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1 PCRETEST(1) PCRETEST(1)
2
3
4 NAME
5 pcretest - a program for testing Perl-compatible regular expressions.
6
7
8 SYNOPSIS
9
10 pcretest [options] [source] [destination]
11
12 pcretest was written as a test program for the PCRE regular expression
13 library itself, but it can also be used for experimenting with regular
14 expressions. This document describes the features of the test program;
15 for details of the regular expressions themselves, see the pcrepattern
16 documentation. For details of the PCRE library function calls and their
17 options, see the pcreapi documentation.
18
19
20 OPTIONS
21
22 -b Behave as if each regex has the /B (show bytecode) modifier;
23 the internal form is output after compilation.
24
25 -C Output the version number of the PCRE library, and all avail-
26 able information about the optional features that are
27 included, and then exit.
28
29 -d Behave as if each regex has the /D (debug) modifier; the
30 internal form and information about the compiled pattern is
31 output after compilation; -d is equivalent to -b -i.
32
33 -dfa Behave as if each data line contains the \D escape sequence;
34 this causes the alternative matching function,
35 pcre_dfa_exec(), to be used instead of the standard
36 pcre_exec() function (more detail is given below).
37
38 -help Output a brief summary these options and then exit.
39
40 -i Behave as if each regex has the /I modifier; information
41 about the compiled pattern is given after compilation.
42
43 -M Behave as if each data line contains the \M escape sequence;
44 this causes PCRE to discover the minimum MATCH_LIMIT and
45 MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46 edly with different limits.
47
48 -m Output the size of each compiled pattern after it has been
49 compiled. This is equivalent to adding /M to each regular
50 expression. For compatibility with earlier versions of
51 pcretest, -s is a synonym for -m.
52
53 -o osize Set the number of elements in the output vector that is used
54 when calling pcre_exec() or pcre_dfa_exec() to be osize. The
55 default value is 45, which is enough for 14 capturing subex-
56 pressions for pcre_exec() or 22 different matches for
57 pcre_dfa_exec(). The vector size can be changed for individ-
58 ual matching calls by including \O in the data line (see
59 below).
60
61 -p Behave as if each regex has the /P modifier; the POSIX wrap-
62 per API is used to call PCRE. None of the other options has
63 any effect when -p is set.
64
65 -q Do not output the version number of pcretest at the start of
66 execution.
67
68 -S size On Unix-like systems, set the size of the runtime stack to
69 size megabytes.
70
71 -t Run each compile, study, and match many times with a timer,
72 and output resulting time per compile or match (in millisec-
73 onds). Do not set -m with -t, because you will then get the
74 size output a zillion times, and the timing will be dis-
75 torted. You can control the number of iterations that are
76 used for timing by following -t with a number (as a separate
77 item on the command line). For example, "-t 1000" would iter-
78 ate 1000 times. The default is to iterate 500000 times.
79
80 -tm This is like -t except that it times only the matching phase,
81 not the compile or study phases.
82
83
84 DESCRIPTION
85
86 If pcretest is given two filename arguments, it reads from the first
87 and writes to the second. If it is given only one filename argument, it
88 reads from that file and writes to stdout. Otherwise, it reads from
89 stdin and writes to stdout, and prompts for each line of input, using
90 "re>" to prompt for regular expressions, and "data>" to prompt for data
91 lines.
92
93 When pcretest is built, a configuration option can specify that it
94 should be linked with the libreadline library. When this is done, if
95 the input is from a terminal, it is read using the readline() function.
96 This provides line-editing and history facilities. The output from the
97 -help option states whether or not readline() will be used.
98
99 The program handles any number of sets of input on a single input file.
100 Each set starts with a regular expression, and continues with any num-
101 ber of data lines to be matched against the pattern.
102
103 Each data line is matched separately and independently. If you want to
104 do multi-line matches, you have to use the \n escape sequence (or \r or
105 \r\n, etc., depending on the newline setting) in a single line of input
106 to encode the newline sequences. There is no limit on the length of
107 data lines; the input buffer is automatically extended if it is too
108 small.
109
110 An empty line signals the end of the data lines, at which point a new
111 regular expression is read. The regular expressions are given enclosed
112 in any non-alphanumeric delimiters other than backslash, for example:
113
114 /(a|bc)x+yz/
115
116 White space before the initial delimiter is ignored. A regular expres-
117 sion may be continued over several input lines, in which case the new-
118 line characters are included within it. It is possible to include the
119 delimiter within the pattern by escaping it, for example
120
121 /abc\/def/
122
123 If you do so, the escape and the delimiter form part of the pattern,
124 but since delimiters are always non-alphanumeric, this does not affect
125 its interpretation. If the terminating delimiter is immediately fol-
126 lowed by a backslash, for example,
127
128 /abc/\
129
130 then a backslash is added to the end of the pattern. This is done to
131 provide a way of testing the error condition that arises if a pattern
132 finishes with a backslash, because
133
134 /abc\/
135
136 is interpreted as the first line of a pattern that starts with "abc/",
137 causing pcretest to read the next line as a continuation of the regular
138 expression.
139
140
141 PATTERN MODIFIERS
142
143 A pattern may be followed by any number of modifiers, which are mostly
144 single characters. Following Perl usage, these are referred to below
145 as, for example, "the /i modifier", even though the delimiter of the
146 pattern need not always be a slash, and no slash is used when writing
147 modifiers. Whitespace may appear between the final pattern delimiter
148 and the first modifier, and between the modifiers themselves.
149
150 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
151 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
152 pile() is called. These four modifier letters have the same effect as
153 they do in Perl. For example:
154
155 /caseless/i
156
157 The following table shows additional modifiers for setting PCRE com-
158 pile-time options that do not correspond to anything in Perl:
159
160 /8 PCRE_UTF8
161 /? PCRE_NO_UTF8_CHECK
162 /A PCRE_ANCHORED
163 /C PCRE_AUTO_CALLOUT
164 /E PCRE_DOLLAR_ENDONLY
165 /f PCRE_FIRSTLINE
166 /J PCRE_DUPNAMES
167 /N PCRE_NO_AUTO_CAPTURE
168 /U PCRE_UNGREEDY
169 /W PCRE_UCP
170 /X PCRE_EXTRA
171 /<JS> PCRE_JAVASCRIPT_COMPAT
172 /<cr> PCRE_NEWLINE_CR
173 /<lf> PCRE_NEWLINE_LF
174 /<crlf> PCRE_NEWLINE_CRLF
175 /<anycrlf> PCRE_NEWLINE_ANYCRLF
176 /<any> PCRE_NEWLINE_ANY
177 /<bsr_anycrlf> PCRE_BSR_ANYCRLF
178 /<bsr_unicode> PCRE_BSR_UNICODE
179
180 The modifiers that are enclosed in angle brackets are literal strings
181 as shown, including the angle brackets, but the letters can be in
182 either case. This example sets multiline matching with CRLF as the line
183 ending sequence:
184
185 /^abc/m<crlf>
186
187 As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
188 any non-printing characters in output strings to be printed using the
189 \x{hh...} notation if they are valid UTF-8 sequences. Full details of
190 the PCRE options are given in the pcreapi documentation.
191
192 Finding all matches in a string
193
194 Searching for all possible matches within each subject string can be
195 requested by the /g or /G modifier. After finding a match, PCRE is
196 called again to search the remainder of the subject string. The differ-
197 ence between /g and /G is that the former uses the startoffset argument
198 to pcre_exec() to start searching at a new point within the entire
199 string (which is in effect what Perl does), whereas the latter passes
200 over a shortened substring. This makes a difference to the matching
201 process if the pattern begins with a lookbehind assertion (including \b
202 or \B).
203
204 If any call to pcre_exec() in a /g or /G sequence matches an empty
205 string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
206 PCRE_ANCHORED flags set in order to search for another, non-empty,
207 match at the same point. If this second match fails, the start offset
208 is advanced, and the normal match is retried. This imitates the way
209 Perl handles such cases when using the /g modifier or the split() func-
210 tion. Normally, the start offset is advanced by one character, but if
211 the newline convention recognizes CRLF as a newline, and the current
212 character is CR followed by LF, an advance of two is used.
213
214 Other modifiers
215
216 There are yet more modifiers for controlling the way pcretest operates.
217
218 The /+ modifier requests that as well as outputting the substring that
219 matched the entire pattern, pcretest should in addition output the
220 remainder of the subject string. This is useful for tests where the
221 subject contains multiple copies of the same substring.
222
223 The /B modifier is a debugging feature. It requests that pcretest out-
224 put a representation of the compiled byte code after compilation. Nor-
225 mally this information contains length and offset values; however, if
226 /Z is also present, this data is replaced by spaces. This is a special
227 feature for use in the automatic test scripts; it ensures that the same
228 output is generated for different internal link sizes.
229
230 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
231 that is, both the /B and the /I modifiers.
232
233 The /F modifier causes pcretest to flip the byte order of the fields in
234 the compiled pattern that contain 2-byte and 4-byte numbers. This
235 facility is for testing the feature in PCRE that allows it to execute
236 patterns that were compiled on a host with a different endianness. This
237 feature is not available when the POSIX interface to PCRE is being
238 used, that is, when the /P pattern modifier is specified. See also the
239 section about saving and reloading compiled patterns below.
240
241 The /I modifier requests that pcretest output information about the
242 compiled pattern (whether it is anchored, has a fixed first character,
243 and so on). It does this by calling pcre_fullinfo() after compiling a
244 pattern. If the pattern is studied, the results of that are also out-
245 put.
246
247 The /K modifier requests pcretest to show names from backtracking con-
248 trol verbs that are returned from calls to pcre_exec(). It causes
249 pcretest to create a pcre_extra block if one has not already been cre-
250 ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
251 the mark field within it, every time that pcre_exec() is called. If the
252 variable that the mark field points to is non-NULL for a match, non-
253 match, or partial match, pcretest prints the string to which it points.
254 For a match, this is shown on a line by itself, tagged with "MK:". For
255 a non-match it is added to the message.
256
257 The /L modifier must be followed directly by the name of a locale, for
258 example,
259
260 /pattern/Lfr_FR
261
262 For this reason, it must be the last modifier. The given locale is set,
263 pcre_maketables() is called to build a set of character tables for the
264 locale, and this is then passed to pcre_compile() when compiling the
265 regular expression. Without an /L (or /T) modifier, NULL is passed as
266 the tables pointer; that is, /L applies only to the expression on which
267 it appears.
268
269 The /M modifier causes the size of memory block used to hold the com-
270 piled pattern to be output.
271
272 The /S modifier causes pcre_study() to be called after the expression
273 has been compiled, and the results used when the expression is matched.
274
275 The /T modifier must be followed by a single digit. It causes a spe-
276 cific set of built-in character tables to be passed to pcre_compile().
277 It is used in the standard PCRE tests to check behaviour with different
278 character tables. The digit specifies the tables as follows:
279
280 0 the default ASCII tables, as distributed in
281 pcre_chartables.c.dist
282 1 a set of tables defining ISO 8859 characters
283
284 In table 1, some characters whose codes are greater than 128 are iden-
285 tified as letters, digits, spaces, etc.
286
287 Using the POSIX wrapper API
288
289 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
290 rather than its native API. When /P is set, the following modifiers set
291 options for the regcomp() function:
292
293 /i REG_ICASE
294 /m REG_NEWLINE
295 /N REG_NOSUB
296 /s REG_DOTALL )
297 /U REG_UNGREEDY ) These options are not part of
298 /W REG_UCP ) the POSIX standard
299 /8 REG_UTF8 )
300
301 The /+ modifier works as described above. All other modifiers are
302 ignored.
303
304
305 DATA LINES
306
307 Before each data line is passed to pcre_exec(), leading and trailing
308 whitespace is removed, and it is then scanned for \ escapes. Some of
309 these are pretty esoteric features, intended for checking out some of
310 the more complicated features of PCRE. If you are just testing "ordi-
311 nary" regular expressions, you probably don't need any of these. The
312 following escapes are recognized:
313
314 \a alarm (BEL, \x07)
315 \b backspace (\x08)
316 \e escape (\x27)
317 \f formfeed (\x0c)
318 \n newline (\x0a)
319 \qdd set the PCRE_MATCH_LIMIT limit to dd
320 (any number of digits)
321 \r carriage return (\x0d)
322 \t tab (\x09)
323 \v vertical tab (\x0b)
324 \nnn octal character (up to 3 octal digits)
325 always a byte unless > 255 in UTF-8 mode
326 \xhh hexadecimal byte (up to 2 hex digits)
327 \x{hh...} hexadecimal character, any number of digits
328 in UTF-8 mode
329 \A pass the PCRE_ANCHORED option to pcre_exec()
330 or pcre_dfa_exec()
331 \B pass the PCRE_NOTBOL option to pcre_exec()
332 or pcre_dfa_exec()
333 \Cdd call pcre_copy_substring() for substring dd
334 after a successful match (number less than 32)
335 \Cname call pcre_copy_named_substring() for substring
336 "name" after a successful match (name termin-
337 ated by next non alphanumeric character)
338 \C+ show the current captured substrings at callout
339 time
340 \C- do not supply a callout function
341 \C!n return 1 instead of 0 when callout number n is
342 reached
343 \C!n!m return 1 instead of 0 when callout number n is
344 reached for the nth time
345 \C*n pass the number n (may be negative) as callout
346 data; this is used as the callout return value
347 \D use the pcre_dfa_exec() match function
348 \F only shortest match for pcre_dfa_exec()
349 \Gdd call pcre_get_substring() for substring dd
350 after a successful match (number less than 32)
351 \Gname call pcre_get_named_substring() for substring
352 "name" after a successful match (name termin-
353 ated by next non-alphanumeric character)
354 \L call pcre_get_substringlist() after a
355 successful match
356 \M discover the minimum MATCH_LIMIT and
357 MATCH_LIMIT_RECURSION settings
358 \N pass the PCRE_NOTEMPTY option to pcre_exec()
359 or pcre_dfa_exec(); if used twice, pass the
360 PCRE_NOTEMPTY_ATSTART option
361 \Odd set the size of the output vector passed to
362 pcre_exec() to dd (any number of digits)
363 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
364 or pcre_dfa_exec(); if used twice, pass the
365 PCRE_PARTIAL_HARD option
366 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
367 (any number of digits)
368 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
369 \S output details of memory get/free calls during matching
370 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
371 or pcre_dfa_exec()
372 \Z pass the PCRE_NOTEOL option to pcre_exec()
373 or pcre_dfa_exec()
374 \? pass the PCRE_NO_UTF8_CHECK option to
375 pcre_exec() or pcre_dfa_exec()
376 \>dd start the match at offset dd (optional "-"; then
377 any number of digits); this sets the startoffset
378 argument for pcre_exec() or pcre_dfa_exec()
379 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
380 or pcre_dfa_exec()
381 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
382 or pcre_dfa_exec()
383 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
384 or pcre_dfa_exec()
385 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
386 or pcre_dfa_exec()
387 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
388 or pcre_dfa_exec()
389
390 Note that \xhh always specifies one byte, even in UTF-8 mode; this
391 makes it possible to construct invalid UTF-8 sequences for testing pur-
392 poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
393 UTF-8 mode, generating more than one byte if the value is greater than
394 127. When not in UTF-8 mode, it generates one byte for values less than
395 256, and causes an error for greater values.
396
397 The escapes that specify line ending sequences are literal strings,
398 exactly as shown. No more than one newline setting should be present in
399 any data line.
400
401 A backslash followed by anything else just escapes the anything else.
402 If the very last character is a backslash, it is ignored. This gives a
403 way of passing an empty line as data, since a real empty line termi-
404 nates the data input.
405
406 If \M is present, pcretest calls pcre_exec() several times, with dif-
407 ferent values in the match_limit and match_limit_recursion fields of
408 the pcre_extra data structure, until it finds the minimum numbers for
409 each parameter that allow pcre_exec() to complete. The match_limit num-
410 ber is a measure of the amount of backtracking that takes place, and
411 checking it out can be instructive. For most simple matches, the number
412 is quite small, but for patterns with very large numbers of matching
413 possibilities, it can become large very quickly with increasing length
414 of subject string. The match_limit_recursion number is a measure of how
415 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
416 memory is needed to complete the match attempt.
417
418 When \O is used, the value specified may be higher or lower than the
419 size set by the -O command line option (or defaulted to 45); \O applies
420 only to the call of pcre_exec() for the line in which it appears.
421
422 If the /P modifier was present on the pattern, causing the POSIX wrap-
423 per API to be used, the only option-setting sequences that have any
424 effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
425 REG_NOTEOL, respectively, to be passed to regexec().
426
427 The use of \x{hh...} to represent UTF-8 characters is not dependent on
428 the use of the /8 modifier on the pattern. It is recognized always.
429 There may be any number of hexadecimal digits inside the braces. The
430 result is from one to six bytes, encoded according to the original
431 UTF-8 rules of RFC 2279. This allows for values in the range 0 to
432 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
433 or indeed valid UTF-8 characters according to the later rules in RFC
434 3629.
435
436
437 THE ALTERNATIVE MATCHING FUNCTION
438
439 By default, pcretest uses the standard PCRE matching function,
440 pcre_exec() to match each data line. From release 6.0, PCRE supports an
441 alternative matching function, pcre_dfa_test(), which operates in a
442 different way, and has some restrictions. The differences between the
443 two functions are described in the pcrematching documentation.
444
445 If a data line contains the \D escape sequence, or if the command line
446 contains the -dfa option, the alternative matching function is called.
447 This function finds all possible matches at a given point. If, however,
448 the \F escape sequence is present in the data line, it stops after the
449 first match is found. This is always the shortest possible match.
450
451
452 DEFAULT OUTPUT FROM PCRETEST
453
454 This section describes the output when the normal matching function,
455 pcre_exec(), is being used.
456
457 When a match succeeds, pcretest outputs the list of captured substrings
458 that pcre_exec() returns, starting with number 0 for the string that
459 matched the whole pattern. Otherwise, it outputs "No match" when the
460 return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
461 tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
462 (Note that this is the entire substring that was inspected during the
463 partial match; it may include characters before the actual match start
464 if a lookbehind assertion, \K, \b, or \B was involved.) For any other
465 returns, it outputs the PCRE negative error number. Here is an example
466 of an interactive pcretest run.
467
468 $ pcretest
469 PCRE version 7.0 30-Nov-2006
470
471 re> /^abc(\d+)/
472 data> abc123
473 0: abc123
474 1: 123
475 data> xyz
476 No match
477
478 Note that unset capturing substrings that are not followed by one that
479 is set are not returned by pcre_exec(), and are not shown by pcretest.
480 In the following example, there are two capturing substrings, but when
481 the first data line is matched, the second, unset substring is not
482 shown. An "internal" unset substring is shown as "<unset>", as for the
483 second data line.
484
485 re> /(a)|(b)/
486 data> a
487 0: a
488 1: a
489 data> b
490 0: b
491 1: <unset>
492 2: b
493
494 If the strings contain any non-printing characters, they are output as
495 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
496 the pattern. See below for the definition of non-printing characters.
497 If the pattern has the /+ modifier, the output for substring 0 is fol-
498 lowed by the the rest of the subject string, identified by "0+" like
499 this:
500
501 re> /cat/+
502 data> cataract
503 0: cat
504 0+ aract
505
506 If the pattern has the /g or /G modifier, the results of successive
507 matching attempts are output in sequence, like this:
508
509 re> /\Bi(\w\w)/g
510 data> Mississippi
511 0: iss
512 1: ss
513 0: iss
514 1: ss
515 0: ipp
516 1: pp
517
518 "No match" is output only if the first match attempt fails.
519
520 If any of the sequences \C, \G, or \L are present in a data line that
521 is successfully matched, the substrings extracted by the convenience
522 functions are output with C, G, or L after the string number instead of
523 a colon. This is in addition to the normal full list. The string length
524 (that is, the return from the extraction function) is given in paren-
525 theses after each string for \C and \G.
526
527 Note that whereas patterns can be continued over several lines (a plain
528 ">" prompt is used for continuations), data lines may not. However new-
529 lines can be included in data by means of the \n escape (or \r, \r\n,
530 etc., depending on the newline sequence setting).
531
532
533 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
534
535 When the alternative matching function, pcre_dfa_exec(), is used (by
536 means of the \D escape sequence or the -dfa command line option), the
537 output consists of a list of all the matches that start at the first
538 point in the subject where there is at least one match. For example:
539
540 re> /(tang|tangerine|tan)/
541 data> yellow tangerine\D
542 0: tangerine
543 1: tang
544 2: tan
545
546 (Using the normal matching function on this data finds only "tang".)
547 The longest matching string is always given first (and numbered zero).
548 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
549 lowed by the partially matching substring. (Note that this is the
550 entire substring that was inspected during the partial match; it may
551 include characters before the actual match start if a lookbehind asser-
552 tion, \K, \b, or \B was involved.)
553
554 If /g is present on the pattern, the search for further matches resumes
555 at the end of the longest match. For example:
556
557 re> /(tang|tangerine|tan)/g
558 data> yellow tangerine and tangy sultana\D
559 0: tangerine
560 1: tang
561 2: tan
562 0: tang
563 1: tan
564 0: tan
565
566 Since the matching function does not support substring capture, the
567 escape sequences that are concerned with captured substrings are not
568 relevant.
569
570
571 RESTARTING AFTER A PARTIAL MATCH
572
573 When the alternative matching function has given the PCRE_ERROR_PARTIAL
574 return, indicating that the subject partially matched the pattern, you
575 can restart the match with additional subject data by means of the \R
576 escape sequence. For example:
577
578 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
579 data> 23ja\P\D
580 Partial match: 23ja
581 data> n05\R\D
582 0: n05
583
584 For further information about partial matching, see the pcrepartial
585 documentation.
586
587
588 CALLOUTS
589
590 If the pattern contains any callout requests, pcretest's callout func-
591 tion is called during matching. This works with both matching func-
592 tions. By default, the called function displays the callout number, the
593 start and current positions in the text at the callout time, and the
594 next pattern item to be tested. For example, the output
595
596 --->pqrabcdef
597 0 ^ ^ \d
598
599 indicates that callout number 0 occurred for a match attempt starting
600 at the fourth character of the subject string, when the pointer was at
601 the seventh character of the data, and when the next pattern item was
602 \d. Just one circumflex is output if the start and current positions
603 are the same.
604
605 Callouts numbered 255 are assumed to be automatic callouts, inserted as
606 a result of the /C pattern modifier. In this case, instead of showing
607 the callout number, the offset in the pattern, preceded by a plus, is
608 output. For example:
609
610 re> /\d?[A-E]\*/C
611 data> E*
612 --->E*
613 +0 ^ \d?
614 +3 ^ [A-E]
615 +8 ^^ \*
616 +10 ^ ^
617 0: E*
618
619 The callout function in pcretest returns zero (carry on matching) by
620 default, but you can use a \C item in a data line (as described above)
621 to change this.
622
623 Inserting callouts can be helpful when using pcretest to check compli-
624 cated regular expressions. For further information about callouts, see
625 the pcrecallout documentation.
626
627
628 NON-PRINTING CHARACTERS
629
630 When pcretest is outputting text in the compiled version of a pattern,
631 bytes other than 32-126 are always treated as non-printing characters
632 are are therefore shown as hex escapes.
633
634 When pcretest 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
636 set for the pattern (using the /L modifier). In this case, the
637 isprint() function to distinguish printing and non-printing characters.
638
639
640 SAVING AND RELOADING COMPILED PATTERNS
641
642 The facilities described in this section are not available when the
643 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
644 ifier is specified.
645
646 When the POSIX interface is not in use, you can cause pcretest to write
647 a compiled pattern to a file, by following the modifiers with > and a
648 file name. For example:
649
650 /pattern/im >/some/file
651
652 See the pcreprecompile documentation for a discussion about saving and
653 re-using compiled patterns.
654
655 The data that is written is binary. The first eight bytes are the
656 length of the compiled pattern data followed by the length of the
657 optional study data, each written as four bytes in big-endian order
658 (most significant byte first). If there is no study data (either the
659 pattern was not studied, or studying did not return any data), the sec-
660 ond length is zero. The lengths are followed by an exact copy of the
661 compiled pattern. If there is additional study data, this follows imme-
662 diately after the compiled pattern. After writing the file, pcretest
663 expects to read a new pattern.
664
665 A saved pattern can be reloaded into pcretest by specifing < and a file
666 name instead of a pattern. The name of the file must not contain a <
667 character, as otherwise pcretest will interpret the line as a pattern
668 delimited by < characters. For example:
669
670 re> </some/file
671 Compiled regex loaded from /some/file
672 No study data
673
674 When the pattern has been loaded, pcretest proceeds to read data lines
675 in the usual way.
676
677 You can copy a file written by pcretest to a different host and reload
678 it there, even if the new host has opposite endianness to the one on
679 which the pattern was compiled. For example, you can compile on an i86
680 machine and run on a SPARC machine.
681
682 File names for saving and reloading can be absolute or relative, but
683 note that the shell facility of expanding a file name that starts with
684 a tilde (~) is not available.
685
686 The ability to save and reload files in pcretest is intended for test-
687 ing and experimentation. It is not intended for production use because
688 only a single pattern can be written to a file. Furthermore, there is
689 no facility for supplying custom character tables for use with a
690 reloaded pattern. If the original pattern was compiled with custom
691 tables, an attempt to match a subject string using a reloaded pattern
692 is likely to cause pcretest to crash. Finally, if you attempt to load
693 a file that is not in the correct format, the result is undefined.
694
695
696 SEE ALSO
697
698 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
699 pcrepattern(3), pcreprecompile(3).
700
701
702 AUTHOR
703
704 Philip Hazel
705 University Computing Service
706 Cambridge CB2 3QH, England.
707
708
709 REVISION
710
711 Last updated: 07 November 2010
712 Copyright (c) 1997-2010 University of Cambridge.

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