1PCRETEST(1) General Commands Manual PCRETEST(1)
2
6 pcretest - a program for testing Perl-compatible regular expressions.
7
9 pcretest [options] [source] [destination]
11 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
20 -b Behave as if each regex has the /B (show bytecode) modifier;
22 the internal form is output after compilation.
23 -C Output the version number of the PCRE library, and all avail‐
25 able information about the optional features that are
26 included, and then exit.
27 -d Behave as if each regex has the /D (debug) modifier; the
29 internal form and information about the compiled pattern is
30 output after compilation; -d is equivalent to -b -i.
31 -dfa Behave as if each data line contains the \D escape sequence;
33 this causes the alternative matching function,
34 pcre_dfa_exec(), to be used instead of the standard
35 pcre_exec() function (more detail is given below).
36 -help Output a brief summary these options and then exit.
38 -i Behave as if each regex has the /I modifier; information
40 about the compiled pattern is given after compilation.
41 -m Output the size of each compiled pattern after it has been
43 compiled. This is equivalent to adding /M to each regular
44 expression. For compatibility with earlier versions of
45 pcretest, -s is a synonym for -m.
46 -o osize Set the number of elements in the output vector that is used
48 when calling pcre_exec() or pcre_dfa_exec() to be osize. The
49 default value is 45, which is enough for 14 capturing subex‐
50 pressions for pcre_exec() or 22 different matches for
51 pcre_dfa_exec(). The vector size can be changed for individ‐
52 ual matching calls by including \O in the data line (see
53 below).
54 -p Behave as if each regex has the /P modifier; the POSIX wrap‐
56 per API is used to call PCRE. None of the other options has
57 any effect when -p is set.
58 -q Do not output the version number of pcretest at the start of
60 execution.
61 -S size On Unix-like systems, set the size of the runtime stack to
63 size megabytes.
64 -t Run each compile, study, and match many times with a timer,
66 and output resulting time per compile or match (in millisec‐
67 onds). Do not set -m with -t, because you will then get the
68 size output a zillion times, and the timing will be dis‐
69 torted. You can control the number of iterations that are
70 used for timing by following -t with a number (as a separate
71 item on the command line). For example, "-t 1000" would iter‐
72 ate 1000 times. The default is to iterate 500000 times.
73 -tm This is like -t except that it times only the matching phase,
75 not the compile or study phases.
76
78 If pcretest is given two filename arguments, it reads from the first
80 and writes to the second. If it is given only one filename argument, it
81 reads from that file and writes to stdout. Otherwise, it reads from
82 stdin and writes to stdout, and prompts for each line of input, using
83 "re>" to prompt for regular expressions, and "data>" to prompt for data
84 lines.
85 The program handles any number of sets of input on a single input file.
87 Each set starts with a regular expression, and continues with any num‐
88 ber of data lines to be matched against the pattern.
89 Each data line is matched separately and independently. If you want to
91 do multi-line matches, you have to use the \n escape sequence (or \r or
92 \r\n, etc., depending on the newline setting) in a single line of input
93 to encode the newline sequences. There is no limit on the length of
94 data lines; the input buffer is automatically extended if it is too
95 small.
96 An empty line signals the end of the data lines, at which point a new
98 regular expression is read. The regular expressions are given enclosed
99 in any non-alphanumeric delimiters other than backslash, for example:
100 /(a|bc)x+yz/
102 White space before the initial delimiter is ignored. A regular expres‐
104 sion may be continued over several input lines, in which case the new‐
105 line characters are included within it. It is possible to include the
106 delimiter within the pattern by escaping it, for example
107 /abc\/def/
109 If you do so, the escape and the delimiter form part of the pattern,
111 but since delimiters are always non-alphanumeric, this does not affect
112 its interpretation. If the terminating delimiter is immediately fol‐
113 lowed by a backslash, for example,
114 /abc/\
116 then a backslash is added to the end of the pattern. This is done to
118 provide a way of testing the error condition that arises if a pattern
119 finishes with a backslash, because
120 /abc\/
122 is interpreted as the first line of a pattern that starts with "abc/",
124 causing pcretest to read the next line as a continuation of the regular
125 expression.
126
128 A pattern may be followed by any number of modifiers, which are mostly
130 single characters. Following Perl usage, these are referred to below
131 as, for example, "the /i modifier", even though the delimiter of the
132 pattern need not always be a slash, and no slash is used when writing
133 modifiers. Whitespace may appear between the final pattern delimiter
134 and the first modifier, and between the modifiers themselves.
135 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
137 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com‐
138 pile() is called. These four modifier letters have the same effect as
139 they do in Perl. For example:
140 /caseless/i
142 The following table shows additional modifiers for setting PCRE options
144 that do not correspond to anything in Perl:
145 /A PCRE_ANCHORED
147 /C PCRE_AUTO_CALLOUT
148 /E PCRE_DOLLAR_ENDONLY
149 /f PCRE_FIRSTLINE
150 /J PCRE_DUPNAMES
151 /N PCRE_NO_AUTO_CAPTURE
152 /U PCRE_UNGREEDY
153 /X PCRE_EXTRA
154 /<cr> PCRE_NEWLINE_CR
155 /<lf> PCRE_NEWLINE_LF
156 /<crlf> PCRE_NEWLINE_CRLF
157 /<anycrlf> PCRE_NEWLINE_ANYCRLF
158 /<any> PCRE_NEWLINE_ANY
159 Those specifying line ending sequences are literal strings as shown,
161 but the letters can be in either case. This example sets multiline
162 matching with CRLF as the line ending sequence:
163 /^abc/m<crlf>
165 Details of the meanings of these PCRE options are given in the pcreapi
167 documentation.
168 Finding all matches in a string
170 Searching for all possible matches within each subject string can be
172 requested by the /g or /G modifier. After finding a match, PCRE is
173 called again to search the remainder of the subject string. The differ‐
174 ence between /g and /G is that the former uses the startoffset argument
175 to pcre_exec() to start searching at a new point within the entire
176 string (which is in effect what Perl does), whereas the latter passes
177 over a shortened substring. This makes a difference to the matching
178 process if the pattern begins with a lookbehind assertion (including \b
179 or \B).
180 If any call to pcre_exec() in a /g or /G sequence matches an empty
182 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
183 flags set in order to search for another, non-empty, match at the same
184 point. If this second match fails, the start offset is advanced by
185 one, and the normal match is retried. This imitates the way Perl han‐
186 dles such cases when using the /g modifier or the split() function.
187 Other modifiers
189 There are yet more modifiers for controlling the way pcretest operates.
191 The /+ modifier requests that as well as outputting the substring that
193 matched the entire pattern, pcretest should in addition output the
194 remainder of the subject string. This is useful for tests where the
195 subject contains multiple copies of the same substring.
196 The /B modifier is a debugging feature. It requests that pcretest out‐
198 put a representation of the compiled byte code after compilation. Nor‐
199 mally this information contains length and offset values; however, if
200 /Z is also present, this data is replaced by spaces. This is a special
201 feature for use in the automatic test scripts; it ensures that the same
202 output is generated for different internal link sizes.
203 The /L modifier must be followed directly by the name of a locale, for
205 example,
206 /pattern/Lfr_FR
208 For this reason, it must be the last modifier. The given locale is set,
210 pcre_maketables() is called to build a set of character tables for the
211 locale, and this is then passed to pcre_compile() when compiling the
212 regular expression. Without an /L modifier, NULL is passed as the
213 tables pointer; that is, /L applies only to the expression on which it
214 appears.
215 The /I modifier requests that pcretest output information about the
217 compiled pattern (whether it is anchored, has a fixed first character,
218 and so on). It does this by calling pcre_fullinfo() after compiling a
219 pattern. If the pattern is studied, the results of that are also out‐
220 put.
221 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
223 that is, both the /B and the /I modifiers.
224 The /F modifier causes pcretest to flip the byte order of the fields in
226 the compiled pattern that contain 2-byte and 4-byte numbers. This
227 facility is for testing the feature in PCRE that allows it to execute
228 patterns that were compiled on a host with a different endianness. This
229 feature is not available when the POSIX interface to PCRE is being
230 used, that is, when the /P pattern modifier is specified. See also the
231 section about saving and reloading compiled patterns below.
232 The /S modifier causes pcre_study() to be called after the expression
234 has been compiled, and the results used when the expression is matched.
235 The /M modifier causes the size of memory block used to hold the com‐
237 piled pattern to be output.
238 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
240 rather than its native API. When this is done, all other modifiers
241 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
242 and REG_NEWLINE is set if /m is present. The wrapper functions force
243 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
244 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
246 set. This turns on support for UTF-8 character handling in PCRE, pro‐
247 vided that it was compiled with this support enabled. This modifier
248 also causes any non-printing characters in output strings to be printed
249 using the \x{hh...} notation if they are valid UTF-8 sequences.
250 If the /? modifier is used with /8, it causes pcretest to call
252 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
253 checking of the string for UTF-8 validity.
254
256 Before each data line is passed to pcre_exec(), leading and trailing
258 whitespace is removed, and it is then scanned for \ escapes. Some of
259 these are pretty esoteric features, intended for checking out some of
260 the more complicated features of PCRE. If you are just testing "ordi‐
261 nary" regular expressions, you probably don't need any of these. The
262 following escapes are recognized:
263 \a alarm (BEL, \x07)
265 \b backspace (\x08)
266 \e escape (\x27)
267 \f formfeed (\x0c)
268 \n newline (\x0a)
269 \qdd set the PCRE_MATCH_LIMIT limit to dd
270 (any number of digits)
271 \r carriage return (\x0d)
272 \t tab (\x09)
273 \v vertical tab (\x0b)
274 \nnn octal character (up to 3 octal digits)
275 \xhh hexadecimal character (up to 2 hex digits)
276 \x{hh...} hexadecimal character, any number of digits
277 in UTF-8 mode
278 \A pass the PCRE_ANCHORED option to pcre_exec()
279 or pcre_dfa_exec()
280 \B pass the PCRE_NOTBOL option to pcre_exec()
281 or pcre_dfa_exec()
282 \Cdd call pcre_copy_substring() for substring dd
283 after a successful match (number less than 32)
284 \Cname call pcre_copy_named_substring() for substring
285 "name" after a successful match (name termin-
286 ated by next non alphanumeric character)
287 \C+ show the current captured substrings at callout
288 time
289 \C- do not supply a callout function
290 \C!n return 1 instead of 0 when callout number n is
291 reached
292 \C!n!m return 1 instead of 0 when callout number n is
293 reached for the nth time
294 \C*n pass the number n (may be negative) as callout
295 data; this is used as the callout return value
296 \D use the pcre_dfa_exec() match function
297 \F only shortest match for pcre_dfa_exec()
298 \Gdd call pcre_get_substring() for substring dd
299 after a successful match (number less than 32)
300 \Gname call pcre_get_named_substring() for substring
301 "name" after a successful match (name termin-
302 ated by next non-alphanumeric character)
303 \L call pcre_get_substringlist() after a
304 successful match
305 \M discover the minimum MATCH_LIMIT and
306 MATCH_LIMIT_RECURSION settings
307 \N pass the PCRE_NOTEMPTY option to pcre_exec()
308 or pcre_dfa_exec()
309 \Odd set the size of the output vector passed to
310 pcre_exec() to dd (any number of digits)
311 \P pass the PCRE_PARTIAL option to pcre_exec()
312 or pcre_dfa_exec()
313 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
314 (any number of digits)
315 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
316 \S output details of memory get/free calls during matching
317 \Z pass the PCRE_NOTEOL option to pcre_exec()
318 or pcre_dfa_exec()
319 \? pass the PCRE_NO_UTF8_CHECK option to
320 pcre_exec() or pcre_dfa_exec()
321 \>dd start the match at offset dd (any number of digits);
322 this sets the startoffset argument for pcre_exec()
323 or pcre_dfa_exec()
324 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
325 or pcre_dfa_exec()
326 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
327 or pcre_dfa_exec()
328 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
329 or pcre_dfa_exec()
330 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
331 or pcre_dfa_exec()
332 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
333 or pcre_dfa_exec()
334 The escapes that specify line ending sequences are literal strings,
336 exactly as shown. No more than one newline setting should be present in
337 any data line.
338 A backslash followed by anything else just escapes the anything else.
340 If the very last character is a backslash, it is ignored. This gives a
341 way of passing an empty line as data, since a real empty line termi‐
342 nates the data input.
343 If \M is present, pcretest calls pcre_exec() several times, with dif‐
345 ferent values in the match_limit and match_limit_recursion fields of
346 the pcre_extra data structure, until it finds the minimum numbers for
347 each parameter that allow pcre_exec() to complete. The match_limit num‐
348 ber is a measure of the amount of backtracking that takes place, and
349 checking it out can be instructive. For most simple matches, the number
350 is quite small, but for patterns with very large numbers of matching
351 possibilities, it can become large very quickly with increasing length
352 of subject string. The match_limit_recursion number is a measure of how
353 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
354 memory is needed to complete the match attempt.
355 When \O is used, the value specified may be higher or lower than the
357 size set by the -O command line option (or defaulted to 45); \O applies
358 only to the call of pcre_exec() for the line in which it appears.
359 If the /P modifier was present on the pattern, causing the POSIX wrap‐
361 per API to be used, the only option-setting sequences that have any
362 effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
363 to be passed to regexec().
364 The use of \x{hh...} to represent UTF-8 characters is not dependent on
366 the use of the /8 modifier on the pattern. It is recognized always.
367 There may be any number of hexadecimal digits inside the braces. The
368 result is from one to six bytes, encoded according to the original
369 UTF-8 rules of RFC 2279. This allows for values in the range 0 to
370 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
371 or indeed valid UTF-8 characters according to the later rules in RFC
372 3629.
373
375 By default, pcretest uses the standard PCRE matching function,
377 pcre_exec() to match each data line. From release 6.0, PCRE supports an
378 alternative matching function, pcre_dfa_test(), which operates in a
379 different way, and has some restrictions. The differences between the
380 two functions are described in the pcrematching documentation.
381 If a data line contains the \D escape sequence, or if the command line
383 contains the -dfa option, the alternative matching function is called.
384 This function finds all possible matches at a given point. If, however,
385 the \F escape sequence is present in the data line, it stops after the
386 first match is found. This is always the shortest possible match.
387
389 This section describes the output when the normal matching function,
391 pcre_exec(), is being used.
392 When a match succeeds, pcretest outputs the list of captured substrings
394 that pcre_exec() returns, starting with number 0 for the string that
395 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
396 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR‐
397 TIAL, respectively, and otherwise the PCRE negative error number. Here
398 is an example of an interactive pcretest run.
399 $ pcretest
401 PCRE version 7.0 30-Nov-2006
402 re> /^abc(\d+)/
404 data> abc123
405 0: abc123
406 1: 123
407 data> xyz
408 No match
409 If the strings contain any non-printing characters, they are output as
411 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
412 the pattern. See below for the definition of non-printing characters.
413 If the pattern has the /+ modifier, the output for substring 0 is fol‐
414 lowed by the the rest of the subject string, identified by "0+" like
415 this:
416 re> /cat/+
418 data> cataract
419 0: cat
420 0+ aract
421 If the pattern has the /g or /G modifier, the results of successive
423 matching attempts are output in sequence, like this:
424 re> /\Bi(\w\w)/g
426 data> Mississippi
427 0: iss
428 1: ss
429 0: iss
430 1: ss
431 0: ipp
432 1: pp
433 "No match" is output only if the first match attempt fails.
435 If any of the sequences \C, \G, or \L are present in a data line that
437 is successfully matched, the substrings extracted by the convenience
438 functions are output with C, G, or L after the string number instead of
439 a colon. This is in addition to the normal full list. The string length
440 (that is, the return from the extraction function) is given in paren‐
441 theses after each string for \C and \G.
442 Note that whereas patterns can be continued over several lines (a plain
444 ">" prompt is used for continuations), data lines may not. However new‐
445 lines can be included in data by means of the \n escape (or \r, \r\n,
446 etc., depending on the newline sequence setting).
447
449 When the alternative matching function, pcre_dfa_exec(), is used (by
451 means of the \D escape sequence or the -dfa command line option), the
452 output consists of a list of all the matches that start at the first
453 point in the subject where there is at least one match. For example:
454 re> /(tang|tangerine|tan)/
456 data> yellow tangerine\D
457 0: tangerine
458 1: tang
459 2: tan
460 (Using the normal matching function on this data finds only "tang".)
462 The longest matching string is always given first (and numbered zero).
463 If /g is present on the pattern, the search for further matches resumes
465 at the end of the longest match. For example:
466 re> /(tang|tangerine|tan)/g
468 data> yellow tangerine and tangy sultana\D
469 0: tangerine
470 1: tang
471 2: tan
472 0: tang
473 1: tan
474 0: tan
475 Since the matching function does not support substring capture, the
477 escape sequences that are concerned with captured substrings are not
478 relevant.
479
481 When the alternative matching function has given the PCRE_ERROR_PARTIAL
483 return, indicating that the subject partially matched the pattern, you
484 can restart the match with additional subject data by means of the \R
485 escape sequence. For example:
486 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
488 data> 23ja\P\D
489 Partial match: 23ja
490 data> n05\R\D
491 0: n05
492 For further information about partial matching, see the pcrepartial
494 documentation.
495
497 If the pattern contains any callout requests, pcretest's callout func‐
499 tion is called during matching. This works with both matching func‐
500 tions. By default, the called function displays the callout number, the
501 start and current positions in the text at the callout time, and the
502 next pattern item to be tested. For example, the output
503 --->pqrabcdef
505 0 ^ ^ \d
506 indicates that callout number 0 occurred for a match attempt starting
508 at the fourth character of the subject string, when the pointer was at
509 the seventh character of the data, and when the next pattern item was
510 \d. Just one circumflex is output if the start and current positions
511 are the same.
512 Callouts numbered 255 are assumed to be automatic callouts, inserted as
514 a result of the /C pattern modifier. In this case, instead of showing
515 the callout number, the offset in the pattern, preceded by a plus, is
516 output. For example:
517 re> /\d?[A-E]\*/C
519 data> E*
520 --->E*
521 +0 ^ \d?
522 +3 ^ [A-E]
523 +8 ^^ \*
524 +10 ^ ^
525 0: E*
526 The callout function in pcretest returns zero (carry on matching) by
528 default, but you can use a \C item in a data line (as described above)
529 to change this.
530 Inserting callouts can be helpful when using pcretest to check compli‐
532 cated regular expressions. For further information about callouts, see
533 the pcrecallout documentation.
534
536 When pcretest is outputting text in the compiled version of a pattern,
538 bytes other than 32-126 are always treated as non-printing characters
539 are are therefore shown as hex escapes.
540 When pcretest is outputting text that is a matched part of a subject
542 string, it behaves in the same way, unless a different locale has been
543 set for the pattern (using the /L modifier). In this case, the
544 isprint() function to distinguish printing and non-printing characters.
545
547 The facilities described in this section are not available when the
549 POSIX inteface to PCRE is being used, that is, when the /P pattern mod‐
550 ifier is specified.
551 When the POSIX interface is not in use, you can cause pcretest to write
553 a compiled pattern to a file, by following the modifiers with > and a
554 file name. For example:
555 /pattern/im >/some/file
557 See the pcreprecompile documentation for a discussion about saving and
559 re-using compiled patterns.
560 The data that is written is binary. The first eight bytes are the
562 length of the compiled pattern data followed by the length of the
563 optional study data, each written as four bytes in big-endian order
564 (most significant byte first). If there is no study data (either the
565 pattern was not studied, or studying did not return any data), the sec‐
566 ond length is zero. The lengths are followed by an exact copy of the
567 compiled pattern. If there is additional study data, this follows imme‐
568 diately after the compiled pattern. After writing the file, pcretest
569 expects to read a new pattern.
570 A saved pattern can be reloaded into pcretest by specifing < and a file
572 name instead of a pattern. The name of the file must not contain a <
573 character, as otherwise pcretest will interpret the line as a pattern
574 delimited by < characters. For example:
575 re> </some/file
577 Compiled regex loaded from /some/file
578 No study data
579 When the pattern has been loaded, pcretest proceeds to read data lines
581 in the usual way.
582 You can copy a file written by pcretest to a different host and reload
584 it there, even if the new host has opposite endianness to the one on
585 which the pattern was compiled. For example, you can compile on an i86
586 machine and run on a SPARC machine.
587 File names for saving and reloading can be absolute or relative, but
589 note that the shell facility of expanding a file name that starts with
590 a tilde (~) is not available.
591 The ability to save and reload files in pcretest is intended for test‐
593 ing and experimentation. It is not intended for production use because
594 only a single pattern can be written to a file. Furthermore, there is
595 no facility for supplying custom character tables for use with a
596 reloaded pattern. If the original pattern was compiled with custom
597 tables, an attempt to match a subject string using a reloaded pattern
598 is likely to cause pcretest to crash. Finally, if you attempt to load
599 a file that is not in the correct format, the result is undefined.
600
602 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
604 pcrepattern(3), pcreprecompile(3).
605
607 Philip Hazel
609 University Computing Service
610 Cambridge CB2 3QH, England.
611
613 Last updated: 21 August 2007
615 Copyright (c) 1997-2007 University of Cambridge.
616 PCRETEST(1)