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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">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] [source] [destination]</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.
46 </P>
47 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
48 <P>
49 <b>-b</b>
50 Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
51 form is output after compilation.
52 </P>
53 <P>
54 <b>-C</b>
55 Output the version number of the PCRE library, and all available information
56 about the optional features that are included, and then exit.
57 </P>
58 <P>
59 <b>-d</b>
60 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
61 form and information about the compiled pattern is output after compilation;
62 <b>-d</b> is equivalent to <b>-b -i</b>.
63 </P>
64 <P>
65 <b>-dfa</b>
66 Behave as if each data line contains the \D escape sequence; this causes the
67 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
68 standard <b>pcre_exec()</b> function (more detail is given below).
69 </P>
70 <P>
71 <b>-help</b>
72 Output a brief summary these options and then exit.
73 </P>
74 <P>
75 <b>-i</b>
76 Behave as if each regex has the <b>/I</b> modifier; information about the
77 compiled pattern is given after compilation.
78 </P>
79 <P>
80 <b>-M</b>
81 Behave as if each data line contains the \M escape sequence; this causes
82 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
83 calling <b>pcre_exec()</b> repeatedly with different limits.
84 </P>
85 <P>
86 <b>-m</b>
87 Output the size of each compiled pattern after it has been compiled. This is
88 equivalent to adding <b>/M</b> to each regular expression. For compatibility
89 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
90 </P>
91 <P>
92 <b>-o</b> <i>osize</i>
93 Set the number of elements in the output vector that is used when calling
94 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
95 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
96 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
97 changed for individual matching calls by including \O in the data line (see
98 below).
99 </P>
100 <P>
101 <b>-p</b>
102 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
103 used to call PCRE. None of the other options has any effect when <b>-p</b> is
104 set.
105 </P>
106 <P>
107 <b>-q</b>
108 Do not output the version number of <b>pcretest</b> at the start of execution.
109 </P>
110 <P>
111 <b>-S</b> <i>size</i>
112 On Unix-like systems, set the size of the runtime stack to <i>size</i>
113 megabytes.
114 </P>
115 <P>
116 <b>-t</b>
117 Run each compile, study, and match many times with a timer, and output
118 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
119 <b>-t</b>, because you will then get the size output a zillion times, and the
120 timing will be distorted. You can control the number of iterations that are
121 used for timing by following <b>-t</b> with a number (as a separate item on the
122 command line). For example, "-t 1000" would iterate 1000 times. The default is
123 to iterate 500000 times.
124 </P>
125 <P>
126 <b>-tm</b>
127 This is like <b>-t</b> except that it times only the matching phase, not the
128 compile or study phases.
129 </P>
130 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
131 <P>
132 If <b>pcretest</b> is given two filename arguments, it reads from the first and
133 writes to the second. If it is given only one filename argument, it reads from
134 that file and writes to stdout. Otherwise, it reads from stdin and writes to
135 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
136 expressions, and "data&#62;" to prompt for data lines.
137 </P>
138 <P>
139 When <b>pcretest</b> is built, a configuration option can specify that it should
140 be linked with the <b>libreadline</b> library. When this is done, if the input
141 is from a terminal, it is read using the <b>readline()</b> function. This
142 provides line-editing and history facilities. The output from the <b>-help</b>
143 option states whether or not <b>readline()</b> will be used.
144 </P>
145 <P>
146 The program handles any number of sets of input on a single input file. Each
147 set starts with a regular expression, and continues with any number of data
148 lines to be matched against the pattern.
149 </P>
150 <P>
151 Each data line is matched separately and independently. If you want to do
152 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
153 etc., depending on the newline setting) in a single line of input to encode the
154 newline sequences. There is no limit on the length of data lines; the input
155 buffer is automatically extended if it is too small.
156 </P>
157 <P>
158 An empty line signals the end of the data lines, at which point a new regular
159 expression is read. The regular expressions are given enclosed in any
160 non-alphanumeric delimiters other than backslash, for example:
161 <pre>
162 /(a|bc)x+yz/
163 </pre>
164 White space before the initial delimiter is ignored. A regular expression may
165 be continued over several input lines, in which case the newline characters are
166 included within it. It is possible to include the delimiter within the pattern
167 by escaping it, for example
168 <pre>
169 /abc\/def/
170 </pre>
171 If you do so, the escape and the delimiter form part of the pattern, but since
172 delimiters are always non-alphanumeric, this does not affect its interpretation.
173 If the terminating delimiter is immediately followed by a backslash, for
174 example,
175 <pre>
176 /abc/\
177 </pre>
178 then a backslash is added to the end of the pattern. This is done to provide a
179 way of testing the error condition that arises if a pattern finishes with a
180 backslash, because
181 <pre>
182 /abc\/
183 </pre>
184 is interpreted as the first line of a pattern that starts with "abc/", causing
185 pcretest to read the next line as a continuation of the regular expression.
186 </P>
187 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
188 <P>
189 A pattern may be followed by any number of modifiers, which are mostly single
190 characters. Following Perl usage, these are referred to below as, for example,
191 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
192 always be a slash, and no slash is used when writing modifiers. Whitespace may
193 appear between the final pattern delimiter and the first modifier, and between
194 the modifiers themselves.
195 </P>
196 <P>
197 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
198 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
199 <b>pcre_compile()</b> is called. These four modifier letters have the same
200 effect as they do in Perl. For example:
201 <pre>
202 /caseless/i
203 </pre>
204 The following table shows additional modifiers for setting PCRE options that do
205 not correspond to anything in Perl:
206 <pre>
207 <b>/8</b> PCRE_UTF8
208 <b>/?</b> PCRE_NO_UTF8_CHECK
209 <b>/A</b> PCRE_ANCHORED
210 <b>/C</b> PCRE_AUTO_CALLOUT
211 <b>/E</b> PCRE_DOLLAR_ENDONLY
212 <b>/f</b> PCRE_FIRSTLINE
213 <b>/J</b> PCRE_DUPNAMES
214 <b>/N</b> PCRE_NO_AUTO_CAPTURE
215 <b>/U</b> PCRE_UNGREEDY
216 <b>/W</b> PCRE_UCP
217 <b>/X</b> PCRE_EXTRA
218 <b>/&#60;JS&#62;</b> PCRE_JAVASCRIPT_COMPAT
219 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
220 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
221 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
222 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
223 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
224 <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
225 <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
226 </pre>
227 The modifiers that are enclosed in angle brackets are literal strings as shown,
228 including the angle brackets, but the letters can be in either case. This
229 example sets multiline matching with CRLF as the line ending sequence:
230 <pre>
231 /^abc/m&#60;crlf&#62;
232 </pre>
233 As well as turning on the PCRE_UTF8 option, the <b>/8</b> modifier also causes
234 any non-printing characters in output strings to be printed using the
235 \x{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
236 options are given in the
237 <a href="pcreapi.html"><b>pcreapi</b></a>
238 documentation.
239 </P>
240 <br><b>
241 Finding all matches in a string
242 </b><br>
243 <P>
244 Searching for all possible matches within each subject string can be requested
245 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
246 again to search the remainder of the subject string. The difference between
247 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
248 <b>pcre_exec()</b> to start searching at a new point within the entire string
249 (which is in effect what Perl does), whereas the latter passes over a shortened
250 substring. This makes a difference to the matching process if the pattern
251 begins with a lookbehind assertion (including \b or \B).
252 </P>
253 <P>
254 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
255 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
256 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
257 same point. If this second match fails, the start offset is advanced by one
258 character, and the normal match is retried. This imitates the way Perl handles
259 such cases when using the <b>/g</b> modifier or the <b>split()</b> function.
260 </P>
261 <br><b>
262 Other modifiers
263 </b><br>
264 <P>
265 There are yet more modifiers for controlling the way <b>pcretest</b>
266 operates.
267 </P>
268 <P>
269 The <b>/+</b> modifier requests that as well as outputting the substring that
270 matched the entire pattern, pcretest should in addition output the remainder of
271 the subject string. This is useful for tests where the subject contains
272 multiple copies of the same substring.
273 </P>
274 <P>
275 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
276 output a representation of the compiled byte code after compilation. Normally
277 this information contains length and offset values; however, if <b>/Z</b> is
278 also present, this data is replaced by spaces. This is a special feature for
279 use in the automatic test scripts; it ensures that the same output is generated
280 for different internal link sizes.
281 </P>
282 <P>
283 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
284 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
285 </P>
286 <P>
287 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
288 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
289 facility is for testing the feature in PCRE that allows it to execute patterns
290 that were compiled on a host with a different endianness. This feature is not
291 available when the POSIX interface to PCRE is being used, that is, when the
292 <b>/P</b> pattern modifier is specified. See also the section about saving and
293 reloading compiled patterns below.
294 </P>
295 <P>
296 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
297 compiled pattern (whether it is anchored, has a fixed first character, and
298 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
299 pattern. If the pattern is studied, the results of that are also output.
300 </P>
301 <P>
302 The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking
303 control verbs that are returned from calls to <b>pcre_exec()</b>. It causes
304 <b>pcretest</b> to create a <b>pcre_extra</b> block if one has not already been
305 created by a call to <b>pcre_study()</b>, and to set the PCRE_EXTRA_MARK flag
306 and the <b>mark</b> field within it, every time that <b>pcre_exec()</b> is
307 called. If the variable that the <b>mark</b> field points to is non-NULL for a
308 match, non-match, or partial match, <b>pcretest</b> prints the string to which
309 it points. For a match, this is shown on a line by itself, tagged with "MK:".
310 For a non-match it is added to the message.
311 </P>
312 <P>
313 The <b>/L</b> modifier must be followed directly by the name of a locale, for
314 example,
315 <pre>
316 /pattern/Lfr_FR
317 </pre>
318 For this reason, it must be the last modifier. The given locale is set,
319 <b>pcre_maketables()</b> is called to build a set of character tables for the
320 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
321 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
322 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
323 </P>
324 <P>
325 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
326 pattern to be output.
327 </P>
328 <P>
329 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
330 API rather than its native API. When this is done, all other modifiers except
331 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
332 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
333 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
334 </P>
335 <P>
336 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
337 expression has been compiled, and the results used when the expression is
338 matched.
339 </P>
340 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
341 <P>
342 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
343 whitespace is removed, and it is then scanned for \ escapes. Some of these are
344 pretty esoteric features, intended for checking out some of the more
345 complicated features of PCRE. If you are just testing "ordinary" regular
346 expressions, you probably don't need any of these. The following escapes are
347 recognized:
348 <pre>
349 \a alarm (BEL, \x07)
350 \b backspace (\x08)
351 \e escape (\x27)
352 \f formfeed (\x0c)
353 \n newline (\x0a)
354 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
355 \r carriage return (\x0d)
356 \t tab (\x09)
357 \v vertical tab (\x0b)
358 \nnn octal character (up to 3 octal digits)
359 \xhh hexadecimal character (up to 2 hex digits)
360 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
361 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
362 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
363 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
364 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
365 ated by next non alphanumeric character)
366 \C+ show the current captured substrings at callout time
367 \C- do not supply a callout function
368 \C!n return 1 instead of 0 when callout number n is reached
369 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
370 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
371 \D use the <b>pcre_dfa_exec()</b> match function
372 \F only shortest match for <b>pcre_dfa_exec()</b>
373 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
374 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
375 ated by next non-alphanumeric character)
376 \L call pcre_get_substringlist() after a successful match
377 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
378 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
379 PCRE_NOTEMPTY_ATSTART option
380 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
381 \P pass the PCRE_PARTIAL_SOFT option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
382 PCRE_PARTIAL_HARD option
383 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
384 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
385 \S output details of memory get/free calls during matching
386 \Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
387 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
388 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
389 \&#62;dd start the match at offset dd (any number of digits);
390 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
391 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
392 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
393 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
394 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
395 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
396 </pre>
397 The escapes that specify line ending sequences are literal strings, exactly as
398 shown. No more than one newline setting should be present in any data line.
399 </P>
400 <P>
401 A backslash followed by anything else just escapes the anything else. If
402 the very last character is a backslash, it is ignored. This gives a way of
403 passing an empty line as data, since a real empty line terminates the data
404 input.
405 </P>
406 <P>
407 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
408 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
409 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
410 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
411 <i>match_limit</i> number is a measure of the amount of backtracking that takes
412 place, and checking it out can be instructive. For most simple matches, the
413 number is quite small, but for patterns with very large numbers of matching
414 possibilities, it can become large very quickly with increasing length of
415 subject string. The <i>match_limit_recursion</i> number is a measure of how much
416 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
417 to complete the match attempt.
418 </P>
419 <P>
420 When \O is used, the value specified may be higher or lower than the size set
421 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
422 the call of <b>pcre_exec()</b> for the line in which it appears.
423 </P>
424 <P>
425 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
426 API to be used, the only option-setting sequences that have any effect are \B
427 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
428 <b>regexec()</b>.
429 </P>
430 <P>
431 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
432 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
433 any number of hexadecimal digits inside the braces. The result is from one to
434 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
435 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
436 valid Unicode code points, or indeed valid UTF-8 characters according to the
437 later rules in RFC 3629.
438 </P>
439 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
440 <P>
441 By default, <b>pcretest</b> uses the standard PCRE matching function,
442 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
443 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
444 different way, and has some restrictions. The differences between the two
445 functions are described in the
446 <a href="pcrematching.html"><b>pcrematching</b></a>
447 documentation.
448 </P>
449 <P>
450 If a data line contains the \D escape sequence, or if the command line
451 contains the <b>-dfa</b> option, the alternative matching function is called.
452 This function finds all possible matches at a given point. If, however, the \F
453 escape sequence is present in the data line, it stops after the first match is
454 found. This is always the shortest possible match.
455 </P>
456 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
457 <P>
458 This section describes the output when the normal matching function,
459 <b>pcre_exec()</b>, is being used.
460 </P>
461 <P>
462 When a match succeeds, pcretest outputs the list of captured substrings that
463 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
464 the whole pattern. Otherwise, it outputs "No match" when the return is
465 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
466 substring when <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL. For any other
467 returns, it outputs the PCRE negative error number. Here is an example of an
468 interactive <b>pcretest</b> run.
469 <pre>
470 $ pcretest
471 PCRE version 7.0 30-Nov-2006
472
473 re&#62; /^abc(\d+)/
474 data&#62; abc123
475 0: abc123
476 1: 123
477 data&#62; xyz
478 No match
479 </pre>
480 Note that unset capturing substrings that are not followed by one that is set
481 are not returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In
482 the following example, there are two capturing substrings, but when the first
483 data line is matched, the second, unset substring is not shown. An "internal"
484 unset substring is shown as "&#60;unset&#62;", as for the second data line.
485 <pre>
486 re&#62; /(a)|(b)/
487 data&#62; a
488 0: a
489 1: a
490 data&#62; b
491 0: b
492 1: &#60;unset&#62;
493 2: b
494 </pre>
495 If the strings contain any non-printing characters, they are output as \0x
496 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
497 pattern. See below for the definition of non-printing characters. If the
498 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
499 the the rest of the subject string, identified by "0+" like this:
500 <pre>
501 re&#62; /cat/+
502 data&#62; cataract
503 0: cat
504 0+ aract
505 </pre>
506 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
507 matching attempts are output in sequence, like this:
508 <pre>
509 re&#62; /\Bi(\w\w)/g
510 data&#62; Mississippi
511 0: iss
512 1: ss
513 0: iss
514 1: ss
515 0: ipp
516 1: pp
517 </pre>
518 "No match" is output only if the first match attempt fails.
519 </P>
520 <P>
521 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
522 data line that is successfully matched, the substrings extracted by the
523 convenience functions are output with C, G, or L after the string number
524 instead of a colon. This is in addition to the normal full list. The string
525 length (that is, the return from the extraction function) is given in
526 parentheses after each string for <b>\C</b> and <b>\G</b>.
527 </P>
528 <P>
529 Note that whereas patterns can be continued over several lines (a plain "&#62;"
530 prompt is used for continuations), data lines may not. However newlines can be
531 included in data by means of the \n escape (or \r, \r\n, etc., depending on
532 the newline sequence setting).
533 </P>
534 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
535 <P>
536 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
537 means of the \D escape sequence or the <b>-dfa</b> command line option), the
538 output consists of a list of all the matches that start at the first point in
539 the subject where there is at least one match. For example:
540 <pre>
541 re&#62; /(tang|tangerine|tan)/
542 data&#62; yellow tangerine\D
543 0: tangerine
544 1: tang
545 2: tan
546 </pre>
547 (Using the normal matching function on this data finds only "tang".) The
548 longest matching string is always given first (and numbered zero). After a
549 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
550 partially matching substring.
551 </P>
552 <P>
553 If <b>/g</b> is present on the pattern, the search for further matches resumes
554 at the end of the longest match. For example:
555 <pre>
556 re&#62; /(tang|tangerine|tan)/g
557 data&#62; yellow tangerine and tangy sultana\D
558 0: tangerine
559 1: tang
560 2: tan
561 0: tang
562 1: tan
563 0: tan
564 </pre>
565 Since the matching function does not support substring capture, the escape
566 sequences that are concerned with captured substrings are not relevant.
567 </P>
568 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
569 <P>
570 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
571 indicating that the subject partially matched the pattern, you can restart the
572 match with additional subject data by means of the \R escape sequence. For
573 example:
574 <pre>
575 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
576 data&#62; 23ja\P\D
577 Partial match: 23ja
578 data&#62; n05\R\D
579 0: n05
580 </pre>
581 For further information about partial matching, see the
582 <a href="pcrepartial.html"><b>pcrepartial</b></a>
583 documentation.
584 </P>
585 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
586 <P>
587 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
588 is called during matching. This works with both matching functions. By default,
589 the called function displays the callout number, the start and current
590 positions in the text at the callout time, and the next pattern item to be
591 tested. For example, the output
592 <pre>
593 ---&#62;pqrabcdef
594 0 ^ ^ \d
595 </pre>
596 indicates that callout number 0 occurred for a match attempt starting at the
597 fourth character of the subject string, when the pointer was at the seventh
598 character of the data, and when the next pattern item was \d. Just one
599 circumflex is output if the start and current positions are the same.
600 </P>
601 <P>
602 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
603 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
604 callout number, the offset in the pattern, preceded by a plus, is output. For
605 example:
606 <pre>
607 re&#62; /\d?[A-E]\*/C
608 data&#62; E*
609 ---&#62;E*
610 +0 ^ \d?
611 +3 ^ [A-E]
612 +8 ^^ \*
613 +10 ^ ^
614 0: E*
615 </pre>
616 The callout function in <b>pcretest</b> returns zero (carry on matching) by
617 default, but you can use a \C item in a data line (as described above) to
618 change this.
619 </P>
620 <P>
621 Inserting callouts can be helpful when using <b>pcretest</b> to check
622 complicated regular expressions. For further information about callouts, see
623 the
624 <a href="pcrecallout.html"><b>pcrecallout</b></a>
625 documentation.
626 </P>
627 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
628 <P>
629 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
630 bytes other than 32-126 are always treated as non-printing characters are are
631 therefore shown as hex escapes.
632 </P>
633 <P>
634 When <b>pcretest</b> is outputting text that is a matched part of a subject
635 string, it behaves in the same way, unless a different locale has been set for
636 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
637 function to distinguish printing and non-printing characters.
638 </P>
639 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
640 <P>
641 The facilities described in this section are not available when the POSIX
642 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
643 specified.
644 </P>
645 <P>
646 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
647 compiled pattern to a file, by following the modifiers with &#62; and a file name.
648 For example:
649 <pre>
650 /pattern/im &#62;/some/file
651 </pre>
652 See the
653 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
654 documentation for a discussion about saving and re-using compiled patterns.
655 </P>
656 <P>
657 The data that is written is binary. The first eight bytes are the length of the
658 compiled pattern data followed by the length of the optional study data, each
659 written as four bytes in big-endian order (most significant byte first). If
660 there is no study data (either the pattern was not studied, or studying did not
661 return any data), the second length is zero. The lengths are followed by an
662 exact copy of the compiled pattern. If there is additional study data, this
663 follows immediately after the compiled pattern. After writing the file,
664 <b>pcretest</b> expects to read a new pattern.
665 </P>
666 <P>
667 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
668 name instead of a pattern. The name of the file must not contain a &#60; character,
669 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
670 characters.
671 For example:
672 <pre>
673 re&#62; &#60;/some/file
674 Compiled regex loaded from /some/file
675 No study data
676 </pre>
677 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
678 the usual way.
679 </P>
680 <P>
681 You can copy a file written by <b>pcretest</b> to a different host and reload it
682 there, even if the new host has opposite endianness to the one on which the
683 pattern was compiled. For example, you can compile on an i86 machine and run on
684 a SPARC machine.
685 </P>
686 <P>
687 File names for saving and reloading can be absolute or relative, but note that
688 the shell facility of expanding a file name that starts with a tilde (~) is not
689 available.
690 </P>
691 <P>
692 The ability to save and reload files in <b>pcretest</b> is intended for testing
693 and experimentation. It is not intended for production use because only a
694 single pattern can be written to a file. Furthermore, there is no facility for
695 supplying custom character tables for use with a reloaded pattern. If the
696 original pattern was compiled with custom tables, an attempt to match a subject
697 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
698 Finally, if you attempt to load a file that is not in the correct format, the
699 result is undefined.
700 </P>
701 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
702 <P>
703 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
704 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
705 </P>
706 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
707 <P>
708 Philip Hazel
709 <br>
710 University Computing Service
711 <br>
712 Cambridge CB2 3QH, England.
713 <br>
714 </P>
715 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
716 <P>
717 Last updated: 12 May 2010
718 <br>
719 Copyright &copy; 1997-2010 University of Cambridge.
720 <br>
721 <p>
722 Return to the <a href="index.html">PCRE index page</a>.
723 </p>

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