This imitates the way Perl handles such cases when using the
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\fB/g\fR modifier or the \fBsplit()\fR function.
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There are a number of other modifiers for controlling the way \fBpcretest\fR
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operates.
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The \fB/+\fR modifier requests that as well as outputting the substring that
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matched the entire pattern, pcretest should in addition output the remainder of
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the subject string. This is useful for tests where the subject contains
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multiple copies of the same substring.
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The \fB/L\fR modifier must be followed directly by the name of a locale, for
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example,
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/pattern/Lfr
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For this reason, it must be the last modifier letter. The given locale is set,
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\fBpcre_maketables()\fR is called to build a set of character tables for the
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locale, and this is then passed to \fBpcre_compile()\fR when compiling the
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regular expression. Without an \fB/L\fR modifier, NULL is passed as the tables
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pointer; that is, \fB/L\fR applies only to the expression on which it appears.
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The \fB/I\fR modifier requests that \fBpcretest\fR output information about the
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compiled expression (whether it is anchored, has a fixed first character, and
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so on). It does this by calling \fBpcre_fullinfo()\fR after compiling an
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expression, and outputting the information it gets back. If the pattern is
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studied, the results of that are also output.
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The \fB/D\fR modifier is a PCRE debugging feature, which also assumes \fB/I\fR.
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It causes the internal form of compiled regular expressions to be output after
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compilation.
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The \fB/S\fR modifier causes \fBpcre_study()\fR to be called after the
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expression has been compiled, and the results used when the expression is
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matched.
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The \fB/M\fR modifier causes the size of memory block used to hold the compiled
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pattern to be output.
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The \fB/P\fR modifier causes \fBpcretest\fR to call PCRE via the POSIX wrapper
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API rather than its native API. When this is done, all other modifiers except
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\fB/i\fR, \fB/m\fR, and \fB/+\fR are ignored. REG_ICASE is set if \fB/i\fR is
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present, and REG_NEWLINE is set if \fB/m\fR is present. The wrapper functions
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force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
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The \fB/8\fR modifier causes \fBpcretest\fR to call PCRE with the PCRE_UTF8
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option set. This turns on the (currently incomplete) support for UTF-8
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character handling in PCRE, provided that it was compiled with this support
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enabled. This modifier also causes any non-printing characters in output
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strings to be printed using the \\x{hh...} notation if they are valid UTF-8
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sequences.
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.SH DATA LINES
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Before each data line is passed to \fBpcre_exec()\fR, leading and trailing
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whitespace is removed, and it is then scanned for \\ escapes. The following are
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recognized:
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\\a alarm (= BEL)
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\\b backspace
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\\e escape
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\\f formfeed
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\\n newline
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\\r carriage return
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\\t tab
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\\v vertical tab
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\\nnn octal character (up to 3 octal digits)
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\\xhh hexadecimal character (up to 2 hex digits)
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\\x{hh...} hexadecimal UTF-8 character
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\\A pass the PCRE_ANCHORED option to \fBpcre_exec()\fR
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\\B pass the PCRE_NOTBOL option to \fBpcre_exec()\fR
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\\Cdd call pcre_copy_substring() for substring dd
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after a successful match (any decimal number
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less than 32)
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\\Gdd call pcre_get_substring() for substring dd
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after a successful match (any decimal number
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less than 32)
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\\L call pcre_get_substringlist() after a
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successful match
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\\N pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fR
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\\Odd set the size of the output vector passed to
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\fBpcre_exec()\fR to dd (any number of decimal
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digits)
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\\Z pass the PCRE_NOTEOL option to \fBpcre_exec()\fR
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When \\O is used, it may be higher or lower than the size set by the \fB-O\fR
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option (or defaulted to 45); \\O applies only to the call of \fBpcre_exec()\fR
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for the line in which it appears.
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A backslash followed by anything else just escapes the anything else. If the
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very last character is a backslash, it is ignored. This gives a way of passing
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an empty line as data, since a real empty line terminates the data input.
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If \fB/P\fR was present on the regex, causing the POSIX wrapper API to be used,
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only \fB\B\fR, and \fB\Z\fR have any effect, causing REG_NOTBOL and REG_NOTEOL
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to be passed to \fBregexec()\fR respectively.
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The use of \\x{hh...} to represent UTF-8 characters is not dependent on the use
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of the \fB/8\fR modifier on the pattern. It is recognized always. There may be
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any number of hexadecimal digits inside the braces. The result is from one to
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six bytes, encoded according to the UTF-8 rules.
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.SH OUTPUT FROM PCRETEST
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When a match succeeds, pcretest outputs the list of captured substrings that
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\fBpcre_exec()\fR returns, starting with number 0 for the string that matched
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the whole pattern. Here is an example of an interactive pcretest run.
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$ pcretest
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PCRE version 2.06 08-Jun-1999
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re> /^abc(\\d+)/
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data> abc123
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0: abc123
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1: 123
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data> xyz
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No match
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If the strings contain any non-printing characters, they are output as \\0x
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escapes, or as \\x{...} escapes if the \fB/8\fR modifier was present on the
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pattern. If the pattern has the \fB/+\fR modifier, then the output for
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substring 0 is followed by the the rest of the subject string, identified by
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"0+" like this:
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re> /cat/+
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data> cataract
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0: cat
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0+ aract
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If the pattern has the \fB/g\fR or \fB/G\fR modifier, the results of successive
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matching attempts are output in sequence, like this:
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re> /\\Bi(\\w\\w)/g
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data> Mississippi
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0: iss
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1: ss
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0: iss
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1: ss
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0: ipp
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1: pp
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"No match" is output only if the first match attempt fails.
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If any of the sequences \fB\\C\fR, \fB\\G\fR, or \fB\\L\fR are present in a
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data line that is successfully matched, the substrings extracted by the
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convenience functions are output with C, G, or L after the string number
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instead of a colon. This is in addition to the normal full list. The string
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length (that is, the return from the extraction function) is given in
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parentheses after each string for \fB\\C\fR and \fB\\G\fR.
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Note that while patterns can be continued over several lines (a plain ">"
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prompt is used for continuations), data lines may not. However newlines can be
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included in data by means of the \\n escape.
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.SH AUTHOR
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Philip Hazel <ph10@cam.ac.uk>
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.br
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University Computing Service,
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.br
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New Museums Site,
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.br
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Cambridge CB2 3QG, England.
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.br
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Phone: +44 1223 334714
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Last updated: 25 August 2002
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.br
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Copyright (c) 1997-2002 University of Cambridge.
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