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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 compile-time
205 options that do 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>/Y</b> PCRE_NO_START_OPTIMIZE
219 <b>/&#60;JS&#62;</b> PCRE_JAVASCRIPT_COMPAT
220 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
221 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
222 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
223 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
224 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
225 <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
226 <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
227 </pre>
228 The modifiers that are enclosed in angle brackets are literal strings as shown,
229 including the angle brackets, but the letters can be in either case. This
230 example sets multiline matching with CRLF as the line ending sequence:
231 <pre>
232 /^abc/m&#60;crlf&#62;
233 </pre>
234 As well as turning on the PCRE_UTF8 option, the <b>/8</b> modifier also causes
235 any non-printing characters in output strings to be printed using the
236 \x{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
237 options are given in the
238 <a href="pcreapi.html"><b>pcreapi</b></a>
239 documentation.
240 </P>
241 <br><b>
242 Finding all matches in a string
243 </b><br>
244 <P>
245 Searching for all possible matches within each subject string can be requested
246 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
247 again to search the remainder of the subject string. The difference between
248 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
249 <b>pcre_exec()</b> to start searching at a new point within the entire string
250 (which is in effect what Perl does), whereas the latter passes over a shortened
251 substring. This makes a difference to the matching process if the pattern
252 begins with a lookbehind assertion (including \b or \B).
253 </P>
254 <P>
255 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
256 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
257 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
258 same point. If this second match fails, the start offset is advanced, and the
259 normal match is retried. This imitates the way Perl handles such cases when
260 using the <b>/g</b> modifier or the <b>split()</b> function. Normally, the start
261 offset is advanced by one character, but if the newline convention recognizes
262 CRLF as a newline, and the current character is CR followed by LF, an advance
263 of two is used.
264 </P>
265 <br><b>
266 Other modifiers
267 </b><br>
268 <P>
269 There are yet more modifiers for controlling the way <b>pcretest</b>
270 operates.
271 </P>
272 <P>
273 The <b>/+</b> modifier requests that as well as outputting the substring that
274 matched the entire pattern, pcretest should in addition output the remainder of
275 the subject string. This is useful for tests where the subject contains
276 multiple copies of the same substring.
277 </P>
278 <P>
279 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
280 output a representation of the compiled byte code after compilation. Normally
281 this information contains length and offset values; however, if <b>/Z</b> is
282 also present, this data is replaced by spaces. This is a special feature for
283 use in the automatic test scripts; it ensures that the same output is generated
284 for different internal link sizes.
285 </P>
286 <P>
287 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
288 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
289 </P>
290 <P>
291 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
292 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
293 facility is for testing the feature in PCRE that allows it to execute patterns
294 that were compiled on a host with a different endianness. This feature is not
295 available when the POSIX interface to PCRE is being used, that is, when the
296 <b>/P</b> pattern modifier is specified. See also the section about saving and
297 reloading compiled patterns below.
298 </P>
299 <P>
300 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
301 compiled pattern (whether it is anchored, has a fixed first character, and
302 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
303 pattern. If the pattern is studied, the results of that are also output.
304 </P>
305 <P>
306 The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking
307 control verbs that are returned from calls to <b>pcre_exec()</b>. It causes
308 <b>pcretest</b> to create a <b>pcre_extra</b> block if one has not already been
309 created by a call to <b>pcre_study()</b>, and to set the PCRE_EXTRA_MARK flag
310 and the <b>mark</b> field within it, every time that <b>pcre_exec()</b> is
311 called. If the variable that the <b>mark</b> field points to is non-NULL for a
312 match, non-match, or partial match, <b>pcretest</b> prints the string to which
313 it points. For a match, this is shown on a line by itself, tagged with "MK:".
314 For a non-match it is added to the message.
315 </P>
316 <P>
317 The <b>/L</b> modifier must be followed directly by the name of a locale, for
318 example,
319 <pre>
320 /pattern/Lfr_FR
321 </pre>
322 For this reason, it must be the last modifier. The given locale is set,
323 <b>pcre_maketables()</b> is called to build a set of character tables for the
324 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
325 regular expression. Without an <b>/L</b> (or <b>/T</b>) modifier, NULL is passed
326 as the tables pointer; that is, <b>/L</b> applies only to the expression on
327 which it appears.
328 </P>
329 <P>
330 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
331 pattern to be output.
332 </P>
333 <P>
334 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
335 expression has been compiled, and the results used when the expression is
336 matched.
337 </P>
338 <P>
339 The <b>/T</b> modifier must be followed by a single digit. It causes a specific
340 set of built-in character tables to be passed to <b>pcre_compile()</b>. It is
341 used in the standard PCRE tests to check behaviour with different character
342 tables. The digit specifies the tables as follows:
343 <pre>
344 0 the default ASCII tables, as distributed in
345 pcre_chartables.c.dist
346 1 a set of tables defining ISO 8859 characters
347 </pre>
348 In table 1, some characters whose codes are greater than 128 are identified as
349 letters, digits, spaces, etc.
350 </P>
351 <br><b>
352 Using the POSIX wrapper API
353 </b><br>
354 <P>
355 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
356 API rather than its native API. When <b>/P</b> is set, the following modifiers
357 set options for the <b>regcomp()</b> function:
358 <pre>
359 /i REG_ICASE
360 /m REG_NEWLINE
361 /N REG_NOSUB
362 /s REG_DOTALL )
363 /U REG_UNGREEDY ) These options are not part of
364 /W REG_UCP ) the POSIX standard
365 /8 REG_UTF8 )
366 </pre>
367 The <b>/+</b> modifier works as described above. All other modifiers are
368 ignored.
369 </P>
370 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
371 <P>
372 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
373 whitespace is removed, and it is then scanned for \ escapes. Some of these are
374 pretty esoteric features, intended for checking out some of the more
375 complicated features of PCRE. If you are just testing "ordinary" regular
376 expressions, you probably don't need any of these. The following escapes are
377 recognized:
378 <pre>
379 \a alarm (BEL, \x07)
380 \b backspace (\x08)
381 \e escape (\x27)
382 \f formfeed (\x0c)
383 \n newline (\x0a)
384 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
385 \r carriage return (\x0d)
386 \t tab (\x09)
387 \v vertical tab (\x0b)
388 \nnn octal character (up to 3 octal digits)
389 always a byte unless &#62; 255 in UTF-8 mode
390 \xhh hexadecimal byte (up to 2 hex digits)
391 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
392 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
393 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
394 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
395 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
396 ated by next non alphanumeric character)
397 \C+ show the current captured substrings at callout time
398 \C- do not supply a callout function
399 \C!n return 1 instead of 0 when callout number n is reached
400 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
401 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
402 \D use the <b>pcre_dfa_exec()</b> match function
403 \F only shortest match for <b>pcre_dfa_exec()</b>
404 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
405 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
406 ated by next non-alphanumeric character)
407 \L call pcre_get_substringlist() after a successful match
408 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
409 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
410 PCRE_NOTEMPTY_ATSTART option
411 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
412 \P pass the PCRE_PARTIAL_SOFT option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
413 PCRE_PARTIAL_HARD option
414 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
415 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
416 \S output details of memory get/free calls during matching
417 \Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
418 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
419 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
420 \&#62;dd start the match at offset dd (optional "-"; then any number of digits); this sets the <i>startoffset</i>
421 argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
422 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
423 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
424 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
425 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
426 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
427 </pre>
428 Note that \xhh always specifies one byte, even in UTF-8 mode; this makes it
429 possible to construct invalid UTF-8 sequences for testing purposes. On the
430 other hand, \x{hh} is interpreted as a UTF-8 character in UTF-8 mode,
431 generating more than one byte if the value is greater than 127. When not in
432 UTF-8 mode, it generates one byte for values less than 256, and causes an error
433 for greater values.
434 </P>
435 <P>
436 The escapes that specify line ending sequences are literal strings, exactly as
437 shown. No more than one newline setting should be present in any data line.
438 </P>
439 <P>
440 A backslash followed by anything else just escapes the anything else. If
441 the very last character is a backslash, it is ignored. This gives a way of
442 passing an empty line as data, since a real empty line terminates the data
443 input.
444 </P>
445 <P>
446 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
447 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
448 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
449 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
450 <i>match_limit</i> number is a measure of the amount of backtracking that takes
451 place, and checking it out can be instructive. For most simple matches, the
452 number is quite small, but for patterns with very large numbers of matching
453 possibilities, it can become large very quickly with increasing length of
454 subject string. The <i>match_limit_recursion</i> number is a measure of how much
455 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
456 to complete the match attempt.
457 </P>
458 <P>
459 When \O is used, the value specified may be higher or lower than the size set
460 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
461 the call of <b>pcre_exec()</b> for the line in which it appears.
462 </P>
463 <P>
464 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
465 API to be used, the only option-setting sequences that have any effect are \B,
466 \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
467 to be passed to <b>regexec()</b>.
468 </P>
469 <P>
470 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
471 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
472 any number of hexadecimal digits inside the braces. The result is from one to
473 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
474 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
475 valid Unicode code points, or indeed valid UTF-8 characters according to the
476 later rules in RFC 3629.
477 </P>
478 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
479 <P>
480 By default, <b>pcretest</b> uses the standard PCRE matching function,
481 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
482 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
483 different way, and has some restrictions. The differences between the two
484 functions are described in the
485 <a href="pcrematching.html"><b>pcrematching</b></a>
486 documentation.
487 </P>
488 <P>
489 If a data line contains the \D escape sequence, or if the command line
490 contains the <b>-dfa</b> option, the alternative matching function is called.
491 This function finds all possible matches at a given point. If, however, the \F
492 escape sequence is present in the data line, it stops after the first match is
493 found. This is always the shortest possible match.
494 </P>
495 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
496 <P>
497 This section describes the output when the normal matching function,
498 <b>pcre_exec()</b>, is being used.
499 </P>
500 <P>
501 When a match succeeds, pcretest outputs the list of captured substrings that
502 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
503 the whole pattern. Otherwise, it outputs "No match" when the return is
504 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
505 substring when <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL. (Note that this is
506 the entire substring that was inspected during the partial match; it may
507 include characters before the actual match start if a lookbehind assertion,
508 \K, \b, or \B was involved.) For any other returns, it outputs the PCRE
509 negative error number. Here is an example of an interactive <b>pcretest</b> run.
510 <pre>
511 $ pcretest
512 PCRE version 7.0 30-Nov-2006
513
514 re&#62; /^abc(\d+)/
515 data&#62; abc123
516 0: abc123
517 1: 123
518 data&#62; xyz
519 No match
520 </pre>
521 Note that unset capturing substrings that are not followed by one that is set
522 are not returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In
523 the following example, there are two capturing substrings, but when the first
524 data line is matched, the second, unset substring is not shown. An "internal"
525 unset substring is shown as "&#60;unset&#62;", as for the second data line.
526 <pre>
527 re&#62; /(a)|(b)/
528 data&#62; a
529 0: a
530 1: a
531 data&#62; b
532 0: b
533 1: &#60;unset&#62;
534 2: b
535 </pre>
536 If the strings contain any non-printing characters, they are output as \0x
537 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
538 pattern. See below for the definition of non-printing characters. If the
539 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
540 the the rest of the subject string, identified by "0+" like this:
541 <pre>
542 re&#62; /cat/+
543 data&#62; cataract
544 0: cat
545 0+ aract
546 </pre>
547 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
548 matching attempts are output in sequence, like this:
549 <pre>
550 re&#62; /\Bi(\w\w)/g
551 data&#62; Mississippi
552 0: iss
553 1: ss
554 0: iss
555 1: ss
556 0: ipp
557 1: pp
558 </pre>
559 "No match" is output only if the first match attempt fails.
560 </P>
561 <P>
562 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
563 data line that is successfully matched, the substrings extracted by the
564 convenience functions are output with C, G, or L after the string number
565 instead of a colon. This is in addition to the normal full list. The string
566 length (that is, the return from the extraction function) is given in
567 parentheses after each string for <b>\C</b> and <b>\G</b>.
568 </P>
569 <P>
570 Note that whereas patterns can be continued over several lines (a plain "&#62;"
571 prompt is used for continuations), data lines may not. However newlines can be
572 included in data by means of the \n escape (or \r, \r\n, etc., depending on
573 the newline sequence setting).
574 </P>
575 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
576 <P>
577 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
578 means of the \D escape sequence or the <b>-dfa</b> command line option), the
579 output consists of a list of all the matches that start at the first point in
580 the subject where there is at least one match. For example:
581 <pre>
582 re&#62; /(tang|tangerine|tan)/
583 data&#62; yellow tangerine\D
584 0: tangerine
585 1: tang
586 2: tan
587 </pre>
588 (Using the normal matching function on this data finds only "tang".) The
589 longest matching string is always given first (and numbered zero). After a
590 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
591 partially matching substring. (Note that this is the entire substring that was
592 inspected during the partial match; it may include characters before the actual
593 match start if a lookbehind assertion, \K, \b, or \B was involved.)
594 </P>
595 <P>
596 If <b>/g</b> is present on the pattern, the search for further matches resumes
597 at the end of the longest match. For example:
598 <pre>
599 re&#62; /(tang|tangerine|tan)/g
600 data&#62; yellow tangerine and tangy sultana\D
601 0: tangerine
602 1: tang
603 2: tan
604 0: tang
605 1: tan
606 0: tan
607 </pre>
608 Since the matching function does not support substring capture, the escape
609 sequences that are concerned with captured substrings are not relevant.
610 </P>
611 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
612 <P>
613 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
614 indicating that the subject partially matched the pattern, you can restart the
615 match with additional subject data by means of the \R escape sequence. For
616 example:
617 <pre>
618 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
619 data&#62; 23ja\P\D
620 Partial match: 23ja
621 data&#62; n05\R\D
622 0: n05
623 </pre>
624 For further information about partial matching, see the
625 <a href="pcrepartial.html"><b>pcrepartial</b></a>
626 documentation.
627 </P>
628 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
629 <P>
630 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
631 is called during matching. This works with both matching functions. By default,
632 the called function displays the callout number, the start and current
633 positions in the text at the callout time, and the next pattern item to be
634 tested. For example, the output
635 <pre>
636 ---&#62;pqrabcdef
637 0 ^ ^ \d
638 </pre>
639 indicates that callout number 0 occurred for a match attempt starting at the
640 fourth character of the subject string, when the pointer was at the seventh
641 character of the data, and when the next pattern item was \d. Just one
642 circumflex is output if the start and current positions are the same.
643 </P>
644 <P>
645 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
646 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
647 callout number, the offset in the pattern, preceded by a plus, is output. For
648 example:
649 <pre>
650 re&#62; /\d?[A-E]\*/C
651 data&#62; E*
652 ---&#62;E*
653 +0 ^ \d?
654 +3 ^ [A-E]
655 +8 ^^ \*
656 +10 ^ ^
657 0: E*
658 </pre>
659 The callout function in <b>pcretest</b> returns zero (carry on matching) by
660 default, but you can use a \C item in a data line (as described above) to
661 change this.
662 </P>
663 <P>
664 Inserting callouts can be helpful when using <b>pcretest</b> to check
665 complicated regular expressions. For further information about callouts, see
666 the
667 <a href="pcrecallout.html"><b>pcrecallout</b></a>
668 documentation.
669 </P>
670 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
671 <P>
672 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
673 bytes other than 32-126 are always treated as non-printing characters are are
674 therefore shown as hex escapes.
675 </P>
676 <P>
677 When <b>pcretest</b> is outputting text that is a matched part of a subject
678 string, it behaves in the same way, unless a different locale has been set for
679 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
680 function to distinguish printing and non-printing characters.
681 </P>
682 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
683 <P>
684 The facilities described in this section are not available when the POSIX
685 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
686 specified.
687 </P>
688 <P>
689 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
690 compiled pattern to a file, by following the modifiers with &#62; and a file name.
691 For example:
692 <pre>
693 /pattern/im &#62;/some/file
694 </pre>
695 See the
696 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
697 documentation for a discussion about saving and re-using compiled patterns.
698 </P>
699 <P>
700 The data that is written is binary. The first eight bytes are the length of the
701 compiled pattern data followed by the length of the optional study data, each
702 written as four bytes in big-endian order (most significant byte first). If
703 there is no study data (either the pattern was not studied, or studying did not
704 return any data), the second length is zero. The lengths are followed by an
705 exact copy of the compiled pattern. If there is additional study data, this
706 follows immediately after the compiled pattern. After writing the file,
707 <b>pcretest</b> expects to read a new pattern.
708 </P>
709 <P>
710 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
711 name instead of a pattern. The name of the file must not contain a &#60; character,
712 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
713 characters.
714 For example:
715 <pre>
716 re&#62; &#60;/some/file
717 Compiled regex loaded from /some/file
718 No study data
719 </pre>
720 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
721 the usual way.
722 </P>
723 <P>
724 You can copy a file written by <b>pcretest</b> to a different host and reload it
725 there, even if the new host has opposite endianness to the one on which the
726 pattern was compiled. For example, you can compile on an i86 machine and run on
727 a SPARC machine.
728 </P>
729 <P>
730 File names for saving and reloading can be absolute or relative, but note that
731 the shell facility of expanding a file name that starts with a tilde (~) is not
732 available.
733 </P>
734 <P>
735 The ability to save and reload files in <b>pcretest</b> is intended for testing
736 and experimentation. It is not intended for production use because only a
737 single pattern can be written to a file. Furthermore, there is no facility for
738 supplying custom character tables for use with a reloaded pattern. If the
739 original pattern was compiled with custom tables, an attempt to match a subject
740 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
741 Finally, if you attempt to load a file that is not in the correct format, the
742 result is undefined.
743 </P>
744 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
745 <P>
746 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
747 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
748 </P>
749 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
750 <P>
751 Philip Hazel
752 <br>
753 University Computing Service
754 <br>
755 Cambridge CB2 3QH, England.
756 <br>
757 </P>
758 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
759 <P>
760 Last updated: 21 November 2010
761 <br>
762 Copyright &copy; 1997-2010 University of Cambridge.
763 <br>
764 <p>
765 Return to the <a href="index.html">PCRE index page</a>.
766 </p>

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