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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 , 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 output.

       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 DATA FORMAT

       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.

PCRE's 8-BIT, 16-BIT AND 32-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.  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 library".

COMMAND LINE OPTIONS

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

       -16	 If both the 8-bit or the 32-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 or the 32-bit
		 library has been built, this option causes an error.

       -32	 If both the 8-bit or the 16-bit,  and	the  32-bit  libraries
		 have  been built, this option causes the 32-bit library to be
		 used. If only the 32-bit library has been built, this is  the
		 default  (so  has no effect). If only the 8-bit or the 16-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  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 environment:
				0x15 or 0x25
				0 if used in an ASCII environment
				exit code is always 0
		   linksize   the configured internal link size (2, 3, or 4)
				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  dis‐
		 able 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 differ‐
		 ent  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 com‐
		 pilation.

		 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 spe‐
		 cific	patterns that should never be studied (see the /S pat‐
		 tern 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 sepa‐
		 rate item on the command line). For example, "-t 1000"	 iter‐
		 ates 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

       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 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:

	 /(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,  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	 modi‐
       fiers.  White  space may appear between the final pattern delimiter and
       the first modifier, and between the modifiers  themselves.  For	refer‐
       ence,  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, PCRE_MULTILINE,
       PCRE_DOTALL,    or    PCRE_EXTENDED    options,	  respectively,	  when
       pcre[16|32]_compile() is called. These four modifier letters  have  the
       same effect as they do in Perl. For example:

	 /caseless/i

   Modifiers for other PCRE options

       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

	 /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:

	 /^abc/m<CRLF>

       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 out‐
       put 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|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() 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|32]_exec()). Values in the offsets vector cor‐
       responding  to higher numbers should be set to -1, and these are output
       as "<unset>". This modifier gives a way of checking that this  is  hap‐
       pening.

       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|32]_fullinfo() after com‐
       piling 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 con‐
       trol 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,

	 /pattern/Lfr_FR

       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 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|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 studied.

       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 misinterpreted.

       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  documen‐
       tation.	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 spe‐
       cific set of built-in character tables to be passed to pcre[16|32]_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.

   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 mis‐
       take; 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	 modi‐
       fiers. 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 Uni‐
       code 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 delimiter.

DATA LINES

       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 mode
	 \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 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|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 pcre[16|32]_exec()
		      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 pcre[16|32]_dfa_exec()
	 \S	    output details of memory get/free calls during matching
	 \Y		pass	 the	PCRE_NO_START_OPTIMIZE	  option    to
       pcre[16|32]_exec()
		      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
       pcre[16|32]_dfa_exec()
	 \<cr>	    pass the PCRE_NEWLINE_CR option to pcre[16|32]_exec()
		      or pcre[16|32]_dfa_exec()
	 \<lf>	    pass the PCRE_NEWLINE_LF option to pcre[16|32]_exec()
		      or pcre[16|32]_dfa_exec()
	 \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre[16|32]_exec()
		      or pcre[16|32]_dfa_exec()
	 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16|32]_exec()
		      or pcre[16|32]_dfa_exec()
	 \<any>	    pass the PCRE_NEWLINE_ANY option to pcre[16|32]_exec()
		      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	 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.

       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 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|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 num‐
       bers for each parameter that allow pcre[16|32]_exec() to complete with‐
       out  error.  Because  this  is testing a specific feature of the normal
       interpretive pcre[16|32]_exec() execution, the use of any JIT optimiza‐
       tion  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|32]_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|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.

DEFAULT OUTPUT FROM PCRETEST

       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 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|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 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. 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 < charac‐
       ters. 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),  pcre32(3),	pcreapi(3),  pcrecallout(3),  pcrejit,
       pcrematching(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).

AUTHOR

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

REVISION

       Last updated: 09 February 2014
       Copyright (c) 1997-2014 University of Cambridge.

PCRE 8.35		       09 February 2014			   PCRETEST(1)
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