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PCRETEST(1)							   PCRETEST(1)

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

SYNOPSIS

       pcretest [options] [source] [destination]

       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 documentation.

OPTIONS

       -b	 Behave as if each regex has the /B (show bytecode)  modifier;
		 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.

       -d	 Behave	 as  if	 each  regex  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_dfa_exec(),   to	 be   used  instead  of	 the  standard
		 pcre_exec() function (more detail is given below).

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

       -i	 Behave as if each regex  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_exec() repeat‐
		 edly 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.  For  compatibility  with	earlier	 versions   of
		 pcretest, -s is a synonym for -m.

       -o osize	 Set  the number of elements in the output vector that is used
		 when calling pcre_exec() or pcre_dfa_exec() to be osize.  The
		 default  value is 45, which is enough for 14 capturing subex‐
		 pressions  for	 pcre_exec()  or  22  different	 matches   for
		 pcre_dfa_exec().  The vector size can be changed for individ‐
		 ual matching calls by including \O  in	 the  data  line  (see
		 below).

       -p	 Behave	 as if each regex has the /P modifier; the POSIX wrap‐
		 per API is used to call PCRE. None of the other  options  has
		 any effect when -p is set.

       -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  runtime  stack  to
		 size megabytes.

       -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.  Whitespace  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_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
	 /?		 PCRE_NO_UTF8_CHECK
	 /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 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 option, the /8 modifier also causes
       any non-printing characters in output strings to be printed  using  the
       \x{hh...}  notation  if they are valid UTF-8 sequences. Full details of
       the PCRE options are given in the pcreapi documentation.

   Finding all matches in a string

       Searching for all possible matches within each subject  string  can  be
       requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
       called again to search the remainder of the subject string. The differ‐
       ence between /g and /G is that the former uses the startoffset argument
       to pcre_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_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.

       The  /B modifier is a debugging feature. It requests that pcretest out‐
       put a representation of the compiled byte code after compilation.  Nor‐
       mally  this  information contains length and offset values; however, if
       /Z is also present, this data is replaced by spaces. This is a  special
       feature for use in the automatic test scripts; it ensures that the same
       output is generated for different internal link sizes.

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

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

       The  /I	modifier  requests  that pcretest output information about the
       compiled pattern (whether it is anchored, has a fixed first  character,
       and  so	on). It does this by calling pcre_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_exec().  It	causes
       pcretest	 to create a pcre_extra block if one has not already been cre‐
       ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
       the mark field within it, every time that pcre_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_maketables()  is called to build a set of character tables for the
       locale, and this is then passed to pcre_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 of memory block used to hold the com‐
       piled pattern to be output.

       The /S modifier causes pcre_study() to be called after  the  expression
       has been compiled, and the results used when the expression is matched.

       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_compile().
       It is used in the standard PCRE tests to check behaviour with different
       character tables. The digit specifies the tables as follows:

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

       In table 1, some characters whose codes are greater than 128 are	 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. When /P is set, the following modifiers set
       options for the regcomp() function:

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

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

DATA LINES

       Before each data line is passed to pcre_exec(),	leading	 and  trailing
       whitespace  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 "ordi‐
       nary" 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	    formfeed (\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 mode
	 \xhh	    hexadecimal byte (up to 2 hex digits)
	 \x{hh...}  hexadecimal character, any number of digits
		      in UTF-8 mode
	 \A	    pass the PCRE_ANCHORED option to pcre_exec()
		      or pcre_dfa_exec()
	 \B	    pass the PCRE_NOTBOL option to pcre_exec()
		      or pcre_dfa_exec()
	 \Cdd	    call pcre_copy_substring() for substring dd
		      after a successful match (number less than 32)
	 \Cname	    call pcre_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_dfa_exec() match function
	 \F	    only shortest match for pcre_dfa_exec()
	 \Gdd	    call pcre_get_substring() for substring dd
		      after a successful match (number less than 32)
	 \Gname	    call pcre_get_named_substring() for substring
		      "name" after a successful match (name termin-
		      ated by next non-alphanumeric character)
	 \L	    call pcre_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_exec()
		      or pcre_dfa_exec(); if used twice, pass the
		      PCRE_NOTEMPTY_ATSTART option
	 \Odd	    set the size of the output vector passed to
		      pcre_exec() to dd (any number of digits)
	 \P	    pass the PCRE_PARTIAL_SOFT option to pcre_exec()
		      or pcre_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_dfa_exec()
	 \S	    output details of memory get/free calls during matching
	 \Y	    pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
		      or pcre_dfa_exec()
	 \Z	    pass the PCRE_NOTEOL option to pcre_exec()
		      or pcre_dfa_exec()
	 \?	    pass the PCRE_NO_UTF8_CHECK option to
		      pcre_exec() or pcre_dfa_exec()
	 \>dd	    start the match at offset dd (optional "-"; then
		      any number of digits); this sets the startoffset
		      argument for pcre_exec() or pcre_dfa_exec()
	 \<cr>	    pass the PCRE_NEWLINE_CR option to pcre_exec()
		      or pcre_dfa_exec()
	 \<lf>	    pass the PCRE_NEWLINE_LF option to pcre_exec()
		      or pcre_dfa_exec()
	 \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
		      or pcre_dfa_exec()
	 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
		      or pcre_dfa_exec()
	 \<any>	    pass the PCRE_NEWLINE_ANY option to pcre_exec()
		      or pcre_dfa_exec()

       Note  that  \xhh	 always	 specifies  one byte, even in UTF-8 mode; this
       makes it possible to construct invalid UTF-8 sequences for testing pur‐
       poses. 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 not in UTF-8 mode, it generates one byte for values less than
       256, and causes an error for greater values.

       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.

       If  \M  is present, pcretest calls pcre_exec() several times, with dif‐
       ferent values in the match_limit and  match_limit_recursion  fields  of
       the  pcre_extra	data structure, until it finds the minimum numbers for
       each parameter that allow pcre_exec() to complete. The match_limit num‐
       ber  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_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 use of \x{hh...} to represent UTF-8 characters is not dependent  on
       the  use	 of  the  /8 modifier on the pattern. It is recognized always.
       There may be any number of hexadecimal digits inside  the  braces.  The
       result  is  from	 one  to  six bytes, encoded according to the original
       UTF-8 rules of RFC 2279. This allows for	 values	 in  the  range	 0  to
       0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
       or indeed valid UTF-8 characters according to the later	rules  in  RFC
       3629.

THE ALTERNATIVE MATCHING FUNCTION

       By   default,  pcretest	uses  the  standard  PCRE  matching  function,
       pcre_exec() to match each data line. From release 6.0, PCRE supports an
       alternative  matching  function,	 pcre_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  called.
       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_exec(), is being used.

       When a match succeeds, pcretest outputs the list of captured substrings
       that  pcre_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 par‐
       tially matching substring when pcre_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
       returns, it outputs the PCRE negative error number. Here is an  example
       of an interactive pcretest run.

	 $ pcretest
	 PCRE version 7.0 30-Nov-2006

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

       Note  that unset capturing substrings that are not followed by one that
       is set are not returned by pcre_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
       \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
       the pattern. See below for the definition of  non-printing  characters.
       If  the pattern has the /+ modifier, the output for substring 0 is fol‐
       lowed 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.

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

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

       (Using  the  normal  matching function on this data finds only "tang".)
       The longest matching string is always given first (and numbered	zero).
       After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", 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, the output

	 --->pqrabcdef
	   0	^  ^	 \d

       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*

       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.

       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 inteface to PCRE is being used, that is, when the /P pattern mod‐
       ifier 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.

       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 follows imme‐
       diately after the compiled pattern. After writing  the  file,  pcretest
       expects to read a new pattern.

       A saved pattern can be reloaded into pcretest by specifing < 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 regex loaded from /some/file
	 No study data

       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.

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

AUTHOR

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

REVISION

       Last updated: 21 November 2010
       Copyright (c) 1997-2010 University of Cambridge.

								   PCRETEST(1)
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