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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-C\fP
28 Output the version number of the PCRE library, and all available information
29 about the optional features that are included, and then exit.
30 .TP 10
31 \fB-d\fP
32 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
33 form is output after compilation.
34 .TP 10
35 \fB-dfa\fP
36 Behave as if each data line contains the \eD escape sequence; this causes the
37 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
38 standard \fBpcre_exec()\fP function (more detail is given below).
39 .TP 10
40 \fB-i\fP
41 Behave as if each regex has the \fB/I\fP modifier; information about the
42 compiled pattern is given after compilation.
43 .TP 10
44 \fB-m\fP
45 Output the size of each compiled pattern after it has been compiled. This is
46 equivalent to adding \fB/M\fP to each regular expression. For compatibility
47 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
48 .TP 10
49 \fB-o\fP \fIosize\fP
50 Set the number of elements in the output vector that is used when calling
51 \fBpcre_exec()\fP to be \fIosize\fP. The default value is 45, which is enough
52 for 14 capturing subexpressions. The vector size can be changed for individual
53 matching calls by including \eO in the data line (see below).
54 .TP 10
55 \fB-p\fP
56 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
57 used to call PCRE. None of the other options has any effect when \fB-p\fP is
58 set.
59 .TP 10
60 \fB-q\fP
61 Do not output the version number of \fBpcretest\fP at the start of execution.
62 .TP 10
63 \fB-S\fP \fIsize\fP
64 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
65 megabytes.
66 .TP 10
67 \fB-t\fP
68 Run each compile, study, and match many times with a timer, and output
69 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
70 \fB-t\fP, because you will then get the size output a zillion times, and the
71 timing will be distorted.
72 .
73 .
74 .SH DESCRIPTION
75 .rs
76 .sp
77 If \fBpcretest\fP is given two filename arguments, it reads from the first and
78 writes to the second. If it is given only one filename argument, it reads from
79 that file and writes to stdout. Otherwise, it reads from stdin and writes to
80 stdout, and prompts for each line of input, using "re>" to prompt for regular
81 expressions, and "data>" to prompt for data lines.
82 .P
83 The program handles any number of sets of input on a single input file. Each
84 set starts with a regular expression, and continues with any number of data
85 lines to be matched against the pattern.
86 .P
87 Each data line is matched separately and independently. If you want to do
88 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
89 depending on the newline setting) in a single line of input to encode the
90 newline characters. There is no limit on the length of data lines; the input
91 buffer is automatically extended if it is too small.
92 .P
93 An empty line signals the end of the data lines, at which point a new regular
94 expression is read. The regular expressions are given enclosed in any
95 non-alphanumeric delimiters other than backslash, for example:
96 .sp
97 /(a|bc)x+yz/
98 .sp
99 White space before the initial delimiter is ignored. A regular expression may
100 be continued over several input lines, in which case the newline characters are
101 included within it. It is possible to include the delimiter within the pattern
102 by escaping it, for example
103 .sp
104 /abc\e/def/
105 .sp
106 If you do so, the escape and the delimiter form part of the pattern, but since
107 delimiters are always non-alphanumeric, this does not affect its interpretation.
108 If the terminating delimiter is immediately followed by a backslash, for
109 example,
110 .sp
111 /abc/\e
112 .sp
113 then a backslash is added to the end of the pattern. This is done to provide a
114 way of testing the error condition that arises if a pattern finishes with a
115 backslash, because
116 .sp
117 /abc\e/
118 .sp
119 is interpreted as the first line of a pattern that starts with "abc/", causing
120 pcretest to read the next line as a continuation of the regular expression.
121 .
122 .
123 .SH "PATTERN MODIFIERS"
124 .rs
125 .sp
126 A pattern may be followed by any number of modifiers, which are mostly single
127 characters. Following Perl usage, these are referred to below as, for example,
128 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
129 always be a slash, and no slash is used when writing modifiers. Whitespace may
130 appear between the final pattern delimiter and the first modifier, and between
131 the modifiers themselves.
132 .P
133 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
134 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
135 \fBpcre_compile()\fP is called. These four modifier letters have the same
136 effect as they do in Perl. For example:
137 .sp
138 /caseless/i
139 .sp
140 The following table shows additional modifiers for setting PCRE options that do
141 not correspond to anything in Perl:
142 .sp
143 \fB/A\fP PCRE_ANCHORED
144 \fB/C\fP PCRE_AUTO_CALLOUT
145 \fB/E\fP PCRE_DOLLAR_ENDONLY
146 \fB/f\fP PCRE_FIRSTLINE
147 \fB/J\fP PCRE_DUPNAMES
148 \fB/N\fP PCRE_NO_AUTO_CAPTURE
149 \fB/U\fP PCRE_UNGREEDY
150 \fB/X\fP PCRE_EXTRA
151 \fB/<cr>\fP PCRE_NEWLINE_CR
152 \fB/<lf>\fP PCRE_NEWLINE_LF
153 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
154 .sp
155 Those specifying line endings are literal strings as shown. Details of the
156 meanings of these PCRE options are given in the
157 .\" HREF
158 \fBpcreapi\fP
159 .\"
160 documentation.
161 .
162 .
163 .SS "Finding all matches in a string"
164 .rs
165 .sp
166 Searching for all possible matches within each subject string can be requested
167 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
168 again to search the remainder of the subject string. The difference between
169 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
170 \fBpcre_exec()\fP to start searching at a new point within the entire string
171 (which is in effect what Perl does), whereas the latter passes over a shortened
172 substring. This makes a difference to the matching process if the pattern
173 begins with a lookbehind assertion (including \eb or \eB).
174 .P
175 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
176 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
177 flags set in order to search for another, non-empty, match at the same point.
178 If this second match fails, the start offset is advanced by one, and the normal
179 match is retried. This imitates the way Perl handles such cases when using the
180 \fB/g\fP modifier or the \fBsplit()\fP function.
181 .
182 .
183 .SS "Other modifiers"
184 .rs
185 .sp
186 There are yet more modifiers for controlling the way \fBpcretest\fP
187 operates.
188 .P
189 The \fB/+\fP modifier requests that as well as outputting the substring that
190 matched the entire pattern, pcretest should in addition output the remainder of
191 the subject string. This is useful for tests where the subject contains
192 multiple copies of the same substring.
193 .P
194 The \fB/L\fP modifier must be followed directly by the name of a locale, for
195 example,
196 .sp
197 /pattern/Lfr_FR
198 .sp
199 For this reason, it must be the last modifier. The given locale is set,
200 \fBpcre_maketables()\fP is called to build a set of character tables for the
201 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
202 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
203 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
204 .P
205 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
206 compiled pattern (whether it is anchored, has a fixed first character, and
207 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
208 pattern. If the pattern is studied, the results of that are also output.
209 .P
210 The \fB/D\fP modifier is a PCRE debugging feature, which also assumes \fB/I\fP.
211 It causes the internal form of compiled regular expressions to be output after
212 compilation. If the pattern was studied, the information returned is also
213 output.
214 .P
215 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
216 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
217 facility is for testing the feature in PCRE that allows it to execute patterns
218 that were compiled on a host with a different endianness. This feature is not
219 available when the POSIX interface to PCRE is being used, that is, when the
220 \fB/P\fP pattern modifier is specified. See also the section about saving and
221 reloading compiled patterns below.
222 .P
223 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
224 expression has been compiled, and the results used when the expression is
225 matched.
226 .P
227 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
228 pattern to be output.
229 .P
230 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
231 API rather than its native API. When this is done, all other modifiers except
232 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
233 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
234 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
235 .P
236 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
237 option set. This turns on support for UTF-8 character handling in PCRE,
238 provided that it was compiled with this support enabled. This modifier also
239 causes any non-printing characters in output strings to be printed using the
240 \ex{hh...} notation if they are valid UTF-8 sequences.
241 .P
242 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
243 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
244 checking of the string for UTF-8 validity.
245 .
246 .
247 .SH "DATA LINES"
248 .rs
249 .sp
250 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
251 whitespace is removed, and it is then scanned for \e escapes. Some of these are
252 pretty esoteric features, intended for checking out some of the more
253 complicated features of PCRE. If you are just testing "ordinary" regular
254 expressions, you probably don't need any of these. The following escapes are
255 recognized:
256 .sp
257 \ea alarm (= BEL)
258 \eb backspace
259 \ee escape
260 \ef formfeed
261 \en newline
262 .\" JOIN
263 \eqdd set the PCRE_MATCH_LIMIT limit to dd
264 (any number of digits)
265 \er carriage return
266 \et tab
267 \ev vertical tab
268 \ennn octal character (up to 3 octal digits)
269 \exhh hexadecimal character (up to 2 hex digits)
270 .\" JOIN
271 \ex{hh...} hexadecimal character, any number of digits
272 in UTF-8 mode
273 .\" JOIN
274 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
275 or \fBpcre_dfa_exec()\fP
276 .\" JOIN
277 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
278 or \fBpcre_dfa_exec()\fP
279 .\" JOIN
280 \eCdd call pcre_copy_substring() for substring dd
281 after a successful match (number less than 32)
282 .\" JOIN
283 \eCname call pcre_copy_named_substring() for substring
284 "name" after a successful match (name termin-
285 ated by next non alphanumeric character)
286 .\" JOIN
287 \eC+ show the current captured substrings at callout
288 time
289 \eC- do not supply a callout function
290 .\" JOIN
291 \eC!n return 1 instead of 0 when callout number n is
292 reached
293 .\" JOIN
294 \eC!n!m return 1 instead of 0 when callout number n is
295 reached for the nth time
296 .\" JOIN
297 \eC*n pass the number n (may be negative) as callout
298 data; this is used as the callout return value
299 \eD use the \fBpcre_dfa_exec()\fP match function
300 \eF only shortest match for \fBpcre_dfa_exec()\fP
301 .\" JOIN
302 \eGdd call pcre_get_substring() for substring dd
303 after a successful match (number less than 32)
304 .\" JOIN
305 \eGname call pcre_get_named_substring() for substring
306 "name" after a successful match (name termin-
307 ated by next non-alphanumeric character)
308 .\" JOIN
309 \eL call pcre_get_substringlist() after a
310 successful match
311 .\" JOIN
312 \eM discover the minimum MATCH_LIMIT and
313 MATCH_LIMIT_RECURSION settings
314 .\" JOIN
315 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
316 or \fBpcre_dfa_exec()\fP
317 .\" JOIN
318 \eOdd set the size of the output vector passed to
319 \fBpcre_exec()\fP to dd (any number of digits)
320 .\" JOIN
321 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
322 or \fBpcre_dfa_exec()\fP
323 .\" JOIN
324 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
325 (any number of digits)
326 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
327 \eS output details of memory get/free calls during matching
328 .\" JOIN
329 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
330 or \fBpcre_dfa_exec()\fP
331 .\" JOIN
332 \e? pass the PCRE_NO_UTF8_CHECK option to
333 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
334 \e>dd start the match at offset dd (any number of digits);
335 .\" JOIN
336 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
337 or \fBpcre_dfa_exec()\fP
338 .\" JOIN
339 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
340 or \fBpcre_dfa_exec()\fP
341 .\" JOIN
342 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
343 or \fBpcre_dfa_exec()\fP
344 .\" JOIN
345 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
346 or \fBpcre_dfa_exec()\fP
347 .sp
348 The escapes that specify line endings are literal strings, exactly as shown.
349 A backslash followed by anything else just escapes the anything else. If the
350 very last character is a backslash, it is ignored. This gives a way of passing
351 an empty line as data, since a real empty line terminates the data input.
352 .P
353 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
354 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
355 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
356 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
357 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
358 place, and checking it out can be instructive. For most simple matches, the
359 number is quite small, but for patterns with very large numbers of matching
360 possibilities, it can become large very quickly with increasing length of
361 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
362 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
363 to complete the match attempt.
364 .P
365 When \eO is used, the value specified may be higher or lower than the size set
366 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
367 the call of \fBpcre_exec()\fP for the line in which it appears.
368 .P
369 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
370 API to be used, the only option-setting sequences that have any effect are \eB
371 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
372 \fBregexec()\fP.
373 .P
374 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
375 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
376 any number of hexadecimal digits inside the braces. The result is from one to
377 six bytes, encoded according to the UTF-8 rules.
378 .
379 .
380 .SH "THE ALTERNATIVE MATCHING FUNCTION"
381 .rs
382 .sp
383 By default, \fBpcretest\fP uses the standard PCRE matching function,
384 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
385 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
386 different way, and has some restrictions. The differences between the two
387 functions are described in the
388 .\" HREF
389 \fBpcrematching\fP
390 .\"
391 documentation.
392 .P
393 If a data line contains the \eD escape sequence, or if the command line
394 contains the \fB-dfa\fP option, the alternative matching function is called.
395 This function finds all possible matches at a given point. If, however, the \eF
396 escape sequence is present in the data line, it stops after the first match is
397 found. This is always the shortest possible match.
398 .
399 .
400 .SH "DEFAULT OUTPUT FROM PCRETEST"
401 .rs
402 .sp
403 This section describes the output when the normal matching function,
404 \fBpcre_exec()\fP, is being used.
405 .P
406 When a match succeeds, pcretest outputs the list of captured substrings that
407 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
408 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
409 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
410 respectively, and otherwise the PCRE negative error number. Here is an example
411 of an interactive \fBpcretest\fP run.
412 .sp
413 $ pcretest
414 PCRE version 5.00 07-Sep-2004
415 .sp
416 re> /^abc(\ed+)/
417 data> abc123
418 0: abc123
419 1: 123
420 data> xyz
421 No match
422 .sp
423 If the strings contain any non-printing characters, they are output as \e0x
424 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
425 pattern. If the pattern has the \fB/+\fP modifier, the output for substring 0
426 is followed by the the rest of the subject string, identified by "0+" like
427 this:
428 .sp
429 re> /cat/+
430 data> cataract
431 0: cat
432 0+ aract
433 .sp
434 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
435 matching attempts are output in sequence, like this:
436 .sp
437 re> /\eBi(\ew\ew)/g
438 data> Mississippi
439 0: iss
440 1: ss
441 0: iss
442 1: ss
443 0: ipp
444 1: pp
445 .sp
446 "No match" is output only if the first match attempt fails.
447 .P
448 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
449 data line that is successfully matched, the substrings extracted by the
450 convenience functions are output with C, G, or L after the string number
451 instead of a colon. This is in addition to the normal full list. The string
452 length (that is, the return from the extraction function) is given in
453 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
454 .P
455 Note that while patterns can be continued over several lines (a plain ">"
456 prompt is used for continuations), data lines may not. However newlines can be
457 included in data by means of the \en escape (or \er or \er\en for those newline
458 settings).
459 .
460 .
461 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
462 .rs
463 .sp
464 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
465 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
466 output consists of a list of all the matches that start at the first point in
467 the subject where there is at least one match. For example:
468 .sp
469 re> /(tang|tangerine|tan)/
470 data> yellow tangerine\eD
471 0: tangerine
472 1: tang
473 2: tan
474 .sp
475 (Using the normal matching function on this data finds only "tang".) The
476 longest matching string is always given first (and numbered zero).
477 .P
478 If \fB/g\P is present on the pattern, the search for further matches resumes
479 at the end of the longest match. For example:
480 .sp
481 re> /(tang|tangerine|tan)/g
482 data> yellow tangerine and tangy sultana\eD
483 0: tangerine
484 1: tang
485 2: tan
486 0: tang
487 1: tan
488 0: tan
489 .sp
490 Since the matching function does not support substring capture, the escape
491 sequences that are concerned with captured substrings are not relevant.
492 .
493 .
494 .SH "RESTARTING AFTER A PARTIAL MATCH"
495 .rs
496 .sp
497 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
498 indicating that the subject partially matched the pattern, you can restart the
499 match with additional subject data by means of the \eR escape sequence. For
500 example:
501 .sp
502 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
503 data> 23ja\eP\eD
504 Partial match: 23ja
505 data> n05\eR\eD
506 0: n05
507 .sp
508 For further information about partial matching, see the
509 .\" HREF
510 \fBpcrepartial\fP
511 .\"
512 documentation.
513 .
514 .
515 .SH CALLOUTS
516 .rs
517 .sp
518 If the pattern contains any callout requests, \fBpcretest\fP's callout function
519 is called during matching. This works with both matching functions. By default,
520 the called function displays the callout number, the start and current
521 positions in the text at the callout time, and the next pattern item to be
522 tested. For example, the output
523 .sp
524 --->pqrabcdef
525 0 ^ ^ \ed
526 .sp
527 indicates that callout number 0 occurred for a match attempt starting at the
528 fourth character of the subject string, when the pointer was at the seventh
529 character of the data, and when the next pattern item was \ed. Just one
530 circumflex is output if the start and current positions are the same.
531 .P
532 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
533 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
534 callout number, the offset in the pattern, preceded by a plus, is output. For
535 example:
536 .sp
537 re> /\ed?[A-E]\e*/C
538 data> E*
539 --->E*
540 +0 ^ \ed?
541 +3 ^ [A-E]
542 +8 ^^ \e*
543 +10 ^ ^
544 0: E*
545 .sp
546 The callout function in \fBpcretest\fP returns zero (carry on matching) by
547 default, but you can use a \eC item in a data line (as described above) to
548 change this.
549 .P
550 Inserting callouts can be helpful when using \fBpcretest\fP to check
551 complicated regular expressions. For further information about callouts, see
552 the
553 .\" HREF
554 \fBpcrecallout\fP
555 .\"
556 documentation.
557 .
558 .
559 .SH "SAVING AND RELOADING COMPILED PATTERNS"
560 .rs
561 .sp
562 The facilities described in this section are not available when the POSIX
563 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
564 specified.
565 .P
566 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
567 compiled pattern to a file, by following the modifiers with > and a file name.
568 For example:
569 .sp
570 /pattern/im >/some/file
571 .sp
572 See the
573 .\" HREF
574 \fBpcreprecompile\fP
575 .\"
576 documentation for a discussion about saving and re-using compiled patterns.
577 .P
578 The data that is written is binary. The first eight bytes are the length of the
579 compiled pattern data followed by the length of the optional study data, each
580 written as four bytes in big-endian order (most significant byte first). If
581 there is no study data (either the pattern was not studied, or studying did not
582 return any data), the second length is zero. The lengths are followed by an
583 exact copy of the compiled pattern. If there is additional study data, this
584 follows immediately after the compiled pattern. After writing the file,
585 \fBpcretest\fP expects to read a new pattern.
586 .P
587 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
588 name instead of a pattern. The name of the file must not contain a < character,
589 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
590 characters.
591 For example:
592 .sp
593 re> </some/file
594 Compiled regex loaded from /some/file
595 No study data
596 .sp
597 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
598 the usual way.
599 .P
600 You can copy a file written by \fBpcretest\fP to a different host and reload it
601 there, even if the new host has opposite endianness to the one on which the
602 pattern was compiled. For example, you can compile on an i86 machine and run on
603 a SPARC machine.
604 .P
605 File names for saving and reloading can be absolute or relative, but note that
606 the shell facility of expanding a file name that starts with a tilde (~) is not
607 available.
608 .P
609 The ability to save and reload files in \fBpcretest\fP is intended for testing
610 and experimentation. It is not intended for production use because only a
611 single pattern can be written to a file. Furthermore, there is no facility for
612 supplying custom character tables for use with a reloaded pattern. If the
613 original pattern was compiled with custom tables, an attempt to match a subject
614 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
615 Finally, if you attempt to load a file that is not in the correct format, the
616 result is undefined.
617 .
618 .
619 .SH AUTHOR
620 .rs
621 .sp
622 Philip Hazel
623 .br
624 University Computing Service,
625 .br
626 Cambridge CB2 3QG, England.
627 .P
628 .in 0
629 Last updated: 29 June 2006
630 .br
631 Copyright (c) 1997-2006 University of Cambridge.

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