PCRETEST(1)                                                        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 origi-
       nal  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) modi-
                 fier; the internal form is output after compilation.

       -C        Output the version number of the PCRE library, and all avail-
                 able   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 cap-
                 turing 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, all
                 the JIT compile options are passed to pcre[16]_study(), caus-
                 ing  just-in-time  optimization  to be set up if it is avail-
                 able, for both full and partial matching. Specific  JIT  com-
                 pile options can be selected by following -s+ with a digit in
                 the range 1 to 7, which selects the JIT compile modes as fol-
                 lows:

                   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.

       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. Out-
       put may also differ if the /C option is present on an  individual  pat-
       tern.  This  uses  callouts to trace the the matching process, and this
       may be different between studied and non-studied patterns. If the  pat-
       tern contains (*MARK) items there may also be differences, for the same
       reason. The -s command line option can be overridden for specific  pat-
       terns 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  millisec-
                 onds).  Do  not set -m with -t, because you will then get the
                 size output a zillion times, and  the  timing  will  be  dis-
                 torted.  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 iter-
                 ate 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 num-
       ber 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 expres-
       sion may be continued over several input lines, in which case the  new-
       line  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  fol-
       lowed 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]_com-
       pile() 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 com-
       pile-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  documenta-
       tion.

   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 differ-
       ence 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() func-
       tion.  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 +  modi-
       fier  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]_exec()). Values in the offsets vector  corre-
       sponding to higher numbers should be set to -1, and these are output as
       "<unset>". This modifier gives a way of checking that this  is  happen-
       ing.

       The  /B modifier is a debugging feature. It requests that pcretest out-
       put 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  fea-
       ture  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 com-
       piled on a host with a different endianness. This feature is not avail-
       able  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 out-
       put.

       The  /K modifier requests pcretest to show names from backtracking con-
       trol 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  compil-
       ing  the  regular  expression.  Without an /L (or /T) modifier, NULL is
       passed as the tables pointer; that is, /L applies only to  the  expres-
       sion 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 pat-
       tern 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 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 misinterpreted.

       If JIT studying is successful, the compiled JIT code will automatically
       be used when pcre[16]_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.

       The  /T  modifier  must be followed by a single digit. It causes a spe-
       cific set of built-in character tables to be  passed  to  pcre[16]_com-
       pile().  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  iden-
       tified 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() func-
       tion:

         /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 trail-
       ing 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 hexa-
       decimal digits inside the braces; invalid  values  provoke  error  mes-
       sages.

       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  termi-
       nates 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  opti-
       mization  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  inter-
       pretive 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 wrap-
       per 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 alterna-
       tive matching function, pcre[16]_dfa_test(), which operates in  a  dif-
       ferent  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 defi-
       nition 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 paren-
       theses 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 new-
       lines 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 exam-
       ple:

           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:", fol-
       lowed 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 asser-
       tion, \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  func-
       tion  is  called  during  matching. This works with both matching func-
       tions. 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 when-
       ever 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  compli-
       cated  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 sec-
       ond 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 test-
       ing 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,  pcrematch-
       ing(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).


AUTHOR

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


REVISION

       Last updated: 21 February 2012
       Copyright (c) 1997-2012 University of Cambridge.
