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<html>
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<head>
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<title>pcretest specification</title>
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</head>
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<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
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This HTML document has been generated automatically from the original man page.
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If there is any nonsense in it, please consult the man page, in case the
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conversion went wrong.<br>
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<ul>
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<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
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<li><a name="TOC2" href="#SEC2">OPTIONS</a>
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<li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
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<li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
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<li><a name="TOC5" href="#SEC5">CALLOUTS</a>
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<li><a name="TOC6" href="#SEC6">DATA LINES</a>
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<li><a name="TOC7" href="#SEC7">OUTPUT FROM PCRETEST</a>
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<li><a name="TOC8" href="#SEC8">AUTHOR</a>
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</ul>
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<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
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<P>
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<b>pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]</b>
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</P>
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<P>
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<b>pcretest</b> 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 document describes the features of the test program; for
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details of the regular expressions themselves, see the
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<a href="pcrepattern.html"><b>pcrepattern</b></a>
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documentation. For details of PCRE and its options, see the
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<a href="pcreapi.html"><b>pcreapi</b></a>
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documentation.
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</P>
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<br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
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<P>
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<b>-C</b>
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Output the version number of the PCRE library, and all available information
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about the optional features that are included, and then exit.
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</P>
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<P>
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<b>-d</b>
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Behave as if each regex had the <b>/D</b> modifier (see below); the internal
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form is output after compilation.
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</P>
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<P>
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<b>-i</b>
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Behave as if each regex had the <b>/I</b> modifier; information about the
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compiled pattern is given after compilation.
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</P>
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<P>
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<b>-m</b>
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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, <b>-s</b> is a synonym for <b>-m</b>.
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</P>
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<P>
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<b>-o</b> <i>osize</i>
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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 <i>osize</i>. 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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</P>
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<P>
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<b>-p</b>
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Behave as if each regex has <b>/P</b> modifier; the POSIX wrapper API is used
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to call PCRE. None of the other options has any effect when <b>-p</b> is set.
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</P>
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<P>
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<b>-t</b>
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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 <b>-t</b> with
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<b>-m</b>, because you will then get the size output 20000 times and the timing
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will be distorted.
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</P>
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<br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
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<P>
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If <b>pcretest</b> 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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</P>
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<P>
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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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</P>
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<P>
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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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</P>
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<P>
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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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</P>
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<P>
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<pre>
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/(a|bc)x+yz/
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</PRE>
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</P>
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<P>
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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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</P>
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<P>
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<pre>
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/abc\/def/
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</PRE>
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</P>
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<P>
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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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</P>
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<P>
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<pre>
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/abc/\
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</PRE>
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</P>
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<P>
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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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</P>
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<P>
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<pre>
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/abc\/
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</PRE>
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</P>
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<P>
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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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</P>
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<br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
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<P>
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The pattern may be followed by <b>i</b>, <b>m</b>, <b>s</b>, or <b>x</b> 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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</P>
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<P>
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<pre>
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/caseless/i
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</PRE>
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</P>
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<P>
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These modifier letters have the same effect as they do in Perl. There are
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others that set PCRE options that do not correspond to anything in Perl:
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<b>/A</b>, <b>/E</b>, <b>/N</b>, <b>/U</b>, and <b>/X</b> set PCRE_ANCHORED,
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PCRE_DOLLAR_ENDONLY, PCRE_NO_AUTO_CAPTURE, PCRE_UNGREEDY, and PCRE_EXTRA
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respectively.
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</P>
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<P>
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Searching for all possible matches within each subject string can be requested
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by the <b>/g</b> or <b>/G</b> 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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<b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
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<b>pcre_exec()</b> 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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</P>
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<P>
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If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> 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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<b>/g</b> modifier or the <b>split()</b> function.
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</P>
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<P>
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There are a number of other modifiers for controlling the way <b>pcretest</b>
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operates.
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</P>
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<P>
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The <b>/+</b> 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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</P>
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<P>
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The <b>/L</b> modifier must be followed directly by the name of a locale, for
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example,
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</P>
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<P>
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<pre>
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/pattern/Lfr
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</PRE>
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</P>
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<P>
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For this reason, it must be the last modifier letter. The given locale is set,
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<b>pcre_maketables()</b> is called to build a set of character tables for the
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locale, and this is then passed to <b>pcre_compile()</b> when compiling the
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regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
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pointer; that is, <b>/L</b> applies only to the expression on which it appears.
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</P>
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<P>
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The <b>/I</b> modifier requests that <b>pcretest</b> 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 <b>pcre_fullinfo()</b> 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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</P>
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<P>
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The <b>/D</b> modifier is a PCRE debugging feature, which also assumes <b>/I</b>.
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It causes the internal form of compiled regular expressions to be output after
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compilation. If the pattern was studied, the information returned is also
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output.
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</P>
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<P>
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The <b>/S</b> modifier causes <b>pcre_study()</b> 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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</P>
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<P>
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The <b>/M</b> modifier causes the size of memory block used to hold the compiled
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pattern to be output.
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</P>
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<P>
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The <b>/P</b> modifier causes <b>pcretest</b> 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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<b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
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present, and REG_NEWLINE is set if <b>/m</b> 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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</P>
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<P>
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The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
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option set. This turns on support for UTF-8 character handling in PCRE,
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provided that it was compiled with this support enabled. This modifier also
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causes any non-printing characters in output strings to be printed using the
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\x{hh...} notation if they are valid UTF-8 sequences.
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</P>
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<P>
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If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
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call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
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checking of the string for UTF-8 validity.
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</P>
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<br><a name="SEC5" href="#TOC1">CALLOUTS</a><br>
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<P>
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If the pattern contains any callout requests, <b>pcretest</b>'s callout function
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will be called. By default, it displays the callout number, and the start and
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current positions in the text at the callout time. For example, the output
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</P>
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<P>
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<pre>
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--->pqrabcdef
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0 ^ ^
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</PRE>
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</P>
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<P>
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indicates that callout number 0 occurred for a match attempt starting at the
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fourth character of the subject string, when the pointer was at the seventh
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character. The callout function returns zero (carry on matching) by default.
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</P>
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<P>
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Inserting callouts may be helpful when using <b>pcretest</b> to check
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complicated regular expressions. For further information about callouts, see
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the
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<a href="pcrecallout.html"><b>pcrecallout</b></a>
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documentation.
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</P>
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<P>
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For testing the PCRE library, additional control of callout behaviour is
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available via escape sequences in the data, as described in the following
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section. In particular, it is possible to pass in a number as callout data (the
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default is zero). If the callout function receives a non-zero number, it
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returns that value instead of zero.
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</P>
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<br><a name="SEC6" href="#TOC1">DATA LINES</a><br>
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<P>
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Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
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whitespace is removed, and it is then scanned for \ escapes. Some of these are
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pretty esoteric features, intended for checking out some of the more
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complicated features of PCRE. If you are just testing "ordinary" regular
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expressions, you probably don't need any of these. The following escapes are
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recognized:
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</P>
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<P>
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<pre>
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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 character, any number of digits
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in UTF-8 mode
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\A pass the PCRE_ANCHORED option to <b>pcre_exec()</b>
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\B pass the PCRE_NOTBOL option to <b>pcre_exec()</b>
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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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\Cname call pcre_copy_named_substring() for substring
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"name" after a successful match (name termin-
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ated by next non alphanumeric character)
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\C+ show the current captured substrings at callout
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time
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\C- do not supply a callout function
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\C!n return 1 instead of 0 when callout number n is
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reached
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\C!n!m return 1 instead of 0 when callout number n is
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reached for the nth time
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\C*n pass the number n (may be negative) as callout
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data
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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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\Gname call pcre_get_named_substring() for substring
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"name" after a successful match (name termin-
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ated by next non-alphanumeric character)
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\L call pcre_get_substringlist() after a
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successful match
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\M discover the minimum MATCH_LIMIT setting
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\N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b>
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\Odd set the size of the output vector passed to
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<b>pcre_exec()</b> to dd (any number of decimal
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digits)
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\S output details of memory get/free calls during matching
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\Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b>
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\? pass the PCRE_NO_UTF8_CHECK option to
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<b>pcre_exec()</b>
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| 330 |
</PRE>
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| 331 |
</P>
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| 332 |
<P>
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| 333 |
If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
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different values in the <i>match_limit</i> field of the <b>pcre_extra</b> data
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structure, until it finds the minimum number that is needed for
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<b>pcre_exec()</b> to complete. This number is a measure of the amount of
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recursion and backtracking that takes place, and checking it out can be
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instructive. For most simple matches, the number is quite small, but for
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patterns with very large numbers of matching possibilities, it can become large
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very quickly with increasing length of subject string.
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| 341 |
</P>
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| 342 |
<P>
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| 343 |
When \O is used, it may be higher or lower than the size set by the <b>-O</b>
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option (or defaulted to 45); \O applies only to the call of <b>pcre_exec()</b>
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for the line in which it appears.
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| 346 |
</P>
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| 347 |
<P>
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| 348 |
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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</P>
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| 352 |
<P>
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If <b>/P</b> was present on the regex, causing the POSIX wrapper API to be used,
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only <b>\B</b>, and <b>\Z</b> have any effect, causing REG_NOTBOL and REG_NOTEOL
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to be passed to <b>regexec()</b> respectively.
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</P>
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<P>
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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 <b>/8</b> 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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</P>
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| 363 |
<br><a name="SEC7" href="#TOC1">OUTPUT FROM PCRETEST</a><br>
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<P>
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| 365 |
When a match succeeds, pcretest outputs the list of captured substrings that
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<b>pcre_exec()</b> 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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</P>
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| 369 |
<P>
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| 370 |
<pre>
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$ pcretest
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PCRE version 4.00 08-Jan-2003
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</PRE>
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| 374 |
</P>
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| 375 |
<P>
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<pre>
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| 377 |
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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</PRE>
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| 384 |
</P>
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| 385 |
<P>
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| 386 |
If the strings contain any non-printing characters, they are output as \0x
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| 387 |
escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
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| 388 |
pattern. If the pattern has the <b>/+</b> modifier, then the output for
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| 389 |
substring 0 is followed by the the rest of the subject string, identified by
|
| 390 |
"0+" like this:
|
| 391 |
</P>
|
| 392 |
<P>
|
| 393 |
<pre>
|
| 394 |
re> /cat/+
|
| 395 |
data> cataract
|
| 396 |
0: cat
|
| 397 |
0+ aract
|
| 398 |
</PRE>
|
| 399 |
</P>
|
| 400 |
<P>
|
| 401 |
If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
|
| 402 |
matching attempts are output in sequence, like this:
|
| 403 |
</P>
|
| 404 |
<P>
|
| 405 |
<pre>
|
| 406 |
re> /\Bi(\w\w)/g
|
| 407 |
data> Mississippi
|
| 408 |
0: iss
|
| 409 |
1: ss
|
| 410 |
0: iss
|
| 411 |
1: ss
|
| 412 |
0: ipp
|
| 413 |
1: pp
|
| 414 |
</PRE>
|
| 415 |
</P>
|
| 416 |
<P>
|
| 417 |
"No match" is output only if the first match attempt fails.
|
| 418 |
</P>
|
| 419 |
<P>
|
| 420 |
If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
|
| 421 |
data line that is successfully matched, the substrings extracted by the
|
| 422 |
convenience functions are output with C, G, or L after the string number
|
| 423 |
instead of a colon. This is in addition to the normal full list. The string
|
| 424 |
length (that is, the return from the extraction function) is given in
|
| 425 |
parentheses after each string for <b>\C</b> and <b>\G</b>.
|
| 426 |
</P>
|
| 427 |
<P>
|
| 428 |
Note that while patterns can be continued over several lines (a plain ">"
|
| 429 |
prompt is used for continuations), data lines may not. However newlines can be
|
| 430 |
included in data by means of the \n escape.
|
| 431 |
</P>
|
| 432 |
<br><a name="SEC8" href="#TOC1">AUTHOR</a><br>
|
| 433 |
<P>
|
| 434 |
Philip Hazel <ph10@cam.ac.uk>
|
| 435 |
<br>
|
| 436 |
University Computing Service,
|
| 437 |
<br>
|
| 438 |
Cambridge CB2 3QG, England.
|
| 439 |
</P>
|
| 440 |
<P>
|
| 441 |
Last updated: 09 December 2003
|
| 442 |
<br>
|
| 443 |
Copyright © 1997-2003 University of Cambridge.
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