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1 <html>
2 <head>
3 <title>pcretest specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcretest man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">COMMAND LINE OPTIONS</a>
18 <li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
19 <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
20 <li><a name="TOC5" href="#SEC5">DATA LINES</a>
21 <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
22 <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
23 <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
24 <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
25 <li><a name="TOC10" href="#SEC10">CALLOUTS</a>
26 <li><a name="TOC11" href="#SEC11">NON-PRINTING CHARACTERS</a>
27 <li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a>
28 <li><a name="TOC13" href="#SEC13">SEE ALSO</a>
29 <li><a name="TOC14" href="#SEC14">AUTHOR</a>
30 <li><a name="TOC15" href="#SEC15">REVISION</a>
31 </ul>
32 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
33 <P>
34 <b>pcretest [options] [input file [output file]]</b>
35 <br>
36 <br>
37 <b>pcretest</b> was written as a test program for the PCRE regular expression
38 library itself, but it can also be used for experimenting with regular
39 expressions. This document describes the features of the test program; for
40 details of the regular expressions themselves, see the
41 <a href="pcrepattern.html"><b>pcrepattern</b></a>
42 documentation. For details of the PCRE library function calls and their
43 options, see the
44 <a href="pcreapi.html"><b>pcreapi</b></a>
45 documentation. The input for <b>pcretest</b> is a sequence of regular expression
46 patterns and strings to be matched, as described below. The output shows the
47 result of each match. Options on the command line and the patterns control PCRE
48 options and exactly what is output.
49 </P>
50 <br><a name="SEC2" href="#TOC1">COMMAND LINE OPTIONS</a><br>
51 <P>
52 <b>-b</b>
53 Behave as if each pattern has the <b>/B</b> (show byte code) modifier; the
54 internal form is output after compilation.
55 </P>
56 <P>
57 <b>-C</b>
58 Output the version number of the PCRE library, and all available information
59 about the optional features that are included, and then exit.
60 </P>
61 <P>
62 <b>-d</b>
63 Behave as if each pattern has the <b>/D</b> (debug) modifier; the internal
64 form and information about the compiled pattern is output after compilation;
65 <b>-d</b> is equivalent to <b>-b -i</b>.
66 </P>
67 <P>
68 <b>-dfa</b>
69 Behave as if each data line contains the \D escape sequence; this causes the
70 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
71 standard <b>pcre_exec()</b> function (more detail is given below).
72 </P>
73 <P>
74 <b>-help</b>
75 Output a brief summary these options and then exit.
76 </P>
77 <P>
78 <b>-i</b>
79 Behave as if each pattern has the <b>/I</b> modifier; information about the
80 compiled pattern is given after compilation.
81 </P>
82 <P>
83 <b>-M</b>
84 Behave as if each data line contains the \M escape sequence; this causes
85 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
86 calling <b>pcre_exec()</b> repeatedly with different limits.
87 </P>
88 <P>
89 <b>-m</b>
90 Output the size of each compiled pattern after it has been compiled. This is
91 equivalent to adding <b>/M</b> to each regular expression.
92 </P>
93 <P>
94 <b>-o</b> <i>osize</i>
95 Set the number of elements in the output vector that is used when calling
96 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
97 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
98 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
99 changed for individual matching calls by including \O in the data line (see
100 below).
101 </P>
102 <P>
103 <b>-p</b>
104 Behave as if each pattern has the <b>/P</b> modifier; the POSIX wrapper API is
105 used to call PCRE. None of the other options has any effect when <b>-p</b> is
106 set.
107 </P>
108 <P>
109 <b>-q</b>
110 Do not output the version number of <b>pcretest</b> at the start of execution.
111 </P>
112 <P>
113 <b>-S</b> <i>size</i>
114 On Unix-like systems, set the size of the run-time stack to <i>size</i>
115 megabytes.
116 </P>
117 <P>
118 <b>-s</b>
119 Behave as if each pattern has the <b>/S</b> modifier; in other words, force each
120 pattern to be studied. If the <b>/I</b> or <b>/D</b> option is present on a
121 pattern (requesting output about the compiled pattern), information about the
122 result of studying is not included when studying is caused only by <b>-s</b> and
123 neither <b>-i</b> nor <b>-d</b> is present on the command line. This behaviour
124 means that the output from tests that are run with and without <b>-s</b> should
125 be identical, except when options that output information about the actual
126 running of a match are set. The <b>-M</b>, <b>-t</b>, and <b>-tm</b> options,
127 which give information about resources used, are likely to produce different
128 output with and without <b>-s</b>. Output may also differ if the <b>/C</b> option
129 is present on an individual pattern. This uses callouts to trace the the
130 matching process, and this may be different between studied and non-studied
131 patterns. If the pattern contains (*MARK) items there may also be differences,
132 for the same reason. The <b>-s</b> command line option can be overridden for
133 specific patterns that should never be studied (see the /S option below).
134 </P>
135 <P>
136 <b>-t</b>
137 Run each compile, study, and match many times with a timer, and output
138 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
139 <b>-t</b>, because you will then get the size output a zillion times, and the
140 timing will be distorted. You can control the number of iterations that are
141 used for timing by following <b>-t</b> with a number (as a separate item on the
142 command line). For example, "-t 1000" would iterate 1000 times. The default is
143 to iterate 500000 times.
144 </P>
145 <P>
146 <b>-tm</b>
147 This is like <b>-t</b> except that it times only the matching phase, not the
148 compile or study phases.
149 </P>
150 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
151 <P>
152 If <b>pcretest</b> is given two filename arguments, it reads from the first and
153 writes to the second. If it is given only one filename argument, it reads from
154 that file and writes to stdout. Otherwise, it reads from stdin and writes to
155 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
156 expressions, and "data&#62;" to prompt for data lines.
157 </P>
158 <P>
159 When <b>pcretest</b> is built, a configuration option can specify that it should
160 be linked with the <b>libreadline</b> library. When this is done, if the input
161 is from a terminal, it is read using the <b>readline()</b> function. This
162 provides line-editing and history facilities. The output from the <b>-help</b>
163 option states whether or not <b>readline()</b> will be used.
164 </P>
165 <P>
166 The program handles any number of sets of input on a single input file. Each
167 set starts with a regular expression, and continues with any number of data
168 lines to be matched against the pattern.
169 </P>
170 <P>
171 Each data line is matched separately and independently. If you want to do
172 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
173 etc., depending on the newline setting) in a single line of input to encode the
174 newline sequences. There is no limit on the length of data lines; the input
175 buffer is automatically extended if it is too small.
176 </P>
177 <P>
178 An empty line signals the end of the data lines, at which point a new regular
179 expression is read. The regular expressions are given enclosed in any
180 non-alphanumeric delimiters other than backslash, for example:
181 <pre>
182 /(a|bc)x+yz/
183 </pre>
184 White space before the initial delimiter is ignored. A regular expression may
185 be continued over several input lines, in which case the newline characters are
186 included within it. It is possible to include the delimiter within the pattern
187 by escaping it, for example
188 <pre>
189 /abc\/def/
190 </pre>
191 If you do so, the escape and the delimiter form part of the pattern, but since
192 delimiters are always non-alphanumeric, this does not affect its interpretation.
193 If the terminating delimiter is immediately followed by a backslash, for
194 example,
195 <pre>
196 /abc/\
197 </pre>
198 then a backslash is added to the end of the pattern. This is done to provide a
199 way of testing the error condition that arises if a pattern finishes with a
200 backslash, because
201 <pre>
202 /abc\/
203 </pre>
204 is interpreted as the first line of a pattern that starts with "abc/", causing
205 pcretest to read the next line as a continuation of the regular expression.
206 </P>
207 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
208 <P>
209 A pattern may be followed by any number of modifiers, which are mostly single
210 characters. Following Perl usage, these are referred to below as, for example,
211 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
212 always be a slash, and no slash is used when writing modifiers. White space may
213 appear between the final pattern delimiter and the first modifier, and between
214 the modifiers themselves.
215 </P>
216 <P>
217 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
218 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
219 <b>pcre_compile()</b> is called. These four modifier letters have the same
220 effect as they do in Perl. For example:
221 <pre>
222 /caseless/i
223 </pre>
224 The following table shows additional modifiers for setting PCRE compile-time
225 options that do not correspond to anything in Perl:
226 <pre>
227 <b>/8</b> PCRE_UTF8
228 <b>/?</b> PCRE_NO_UTF8_CHECK
229 <b>/A</b> PCRE_ANCHORED
230 <b>/C</b> PCRE_AUTO_CALLOUT
231 <b>/E</b> PCRE_DOLLAR_ENDONLY
232 <b>/f</b> PCRE_FIRSTLINE
233 <b>/J</b> PCRE_DUPNAMES
234 <b>/N</b> PCRE_NO_AUTO_CAPTURE
235 <b>/U</b> PCRE_UNGREEDY
236 <b>/W</b> PCRE_UCP
237 <b>/X</b> PCRE_EXTRA
238 <b>/Y</b> PCRE_NO_START_OPTIMIZE
239 <b>/&#60;JS&#62;</b> PCRE_JAVASCRIPT_COMPAT
240 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
241 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
242 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
243 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
244 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
245 <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
246 <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
247 </pre>
248 The modifiers that are enclosed in angle brackets are literal strings as shown,
249 including the angle brackets, but the letters within can be in either case.
250 This example sets multiline matching with CRLF as the line ending sequence:
251 <pre>
252 /^abc/m&#60;CRLF&#62;
253 </pre>
254 As well as turning on the PCRE_UTF8 option, the <b>/8</b> modifier also causes
255 any non-printing characters in output strings to be printed using the
256 \x{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
257 options are given in the
258 <a href="pcreapi.html"><b>pcreapi</b></a>
259 documentation.
260 </P>
261 <br><b>
262 Finding all matches in a string
263 </b><br>
264 <P>
265 Searching for all possible matches within each subject string can be requested
266 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
267 again to search the remainder of the subject string. The difference between
268 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
269 <b>pcre_exec()</b> to start searching at a new point within the entire string
270 (which is in effect what Perl does), whereas the latter passes over a shortened
271 substring. This makes a difference to the matching process if the pattern
272 begins with a lookbehind assertion (including \b or \B).
273 </P>
274 <P>
275 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
276 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
277 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
278 same point. If this second match fails, the start offset is advanced, and the
279 normal match is retried. This imitates the way Perl handles such cases when
280 using the <b>/g</b> modifier or the <b>split()</b> function. Normally, the start
281 offset is advanced by one character, but if the newline convention recognizes
282 CRLF as a newline, and the current character is CR followed by LF, an advance
283 of two is used.
284 </P>
285 <br><b>
286 Other modifiers
287 </b><br>
288 <P>
289 There are yet more modifiers for controlling the way <b>pcretest</b>
290 operates.
291 </P>
292 <P>
293 The <b>/+</b> modifier requests that as well as outputting the substring that
294 matched the entire pattern, <b>pcretest</b> should in addition output the
295 remainder of the subject string. This is useful for tests where the subject
296 contains multiple copies of the same substring. If the <b>+</b> modifier appears
297 twice, the same action is taken for captured substrings. In each case the
298 remainder is output on the following line with a plus character following the
299 capture number.
300 </P>
301 <P>
302 The <b>/=</b> modifier requests that the values of all potential captured
303 parentheses be output after a match by <b>pcre_exec()</b>. By default, only
304 those up to the highest one actually used in the match are output
305 (corresponding to the return code from <b>pcre_exec()</b>). Values in the
306 offsets vector corresponding to higher numbers should be set to -1, and these
307 are output as "&#60;unset&#62;". This modifier gives a way of checking that this is
308 happening.
309 </P>
310 <P>
311 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
312 output a representation of the compiled byte code after compilation. Normally
313 this information contains length and offset values; however, if <b>/Z</b> is
314 also present, this data is replaced by spaces. This is a special feature for
315 use in the automatic test scripts; it ensures that the same output is generated
316 for different internal link sizes.
317 </P>
318 <P>
319 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
320 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
321 </P>
322 <P>
323 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
324 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
325 facility is for testing the feature in PCRE that allows it to execute patterns
326 that were compiled on a host with a different endianness. This feature is not
327 available when the POSIX interface to PCRE is being used, that is, when the
328 <b>/P</b> pattern modifier is specified. See also the section about saving and
329 reloading compiled patterns below.
330 </P>
331 <P>
332 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
333 compiled pattern (whether it is anchored, has a fixed first character, and
334 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
335 pattern. If the pattern is studied, the results of that are also output.
336 </P>
337 <P>
338 The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking
339 control verbs that are returned from calls to <b>pcre_exec()</b>. It causes
340 <b>pcretest</b> to create a <b>pcre_extra</b> block if one has not already been
341 created by a call to <b>pcre_study()</b>, and to set the PCRE_EXTRA_MARK flag
342 and the <b>mark</b> field within it, every time that <b>pcre_exec()</b> is
343 called. If the variable that the <b>mark</b> field points to is non-NULL for a
344 match, non-match, or partial match, <b>pcretest</b> prints the string to which
345 it points. For a match, this is shown on a line by itself, tagged with "MK:".
346 For a non-match it is added to the message.
347 </P>
348 <P>
349 The <b>/L</b> modifier must be followed directly by the name of a locale, for
350 example,
351 <pre>
352 /pattern/Lfr_FR
353 </pre>
354 For this reason, it must be the last modifier. The given locale is set,
355 <b>pcre_maketables()</b> is called to build a set of character tables for the
356 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
357 regular expression. Without an <b>/L</b> (or <b>/T</b>) modifier, NULL is passed
358 as the tables pointer; that is, <b>/L</b> applies only to the expression on
359 which it appears.
360 </P>
361 <P>
362 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
363 pattern to be output.
364 </P>
365 <P>
366 If the <b>/S</b> modifier appears once, it causes <b>pcre_study()</b> to be
367 called after the expression has been compiled, and the results used when the
368 expression is matched. If <b>/S</b> appears twice, it suppresses studying, even
369 if it was requested externally by the <b>-s</b> command line option. This makes
370 it possible to specify that certain patterns are always studied, and others are
371 never studied, independently of <b>-s</b>. This feature is used in the test
372 files in a few cases where the output is different when the pattern is studied.
373 </P>
374 <P>
375 The <b>/T</b> modifier must be followed by a single digit. It causes a specific
376 set of built-in character tables to be passed to <b>pcre_compile()</b>. It is
377 used in the standard PCRE tests to check behaviour with different character
378 tables. The digit specifies the tables as follows:
379 <pre>
380 0 the default ASCII tables, as distributed in
381 pcre_chartables.c.dist
382 1 a set of tables defining ISO 8859 characters
383 </pre>
384 In table 1, some characters whose codes are greater than 128 are identified as
385 letters, digits, spaces, etc.
386 </P>
387 <br><b>
388 Using the POSIX wrapper API
389 </b><br>
390 <P>
391 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
392 API rather than its native API. When <b>/P</b> is set, the following modifiers
393 set options for the <b>regcomp()</b> function:
394 <pre>
395 /i REG_ICASE
396 /m REG_NEWLINE
397 /N REG_NOSUB
398 /s REG_DOTALL )
399 /U REG_UNGREEDY ) These options are not part of
400 /W REG_UCP ) the POSIX standard
401 /8 REG_UTF8 )
402 </pre>
403 The <b>/+</b> modifier works as described above. All other modifiers are
404 ignored.
405 </P>
406 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
407 <P>
408 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
409 white space is removed, and it is then scanned for \ escapes. Some of these
410 are pretty esoteric features, intended for checking out some of the more
411 complicated features of PCRE. If you are just testing "ordinary" regular
412 expressions, you probably don't need any of these. The following escapes are
413 recognized:
414 <pre>
415 \a alarm (BEL, \x07)
416 \b backspace (\x08)
417 \e escape (\x27)
418 \f form feed (\x0c)
419 \n newline (\x0a)
420 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
421 \r carriage return (\x0d)
422 \t tab (\x09)
423 \v vertical tab (\x0b)
424 \nnn octal character (up to 3 octal digits)
425 always a byte unless &#62; 255 in UTF-8 mode
426 \xhh hexadecimal byte (up to 2 hex digits)
427 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
428 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
429 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
430 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
431 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
432 ated by next non alphanumeric character)
433 \C+ show the current captured substrings at callout time
434 \C- do not supply a callout function
435 \C!n return 1 instead of 0 when callout number n is reached
436 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
437 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
438 \D use the <b>pcre_dfa_exec()</b> match function
439 \F only shortest match for <b>pcre_dfa_exec()</b>
440 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
441 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
442 ated by next non-alphanumeric character)
443 \L call pcre_get_substringlist() after a successful match
444 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
445 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
446 PCRE_NOTEMPTY_ATSTART option
447 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
448 \P pass the PCRE_PARTIAL_SOFT option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
449 PCRE_PARTIAL_HARD option
450 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
451 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
452 \S output details of memory get/free calls during matching
453 \Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
454 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
455 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
456 \&#62;dd start the match at offset dd (optional "-"; then any number of digits); this sets the <i>startoffset</i>
457 argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
458 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
459 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
460 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
461 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
462 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
463 </pre>
464 Note that \xhh always specifies one byte, even in UTF-8 mode; this makes it
465 possible to construct invalid UTF-8 sequences for testing purposes. On the
466 other hand, \x{hh} is interpreted as a UTF-8 character in UTF-8 mode,
467 generating more than one byte if the value is greater than 127. When not in
468 UTF-8 mode, it generates one byte for values less than 256, and causes an error
469 for greater values.
470 </P>
471 <P>
472 The escapes that specify line ending sequences are literal strings, exactly as
473 shown. No more than one newline setting should be present in any data line.
474 </P>
475 <P>
476 A backslash followed by anything else just escapes the anything else. If
477 the very last character is a backslash, it is ignored. This gives a way of
478 passing an empty line as data, since a real empty line terminates the data
479 input.
480 </P>
481 <P>
482 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
483 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
484 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
485 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
486 <i>match_limit</i> number is a measure of the amount of backtracking that takes
487 place, and checking it out can be instructive. For most simple matches, the
488 number is quite small, but for patterns with very large numbers of matching
489 possibilities, it can become large very quickly with increasing length of
490 subject string. The <i>match_limit_recursion</i> number is a measure of how much
491 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
492 to complete the match attempt.
493 </P>
494 <P>
495 When \O is used, the value specified may be higher or lower than the size set
496 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
497 the call of <b>pcre_exec()</b> for the line in which it appears.
498 </P>
499 <P>
500 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
501 API to be used, the only option-setting sequences that have any effect are \B,
502 \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
503 to be passed to <b>regexec()</b>.
504 </P>
505 <P>
506 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
507 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
508 any number of hexadecimal digits inside the braces. The result is from one to
509 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
510 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
511 valid Unicode code points, or indeed valid UTF-8 characters according to the
512 later rules in RFC 3629.
513 </P>
514 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
515 <P>
516 By default, <b>pcretest</b> uses the standard PCRE matching function,
517 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
518 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
519 different way, and has some restrictions. The differences between the two
520 functions are described in the
521 <a href="pcrematching.html"><b>pcrematching</b></a>
522 documentation.
523 </P>
524 <P>
525 If a data line contains the \D escape sequence, or if the command line
526 contains the <b>-dfa</b> option, the alternative matching function is called.
527 This function finds all possible matches at a given point. If, however, the \F
528 escape sequence is present in the data line, it stops after the first match is
529 found. This is always the shortest possible match.
530 </P>
531 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
532 <P>
533 This section describes the output when the normal matching function,
534 <b>pcre_exec()</b>, is being used.
535 </P>
536 <P>
537 When a match succeeds, <b>pcretest</b> outputs the list of captured substrings
538 that <b>pcre_exec()</b> returns, starting with number 0 for the string that
539 matched the whole pattern. Otherwise, it outputs "No match" when the return is
540 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
541 substring when <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL. (Note that this is
542 the entire substring that was inspected during the partial match; it may
543 include characters before the actual match start if a lookbehind assertion,
544 \K, \b, or \B was involved.) For any other return, <b>pcretest</b> outputs
545 the PCRE negative error number and a short descriptive phrase. If the error is
546 a failed UTF-8 string check, the byte offset of the start of the failing
547 character and the reason code are also output, provided that the size of the
548 output vector is at least two. Here is an example of an interactive
549 <b>pcretest</b> run.
550 <pre>
551 $ pcretest
552 PCRE version 8.13 2011-04-30
553
554 re&#62; /^abc(\d+)/
555 data&#62; abc123
556 0: abc123
557 1: 123
558 data&#62; xyz
559 No match
560 </pre>
561 Unset capturing substrings that are not followed by one that is set are not
562 returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In the
563 following example, there are two capturing substrings, but when the first data
564 line is matched, the second, unset substring is not shown. An "internal" unset
565 substring is shown as "&#60;unset&#62;", as for the second data line.
566 <pre>
567 re&#62; /(a)|(b)/
568 data&#62; a
569 0: a
570 1: a
571 data&#62; b
572 0: b
573 1: &#60;unset&#62;
574 2: b
575 </pre>
576 If the strings contain any non-printing characters, they are output as \0x
577 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
578 pattern. See below for the definition of non-printing characters. If the
579 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
580 the the rest of the subject string, identified by "0+" like this:
581 <pre>
582 re&#62; /cat/+
583 data&#62; cataract
584 0: cat
585 0+ aract
586 </pre>
587 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
588 matching attempts are output in sequence, like this:
589 <pre>
590 re&#62; /\Bi(\w\w)/g
591 data&#62; Mississippi
592 0: iss
593 1: ss
594 0: iss
595 1: ss
596 0: ipp
597 1: pp
598 </pre>
599 "No match" is output only if the first match attempt fails. Here is an example
600 of a failure message (the offset 4 that is specified by \&#62;4 is past the end of
601 the subject string):
602 <pre>
603 re&#62; /xyz/
604 data&#62; xyz\&#62;4
605 Error -24 (bad offset value)
606 </PRE>
607 </P>
608 <P>
609 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
610 data line that is successfully matched, the substrings extracted by the
611 convenience functions are output with C, G, or L after the string number
612 instead of a colon. This is in addition to the normal full list. The string
613 length (that is, the return from the extraction function) is given in
614 parentheses after each string for <b>\C</b> and <b>\G</b>.
615 </P>
616 <P>
617 Note that whereas patterns can be continued over several lines (a plain "&#62;"
618 prompt is used for continuations), data lines may not. However newlines can be
619 included in data by means of the \n escape (or \r, \r\n, etc., depending on
620 the newline sequence setting).
621 </P>
622 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
623 <P>
624 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
625 means of the \D escape sequence or the <b>-dfa</b> command line option), the
626 output consists of a list of all the matches that start at the first point in
627 the subject where there is at least one match. For example:
628 <pre>
629 re&#62; /(tang|tangerine|tan)/
630 data&#62; yellow tangerine\D
631 0: tangerine
632 1: tang
633 2: tan
634 </pre>
635 (Using the normal matching function on this data finds only "tang".) The
636 longest matching string is always given first (and numbered zero). After a
637 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
638 partially matching substring. (Note that this is the entire substring that was
639 inspected during the partial match; it may include characters before the actual
640 match start if a lookbehind assertion, \K, \b, or \B was involved.)
641 </P>
642 <P>
643 If <b>/g</b> is present on the pattern, the search for further matches resumes
644 at the end of the longest match. For example:
645 <pre>
646 re&#62; /(tang|tangerine|tan)/g
647 data&#62; yellow tangerine and tangy sultana\D
648 0: tangerine
649 1: tang
650 2: tan
651 0: tang
652 1: tan
653 0: tan
654 </pre>
655 Since the matching function does not support substring capture, the escape
656 sequences that are concerned with captured substrings are not relevant.
657 </P>
658 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
659 <P>
660 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
661 indicating that the subject partially matched the pattern, you can restart the
662 match with additional subject data by means of the \R escape sequence. For
663 example:
664 <pre>
665 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
666 data&#62; 23ja\P\D
667 Partial match: 23ja
668 data&#62; n05\R\D
669 0: n05
670 </pre>
671 For further information about partial matching, see the
672 <a href="pcrepartial.html"><b>pcrepartial</b></a>
673 documentation.
674 </P>
675 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
676 <P>
677 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
678 is called during matching. This works with both matching functions. By default,
679 the called function displays the callout number, the start and current
680 positions in the text at the callout time, and the next pattern item to be
681 tested. For example, the output
682 <pre>
683 ---&#62;pqrabcdef
684 0 ^ ^ \d
685 </pre>
686 indicates that callout number 0 occurred for a match attempt starting at the
687 fourth character of the subject string, when the pointer was at the seventh
688 character of the data, and when the next pattern item was \d. Just one
689 circumflex is output if the start and current positions are the same.
690 </P>
691 <P>
692 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
693 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
694 callout number, the offset in the pattern, preceded by a plus, is output. For
695 example:
696 <pre>
697 re&#62; /\d?[A-E]\*/C
698 data&#62; E*
699 ---&#62;E*
700 +0 ^ \d?
701 +3 ^ [A-E]
702 +8 ^^ \*
703 +10 ^ ^
704 0: E*
705 </pre>
706 If a pattern contains (*MARK) items, an additional line is output whenever
707 a change of latest mark is passed to the callout function. For example:
708 <pre>
709 re&#62; /a(*MARK:X)bc/C
710 data&#62; abc
711 ---&#62;abc
712 +0 ^ a
713 +1 ^^ (*MARK:X)
714 +10 ^^ b
715 Latest Mark: X
716 +11 ^ ^ c
717 +12 ^ ^
718 0: abc
719 </pre>
720 The mark changes between matching "a" and "b", but stays the same for the rest
721 of the match, so nothing more is output. If, as a result of backtracking, the
722 mark reverts to being unset, the text "&#60;unset&#62;" is output.
723 </P>
724 <P>
725 The callout function in <b>pcretest</b> returns zero (carry on matching) by
726 default, but you can use a \C item in a data line (as described above) to
727 change this and other parameters of the callout.
728 </P>
729 <P>
730 Inserting callouts can be helpful when using <b>pcretest</b> to check
731 complicated regular expressions. For further information about callouts, see
732 the
733 <a href="pcrecallout.html"><b>pcrecallout</b></a>
734 documentation.
735 </P>
736 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
737 <P>
738 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
739 bytes other than 32-126 are always treated as non-printing characters are are
740 therefore shown as hex escapes.
741 </P>
742 <P>
743 When <b>pcretest</b> is outputting text that is a matched part of a subject
744 string, it behaves in the same way, unless a different locale has been set for
745 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
746 function to distinguish printing and non-printing characters.
747 </P>
748 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
749 <P>
750 The facilities described in this section are not available when the POSIX
751 interface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
752 specified.
753 </P>
754 <P>
755 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
756 compiled pattern to a file, by following the modifiers with &#62; and a file name.
757 For example:
758 <pre>
759 /pattern/im &#62;/some/file
760 </pre>
761 See the
762 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
763 documentation for a discussion about saving and re-using compiled patterns.
764 </P>
765 <P>
766 The data that is written is binary. The first eight bytes are the length of the
767 compiled pattern data followed by the length of the optional study data, each
768 written as four bytes in big-endian order (most significant byte first). If
769 there is no study data (either the pattern was not studied, or studying did not
770 return any data), the second length is zero. The lengths are followed by an
771 exact copy of the compiled pattern. If there is additional study data, this
772 follows immediately after the compiled pattern. After writing the file,
773 <b>pcretest</b> expects to read a new pattern.
774 </P>
775 <P>
776 A saved pattern can be reloaded into <b>pcretest</b> by specifying &#60; and a file
777 name instead of a pattern. The name of the file must not contain a &#60; character,
778 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
779 characters.
780 For example:
781 <pre>
782 re&#62; &#60;/some/file
783 Compiled pattern loaded from /some/file
784 No study data
785 </pre>
786 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
787 the usual way.
788 </P>
789 <P>
790 You can copy a file written by <b>pcretest</b> to a different host and reload it
791 there, even if the new host has opposite endianness to the one on which the
792 pattern was compiled. For example, you can compile on an i86 machine and run on
793 a SPARC machine.
794 </P>
795 <P>
796 File names for saving and reloading can be absolute or relative, but note that
797 the shell facility of expanding a file name that starts with a tilde (~) is not
798 available.
799 </P>
800 <P>
801 The ability to save and reload files in <b>pcretest</b> is intended for testing
802 and experimentation. It is not intended for production use because only a
803 single pattern can be written to a file. Furthermore, there is no facility for
804 supplying custom character tables for use with a reloaded pattern. If the
805 original pattern was compiled with custom tables, an attempt to match a subject
806 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
807 Finally, if you attempt to load a file that is not in the correct format, the
808 result is undefined.
809 </P>
810 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
811 <P>
812 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
813 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
814 </P>
815 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
816 <P>
817 Philip Hazel
818 <br>
819 University Computing Service
820 <br>
821 Cambridge CB2 3QH, England.
822 <br>
823 </P>
824 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
825 <P>
826 Last updated: 01 August 2011
827 <br>
828 Copyright &copy; 1997-2011 University of Cambridge.
829 <br>
830 <p>
831 Return to the <a href="index.html">PCRE index page</a>.
832 </p>

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