trunk/doc/pcretest.txt

PCRETEST(1)                                                        PCRETEST(1)


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

SYNOPSIS
       pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [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  PCRE and its options, see the pcreapi
       documentation.


OPTIONS


       -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 had the /D modifier (see below);  the
                 internal form is output after compilation.

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

       -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 to be osize. The default value is 45, which
                 is  enough  for  14 capturing subexpressions. The vector size
                 can be changed for individual matching calls by including  \O
                 in the data line (see below).

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

       -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 -t with -m, because you will then get the
                 size output 20000 times and the timing will be distorted.


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.

       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  line  is  matched separately and independently. If you want to do
       multiple-line matches, you have to use the \n escape sequence in a sin-
       gle  line of input to encode the newline characters. The maximum length
       of data line is 30,000 characters.

       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-alphameric 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-alphameric, 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

       The pattern may be followed by i, m, s, or x to set the  PCRE_CASELESS,
       PCRE_MULTILINE,  PCRE_DOTALL,  or  PCRE_EXTENDED options, respectively.
       For example:

         /caseless/i

       These modifier letters have the same effect as they do in  Perl.  There
       are  others that set PCRE options that do not correspond to anything in
       Perl: /A, /E, /N, /U, and /X  set  PCRE_ANCHORED,  PCRE_DOLLAR_ENDONLY,
       PCRE_NO_AUTO_CAPTURE, PCRE_UNGREEDY, and PCRE_EXTRA respectively.

       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 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  by
       one,  and  the normal match is retried. This imitates the way Perl han-
       dles such cases when using the /g modifier or the split() function.

       There are a number of other 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 /L modifier must be followed directly by the name of a locale,  for
       example,

         /pattern/Lfr

       For  this reason, it must be the last modifier letter. 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 compil-
       ing the regular expression. Without an /L modifier, NULL is  passed  as
       the tables pointer; that is, /L applies only to the expression on which
       it appears.

       The /I modifier requests that pcretest  output  information  about  the
       compiled  expression (whether it is anchored, has a fixed first charac-
       ter, and so on). It does this by calling pcre_fullinfo() after  compil-
       ing  an expression, and outputting the information it gets back. If the
       pattern is studied, the results of that are also output.

       The /D modifier is a PCRE debugging feature, which also assumes /I.  It
       causes  the  internal form of compiled regular expressions to be output
       after compilation. If the pattern was studied, the information returned
       is also 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  /M  modifier causes the size of memory block used to hold the com-
       piled pattern to be output.

       The /P modifier causes pcretest to call PCRE via the POSIX wrapper  API
       rather  than  its  native  API.  When this is done, all other modifiers
       except /i, /m, and /+ are ignored. REG_ICASE is set if /i  is  present,
       and  REG_NEWLINE  is  set if /m is present. The wrapper functions force
       PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is  set.

       The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
       set. This turns on support for UTF-8 character handling in  PCRE,  pro-
       vided  that  it  was  compiled with this support enabled. This 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.

       If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call
       pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the
       checking of the string for UTF-8 validity.


CALLOUTS

       If  the pattern contains any callout requests, pcretest's callout func-
       tion will be called. By default, it displays the  callout  number,  and
       the  start  and  current positions in the text at the callout time. For
       example, the output

         --->pqrabcdef
           0    ^  ^

       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. The callout  function  returns  zero  (carry  on
       matching) by default.

       Inserting  callouts may be helpful when using pcretest to check compli-
       cated regular expressions. For further information about callouts,  see
       the pcrecallout documentation.

       For  testing  the PCRE library, additional control of callout behaviour
       is available via escape sequences in the data, as described in the fol-
       lowing  section.  In  particular, it is possible to pass in a number as
       callout data (the default is zero). If the callout function receives  a
       non-zero number, it returns that value instead of zero.


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)
         \b         backspace
         \e         escape
         \f         formfeed
         \n         newline
         \r         carriage return
         \t         tab
         \v         vertical tab
         \nnn       octal character (up to 3 octal digits)
         \xhh       hexadecimal character (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()
         \B         pass the PCRE_NOTBOL option to pcre_exec()
         \Cdd       call pcre_copy_substring() for substring dd
                      after a successful match (any decimal 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
         \Gdd       call pcre_get_substring() for substring dd
                      after a successful match (any decimal 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 setting
         \N         pass the PCRE_NOTEMPTY option to pcre_exec()
         \Odd       set the size of the output vector passed to
                      pcre_exec() to dd (any number of decimal
                      digits)
         \S         output details of memory get/free calls during matching
         \Z         pass the PCRE_NOTEOL option to pcre_exec()
         \?         pass the PCRE_NO_UTF8_CHECK option to
                      pcre_exec()

       If \M is present, pcretest calls pcre_exec() several times,  with  dif-
       ferent  values  in  the match_limit field of the pcre_extra data struc-
       ture, until it finds the minimum number that is needed for  pcre_exec()
       to  complete.  This  number is a measure of the amount of recursion and
       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.

       When  \O is used, it may be higher or lower than the size set by the -O
       option (or defaulted to 45); \O applies only to the call of pcre_exec()
       for the line in which it appears.

       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 /P was present on the regex, causing the POSIX  wrapper  API  to  be
       used,  only  0  causing  REG_NOTBOL  and  REG_NOTEOL  to  be  passed to
       regexec() respectively.

       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 UTF-8 rules.


OUTPUT FROM PCRETEST

       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.  Here  is  an  example  of  an  interactive
       pcretest run.

         $ pcretest
         PCRE version 4.00 08-Jan-2003

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

       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.  If  the pattern has the /+ modifier, then the output for
       substring 0 is followed by the the rest of the subject string,  identi-
       fied 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  while 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.


AUTHOR

       Philip Hazel <ph10@cam.ac.uk>
       University Computing Service,
       Cambridge CB2 3QG, England.

Last updated: 09 December 2003
Copyright (c) 1997-2003 University of Cambridge.
1	nigel	73	PCRETEST(1) PCRETEST(1)
2	nigel	41
3
4	nigel	73
5			NAME
6			pcretest - a program for testing Perl-compatible regular expressions.
7
8	nigel	53	SYNOPSIS
9	nigel	73	pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]
10	nigel	41
11	nigel	73	pcretest was written as a test program for the PCRE regular expression
12			library itself, but it can also be used for experimenting with regular
13			expressions. This document describes the features of the test program;
14			for details of the regular expressions themselves, see the pcrepattern
15			documentation. For details of PCRE and its options, see the pcreapi
16			documentation.
17	nigel	41
18
19	nigel	63	OPTIONS
20	nigel	41
21	nigel	63
22	nigel	73	-C Output the version number of the PCRE library, and all avail-
23			able information about the optional features that are
24			included, and then exit.
25	nigel	63
26	nigel	73	-d Behave as if each regex had the /D modifier (see below); the
27			internal form is output after compilation.
28	nigel	41
29	nigel	73	-i Behave as if each regex had the /I modifier; information
30			about the compiled pattern is given after compilation.
31	nigel	41
32	nigel	73	-m Output the size of each compiled pattern after it has been
33			compiled. This is equivalent to adding /M to each regular
34			expression. For compatibility with earlier versions of
35			pcretest, -s is a synonym for -m.
36	nigel	41
37	nigel	73	-o osize Set the number of elements in the output vector that is used
38			when calling PCRE to be osize. The default value is 45, which
39			is enough for 14 capturing subexpressions. The vector size
40			can be changed for individual matching calls by including \O
41			in the data line (see below).
42	nigel	41
43	nigel	73	-p Behave as if each regex has /P modifier; the POSIX wrapper
44			API is used to call PCRE. None of the other options has any
45			effect when -p is set.
46	nigel	41
47	nigel	73	-t Run each compile, study, and match many times with a timer,
48			and output resulting time per compile or match (in millisec-
49			onds). Do not set -t with -m, because you will then get the
50			size output 20000 times and the timing will be distorted.
51	nigel	49
52
53	nigel	63	DESCRIPTION
54	nigel	41
55	nigel	73	If pcretest is given two filename arguments, it reads from the first
56			and writes to the second. If it is given only one filename argument, it
57			reads from that file and writes to stdout. Otherwise, it reads from
58			stdin and writes to stdout, and prompts for each line of input, using
59			"re>" to prompt for regular expressions, and "data>" to prompt for data
60			lines.
61	nigel	41
62	nigel	73	The program handles any number of sets of input on a single input file.
63			Each set starts with a regular expression, and continues with any num-
64			ber of data lines to be matched against the pattern.
65	nigel	41
66	nigel	73	Each line is matched separately and independently. If you want to do
67			multiple-line matches, you have to use the \n escape sequence in a sin-
68			gle line of input to encode the newline characters. The maximum length
69			of data line is 30,000 characters.
70	nigel	63
71	nigel	73	An empty line signals the end of the data lines, at which point a new
72			regular expression is read. The regular expressions are given enclosed
73			in any non-alphameric delimiters other than backslash, for example
74	nigel	63
75	nigel	73	/(a\|bc)x+yz/
76	nigel	41
77	nigel	73	White space before the initial delimiter is ignored. A regular expres-
78			sion may be continued over several input lines, in which case the new-
79			line characters are included within it. It is possible to include the
80			delimiter within the pattern by escaping it, for example
81	nigel	41
82	nigel	73	/abc\/def/
83	nigel	41
84	nigel	73	If you do so, the escape and the delimiter form part of the pattern,
85			but since delimiters are always non-alphameric, this does not affect
86			its interpretation. If the terminating delimiter is immediately fol-
87			lowed by a backslash, for example,
88	nigel	41
89	nigel	73	/abc/\
90	nigel	41
91	nigel	73	then a backslash is added to the end of the pattern. This is done to
92			provide a way of testing the error condition that arises if a pattern
93			finishes with a backslash, because
94	nigel	49
95	nigel	73	/abc\/
96	nigel	49
97	nigel	73	is interpreted as the first line of a pattern that starts with "abc/",
98			causing pcretest to read the next line as a continuation of the regular
99			expression.
100	nigel	49
101	nigel	41
102	nigel	63	PATTERN MODIFIERS
103	nigel	41
104	nigel	73	The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,
105			PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively.
106			For example:
107	nigel	41
108	nigel	73	/caseless/i
109	nigel	41
110	nigel	73	These modifier letters have the same effect as they do in Perl. There
111			are others that set PCRE options that do not correspond to anything in
112			Perl: /A, /E, /N, /U, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY,
113			PCRE_NO_AUTO_CAPTURE, PCRE_UNGREEDY, and PCRE_EXTRA respectively.
114	nigel	41
115	nigel	73	Searching for all possible matches within each subject string can be
116			requested by the /g or /G modifier. After finding a match, PCRE is
117			called again to search the remainder of the subject string. The differ-
118			ence between /g and /G is that the former uses the startoffset argument
119			to pcre_exec() to start searching at a new point within the entire
120			string (which is in effect what Perl does), whereas the latter passes
121			over a shortened substring. This makes a difference to the matching
122			process if the pattern begins with a lookbehind assertion (including \b
123			or \B).
124	nigel	49
125	nigel	73	If any call to pcre_exec() in a /g or /G sequence matches an empty
126			string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
127			flags set in order to search for another, non-empty, match at the same
128			point. If this second match fails, the start offset is advanced by
129			one, and the normal match is retried. This imitates the way Perl han-
130			dles such cases when using the /g modifier or the split() function.
131	nigel	49
132	nigel	73	There are a number of other modifiers for controlling the way pcretest
133			operates.
134	nigel	49
135	nigel	73	The /+ modifier requests that as well as outputting the substring that
136			matched the entire pattern, pcretest should in addition output the
137			remainder of the subject string. This is useful for tests where the
138			subject contains multiple copies of the same substring.
139	nigel	41
140	nigel	73	The /L modifier must be followed directly by the name of a locale, for
141			example,
142	nigel	41
143	nigel	73	/pattern/Lfr
144	nigel	41
145	nigel	73	For this reason, it must be the last modifier letter. The given locale
146			is set, pcre_maketables() is called to build a set of character tables
147			for the locale, and this is then passed to pcre_compile() when compil-
148			ing the regular expression. Without an /L modifier, NULL is passed as
149			the tables pointer; that is, /L applies only to the expression on which
150			it appears.
151	nigel	41
152	nigel	73	The /I modifier requests that pcretest output information about the
153			compiled expression (whether it is anchored, has a fixed first charac-
154			ter, and so on). It does this by calling pcre_fullinfo() after compil-
155			ing an expression, and outputting the information it gets back. If the
156			pattern is studied, the results of that are also output.
157	nigel	63
158	nigel	73	The /D modifier is a PCRE debugging feature, which also assumes /I. It
159			causes the internal form of compiled regular expressions to be output
160			after compilation. If the pattern was studied, the information returned
161			is also output.
162	nigel	41
163	nigel	73	The /S modifier causes pcre_study() to be called after the expression
164			has been compiled, and the results used when the expression is matched.
165	nigel	41
166	nigel	73	The /M modifier causes the size of memory block used to hold the com-
167			piled pattern to be output.
168	nigel	41
169	nigel	73	The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
170			rather than its native API. When this is done, all other modifiers
171			except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
172			and REG_NEWLINE is set if /m is present. The wrapper functions force
173			PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
174	nigel	41
175	nigel	73	The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
176			set. This turns on support for UTF-8 character handling in PCRE, pro-
177			vided that it was compiled with this support enabled. This modifier
178			also causes any non-printing characters in output strings to be printed
179			using the \x{hh...} notation if they are valid UTF-8 sequences.
180	nigel	41
181	nigel	73	If the /? modifier is used with /8, it causes pcretest to call
182			pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
183			checking of the string for UTF-8 validity.
184	nigel	41
185	nigel	71
186	nigel	63	CALLOUTS
187	nigel	49
188	nigel	73	If the pattern contains any callout requests, pcretest's callout func-
189			tion will be called. By default, it displays the callout number, and
190			the start and current positions in the text at the callout time. For
191			example, the output
192	nigel	63
193	nigel	73	--->pqrabcdef
194			0 ^ ^
195	nigel	63
196	nigel	73	indicates that callout number 0 occurred for a match attempt starting
197			at the fourth character of the subject string, when the pointer was at
198			the seventh character. The callout function returns zero (carry on
199			matching) by default.
200	nigel	63
201	nigel	73	Inserting callouts may be helpful when using pcretest to check compli-
202			cated regular expressions. For further information about callouts, see
203			the pcrecallout documentation.
204	nigel	63
205	nigel	73	For testing the PCRE library, additional control of callout behaviour
206			is available via escape sequences in the data, as described in the fol-
207			lowing section. In particular, it is possible to pass in a number as
208			callout data (the default is zero). If the callout function receives a
209			non-zero number, it returns that value instead of zero.
210	nigel	63
211
212	nigel	53	DATA LINES
213	nigel	63
214	nigel	73	Before each data line is passed to pcre_exec(), leading and trailing
215			whitespace is removed, and it is then scanned for \ escapes. Some of
216			these are pretty esoteric features, intended for checking out some of
217			the more complicated features of PCRE. If you are just testing "ordi-
218			nary" regular expressions, you probably don't need any of these. The
219			following escapes are recognized:
220	nigel	49
221	nigel	73	\a alarm (= BEL)
222			\b backspace
223			\e escape
224			\f formfeed
225			\n newline
226			\r carriage return
227			\t tab
228			\v vertical tab
229			\nnn octal character (up to 3 octal digits)
230			\xhh hexadecimal character (up to 2 hex digits)
231			\x{hh...} hexadecimal character, any number of digits
232			in UTF-8 mode
233			\A pass the PCRE_ANCHORED option to pcre_exec()
234			\B pass the PCRE_NOTBOL option to pcre_exec()
235			\Cdd call pcre_copy_substring() for substring dd
236			after a successful match (any decimal number
237			less than 32)
238			\Cname call pcre_copy_named_substring() for substring
239			"name" after a successful match (name termin-
240			ated by next non alphanumeric character)
241			\C+ show the current captured substrings at callout
242			time
243			\C- do not supply a callout function
244			\C!n return 1 instead of 0 when callout number n is
245			reached
246			\C!n!m return 1 instead of 0 when callout number n is
247			reached for the nth time
248			\C*n pass the number n (may be negative) as callout
249			data
250			\Gdd call pcre_get_substring() for substring dd
251			after a successful match (any decimal number
252			less than 32)
253			\Gname call pcre_get_named_substring() for substring
254			"name" after a successful match (name termin-
255			ated by next non-alphanumeric character)
256			\L call pcre_get_substringlist() after a
257			successful match
258			\M discover the minimum MATCH_LIMIT setting
259			\N pass the PCRE_NOTEMPTY option to pcre_exec()
260			\Odd set the size of the output vector passed to
261			pcre_exec() to dd (any number of decimal
262			digits)
263			\S output details of memory get/free calls during matching
264			\Z pass the PCRE_NOTEOL option to pcre_exec()
265			\? pass the PCRE_NO_UTF8_CHECK option to
266			pcre_exec()
267	nigel	71
268	nigel	73	If \M is present, pcretest calls pcre_exec() several times, with dif-
269			ferent values in the match_limit field of the pcre_extra data struc-
270			ture, until it finds the minimum number that is needed for pcre_exec()
271			to complete. This number is a measure of the amount of recursion and
272			backtracking that takes place, and checking it out can be instructive.
273			For most simple matches, the number is quite small, but for patterns
274			with very large numbers of matching possibilities, it can become large
275			very quickly with increasing length of subject string.
276	nigel	41
277	nigel	73	When \O is used, it may be higher or lower than the size set by the -O
278			option (or defaulted to 45); \O applies only to the call of pcre_exec()
279			for the line in which it appears.
280	nigel	63
281	nigel	73	A backslash followed by anything else just escapes the anything else.
282			If the very last character is a backslash, it is ignored. This gives a
283			way of passing an empty line as data, since a real empty line termi-
284			nates the data input.
285	nigel	41
286	nigel	73	If /P was present on the regex, causing the POSIX wrapper API to be
287			used, only 0 causing REG_NOTBOL and REG_NOTEOL to be passed to
288			regexec() respectively.
289	nigel	41
290	nigel	73	The use of \x{hh...} to represent UTF-8 characters is not dependent on
291			the use of the /8 modifier on the pattern. It is recognized always.
292			There may be any number of hexadecimal digits inside the braces. The
293			result is from one to six bytes, encoded according to the UTF-8 rules.
294	nigel	53
295
296	nigel	63	OUTPUT FROM PCRETEST
297	nigel	53
298	nigel	73	When a match succeeds, pcretest outputs the list of captured substrings
299			that pcre_exec() returns, starting with number 0 for the string that
300			matched the whole pattern. Here is an example of an interactive
301			pcretest run.
302	nigel	53
303	nigel	73	$ pcretest
304			PCRE version 4.00 08-Jan-2003
305	nigel	53
306	nigel	73	re> /^abc(\d+)/
307			data> abc123
308			0: abc123
309			1: 123
310			data> xyz
311			No match
312	nigel	53
313	nigel	73	If the strings contain any non-printing characters, they are output as
314			\0x escapes, or as \x{...} escapes if the /8 modifier was present on
315			the pattern. If the pattern has the /+ modifier, then the output for
316			substring 0 is followed by the the rest of the subject string, identi-
317			fied by "0+" like this:
318	nigel	53
319	nigel	73	re> /cat/+
320			data> cataract
321			0: cat
322			0+ aract
323	nigel	53
324	nigel	73	If the pattern has the /g or /G modifier, the results of successive
325			matching attempts are output in sequence, like this:
326	nigel	53
327	nigel	73	re> /\Bi(\w\w)/g
328			data> Mississippi
329			0: iss
330			1: ss
331			0: iss
332			1: ss
333			0: ipp
334			1: pp
335	nigel	53
336	nigel	73	"No match" is output only if the first match attempt fails.
337	nigel	53
338	nigel	73	If any of the sequences \C, \G, or \L are present in a data line that
339			is successfully matched, the substrings extracted by the convenience
340			functions are output with C, G, or L after the string number instead of
341			a colon. This is in addition to the normal full list. The string length
342			(that is, the return from the extraction function) is given in paren-
343			theses after each string for \C and \G.
344	nigel	53
345	nigel	73	Note that while patterns can be continued over several lines (a plain
346			">" prompt is used for continuations), data lines may not. However new-
347			lines can be included in data by means of the \n escape.
348	nigel	53
349
350	nigel	63	AUTHOR
351	nigel	53
352	nigel	73	Philip Hazel <ph10@cam.ac.uk>
353			University Computing Service,
354			Cambridge CB2 3QG, England.
355	nigel	53
356	nigel	73	Last updated: 09 December 2003
357	nigel	63	Copyright (c) 1997-2003 University of Cambridge.