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1 .TH PCRETEST 1
2 .SH NAME
3 pcretest - a program for testing Perl-compatible regular expressions.
4 .SH SYNOPSIS
5 .rs
6 .sp
7 .B pcretest "[options] [source] [destination]"
8 .sp
9 \fBpcretest\fP was written as a test program for the PCRE regular expression
10 library itself, but it can also be used for experimenting with regular
11 expressions. This document describes the features of the test program; for
12 details of the regular expressions themselves, see the
13 .\" HREF
14 \fBpcrepattern\fP
15 .\"
16 documentation. For details of the PCRE library function calls and their
17 options, see the
18 .\" HREF
19 \fBpcreapi\fP
20 .\"
21 documentation.
22 .
23 .
24 .SH OPTIONS
25 .rs
26 .TP 10
27 \fB-b\fP
28 Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal
29 form is output after compilation.
30 .TP 10
31 \fB-C\fP
32 Output the version number of the PCRE library, and all available information
33 about the optional features that are included, and then exit.
34 .TP 10
35 \fB-d\fP
36 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
37 form and information about the compiled pattern is output after compilation;
38 \fB-d\fP is equivalent to \fB-b -i\fP.
39 .TP 10
40 \fB-dfa\fP
41 Behave as if each data line contains the \eD escape sequence; this causes the
42 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
43 standard \fBpcre_exec()\fP function (more detail is given below).
44 .TP 10
45 \fB-help\fP
46 Output a brief summary these options and then exit.
47 .TP 10
48 \fB-i\fP
49 Behave as if each regex has the \fB/I\fP modifier; information about the
50 compiled pattern is given after compilation.
51 .TP 10
52 \fB-m\fP
53 Output the size of each compiled pattern after it has been compiled. This is
54 equivalent to adding \fB/M\fP to each regular expression. For compatibility
55 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
56 .TP 10
57 \fB-o\fP \fIosize\fP
58 Set the number of elements in the output vector that is used when calling
59 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
60 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
61 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
62 changed for individual matching calls by including \eO in the data line (see
63 below).
64 .TP 10
65 \fB-p\fP
66 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
67 used to call PCRE. None of the other options has any effect when \fB-p\fP is
68 set.
69 .TP 10
70 \fB-q\fP
71 Do not output the version number of \fBpcretest\fP at the start of execution.
72 .TP 10
73 \fB-S\fP \fIsize\fP
74 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
75 megabytes.
76 .TP 10
77 \fB-t\fP
78 Run each compile, study, and match many times with a timer, and output
79 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
80 \fB-t\fP, because you will then get the size output a zillion times, and the
81 timing will be distorted. You can control the number of iterations that are
82 used for timing by following \fB-t\fP with a number (as a separate item on the
83 command line). For example, "-t 1000" would iterate 1000 times. The default is
84 to iterate 500000 times.
85 .TP 10
86 \fB-tm\fP
87 This is like \fB-t\fP except that it times only the matching phase, not the
88 compile or study phases.
89 .
90 .
91 .SH DESCRIPTION
92 .rs
93 .sp
94 If \fBpcretest\fP is given two filename arguments, it reads from the first and
95 writes to the second. If it is given only one filename argument, it reads from
96 that file and writes to stdout. Otherwise, it reads from stdin and writes to
97 stdout, and prompts for each line of input, using "re>" to prompt for regular
98 expressions, and "data>" to prompt for data lines.
99 .P
100 The program handles any number of sets of input on a single input file. Each
101 set starts with a regular expression, and continues with any number of data
102 lines to be matched against the pattern.
103 .P
104 Each data line is matched separately and independently. If you want to do
105 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
106 etc., depending on the newline setting) in a single line of input to encode the
107 newline sequences. There is no limit on the length of data lines; the input
108 buffer is automatically extended if it is too small.
109 .P
110 An empty line signals the end of the data lines, at which point a new regular
111 expression is read. The regular expressions are given enclosed in any
112 non-alphanumeric delimiters other than backslash, for example:
113 .sp
114 /(a|bc)x+yz/
115 .sp
116 White space before the initial delimiter is ignored. A regular expression may
117 be continued over several input lines, in which case the newline characters are
118 included within it. It is possible to include the delimiter within the pattern
119 by escaping it, for example
120 .sp
121 /abc\e/def/
122 .sp
123 If you do so, the escape and the delimiter form part of the pattern, but since
124 delimiters are always non-alphanumeric, this does not affect its interpretation.
125 If the terminating delimiter is immediately followed by a backslash, for
126 example,
127 .sp
128 /abc/\e
129 .sp
130 then a backslash is added to the end of the pattern. This is done to provide a
131 way of testing the error condition that arises if a pattern finishes with a
132 backslash, because
133 .sp
134 /abc\e/
135 .sp
136 is interpreted as the first line of a pattern that starts with "abc/", causing
137 pcretest to read the next line as a continuation of the regular expression.
138 .
139 .
140 .SH "PATTERN MODIFIERS"
141 .rs
142 .sp
143 A pattern may be followed by any number of modifiers, which are mostly single
144 characters. Following Perl usage, these are referred to below as, for example,
145 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
146 always be a slash, and no slash is used when writing modifiers. Whitespace may
147 appear between the final pattern delimiter and the first modifier, and between
148 the modifiers themselves.
149 .P
150 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
151 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
152 \fBpcre_compile()\fP is called. These four modifier letters have the same
153 effect as they do in Perl. For example:
154 .sp
155 /caseless/i
156 .sp
157 The following table shows additional modifiers for setting PCRE options that do
158 not correspond to anything in Perl:
159 .sp
160 \fB/A\fP PCRE_ANCHORED
161 \fB/C\fP PCRE_AUTO_CALLOUT
162 \fB/E\fP PCRE_DOLLAR_ENDONLY
163 \fB/f\fP PCRE_FIRSTLINE
164 \fB/J\fP PCRE_DUPNAMES
165 \fB/N\fP PCRE_NO_AUTO_CAPTURE
166 \fB/U\fP PCRE_UNGREEDY
167 \fB/X\fP PCRE_EXTRA
168 \fB/<cr>\fP PCRE_NEWLINE_CR
169 \fB/<lf>\fP PCRE_NEWLINE_LF
170 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
171 \fB/<anycrlf>\fP PCRE_NEWLINE_ANY
172 \fB/<any>\fP PCRE_NEWLINE_ANY
173 .sp
174 Those specifying line ending sequencess are literal strings as shown. This
175 example sets multiline matching with CRLF as the line ending sequence:
176 .sp
177 /^abc/m<crlf>
178 .sp
179 Details of the meanings of these PCRE options are given in the
180 .\" HREF
181 \fBpcreapi\fP
182 .\"
183 documentation.
184 .
185 .
186 .SS "Finding all matches in a string"
187 .rs
188 .sp
189 Searching for all possible matches within each subject string can be requested
190 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
191 again to search the remainder of the subject string. The difference between
192 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
193 \fBpcre_exec()\fP to start searching at a new point within the entire string
194 (which is in effect what Perl does), whereas the latter passes over a shortened
195 substring. This makes a difference to the matching process if the pattern
196 begins with a lookbehind assertion (including \eb or \eB).
197 .P
198 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
199 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
200 flags set in order to search for another, non-empty, match at the same point.
201 If this second match fails, the start offset is advanced by one, and the normal
202 match is retried. This imitates the way Perl handles such cases when using the
203 \fB/g\fP modifier or the \fBsplit()\fP function.
204 .
205 .
206 .SS "Other modifiers"
207 .rs
208 .sp
209 There are yet more modifiers for controlling the way \fBpcretest\fP
210 operates.
211 .P
212 The \fB/+\fP modifier requests that as well as outputting the substring that
213 matched the entire pattern, pcretest should in addition output the remainder of
214 the subject string. This is useful for tests where the subject contains
215 multiple copies of the same substring.
216 .P
217 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
218 output a representation of the compiled byte code after compilation. Normally
219 this information contains length and offset values; however, if \fB/Z\fP is
220 also present, this data is replaced by spaces. This is a special feature for
221 use in the automatic test scripts; it ensures that the same output is generated
222 for different internal link sizes.
223 .P
224 The \fB/L\fP modifier must be followed directly by the name of a locale, for
225 example,
226 .sp
227 /pattern/Lfr_FR
228 .sp
229 For this reason, it must be the last modifier. The given locale is set,
230 \fBpcre_maketables()\fP is called to build a set of character tables for the
231 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
232 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
233 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
234 .P
235 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
236 compiled pattern (whether it is anchored, has a fixed first character, and
237 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
238 pattern. If the pattern is studied, the results of that are also output.
239 .P
240 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
241 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
242 .P
243 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
244 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
245 facility is for testing the feature in PCRE that allows it to execute patterns
246 that were compiled on a host with a different endianness. This feature is not
247 available when the POSIX interface to PCRE is being used, that is, when the
248 \fB/P\fP pattern modifier is specified. See also the section about saving and
249 reloading compiled patterns below.
250 .P
251 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
252 expression has been compiled, and the results used when the expression is
253 matched.
254 .P
255 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
256 pattern to be output.
257 .P
258 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
259 API rather than its native API. When this is done, all other modifiers except
260 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
261 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
262 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
263 .P
264 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
265 option set. This turns on support for UTF-8 character handling in PCRE,
266 provided that it was compiled with this support enabled. This modifier also
267 causes any non-printing characters in output strings to be printed using the
268 \ex{hh...} notation if they are valid UTF-8 sequences.
269 .P
270 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
271 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
272 checking of the string for UTF-8 validity.
273 .
274 .
275 .SH "DATA LINES"
276 .rs
277 .sp
278 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
279 whitespace is removed, and it is then scanned for \e escapes. Some of these are
280 pretty esoteric features, intended for checking out some of the more
281 complicated features of PCRE. If you are just testing "ordinary" regular
282 expressions, you probably don't need any of these. The following escapes are
283 recognized:
284 .sp
285 \ea alarm (BEL, \ex07)
286 \eb backspace (\ex08)
287 \ee escape (\ex27)
288 \ef formfeed (\ex0c)
289 \en newline (\ex0a)
290 .\" JOIN
291 \eqdd set the PCRE_MATCH_LIMIT limit to dd
292 (any number of digits)
293 \er carriage return (\ex0d)
294 \et tab (\ex09)
295 \ev vertical tab (\ex0b)
296 \ennn octal character (up to 3 octal digits)
297 \exhh hexadecimal character (up to 2 hex digits)
298 .\" JOIN
299 \ex{hh...} hexadecimal character, any number of digits
300 in UTF-8 mode
301 .\" JOIN
302 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
303 or \fBpcre_dfa_exec()\fP
304 .\" JOIN
305 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
306 or \fBpcre_dfa_exec()\fP
307 .\" JOIN
308 \eCdd call pcre_copy_substring() for substring dd
309 after a successful match (number less than 32)
310 .\" JOIN
311 \eCname call pcre_copy_named_substring() for substring
312 "name" after a successful match (name termin-
313 ated by next non alphanumeric character)
314 .\" JOIN
315 \eC+ show the current captured substrings at callout
316 time
317 \eC- do not supply a callout function
318 .\" JOIN
319 \eC!n return 1 instead of 0 when callout number n is
320 reached
321 .\" JOIN
322 \eC!n!m return 1 instead of 0 when callout number n is
323 reached for the nth time
324 .\" JOIN
325 \eC*n pass the number n (may be negative) as callout
326 data; this is used as the callout return value
327 \eD use the \fBpcre_dfa_exec()\fP match function
328 \eF only shortest match for \fBpcre_dfa_exec()\fP
329 .\" JOIN
330 \eGdd call pcre_get_substring() for substring dd
331 after a successful match (number less than 32)
332 .\" JOIN
333 \eGname call pcre_get_named_substring() for substring
334 "name" after a successful match (name termin-
335 ated by next non-alphanumeric character)
336 .\" JOIN
337 \eL call pcre_get_substringlist() after a
338 successful match
339 .\" JOIN
340 \eM discover the minimum MATCH_LIMIT and
341 MATCH_LIMIT_RECURSION settings
342 .\" JOIN
343 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
344 or \fBpcre_dfa_exec()\fP
345 .\" JOIN
346 \eOdd set the size of the output vector passed to
347 \fBpcre_exec()\fP to dd (any number of digits)
348 .\" JOIN
349 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
350 or \fBpcre_dfa_exec()\fP
351 .\" JOIN
352 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
353 (any number of digits)
354 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
355 \eS output details of memory get/free calls during matching
356 .\" JOIN
357 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
358 or \fBpcre_dfa_exec()\fP
359 .\" JOIN
360 \e? pass the PCRE_NO_UTF8_CHECK option to
361 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
362 \e>dd start the match at offset dd (any number of digits);
363 .\" JOIN
364 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
365 or \fBpcre_dfa_exec()\fP
366 .\" JOIN
367 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
368 or \fBpcre_dfa_exec()\fP
369 .\" JOIN
370 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
371 or \fBpcre_dfa_exec()\fP
372 .\" JOIN
373 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
374 or \fBpcre_dfa_exec()\fP
375 .\" JOIN
376 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
377 or \fBpcre_dfa_exec()\fP
378 .\" JOIN
379 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
380 or \fBpcre_dfa_exec()\fP
381 .sp
382 The escapes that specify line ending sequences are literal strings, exactly as
383 shown. No more than one newline setting should be present in any data line.
384 .P
385 A backslash followed by anything else just escapes the anything else. If
386 the very last character is a backslash, it is ignored. This gives a way of
387 passing an empty line as data, since a real empty line terminates the data
388 input.
389 .P
390 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
391 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
392 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
393 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
394 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
395 place, and checking it out can be instructive. For most simple matches, the
396 number is quite small, but for patterns with very large numbers of matching
397 possibilities, it can become large very quickly with increasing length of
398 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
399 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
400 to complete the match attempt.
401 .P
402 When \eO is used, the value specified may be higher or lower than the size set
403 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
404 the call of \fBpcre_exec()\fP for the line in which it appears.
405 .P
406 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
407 API to be used, the only option-setting sequences that have any effect are \eB
408 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
409 \fBregexec()\fP.
410 .P
411 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
412 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
413 any number of hexadecimal digits inside the braces. The result is from one to
414 six bytes, encoded according to the UTF-8 rules.
415 .
416 .
417 .SH "THE ALTERNATIVE MATCHING FUNCTION"
418 .rs
419 .sp
420 By default, \fBpcretest\fP uses the standard PCRE matching function,
421 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
422 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
423 different way, and has some restrictions. The differences between the two
424 functions are described in the
425 .\" HREF
426 \fBpcrematching\fP
427 .\"
428 documentation.
429 .P
430 If a data line contains the \eD escape sequence, or if the command line
431 contains the \fB-dfa\fP option, the alternative matching function is called.
432 This function finds all possible matches at a given point. If, however, the \eF
433 escape sequence is present in the data line, it stops after the first match is
434 found. This is always the shortest possible match.
435 .
436 .
437 .SH "DEFAULT OUTPUT FROM PCRETEST"
438 .rs
439 .sp
440 This section describes the output when the normal matching function,
441 \fBpcre_exec()\fP, is being used.
442 .P
443 When a match succeeds, pcretest outputs the list of captured substrings that
444 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
445 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
446 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
447 respectively, and otherwise the PCRE negative error number. Here is an example
448 of an interactive \fBpcretest\fP run.
449 .sp
450 $ pcretest
451 PCRE version 7.0 30-Nov-2006
452 .sp
453 re> /^abc(\ed+)/
454 data> abc123
455 0: abc123
456 1: 123
457 data> xyz
458 No match
459 .sp
460 If the strings contain any non-printing characters, they are output as \e0x
461 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
462 pattern. See below for the definition of non-printing characters. If the
463 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
464 the the rest of the subject string, identified by "0+" like this:
465 .sp
466 re> /cat/+
467 data> cataract
468 0: cat
469 0+ aract
470 .sp
471 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
472 matching attempts are output in sequence, like this:
473 .sp
474 re> /\eBi(\ew\ew)/g
475 data> Mississippi
476 0: iss
477 1: ss
478 0: iss
479 1: ss
480 0: ipp
481 1: pp
482 .sp
483 "No match" is output only if the first match attempt fails.
484 .P
485 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
486 data line that is successfully matched, the substrings extracted by the
487 convenience functions are output with C, G, or L after the string number
488 instead of a colon. This is in addition to the normal full list. The string
489 length (that is, the return from the extraction function) is given in
490 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
491 .P
492 Note that whereas patterns can be continued over several lines (a plain ">"
493 prompt is used for continuations), data lines may not. However newlines can be
494 included in data by means of the \en escape (or \er, \er\en, etc., depending on
495 the newline sequence setting).
496 .
497 .
498 .
499 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
500 .rs
501 .sp
502 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
503 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
504 output consists of a list of all the matches that start at the first point in
505 the subject where there is at least one match. For example:
506 .sp
507 re> /(tang|tangerine|tan)/
508 data> yellow tangerine\eD
509 0: tangerine
510 1: tang
511 2: tan
512 .sp
513 (Using the normal matching function on this data finds only "tang".) The
514 longest matching string is always given first (and numbered zero).
515 .P
516 If \fB/g\fP is present on the pattern, the search for further matches resumes
517 at the end of the longest match. For example:
518 .sp
519 re> /(tang|tangerine|tan)/g
520 data> yellow tangerine and tangy sultana\eD
521 0: tangerine
522 1: tang
523 2: tan
524 0: tang
525 1: tan
526 0: tan
527 .sp
528 Since the matching function does not support substring capture, the escape
529 sequences that are concerned with captured substrings are not relevant.
530 .
531 .
532 .SH "RESTARTING AFTER A PARTIAL MATCH"
533 .rs
534 .sp
535 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
536 indicating that the subject partially matched the pattern, you can restart the
537 match with additional subject data by means of the \eR escape sequence. For
538 example:
539 .sp
540 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
541 data> 23ja\eP\eD
542 Partial match: 23ja
543 data> n05\eR\eD
544 0: n05
545 .sp
546 For further information about partial matching, see the
547 .\" HREF
548 \fBpcrepartial\fP
549 .\"
550 documentation.
551 .
552 .
553 .SH CALLOUTS
554 .rs
555 .sp
556 If the pattern contains any callout requests, \fBpcretest\fP's callout function
557 is called during matching. This works with both matching functions. By default,
558 the called function displays the callout number, the start and current
559 positions in the text at the callout time, and the next pattern item to be
560 tested. For example, the output
561 .sp
562 --->pqrabcdef
563 0 ^ ^ \ed
564 .sp
565 indicates that callout number 0 occurred for a match attempt starting at the
566 fourth character of the subject string, when the pointer was at the seventh
567 character of the data, and when the next pattern item was \ed. Just one
568 circumflex is output if the start and current positions are the same.
569 .P
570 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
571 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
572 callout number, the offset in the pattern, preceded by a plus, is output. For
573 example:
574 .sp
575 re> /\ed?[A-E]\e*/C
576 data> E*
577 --->E*
578 +0 ^ \ed?
579 +3 ^ [A-E]
580 +8 ^^ \e*
581 +10 ^ ^
582 0: E*
583 .sp
584 The callout function in \fBpcretest\fP returns zero (carry on matching) by
585 default, but you can use a \eC item in a data line (as described above) to
586 change this.
587 .P
588 Inserting callouts can be helpful when using \fBpcretest\fP to check
589 complicated regular expressions. For further information about callouts, see
590 the
591 .\" HREF
592 \fBpcrecallout\fP
593 .\"
594 documentation.
595 .
596 .
597 .
598 .SH "NON-PRINTING CHARACTERS"
599 .rs
600 .sp
601 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
602 bytes other than 32-126 are always treated as non-printing characters are are
603 therefore shown as hex escapes.
604 .P
605 When \fBpcretest\fP is outputting text that is a matched part of a subject
606 string, it behaves in the same way, unless a different locale has been set for
607 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
608 function to distinguish printing and non-printing characters.
609 .
610 .
611 .
612 .SH "SAVING AND RELOADING COMPILED PATTERNS"
613 .rs
614 .sp
615 The facilities described in this section are not available when the POSIX
616 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
617 specified.
618 .P
619 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
620 compiled pattern to a file, by following the modifiers with > and a file name.
621 For example:
622 .sp
623 /pattern/im >/some/file
624 .sp
625 See the
626 .\" HREF
627 \fBpcreprecompile\fP
628 .\"
629 documentation for a discussion about saving and re-using compiled patterns.
630 .P
631 The data that is written is binary. The first eight bytes are the length of the
632 compiled pattern data followed by the length of the optional study data, each
633 written as four bytes in big-endian order (most significant byte first). If
634 there is no study data (either the pattern was not studied, or studying did not
635 return any data), the second length is zero. The lengths are followed by an
636 exact copy of the compiled pattern. If there is additional study data, this
637 follows immediately after the compiled pattern. After writing the file,
638 \fBpcretest\fP expects to read a new pattern.
639 .P
640 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
641 name instead of a pattern. The name of the file must not contain a < character,
642 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
643 characters.
644 For example:
645 .sp
646 re> </some/file
647 Compiled regex loaded from /some/file
648 No study data
649 .sp
650 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
651 the usual way.
652 .P
653 You can copy a file written by \fBpcretest\fP to a different host and reload it
654 there, even if the new host has opposite endianness to the one on which the
655 pattern was compiled. For example, you can compile on an i86 machine and run on
656 a SPARC machine.
657 .P
658 File names for saving and reloading can be absolute or relative, but note that
659 the shell facility of expanding a file name that starts with a tilde (~) is not
660 available.
661 .P
662 The ability to save and reload files in \fBpcretest\fP is intended for testing
663 and experimentation. It is not intended for production use because only a
664 single pattern can be written to a file. Furthermore, there is no facility for
665 supplying custom character tables for use with a reloaded pattern. If the
666 original pattern was compiled with custom tables, an attempt to match a subject
667 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
668 Finally, if you attempt to load a file that is not in the correct format, the
669 result is undefined.
670 .
671 .
672 .SH "SEE ALSO"
673 .rs
674 .sp
675 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
676 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
677 .
678 .
679 .SH AUTHOR
680 .rs
681 .sp
682 .nf
683 Philip Hazel
684 University Computing Service
685 Cambridge CB2 3QH, England.
686 .fi
687 .
688 .
689 .SH REVISION
690 .rs
691 .sp
692 .nf
693 Last updated: 16 April 2007
694 Copyright (c) 1997-2007 University of Cambridge.
695 .fi

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