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<TITLE>pcretest specification</TITLE>
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<body bgcolor="#FFFFFF" text="#00005A">
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<H1>pcretest specification</H1>
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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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<LI><A NAME="TOC1" HREF="#SEC1">NAME</A>
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<LI><A NAME="TOC2" HREF="#SEC2">SYNOPSIS</A>
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<LI><A NAME="TOC3" HREF="#SEC3">OPTIONS</A>
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<LI><A NAME="TOC4" HREF="#SEC4">DESCRIPTION</A>
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<LI><A NAME="TOC5" HREF="#SEC5">PATTERN MODIFIERS</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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<LI><A NAME="SEC1" HREF="#TOC1">NAME</A>
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pcretest - a program for testing Perl-compatible regular expressions.
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<LI><A NAME="SEC2" HREF="#TOC1">SYNOPSIS</A>
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<B>pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]</B>
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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 man page describes the features of the test program; for
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details of the regular expressions themselves, see the <B>pcre</B> man page.
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<LI><A NAME="SEC3" HREF="#TOC1">OPTIONS</A>
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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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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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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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<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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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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Run each compile, study, and match 20000 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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<LI><A NAME="SEC4" HREF="#TOC1">DESCRIPTION</A>
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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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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. An empty line signals the end of the
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data lines, at which point a new regular expression is read. The regular
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expressions are given enclosed in any non-alphameric delimiters other than
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backslash, for example
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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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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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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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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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<LI><A NAME="SEC5" HREF="#TOC1">PATTERN MODIFIERS</A>
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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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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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<B>/A</B>, <B>/E</B>, and <B>/X</B> 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 <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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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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There are a number of other modifiers for controlling the way <B>pcretest</B>
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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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The <B>/L</B> modifier must be followed directly by the name of a locale, for
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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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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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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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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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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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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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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 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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<LI><A NAME="SEC6" HREF="#TOC1">DATA LINES</A>
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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. The following are
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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 <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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\Gdd call pcre_get_substring() for substring dd
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after a successful match (any decimal number
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\L call pcre_get_substringlist() after a
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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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\Z pass the PCRE_NOTEOL option to <B>pcre_exec()</B>
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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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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 <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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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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<LI><A NAME="SEC7" HREF="#TOC1">OUTPUT FROM PCRETEST</A>
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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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PCRE version 2.06 08-Jun-1999
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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 <B>/8</B> modifier was present on the
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pattern. If the pattern has the <B>/+</B> 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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If the pattern has the <B>/g</B> or <B>/G</B> modifier, the results of successive
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matching attempts are output in sequence, like this:
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data> Mississippi
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"No match" is output only if the first match attempt fails.
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If any of the sequences <B>\C</B>, <B>\G</B>, or <B>\L</B> 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 <B>\C</B> and <B>\G</B>.
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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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<LI><A NAME="SEC8" HREF="#TOC1">AUTHOR</A>
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Philip Hazel <ph10@cam.ac.uk>
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University Computing Service,
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Cambridge CB2 3QG, England.
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Phone: +44 1223 334714
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Last updated: 15 August 2001
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Copyright (c) 1997-2001 University of Cambridge.
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