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Mon Apr 16 13:25:10 2007 UTC (14 years, 1 month ago) by ph10
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Fix bugs in the documentation.
3 pcretest - a program for testing Perl-compatible regular expressions.
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 .
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 .
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 .
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
168 \fB/<cr>\fP PCRE_NEWLINE_CR
169 \fB/<lf>\fP PCRE_NEWLINE_LF
170 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
171 \fB/<any>\fP PCRE_NEWLINE_ANY
172 .sp
173 Those specifying line ending sequencess are literal strings as shown. This
174 example sets multiline matching with CRLF as the line ending sequence:
175 .sp
176 /^abc/m<crlf>
177 .sp
178 Details of the meanings of these PCRE options are given in the
179 .\" HREF
180 \fBpcreapi\fP
181 .\"
182 documentation.
183 .
184 .
185 .SS "Finding all matches in a string"
186 .rs
187 .sp
188 Searching for all possible matches within each subject string can be requested
189 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
190 again to search the remainder of the subject string. The difference between
191 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
192 \fBpcre_exec()\fP to start searching at a new point within the entire string
193 (which is in effect what Perl does), whereas the latter passes over a shortened
194 substring. This makes a difference to the matching process if the pattern
195 begins with a lookbehind assertion (including \eb or \eB).
196 .P
197 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
198 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
199 flags set in order to search for another, non-empty, match at the same point.
200 If this second match fails, the start offset is advanced by one, and the normal
201 match is retried. This imitates the way Perl handles such cases when using the
202 \fB/g\fP modifier or the \fBsplit()\fP function.
203 .
204 .
205 .SS "Other modifiers"
206 .rs
207 .sp
208 There are yet more modifiers for controlling the way \fBpcretest\fP
209 operates.
210 .P
211 The \fB/+\fP modifier requests that as well as outputting the substring that
212 matched the entire pattern, pcretest should in addition output the remainder of
213 the subject string. This is useful for tests where the subject contains
214 multiple copies of the same substring.
215 .P
216 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
217 output a representation of the compiled byte code after compilation. Normally
218 this information contains length and offset values; however, if \fB/Z\fP is
219 also present, this data is replaced by spaces. This is a special feature for
220 use in the automatic test scripts; it ensures that the same output is generated
221 for different internal link sizes.
222 .P
223 The \fB/L\fP modifier must be followed directly by the name of a locale, for
224 example,
225 .sp
226 /pattern/Lfr_FR
227 .sp
228 For this reason, it must be the last modifier. The given locale is set,
229 \fBpcre_maketables()\fP is called to build a set of character tables for the
230 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
231 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
232 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
233 .P
234 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
235 compiled pattern (whether it is anchored, has a fixed first character, and
236 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
237 pattern. If the pattern is studied, the results of that are also output.
238 .P
239 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
240 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
241 .P
242 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
243 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
244 facility is for testing the feature in PCRE that allows it to execute patterns
245 that were compiled on a host with a different endianness. This feature is not
246 available when the POSIX interface to PCRE is being used, that is, when the
247 \fB/P\fP pattern modifier is specified. See also the section about saving and
248 reloading compiled patterns below.
249 .P
250 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
251 expression has been compiled, and the results used when the expression is
252 matched.
253 .P
254 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
255 pattern to be output.
256 .P
257 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
258 API rather than its native API. When this is done, all other modifiers except
259 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
260 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
261 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
262 .P
263 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
264 option set. This turns on support for UTF-8 character handling in PCRE,
265 provided that it was compiled with this support enabled. This modifier also
266 causes any non-printing characters in output strings to be printed using the
267 \ex{hh...} notation if they are valid UTF-8 sequences.
268 .P
269 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
270 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
271 checking of the string for UTF-8 validity.
272 .
273 .
275 .rs
276 .sp
277 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
278 whitespace is removed, and it is then scanned for \e escapes. Some of these are
279 pretty esoteric features, intended for checking out some of the more
280 complicated features of PCRE. If you are just testing "ordinary" regular
281 expressions, you probably don't need any of these. The following escapes are
282 recognized:
283 .sp
284 \ea alarm (BEL, \ex07)
285 \eb backspace (\ex08)
286 \ee escape (\ex27)
287 \ef formfeed (\ex0c)
288 \en newline (\ex0a)
289 .\" JOIN
290 \eqdd set the PCRE_MATCH_LIMIT limit to dd
291 (any number of digits)
292 \er carriage return (\ex0d)
293 \et tab (\ex09)
294 \ev vertical tab (\ex0b)
295 \ennn octal character (up to 3 octal digits)
296 \exhh hexadecimal character (up to 2 hex digits)
297 .\" JOIN
298 \ex{hh...} hexadecimal character, any number of digits
299 in UTF-8 mode
300 .\" JOIN
301 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
302 or \fBpcre_dfa_exec()\fP
303 .\" JOIN
304 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
305 or \fBpcre_dfa_exec()\fP
306 .\" JOIN
307 \eCdd call pcre_copy_substring() for substring dd
308 after a successful match (number less than 32)
309 .\" JOIN
310 \eCname call pcre_copy_named_substring() for substring
311 "name" after a successful match (name termin-
312 ated by next non alphanumeric character)
313 .\" JOIN
314 \eC+ show the current captured substrings at callout
315 time
316 \eC- do not supply a callout function
317 .\" JOIN
318 \eC!n return 1 instead of 0 when callout number n is
319 reached
320 .\" JOIN
321 \eC!n!m return 1 instead of 0 when callout number n is
322 reached for the nth time
323 .\" JOIN
324 \eC*n pass the number n (may be negative) as callout
325 data; this is used as the callout return value
326 \eD use the \fBpcre_dfa_exec()\fP match function
327 \eF only shortest match for \fBpcre_dfa_exec()\fP
328 .\" JOIN
329 \eGdd call pcre_get_substring() for substring dd
330 after a successful match (number less than 32)
331 .\" JOIN
332 \eGname call pcre_get_named_substring() for substring
333 "name" after a successful match (name termin-
334 ated by next non-alphanumeric character)
335 .\" JOIN
336 \eL call pcre_get_substringlist() after a
337 successful match
338 .\" JOIN
339 \eM discover the minimum MATCH_LIMIT and
341 .\" JOIN
342 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
343 or \fBpcre_dfa_exec()\fP
344 .\" JOIN
345 \eOdd set the size of the output vector passed to
346 \fBpcre_exec()\fP to dd (any number of digits)
347 .\" JOIN
348 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
349 or \fBpcre_dfa_exec()\fP
350 .\" JOIN
351 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
352 (any number of digits)
353 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
354 \eS output details of memory get/free calls during matching
355 .\" JOIN
356 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
357 or \fBpcre_dfa_exec()\fP
358 .\" JOIN
359 \e? pass the PCRE_NO_UTF8_CHECK option to
360 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
361 \e>dd start the match at offset dd (any number of digits);
362 .\" JOIN
363 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
364 or \fBpcre_dfa_exec()\fP
365 .\" JOIN
366 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
367 or \fBpcre_dfa_exec()\fP
368 .\" JOIN
369 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
370 or \fBpcre_dfa_exec()\fP
371 .\" JOIN
372 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
373 or \fBpcre_dfa_exec()\fP
374 .\" JOIN
375 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
376 or \fBpcre_dfa_exec()\fP
377 .sp
378 The escapes that specify line ending sequences are literal strings, exactly as
379 shown. No more than one newline setting should be present in any data line.
380 .P
381 A backslash followed by anything else just escapes the anything else. If
382 the very last character is a backslash, it is ignored. This gives a way of
383 passing an empty line as data, since a real empty line terminates the data
384 input.
385 .P
386 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
387 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
388 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
389 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
390 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
391 place, and checking it out can be instructive. For most simple matches, the
392 number is quite small, but for patterns with very large numbers of matching
393 possibilities, it can become large very quickly with increasing length of
394 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
395 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
396 to complete the match attempt.
397 .P
398 When \eO is used, the value specified may be higher or lower than the size set
399 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
400 the call of \fBpcre_exec()\fP for the line in which it appears.
401 .P
402 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
403 API to be used, the only option-setting sequences that have any effect are \eB
404 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
405 \fBregexec()\fP.
406 .P
407 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
408 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
409 any number of hexadecimal digits inside the braces. The result is from one to
410 six bytes, encoded according to the UTF-8 rules.
411 .
412 .
414 .rs
415 .sp
416 By default, \fBpcretest\fP uses the standard PCRE matching function,
417 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
418 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
419 different way, and has some restrictions. The differences between the two
420 functions are described in the
421 .\" HREF
422 \fBpcrematching\fP
423 .\"
424 documentation.
425 .P
426 If a data line contains the \eD escape sequence, or if the command line
427 contains the \fB-dfa\fP option, the alternative matching function is called.
428 This function finds all possible matches at a given point. If, however, the \eF
429 escape sequence is present in the data line, it stops after the first match is
430 found. This is always the shortest possible match.
431 .
432 .
434 .rs
435 .sp
436 This section describes the output when the normal matching function,
437 \fBpcre_exec()\fP, is being used.
438 .P
439 When a match succeeds, pcretest outputs the list of captured substrings that
440 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
441 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
442 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
443 respectively, and otherwise the PCRE negative error number. Here is an example
444 of an interactive \fBpcretest\fP run.
445 .sp
446 $ pcretest
447 PCRE version 7.0 30-Nov-2006
448 .sp
449 re> /^abc(\ed+)/
450 data> abc123
451 0: abc123
452 1: 123
453 data> xyz
454 No match
455 .sp
456 If the strings contain any non-printing characters, they are output as \e0x
457 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
458 pattern. See below for the definition of non-printing characters. If the
459 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
460 the the rest of the subject string, identified by "0+" like this:
461 .sp
462 re> /cat/+
463 data> cataract
464 0: cat
465 0+ aract
466 .sp
467 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
468 matching attempts are output in sequence, like this:
469 .sp
470 re> /\eBi(\ew\ew)/g
471 data> Mississippi
472 0: iss
473 1: ss
474 0: iss
475 1: ss
476 0: ipp
477 1: pp
478 .sp
479 "No match" is output only if the first match attempt fails.
480 .P
481 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
482 data line that is successfully matched, the substrings extracted by the
483 convenience functions are output with C, G, or L after the string number
484 instead of a colon. This is in addition to the normal full list. The string
485 length (that is, the return from the extraction function) is given in
486 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
487 .P
488 Note that whereas patterns can be continued over several lines (a plain ">"
489 prompt is used for continuations), data lines may not. However newlines can be
490 included in data by means of the \en escape (or \er, \er\en, etc., depending on
491 the newline sequence setting).
492 .
493 .
494 .
496 .rs
497 .sp
498 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
499 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
500 output consists of a list of all the matches that start at the first point in
501 the subject where there is at least one match. For example:
502 .sp
503 re> /(tang|tangerine|tan)/
504 data> yellow tangerine\eD
505 0: tangerine
506 1: tang
507 2: tan
508 .sp
509 (Using the normal matching function on this data finds only "tang".) The
510 longest matching string is always given first (and numbered zero).
511 .P
512 If \fB/g\fP is present on the pattern, the search for further matches resumes
513 at the end of the longest match. For example:
514 .sp
515 re> /(tang|tangerine|tan)/g
516 data> yellow tangerine and tangy sultana\eD
517 0: tangerine
518 1: tang
519 2: tan
520 0: tang
521 1: tan
522 0: tan
523 .sp
524 Since the matching function does not support substring capture, the escape
525 sequences that are concerned with captured substrings are not relevant.
526 .
527 .
529 .rs
530 .sp
531 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
532 indicating that the subject partially matched the pattern, you can restart the
533 match with additional subject data by means of the \eR escape sequence. For
534 example:
535 .sp
536 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
537 data> 23ja\eP\eD
538 Partial match: 23ja
539 data> n05\eR\eD
540 0: n05
541 .sp
542 For further information about partial matching, see the
543 .\" HREF
544 \fBpcrepartial\fP
545 .\"
546 documentation.
547 .
548 .
550 .rs
551 .sp
552 If the pattern contains any callout requests, \fBpcretest\fP's callout function
553 is called during matching. This works with both matching functions. By default,
554 the called function displays the callout number, the start and current
555 positions in the text at the callout time, and the next pattern item to be
556 tested. For example, the output
557 .sp
558 --->pqrabcdef
559 0 ^ ^ \ed
560 .sp
561 indicates that callout number 0 occurred for a match attempt starting at the
562 fourth character of the subject string, when the pointer was at the seventh
563 character of the data, and when the next pattern item was \ed. Just one
564 circumflex is output if the start and current positions are the same.
565 .P
566 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
567 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
568 callout number, the offset in the pattern, preceded by a plus, is output. For
569 example:
570 .sp
571 re> /\ed?[A-E]\e*/C
572 data> E*
573 --->E*
574 +0 ^ \ed?
575 +3 ^ [A-E]
576 +8 ^^ \e*
577 +10 ^ ^
578 0: E*
579 .sp
580 The callout function in \fBpcretest\fP returns zero (carry on matching) by
581 default, but you can use a \eC item in a data line (as described above) to
582 change this.
583 .P
584 Inserting callouts can be helpful when using \fBpcretest\fP to check
585 complicated regular expressions. For further information about callouts, see
586 the
587 .\" HREF
588 \fBpcrecallout\fP
589 .\"
590 documentation.
591 .
592 .
593 .
595 .rs
596 .sp
597 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
598 bytes other than 32-126 are always treated as non-printing characters are are
599 therefore shown as hex escapes.
600 .P
601 When \fBpcretest\fP is outputting text that is a matched part of a subject
602 string, it behaves in the same way, unless a different locale has been set for
603 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
604 function to distinguish printing and non-printing characters.
605 .
606 .
607 .
609 .rs
610 .sp
611 The facilities described in this section are not available when the POSIX
612 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
613 specified.
614 .P
615 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
616 compiled pattern to a file, by following the modifiers with > and a file name.
617 For example:
618 .sp
619 /pattern/im >/some/file
620 .sp
621 See the
622 .\" HREF
623 \fBpcreprecompile\fP
624 .\"
625 documentation for a discussion about saving and re-using compiled patterns.
626 .P
627 The data that is written is binary. The first eight bytes are the length of the
628 compiled pattern data followed by the length of the optional study data, each
629 written as four bytes in big-endian order (most significant byte first). If
630 there is no study data (either the pattern was not studied, or studying did not
631 return any data), the second length is zero. The lengths are followed by an
632 exact copy of the compiled pattern. If there is additional study data, this
633 follows immediately after the compiled pattern. After writing the file,
634 \fBpcretest\fP expects to read a new pattern.
635 .P
636 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
637 name instead of a pattern. The name of the file must not contain a < character,
638 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
639 characters.
640 For example:
641 .sp
642 re> </some/file
643 Compiled regex loaded from /some/file
644 No study data
645 .sp
646 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
647 the usual way.
648 .P
649 You can copy a file written by \fBpcretest\fP to a different host and reload it
650 there, even if the new host has opposite endianness to the one on which the
651 pattern was compiled. For example, you can compile on an i86 machine and run on
652 a SPARC machine.
653 .P
654 File names for saving and reloading can be absolute or relative, but note that
655 the shell facility of expanding a file name that starts with a tilde (~) is not
656 available.
657 .P
658 The ability to save and reload files in \fBpcretest\fP is intended for testing
659 and experimentation. It is not intended for production use because only a
660 single pattern can be written to a file. Furthermore, there is no facility for
661 supplying custom character tables for use with a reloaded pattern. If the
662 original pattern was compiled with custom tables, an attempt to match a subject
663 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
664 Finally, if you attempt to load a file that is not in the correct format, the
665 result is undefined.
666 .
667 .
668 .SH "SEE ALSO"
669 .rs
670 .sp
671 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
672 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
673 .
674 .
676 .rs
677 .sp
678 .nf
679 Philip Hazel
680 University Computing Service
681 Cambridge CB2 3QH, England.
682 .fi
683 .
684 .
686 .rs
687 .sp
688 .nf
689 Last updated: 06 March 2007
690 Copyright (c) 1997-2007 University of Cambridge.
691 .fi


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