pcretest(1) — Linux manual page


PCRETEST(1)              General Commands Manual             PCRETEST(1)

NAME         top

       pcretest - a program for testing Perl-compatible regular

SYNOPSIS         top

       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 , pcre16 and pcre32 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

       As PCRE has evolved, it has acquired many different features, and
       as a result, pcretest now has rather a lot of obscure options for
       testing every possible feature. Some of these options are
       specifically designed for use in conjunction with the test script
       and data files that are distributed as part of PCRE, and are
       unlikely to be of use otherwise. They are all documented here,
       but without much justification.


       Input to pcretest is processed line by line, either by calling
       the C library's fgets() function, or via the libreadline library
       (see below). In Unix-like environments, fgets() treats any bytes
       other than newline as data characters. However, in some Windows
       environments character 26 (hex 1A) causes an immediate end of
       file, and no further data is read. For maximum portability,
       therefore, it is safest to use only ASCII characters in pcretest
       input files.

       The input is processed using using C's string functions, so must
       not contain binary zeroes, even though in Unix-like environments,
       fgets() treats any bytes other than newline as data characters.

PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES         top

       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. From release 8.32, a third library can be built,
       supporting character strings encoded in 32-bit units. The
       pcretest program can be used to test all three libraries.
       However, it is itself still an 8-bit program, reading 8-bit input
       and writing 8-bit output.  When testing the 16-bit or 32-bit
       library, the patterns and data strings are converted to 16- or
       32-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|32]_xx
       below mean "pcre_xx when using the 8-bit library, pcre16_xx when
       using the 16-bit library, or pcre32_xx when using the 32-bit


       -8     If the 8-bit library has been built, this option causes it
              to be used (this is the default). If the 8-bit library has
              not been built, this option causes an error.

       -16    If the 16-bit library has been built, this option causes
              it to be used. If only the 16-bit library has been built,
              this is the default. If the 16-bit library has not been
              built, this option causes an error.

       -32    If the 32-bit library has been built, this option causes
              it to be used. If only the 32-bit library has been built,
              this is the default. If the 32-bit library has not 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 with zero exit code. 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 and set the exit code as indicated:

                ebcdic-nl  the code for LF (= NL) in an EBCDIC
                             0x15 or 0x25
                             0 if used in an ASCII environment
                             exit code is always 0
                linksize   the configured internal link size (2, 3, or
                             exit code is set to the link size
                newline    the default newline setting:
                             CR, LF, CRLF, ANYCRLF, or ANY
                             exit code is always 0
                bsr        the default setting for what \R matches:
                             ANYCRLF or ANY
                             exit code is always 0

              The following options output 1 for true or 0 for false,
              and set the exit code to the same value:

                ebcdic     compiled for an EBCDIC environment
                jit        just-in-time support is available
                pcre16     the 16-bit library was built
                pcre32     the 32-bit library was built
                pcre8      the 8-bit library was built
                ucp        Unicode property support is available
                utf        UTF-8 and/or UTF-16 and/or UTF-32 support
                             is available

              If an unknown option is given, an error message is output;
              the exit code is 0.

       -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|32]_dfa_exec(), to be used instead of the standard
              pcre[16|32]_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|32]_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     Behave as if each pattern has the /O modifier, that is
              disable auto-possessification for all patterns.

       -o osize
              Set the number of elements in the output vector that is
              used when calling pcre[16|32]_exec() or
              pcre[16|32]_dfa_exec() to be osize. The default value is
              45, which is enough for 14 capturing subexpressions for
              pcre[16|32]_exec() or 22 different matches for
              pcre[16|32]_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,
              all the JIT compile options are passed to
              pcre[16|32]_study(), causing just-in-time optimization to
              be set up if it is available, for both full and partial
              matching. Specific JIT compile options can be selected by
              following -s+ with a digit in the range 1 to 7, which
              selects the JIT compile modes as follows:

                1  normal match only
                2  soft partial match only
                3  normal match and soft partial match
                4  hard partial match only
                6  soft and hard partial match
                7  all three modes (default)

              If -s++ is used instead of -s+ (with or without a
              following digit), the text "(JIT)" is added to the first
              output line after a match or no match when JIT-compiled
              code was actually used.

              Note that there are pattern options that can override -s,
              either specifying no studying at all, or suppressing JIT

              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 the resulting times per compile, study,
              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" iterates 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.

       -T -TM These behave like -t and -tm, but in addition, at the end
              of a run, the total times for all compiles, studies, and
              matches are output.

DESCRIPTION         top

       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 that 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:


       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


       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,


       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


       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.


       A pattern may be followed by any number of modifiers, which are
       mostly single characters, though some of these can be qualified
       by further 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. For reference, here is a complete list
       of modifiers. They fall into several groups that are described in
       detail in the following sections.

         /8              set UTF mode
         /9              set PCRE_NEVER_UTF (locks out UTF mode)
         /?              disable UTF validity check
         /+              show remainder of subject after match
         /=              show all captures (not just those that are set)

         /A              set PCRE_ANCHORED
         /B              show compiled code
         /C              set PCRE_AUTO_CALLOUT
         /D              same as /B plus /I
         /E              set PCRE_DOLLAR_ENDONLY
         /F              flip byte order in compiled pattern
         /f              set PCRE_FIRSTLINE
         /G              find all matches (shorten string)
         /g              find all matches (use startoffset)
         /I              show information about pattern
         /i              set PCRE_CASELESS
         /J              set PCRE_DUPNAMES
         /K              show backtracking control names
         /L              set locale
         /M              show compiled memory size
         /m              set PCRE_MULTILINE
         /N              set PCRE_NO_AUTO_CAPTURE
         /O              set PCRE_NO_AUTO_POSSESS
         /P              use the POSIX wrapper
         /Q              test external stack check function
         /S              study the pattern after compilation
         /s              set PCRE_DOTALL
         /T              select character tables
         /U              set PCRE_UNGREEDY
         /W              set PCRE_UCP
         /X              set PCRE_EXTRA
         /x              set PCRE_EXTENDED
         /Y              set PCRE_NO_START_OPTIMIZE
         /Z              don't show lengths in /B output

         /<any>          set PCRE_NEWLINE_ANY
         /<anycrlf>      set PCRE_NEWLINE_ANYCRLF
         /<cr>           set PCRE_NEWLINE_CR
         /<crlf>         set PCRE_NEWLINE_CRLF
         /<lf>           set PCRE_NEWLINE_LF
         /<bsr_anycrlf>  set PCRE_BSR_ANYCRLF
         /<bsr_unicode>  set PCRE_BSR_UNICODE
         /<JS>           set PCRE_JAVASCRIPT_COMPAT

   Perl-compatible modifiers

       The /i, /m, /s, and /x modifiers set the PCRE_CASELESS,
       respectively, when pcre[16|32]_compile() is called. These four
       modifier letters have the same effect as they do in Perl. For


   Modifiers for other PCRE options

       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

         /8              PCRE_UTF32          ) when using the 32-bit
         /?              PCRE_NO_UTF32_CHECK )   library

         /9              PCRE_NEVER_UTF
         /A              PCRE_ANCHORED
         /C              PCRE_AUTO_CALLOUT
         /E              PCRE_DOLLAR_ENDONLY
         /f              PCRE_FIRSTLINE
         /J              PCRE_DUPNAMES
         /N              PCRE_NO_AUTO_CAPTURE
         /O              PCRE_NO_AUTO_POSSESS
         /U              PCRE_UNGREEDY
         /W              PCRE_UCP
         /X              PCRE_EXTRA
         /Y              PCRE_NO_START_OPTIMIZE
         /<any>          PCRE_NEWLINE_ANY
         /<anycrlf>      PCRE_NEWLINE_ANYCRLF
         /<cr>           PCRE_NEWLINE_CR
         /<crlf>         PCRE_NEWLINE_CRLF
         /<lf>           PCRE_NEWLINE_LF
         /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
         /<bsr_unicode>  PCRE_BSR_UNICODE
         /<JS>           PCRE_JAVASCRIPT_COMPAT

       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:


       As well as turning on the PCRE_UTF8/16/32 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

   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|32]_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|32]_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

       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+ and /S++ have other meanings.

       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|32]_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|32]_fullinfo() after compiling a pattern. If the pattern
       is studied, the results of that are also output. In this output,
       the word "char" means a non-UTF character, that is, the value of
       a single data item (8-bit, 16-bit, or 32-bit, depending on the
       library that is being tested).

       The /K modifier requests pcretest to show names from backtracking
       control verbs that are returned from calls to pcre[16|32]_exec().
       It causes pcretest to create a pcre[16|32]_extra block if one has
       not already been created by a call to pcre[16|32]_study(), and to
       set the PCRE_EXTRA_MARK flag and the mark field within it, every
       time that pcre[16|32]_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,


       For this reason, it must be the last modifier. The given locale
       is set, pcre[16|32]_maketables() is called to build a set of
       character tables for the locale, and this is then passed to
       pcre[16|32]_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

       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|32] 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.

       The /Q modifier is used to test the use of pcre_stack_guard. It
       must be followed by '0' or '1', specifying the return code to be
       given from an external function that is passed to PCRE and used
       for stack checking during compilation (see the pcreapi
       documentation for details).

       The /S modifier causes pcre[16|32]_study() to be called after the
       expression has been compiled, and the results used when the
       expression is matched. There are a number of qualifying
       characters that may follow /S.  They may appear in any order.

       If /S is followed by an exclamation mark, pcre[16|32]_study() is
       called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always
       to return a pcre_extra block, even when studying discovers no
       useful information.

       If /S is followed by a second S character, 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

       If the /S modifier is followed by a + character, the call to
       pcre[16|32]_study() is made with all the JIT study options,
       requesting just-in-time optimization support if it is available,
       for both normal and partial matching. If you want to restrict the
       JIT compiling modes, you can follow /S+ with a digit in the range
       1 to 7:

         1  normal match only
         2  soft partial match only
         3  normal match and soft partial match
         4  hard partial match only
         6  soft and hard partial match
         7  all three modes (default)

       If /S++ is used instead of /S+ (with or without a following
       digit), the text "(JIT)" is added to the first output line after
       a match or no match when JIT-compiled code was actually used.

       Note that there is also an independent /+ modifier; it must not
       be given immediately after /S or /S+ because this will be

       If JIT studying is successful, the compiled JIT code will
       automatically be used when pcre[16|32]_exec() is run, except when
       incompatible run-time options are specified. For more details,
       see the pcrejit documentation. See also the \J escape sequence
       below for a way of setting the size of the JIT stack.

       Finally, if /S is followed by a minus character, JIT compilation
       is suppressed, even if it was requested externally by the -s
       command line option. This makes it possible to specify that JIT
       is never to be used for certain patterns.

       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|32]_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
         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

   Locking out certain modifiers

       PCRE can be compiled with or without support for certain features
       such as UTF-8/16/32 or Unicode properties. Accordingly, the
       standard tests are split up into a number of different files that
       are selected for running depending on which features are
       available. When updating the tests, it is all too easy to put a
       new test into the wrong file by mistake; for example, to put a
       test that requires UTF support into a file that is used when it
       is not available. To help detect such mistakes as early as
       possible, there is a facility for locking out specific modifiers.
       If an input line for pcretest starts with the string "< forbid "
       the following sequence of characters is taken as a list of
       forbidden modifiers. For example, in the test files that must not
       use UTF or Unicode property support, this line appears:

         < forbid 8W

       This locks out the /8 and /W modifiers. An immediate error is
       given if they are subsequently encountered. If the character
       string contains < but not >, all the multi-character modifiers
       that begin with < are locked out. Otherwise, such modifiers must
       be explicitly listed, for example:

         < forbid <JS><cr>

       There must be a single space between < and "forbid" for this
       feature to be recognised. If there is not, the line is
       interpreted either as a request to re-load a pre-compiled pattern
       (see "SAVING AND RELOADING COMPILED PATTERNS" below) or, if there
       is a another < character, as a pattern that uses < as its

DATA LINES         top

       Before each data line is passed to pcre[16|32]_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 or 32-bit
         \o{dd...}  octal character (any number of octal digits}
         \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|32]_exec()
                      or pcre[16|32]_dfa_exec()
         \B         pass the PCRE_NOTBOL option to pcre[16|32]_exec()
                      or pcre[16|32]_dfa_exec()
         \Cdd       call pcre[16|32]_copy_substring() for substring dd
                      after a successful match (number less than 32)
         \Cname     call pcre[16|32]_copy_named_substring() for
                      "name" after a successful match (name termin-
                      ated by next non alphanumeric character)
         \C+        show the current captured substrings at callout
         \C-        do not supply a callout function
         \C!n       return 1 instead of 0 when callout number n is
         \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|32]_dfa_exec() match function
         \F         only shortest match for pcre[16|32]_dfa_exec()
         \Gdd       call pcre[16|32]_get_substring() for substring dd
                      after a successful match (number less than 32)
         \Gname     call pcre[16|32]_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|32]_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|32]_exec()
                      or pcre[16|32]_dfa_exec(); if used twice, pass the
                      PCRE_NOTEMPTY_ATSTART option
         \Odd       set the size of the output vector passed to
                      pcre[16|32]_exec() to dd (any number of digits)
         \P         pass the PCRE_PARTIAL_SOFT option to
                      or pcre[16|32]_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
         \S         output details of memory get/free calls during
         \Y         pass the PCRE_NO_START_OPTIMIZE option to
                      or pcre[16|32]_dfa_exec()
         \Z         pass the PCRE_NOTEOL option to pcre[16|32]_exec()
                      or pcre[16|32]_dfa_exec()
         \?         pass the PCRE_NO_UTF[8|16|32]_CHECK option to
                      pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
         \>dd       start the match at offset dd (optional "-"; then
                      any number of digits); this sets the startoffset
                      argument for pcre[16|32]_exec() or
         \<cr>      pass the PCRE_NEWLINE_CR option to
                      or pcre[16|32]_dfa_exec()
         \<lf>      pass the PCRE_NEWLINE_LF option to
                      or pcre[16|32]_dfa_exec()
         \<crlf>    pass the PCRE_NEWLINE_CRLF option to
                      or pcre[16|32]_dfa_exec()
         \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to
                      or pcre[16|32]_dfa_exec()
         \<any>     pass the PCRE_NEWLINE_ANY option to
                      or pcre[16|32]_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.

       In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted.
       This makes it possible to construct invalid UTF-32 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|32]_exec() several
       times, with different values in the match_limit and
       match_limit_recursion fields of the pcre[16|32]_extra data
       structure, until it finds the minimum numbers for each parameter
       that allow pcre[16|32]_exec() to complete without error. Because
       this is testing a specific feature of the normal interpretive
       pcre[16|32]_exec() execution, the use of any JIT optimization
       that might have been set up by the /S+ qualifier of -s+ option is

       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|32]_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


       By default, pcretest uses the standard PCRE matching function,
       pcre[16|32]_exec() to match each data line. PCRE also supports an
       alternative matching function, pcre[16|32]_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.


       This section describes the output when the normal matching
       function, pcre[16|32]_exec(), is being used.

       When a match succeeds, pcretest outputs the list of captured
       substrings that pcre[16|32]_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|32]_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|32]_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

       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


       When the alternative matching function, pcre[16|32]_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

       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.


       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:

         data> 23ja\P\D
         Partial match: 23ja
         data> n05\R\D
          0: n05

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

CALLOUTS         top

       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

           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*
          +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
          +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

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


       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.


       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. There must be no space between
       < and the file name, which 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         top

       pcre(3), pcre16(3), pcre32(3), pcreapi(3), pcrecallout(3),
       pcrejit, pcrematching(3), pcrepartial(d), pcrepattern(3),

AUTHOR         top

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

REVISION         top

       Last updated: 10 February 2020
       Copyright (c) 1997-2020 University of Cambridge.

COLOPHON         top

       This page is part of the PCRE (Perl Compatible Regular
       Expressions) project.  Information about the project can be found
       at ⟨http://www.pcre.org/⟩.  If you have a bug report for this
       manual page, see
       ⟨http://bugs.exim.org/enter_bug.cgi?product=PCRE⟩.  This page was
       obtained from the tarball pcre-8.45.tar.gz fetched from
       ⟨ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/⟩ on
       2021-08-27.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to

PCRE 8.44                   10 February 2020                 PCRETEST(1)

Pages that refer to this page: pcregrep(1)