PCRETEST(1)                OpenBSD Reference Manual                PCRETEST(1)



NAME
       pcretest - a program for testing Perl-compatible regular expressions.

SYNOPSIS

       pcretest [options] [input file [output file]]

       pcretest was written as a test program for the PCRE regular expression
       library itself, but it can also be used for experimenting with regular
       expressions. This document describes the features of the test program;
       for details of the regular expressions themselves, see the pcrepattern
       documentation. For details of the PCRE library function calls and their
       options, see the pcreapi and pcre16 documentation. The input for
       pcretest is a sequence of regular expression patterns and strings to be
       matched, as described below. The output shows the result of each match.
       Options on the command line and the patterns control PCRE options and
       exactly what is output.

PCRE's 8-BIT and 16-BIT LIBRARIES

       From release 8.30, two separate PCRE libraries can be built. The
       original one supports 8-bit character strings, whereas the newer 16-bit
       library supports character strings encoded in 16-bit units. The
       pcretest program can be used to test both libraries. However, it is
       itself still an 8-bit program, reading 8-bit input and writing 8-bit
       output. When testing the 16-bit library, the patterns and data strings
       are converted to 16-bit format before being passed to the PCRE library
       functions. Results are converted to 8-bit for output.

       References to functions and structures of the form pcre[16]_xx below
       mean "pcre_xx when using the 8-bit library or pcre16_xx when using the
       16-bit library".

COMMAND LINE OPTIONS

       -16       If both the 8-bit and the 16-bit libraries have been built,
                 this option causes the 16-bit library to be used. If only the
                 16-bit library has been built, this is the default (so has no
                 effect). If only the 8-bit library has been built, this
                 option causes an error.

       -b        Behave as if each pattern has the /B (show byte code)
                 modifier; the internal form is output after compilation.

       -C        Output the version number of the PCRE library, and all
                 available information about the optional features that are
                 included, and then exit. All other options are ignored.

       -C option Output information about a specific build-time option, then
                 exit. This functionality is intended for use in scripts such
                 as RunTest. The following options output the value indicated:

                   linksize   the internal link size (2, 3, or 4)
                   newline    the default newline setting:
                                CR, LF, CRLF, ANYCRLF, or ANY

                 The following options output 1 for true or zero for false:

                   jit        just-in-time support is available
                   pcre16     the 16-bit library was built
                   pcre8      the 8-bit library was built
                   ucp        Unicode property support is available
                   utf        UTF-8 and/or UTF-16 support is available

       -d        Behave as if each pattern has the /D (debug) modifier; the
                 internal form and information about the compiled pattern is
                 output after compilation; -d is equivalent to -b -i.

       -dfa      Behave as if each data line contains the \D escape sequence;
                 this causes the alternative matching function,
                 pcre[16]_dfa_exec(), to be used instead of the standard
                 pcre[16]_exec() function (more detail is given below).

       -help     Output a brief summary these options and then exit.

       -i        Behave as if each pattern has the /I modifier; information
                 about the compiled pattern is given after compilation.

       -M        Behave as if each data line contains the \M escape sequence;
                 this causes PCRE to discover the minimum MATCH_LIMIT and
                 MATCH_LIMIT_RECURSION settings by calling pcre[16]_exec()
                 repeatedly with different limits.

       -m        Output the size of each compiled pattern after it has been
                 compiled. This is equivalent to adding /M to each regular
                 expression. The size is given in bytes for both libraries.

       -o osize  Set the number of elements in the output vector that is used
                 when calling pcre[16]_exec() or pcre[16]_dfa_exec() to be
                 osize. The default value is 45, which is enough for 14
                 capturing subexpressions for pcre[16]_exec() or 22 different
                 matches for pcre[16]_dfa_exec().  The vector size can be
                 changed for individual matching calls by including \O in the
                 data line (see below).

       -p        Behave as if each pattern has the /P modifier; the POSIX
                 wrapper API is used to call PCRE. None of the other options
                 has any effect when -p is set. This option can be used only
                 with the 8-bit library.

       -q        Do not output the version number of pcretest at the start of
                 execution.

       -S size   On Unix-like systems, set the size of the run-time stack to
                 size megabytes.

       -s or -s+ Behave as if each pattern has the /S modifier; in other
                 words, force each pattern to be studied. If -s+ is used, the
                 PCRE_STUDY_JIT_COMPILE flag is passed to pcre[16]_study(),
                 causing just-in-time optimization to be set up if it is
                 available. If the /I or /D option is present on a pattern
                 (requesting output about the compiled pattern), information
                 about the result of studying is not included when studying is
                 caused only by -s and neither -i nor -d is present on the
                 command line. This behaviour means that the output from tests
                 that are run with and without -s should be identical, except
                 when options that output information about the actual running
                 of a match are set.

                 The -M, -t, and -tm options, which give information about
                 resources used, are likely to produce different output with
                 and without -s. Output may also differ if the /C option is
                 present on an individual pattern. This uses callouts to trace
                 the the matching process, and this may be different between
                 studied and non-studied patterns. If the pattern contains
                 (*MARK) items there may also be differences, for the same
                 reason. The -s command line option can be overridden for
                 specific patterns that should never be studied (see the /S
                 pattern modifier below).

       -t        Run each compile, study, and match many times with a timer,
                 and output resulting time per compile or match (in
                 milliseconds). Do not set -m with -t, because you will then
                 get the size output a zillion times, and the timing will be
                 distorted. You can control the number of iterations that are
                 used for timing by following -t with a number (as a separate
                 item on the command line). For example, "-t 1000" would
                 iterate 1000 times. The default is to iterate 500000 times.

       -tm       This is like -t except that it times only the matching phase,
                 not the compile or study phases.

DESCRIPTION

       If pcretest is given two filename arguments, it reads from the first
       and writes to the second. If it is given only one filename argument, it
       reads from that file and writes to stdout. Otherwise, it reads from
       stdin and writes to stdout, and prompts for each line of input, using
       "re>" to prompt for regular expressions, and "data>" to prompt for data
       lines.

       When pcretest is built, a configuration option can specify that it
       should be linked with the libreadline library. When this is done, if
       the input is from a terminal, it is read using the readline() function.
       This provides line-editing and history facilities. The output from the
       -help option states whether or not readline() will be used.

       The program handles any number of sets of input on a single input file.
       Each set starts with a regular expression, and continues with any
       number of data lines to be matched against the pattern.

       Each data line is matched separately and independently. If you want to
       do multi-line matches, you have to use the \n escape sequence (or \r or
       \r\n, etc., depending on the newline setting) in a single line of input
       to encode the newline sequences. There is no limit on the length of
       data lines; the input buffer is automatically extended if it is too
       small.

       An empty line signals the end of the data lines, at which point a new
       regular expression is read. The regular expressions are given enclosed
       in any non-alphanumeric delimiters other than backslash, for example:

         /(a|bc)x+yz/

       White space before the initial delimiter is ignored. A regular
       expression may be continued over several input lines, in which case the
       newline characters are included within it. It is possible to include
       the delimiter within the pattern by escaping it, for example

         /abc\/def/

       If you do so, the escape and the delimiter form part of the pattern,
       but since delimiters are always non-alphanumeric, this does not affect
       its interpretation.  If the terminating delimiter is immediately
       followed by a backslash, for example,

         /abc/\

       then a backslash is added to the end of the pattern. This is done to
       provide a way of testing the error condition that arises if a pattern
       finishes with a backslash, because

         /abc\/

       is interpreted as the first line of a pattern that starts with "abc/",
       causing pcretest to read the next line as a continuation of the regular
       expression.

PATTERN MODIFIERS

       A pattern may be followed by any number of modifiers, which are mostly
       single characters. Following Perl usage, these are referred to below
       as, for example, "the /i modifier", even though the delimiter of the
       pattern need not always be a slash, and no slash is used when writing
       modifiers. White space may appear between the final pattern delimiter
       and the first modifier, and between the modifiers themselves.

       The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
       PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
       pcre[16]_compile() is called. These four modifier letters have the same
       effect as they do in Perl. For example:

         /caseless/i

       The following table shows additional modifiers for setting PCRE
       compile-time options that do not correspond to anything in Perl:

         /8              PCRE_UTF8           ) when using the 8-bit
         /?              PCRE_NO_UTF8_CHECK  )   library

         /8              PCRE_UTF16          ) when using the 16-bit
         /?              PCRE_NO_UTF16_CHECK )   library

         /A              PCRE_ANCHORED
         /C              PCRE_AUTO_CALLOUT
         /E              PCRE_DOLLAR_ENDONLY
         /f              PCRE_FIRSTLINE
         /J              PCRE_DUPNAMES
         /N              PCRE_NO_AUTO_CAPTURE
         /U              PCRE_UNGREEDY
         /W              PCRE_UCP
         /X              PCRE_EXTRA
         /Y              PCRE_NO_START_OPTIMIZE
         /<JS>           PCRE_JAVASCRIPT_COMPAT
         /<cr>           PCRE_NEWLINE_CR
         /<lf>           PCRE_NEWLINE_LF
         /<crlf>         PCRE_NEWLINE_CRLF
         /<anycrlf>      PCRE_NEWLINE_ANYCRLF
         /<any>          PCRE_NEWLINE_ANY
         /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
         /<bsr_unicode>  PCRE_BSR_UNICODE

       The modifiers that are enclosed in angle brackets are literal strings
       as shown, including the angle brackets, but the letters within can be
       in either case.  This example sets multiline matching with CRLF as the
       line ending sequence:

         /^abc/m<CRLF>

       As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes
       all non-printing characters in output strings to be printed using the
       \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
       without the curly brackets.

       Full details of the PCRE options are given in the pcreapi
       documentation.

   Finding all matches in a string

       Searching for all possible matches within each subject string can be
       requested by the /g or /G modifier. After finding a match, PCRE is
       called again to search the remainder of the subject string. The
       difference between /g and /G is that the former uses the startoffset
       argument to pcre[16]_exec() to start searching at a new point within
       the entire string (which is in effect what Perl does), whereas the
       latter passes over a shortened substring. This makes a difference to
       the matching process if the pattern begins with a lookbehind assertion
       (including \b or \B).

       If any call to pcre[16]_exec() in a /g or /G sequence matches an empty
       string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
       PCRE_ANCHORED flags set in order to search for another, non-empty,
       match at the same point. If this second match fails, the start offset
       is advanced, and the normal match is retried. This imitates the way
       Perl handles such cases when using the /g modifier or the split()
       function. Normally, the start offset is advanced by one character, but
       if the newline convention recognizes CRLF as a newline, and the current
       character is CR followed by LF, an advance of two is used.

   Other modifiers

       There are yet more modifiers for controlling the way pcretest operates.

       The /+ modifier requests that as well as outputting the substring that
       matched the entire pattern, pcretest should in addition output the
       remainder of the subject string. This is useful for tests where the
       subject contains multiple copies of the same substring. If the +
       modifier appears twice, the same action is taken for captured
       substrings. In each case the remainder is output on the following line
       with a plus character following the capture number. Note that this
       modifier must not immediately follow the /S modifier because /S+ has
       another meaning.

       The /= modifier requests that the values of all potential captured
       parentheses be output after a match. By default, only those up to the
       highest one actually used in the match are output (corresponding to the
       return code from pcre[16]_exec()). Values in the offsets vector
       corresponding to higher numbers should be set to -1, and these are
       output as "<unset>". This modifier gives a way of checking that this is
       happening.

       The /B modifier is a debugging feature. It requests that pcretest
       output a representation of the compiled code after compilation.
       Normally this information contains length and offset values; however,
       if /Z is also present, this data is replaced by spaces. This is a
       special feature for use in the automatic test scripts; it ensures that
       the same output is generated for different internal link sizes.

       The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
       that is, both the /B and the /I modifiers.

       The /F modifier causes pcretest to flip the byte order of the 2-byte
       and 4-byte fields in the compiled pattern. This facility is for testing
       the feature in PCRE that allows it to execute patterns that were
       compiled on a host with a different endianness. This feature is not
       available when the POSIX interface to PCRE is being used, that is, when
       the /P pattern modifier is specified. See also the section about saving
       and reloading compiled patterns below.

       The /I modifier requests that pcretest output information about the
       compiled pattern (whether it is anchored, has a fixed first character,
       and so on). It does this by calling pcre[16]_fullinfo() after compiling
       a pattern. If the pattern is studied, the results of that are also
       output.

       The /K modifier requests pcretest to show names from backtracking
       control verbs that are returned from calls to pcre[16]_exec(). It
       causes pcretest to create a pcre[16]_extra block if one has not already
       been created by a call to pcre[16]_study(), and to set the
       PCRE_EXTRA_MARK flag and the mark field within it, every time that
       pcre[16]_exec() is called. If the variable that the mark field points
       to is non-NULL for a match, non-match, or partial match, pcretest
       prints the string to which it points. For a match, this is shown on a
       line by itself, tagged with "MK:". For a non-match it is added to the
       message.

       The /L modifier must be followed directly by the name of a locale, for
       example,

         /pattern/Lfr_FR

       For this reason, it must be the last modifier. The given locale is set,
       pcre[16]_maketables() is called to build a set of character tables for
       the locale, and this is then passed to pcre[16]_compile() when
       compiling the regular expression. Without an /L (or /T) modifier, NULL
       is passed as the tables pointer; that is, /L applies only to the
       expression on which it appears.

       The /M modifier causes the size in bytes of the memory block used to
       hold the compiled pattern to be output. This does not include the size
       of the pcre[16] block; it is just the actual compiled data. If the
       pattern is successfully studied with the PCRE_STUDY_JIT_COMPILE option,
       the size of the JIT compiled code is also output.

       If the /S modifier appears once, it causes pcre[16]_study() to be
       called after the expression has been compiled, and the results used
       when the expression is matched. If /S appears twice, it suppresses
       studying, even if it was requested externally by the -s command line
       option. This makes it possible to specify that certain patterns are
       always studied, and others are never studied, independently of -s. This
       feature is used in the test files in a few cases where the output is
       different when the pattern is studied.

       If the /S modifier is immediately followed by a + character, the call
       to pcre[16]_study() is made with the PCRE_STUDY_JIT_COMPILE option,
       requesting just-in-time optimization support if it is available. Note
       that there is also a /+ modifier; it must not be given immediately
       after /S because this will be misinterpreted. If JIT studying is
       successful, it will automatically be used when pcre[16]_exec() is run,
       except when incompatible run-time options are specified. These include
       the partial matching options; a complete list is given in the pcrejit
       documentation. See also the \J escape sequence below for a way of
       setting the size of the JIT stack.

       The /T modifier must be followed by a single digit. It causes a
       specific set of built-in character tables to be passed to
       pcre[16]_compile(). It is used in the standard PCRE tests to check
       behaviour with different character tables. The digit specifies the
       tables as follows:

         0   the default ASCII tables, as distributed in
               pcre_chartables.c.dist
         1   a set of tables defining ISO 8859 characters

       In table 1, some characters whose codes are greater than 128 are
       identified as letters, digits, spaces, etc.

   Using the POSIX wrapper API

       The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
       rather than its native API. This supports only the 8-bit library. When
       /P is set, the following modifiers set options for the regcomp()
       function:

         /i    REG_ICASE
         /m    REG_NEWLINE
         /N    REG_NOSUB
         /s    REG_DOTALL     )
         /U    REG_UNGREEDY   ) These options are not part of
         /W    REG_UCP        )   the POSIX standard
         /8    REG_UTF8       )

       The /+ modifier works as described above. All other modifiers are
       ignored.

DATA LINES

       Before each data line is passed to pcre[16]_exec(), leading and
       trailing white space is removed, and it is then scanned for \ escapes.
       Some of these are pretty esoteric features, intended for checking out
       some of the more complicated features of PCRE. If you are just testing
       "ordinary" regular expressions, you probably don't need any of these.
       The following escapes are recognized:

         \a         alarm (BEL, \x07)
         \b         backspace (\x08)
         \e         escape (\x27)
         \f         form feed (\x0c)
         \n         newline (\x0a)
         \qdd       set the PCRE_MATCH_LIMIT limit to dd
                      (any number of digits)
         \r         carriage return (\x0d)
         \t         tab (\x09)
         \v         vertical tab (\x0b)
         \nnn       octal character (up to 3 octal digits); always
                      a byte unless > 255 in UTF-8 or 16-bit mode
         \xhh       hexadecimal byte (up to 2 hex digits)
         \x{hh...}  hexadecimal character (any number of hex digits)
         \A         pass the PCRE_ANCHORED option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \B         pass the PCRE_NOTBOL option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \Cdd       call pcre[16]_copy_substring() for substring dd
                      after a successful match (number less than 32)
         \Cname     call pcre[16]_copy_named_substring() for substring
                      "name" after a successful match (name termin-
                      ated by next non alphanumeric character)
         \C+        show the current captured substrings at callout
                      time
         \C-        do not supply a callout function
         \C!n       return 1 instead of 0 when callout number n is
                      reached
         \C!n!m     return 1 instead of 0 when callout number n is
                      reached for the nth time
         \C*n       pass the number n (may be negative) as callout
                      data; this is used as the callout return value
         \D         use the pcre[16]_dfa_exec() match function
         \F         only shortest match for pcre[16]_dfa_exec()
         \Gdd       call pcre[16]_get_substring() for substring dd
                      after a successful match (number less than 32)
         \Gname     call pcre[16]_get_named_substring() for substring
                      "name" after a successful match (name termin-
                      ated by next non-alphanumeric character)
         \Jdd       set up a JIT stack of dd kilobytes maximum (any
                      number of digits)
         \L         call pcre[16]_get_substringlist() after a
                      successful match
         \M         discover the minimum MATCH_LIMIT and
                      MATCH_LIMIT_RECURSION settings
         \N         pass the PCRE_NOTEMPTY option to pcre[16]_exec()
                      or pcre[16]_dfa_exec(); if used twice, pass the
                      PCRE_NOTEMPTY_ATSTART option
         \Odd       set the size of the output vector passed to
                      pcre[16]_exec() to dd (any number of digits)
         \P         pass the PCRE_PARTIAL_SOFT option to pcre[16]_exec()
                      or pcre[16]_dfa_exec(); if used twice, pass the
                      PCRE_PARTIAL_HARD option
         \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
                      (any number of digits)
         \R         pass the PCRE_DFA_RESTART option to pcre[16]_dfa_exec()
         \S         output details of memory get/free calls during matching
         \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \Z         pass the PCRE_NOTEOL option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \?         pass the PCRE_NO_UTF[8|16]_CHECK option to
                      pcre[16]_exec() or pcre[16]_dfa_exec()
         \>dd       start the match at offset dd (optional "-"; then
                      any number of digits); this sets the startoffset
                      argument for pcre[16]_exec() or pcre[16]_dfa_exec()
         \<cr>      pass the PCRE_NEWLINE_CR option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \<lf>      pass the PCRE_NEWLINE_LF option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()
         \<any>     pass the PCRE_NEWLINE_ANY option to pcre[16]_exec()
                      or pcre[16]_dfa_exec()

       The use of \x{hh...} is not dependent on the use of the /8 modifier on
       the pattern. It is recognized always. There may be any number of
       hexadecimal digits inside the braces; invalid values provoke error
       messages.

       Note that \xhh specifies one byte rather than one character in UTF-8
       mode; this makes it possible to construct invalid UTF-8 sequences for
       testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
       character in UTF-8 mode, generating more than one byte if the value is
       greater than 127.  When testing the 8-bit library not in UTF-8 mode,
       \x{hh} generates one byte for values less than 256, and causes an error
       for greater values.

       In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
       possible to construct invalid UTF-16 sequences for testing purposes.

       The escapes that specify line ending sequences are literal strings,
       exactly as shown. No more than one newline setting should be present in
       any data line.

       A backslash followed by anything else just escapes the anything else.
       If the very last character is a backslash, it is ignored. This gives a
       way of passing an empty line as data, since a real empty line
       terminates the data input.

       The \J escape provides a way of setting the maximum stack size that is
       used by the just-in-time optimization code. It is ignored if JIT
       optimization is not being used. Providing a stack that is larger than
       the default 32K is necessary only for very complicated patterns.

       If \M is present, pcretest calls pcre[16]_exec() several times, with
       different values in the match_limit and match_limit_recursion fields of
       the pcre[16]_extra data structure, until it finds the minimum numbers
       for each parameter that allow pcre[16]_exec() to complete without
       error. Because this is testing a specific feature of the normal
       interpretive pcre[16]_exec() execution, the use of any JIT optimization
       that might have been set up by the /S+ qualifier of -s+ option is
       disabled.

       The match_limit number is a measure of the amount of backtracking that
       takes place, and checking it out can be instructive. For most simple
       matches, the number is quite small, but for patterns with very large
       numbers of matching possibilities, it can become large very quickly
       with increasing length of subject string. The match_limit_recursion
       number is a measure of how much stack (or, if PCRE is compiled with
       NO_RECURSE, how much heap) memory is needed to complete the match
       attempt.

       When \O is used, the value specified may be higher or lower than the
       size set by the -O command line option (or defaulted to 45); \O applies
       only to the call of pcre[16]_exec() for the line in which it appears.

       If the /P modifier was present on the pattern, causing the POSIX
       wrapper API to be used, the only option-setting sequences that have any
       effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
       REG_NOTEOL, respectively, to be passed to regexec().

THE ALTERNATIVE MATCHING FUNCTION

       By default, pcretest uses the standard PCRE matching function,
       pcre[16]_exec() to match each data line. PCRE also supports an
       alternative matching function, pcre[16]_dfa_test(), which operates in a
       different way, and has some restrictions. The differences between the
       two functions are described in the pcrematching documentation.

       If a data line contains the \D escape sequence, or if the command line
       contains the -dfa option, the alternative matching function is used.
       This function finds all possible matches at a given point. If, however,
       the \F escape sequence is present in the data line, it stops after the
       first match is found. This is always the shortest possible match.

DEFAULT OUTPUT FROM PCRETEST

       This section describes the output when the normal matching function,
       pcre[16]_exec(), is being used.

       When a match succeeds, pcretest outputs the list of captured substrings
       that pcre[16]_exec() returns, starting with number 0 for the string
       that matched the whole pattern. Otherwise, it outputs "No match" when
       the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the
       partially matching substring when pcre[16]_exec() returns
       PCRE_ERROR_PARTIAL. (Note that this is the entire substring that was
       inspected during the partial match; it may include characters before
       the actual match start if a lookbehind assertion, \K, \b, or \B was
       involved.) For any other return, pcretest outputs the PCRE negative
       error number and a short descriptive phrase. If the error is a failed
       UTF string check, the offset of the start of the failing character and
       the reason code are also output, provided that the size of the output
       vector is at least two. Here is an example of an interactive pcretest
       run.

         $ pcretest
         PCRE version 8.13 2011-04-30

           re> /^abc(\d+)/
         data> abc123
          0: abc123
          1: 123
         data> xyz
         No match

       Unset capturing substrings that are not followed by one that is set are
       not returned by pcre[16]_exec(), and are not shown by pcretest. In the
       following example, there are two capturing substrings, but when the
       first data line is matched, the second, unset substring is not shown.
       An "internal" unset substring is shown as "<unset>", as for the second
       data line.

           re> /(a)|(b)/
         data> a
          0: a
          1: a
         data> b
          0: b
          1: <unset>
          2: b

       If the strings contain any non-printing characters, they are output as
       \xhh escapes if the value is less than 256 and UTF mode is not set.
       Otherwise they are output as \x{hh...} escapes. See below for the
       definition of non-printing characters. If the pattern has the /+
       modifier, the output for substring 0 is followed by the the rest of the
       subject string, identified by "0+" like this:

           re> /cat/+
         data> cataract
          0: cat
          0+ aract

       If the pattern has the /g or /G modifier, the results of successive
       matching attempts are output in sequence, like this:

           re> /\Bi(\w\w)/g
         data> Mississippi
          0: iss
          1: ss
          0: iss
          1: ss
          0: ipp
          1: pp

       "No match" is output only if the first match attempt fails. Here is an
       example of a failure message (the offset 4 that is specified by \>4 is
       past the end of the subject string):

           re> /xyz/
         data> xyz\>4
         Error -24 (bad offset value)

       If any of the sequences \C, \G, or \L are present in a data line that
       is successfully matched, the substrings extracted by the convenience
       functions are output with C, G, or L after the string number instead of
       a colon. This is in addition to the normal full list. The string length
       (that is, the return from the extraction function) is given in
       parentheses after each string for \C and \G.

       Note that whereas patterns can be continued over several lines (a plain
       ">" prompt is used for continuations), data lines may not. However
       newlines can be included in data by means of the \n escape (or \r,
       \r\n, etc., depending on the newline sequence setting).

OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION

       When the alternative matching function, pcre[16]_dfa_exec(), is used
       (by means of the \D escape sequence or the -dfa command line option),
       the output consists of a list of all the matches that start at the
       first point in the subject where there is at least one match. For
       example:

           re> /(tang|tangerine|tan)/
         data> yellow tangerine\D
          0: tangerine
          1: tang
          2: tan

       (Using the normal matching function on this data finds only "tang".)
       The longest matching string is always given first (and numbered zero).
       After a PCRE_ERROR_PARTIAL return, the output is "Partial match:",
       followed by the partially matching substring. (Note that this is the
       entire substring that was inspected during the partial match; it may
       include characters before the actual match start if a lookbehind
       assertion, \K, \b, or \B was involved.)

       If /g is present on the pattern, the search for further matches resumes
       at the end of the longest match. For example:

           re> /(tang|tangerine|tan)/g
         data> yellow tangerine and tangy sultana\D
          0: tangerine
          1: tang
          2: tan
          0: tang
          1: tan
          0: tan

       Since the matching function does not support substring capture, the
       escape sequences that are concerned with captured substrings are not
       relevant.

RESTARTING AFTER A PARTIAL MATCH

       When the alternative matching function has given the PCRE_ERROR_PARTIAL
       return, indicating that the subject partially matched the pattern, you
       can restart the match with additional subject data by means of the \R
       escape sequence. For example:

           re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
         data> 23ja\P\D
         Partial match: 23ja
         data> n05\R\D
          0: n05

       For further information about partial matching, see the pcrepartial
       documentation.

CALLOUTS

       If the pattern contains any callout requests, pcretest's callout
       function is called during matching. This works with both matching
       functions. By default, the called function displays the callout number,
       the start and current positions in the text at the callout time, and
       the next pattern item to be tested. For example:

         --->pqrabcdef
           0    ^  ^     \d

       This output indicates that callout number 0 occurred for a match
       attempt starting at the fourth character of the subject string, when
       the pointer was at the seventh character of the data, and when the next
       pattern item was \d. Just one circumflex is output if the start and
       current positions are the same.

       Callouts numbered 255 are assumed to be automatic callouts, inserted as
       a result of the /C pattern modifier. In this case, instead of showing
       the callout number, the offset in the pattern, preceded by a plus, is
       output. For example:

           re> /\d?[A-E]\*/C
         data> E*
         --->E*
          +0 ^      \d?
          +3 ^      [A-E]
          +8 ^^     \*
         +10 ^ ^
          0: E*

       If a pattern contains (*MARK) items, an additional line is output
       whenever a change of latest mark is passed to the callout function. For
       example:

           re> /a(*MARK:X)bc/C
         data> abc
         --->abc
          +0 ^       a
          +1 ^^      (*MARK:X)
         +10 ^^      b
         Latest Mark: X
         +11 ^ ^     c
         +12 ^  ^
          0: abc

       The mark changes between matching "a" and "b", but stays the same for
       the rest of the match, so nothing more is output. If, as a result of
       backtracking, the mark reverts to being unset, the text "<unset>" is
       output.

       The callout function in pcretest returns zero (carry on matching) by
       default, but you can use a \C item in a data line (as described above)
       to change this and other parameters of the callout.

       Inserting callouts can be helpful when using pcretest to check
       complicated regular expressions. For further information about
       callouts, see the pcrecallout documentation.

NON-PRINTING CHARACTERS

       When pcretest is outputting text in the compiled version of a pattern,
       bytes other than 32-126 are always treated as non-printing characters
       are are therefore shown as hex escapes.

       When pcretest is outputting text that is a matched part of a subject
       string, it behaves in the same way, unless a different locale has been
       set for the pattern (using the /L modifier). In this case, the
       isprint() function to distinguish printing and non-printing characters.

SAVING AND RELOADING COMPILED PATTERNS

       The facilities described in this section are not available when the
       POSIX interface to PCRE is being used, that is, when the /P pattern
       modifier is specified.

       When the POSIX interface is not in use, you can cause pcretest to write
       a compiled pattern to a file, by following the modifiers with > and a
       file name.  For example:

         /pattern/im >/some/file

       See the pcreprecompile documentation for a discussion about saving and
       re-using compiled patterns.  Note that if the pattern was successfully
       studied with JIT optimization, the JIT data cannot be saved.

       The data that is written is binary. The first eight bytes are the
       length of the compiled pattern data followed by the length of the
       optional study data, each written as four bytes in big-endian order
       (most significant byte first). If there is no study data (either the
       pattern was not studied, or studying did not return any data), the
       second length is zero. The lengths are followed by an exact copy of the
       compiled pattern. If there is additional study data, this (excluding
       any JIT data) follows immediately after the compiled pattern. After
       writing the file, pcretest expects to read a new pattern.

       A saved pattern can be reloaded into pcretest by specifying < and a
       file name instead of a pattern. The name of the file must not contain a
       < character, as otherwise pcretest will interpret the line as a pattern
       delimited by < characters.  For example:

          re> </some/file
         Compiled pattern loaded from /some/file
         No study data

       If the pattern was previously studied with the JIT optimization, the
       JIT information cannot be saved and restored, and so is lost. When the
       pattern has been loaded, pcretest proceeds to read data lines in the
       usual way.

       You can copy a file written by pcretest to a different host and reload
       it there, even if the new host has opposite endianness to the one on
       which the pattern was compiled. For example, you can compile on an i86
       machine and run on a SPARC machine. When a pattern is reloaded on a
       host with different endianness, the confirmation message is changed to:

         Compiled pattern (byte-inverted) loaded from /some/file

       The test suite contains some saved pre-compiled patterns with different
       endianness. These are reloaded using "<!" instead of just "<". This
       suppresses the "(byte-inverted)" text so that the output is the same on
       all hosts. It also forces debugging output once the pattern has been
       reloaded.

       File names for saving and reloading can be absolute or relative, but
       note that the shell facility of expanding a file name that starts with
       a tilde (~) is not available.

       The ability to save and reload files in pcretest is intended for
       testing and experimentation. It is not intended for production use
       because only a single pattern can be written to a file. Furthermore,
       there is no facility for supplying custom character tables for use with
       a reloaded pattern. If the original pattern was compiled with custom
       tables, an attempt to match a subject string using a reloaded pattern
       is likely to cause pcretest to crash.  Finally, if you attempt to load
       a file that is not in the correct format, the result is undefined.

SEE ALSO

       pcre(3), pcre16(3), pcreapi(3), pcrecallout(3), pcrejit,
       pcrematching(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).

AUTHOR

       Philip Hazel
       University Computing Service
       Cambridge CB2 3QH, England.

REVISION

       Last updated: 14 January 2012
       Copyright (c) 1997-2012 University of Cambridge.



                                                                   PCRETEST(1)
