1 PCRETEST(1) PCRETEST(1)
5 pcretest - a program for testing Perl-compatible regular expressions.
10 pcretest [options] [source] [destination]
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.
22 -b Behave as if each regex has the /B (show bytecode) modifier;
23 the internal form is output after compilation.
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.
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.
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).
38 -help Output a brief summary these options and then exit.
40 -i Behave as if each regex has the /I modifier; information
41 about the compiled pattern is given after compilation.
43 -m Output the size of each compiled pattern after it has been
44 compiled. This is equivalent to adding /M to each regular
45 expression. For compatibility with earlier versions of
46 pcretest, -s is a synonym for -m.
48 -o osize Set the number of elements in the output vector that is used
49 when calling pcre_exec() or pcre_dfa_exec() to be osize. The
50 default value is 45, which is enough for 14 capturing subex-
51 pressions for pcre_exec() or 22 different matches for
52 pcre_dfa_exec(). The vector size can be changed for individ-
53 ual matching calls by including \O in the data line (see
56 -p Behave as if each regex has the /P modifier; the POSIX wrap-
57 per API is used to call PCRE. None of the other options has
58 any effect when -p is set.
60 -q Do not output the version number of pcretest at the start of
63 -S size On Unix-like systems, set the size of the runtime stack to
66 -t Run each compile, study, and match many times with a timer,
67 and output resulting time per compile or match (in millisec-
68 onds). Do not set -m with -t, because you will then get the
69 size output a zillion times, and the timing will be dis-
70 torted. You can control the number of iterations that are
71 used for timing by following -t with a number (as a separate
72 item on the command line). For example, "-t 1000" would iter-
73 ate 1000 times. The default is to iterate 500000 times.
75 -tm This is like -t except that it times only the matching phase,
76 not the compile or study phases.
81 If pcretest is given two filename arguments, it reads from the first
82 and writes to the second. If it is given only one filename argument, it
83 reads from that file and writes to stdout. Otherwise, it reads from
84 stdin and writes to stdout, and prompts for each line of input, using
85 "re>" to prompt for regular expressions, and "data>" to prompt for data
88 When pcretest is built, a configuration option can specify that it
89 should be linked with the libreadline library. When this is done, if
90 the input is from a terminal, it is read using the readline() function.
91 This provides line-editing and history facilities. The output from the
92 -help option states whether or not readline() will be used.
94 The program handles any number of sets of input on a single input file.
95 Each set starts with a regular expression, and continues with any num-
96 ber of data lines to be matched against the pattern.
98 Each data line is matched separately and independently. If you want to
99 do multi-line matches, you have to use the \n escape sequence (or \r or
100 \r\n, etc., depending on the newline setting) in a single line of input
101 to encode the newline sequences. There is no limit on the length of
102 data lines; the input buffer is automatically extended if it is too
105 An empty line signals the end of the data lines, at which point a new
106 regular expression is read. The regular expressions are given enclosed
107 in any non-alphanumeric delimiters other than backslash, for example:
111 White space before the initial delimiter is ignored. A regular expres-
112 sion may be continued over several input lines, in which case the new-
113 line characters are included within it. It is possible to include the
114 delimiter within the pattern by escaping it, for example
118 If you do so, the escape and the delimiter form part of the pattern,
119 but since delimiters are always non-alphanumeric, this does not affect
120 its interpretation. If the terminating delimiter is immediately fol-
121 lowed by a backslash, for example,
125 then a backslash is added to the end of the pattern. This is done to
126 provide a way of testing the error condition that arises if a pattern
127 finishes with a backslash, because
131 is interpreted as the first line of a pattern that starts with "abc/",
132 causing pcretest to read the next line as a continuation of the regular
138 A pattern may be followed by any number of modifiers, which are mostly
139 single characters. Following Perl usage, these are referred to below
140 as, for example, "the /i modifier", even though the delimiter of the
141 pattern need not always be a slash, and no slash is used when writing
142 modifiers. Whitespace may appear between the final pattern delimiter
143 and the first modifier, and between the modifiers themselves.
145 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
146 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
147 pile() is called. These four modifier letters have the same effect as
148 they do in Perl. For example:
152 The following table shows additional modifiers for setting PCRE options
153 that do not correspond to anything in Perl:
157 /E PCRE_DOLLAR_ENDONLY
160 /N PCRE_NO_AUTO_CAPTURE
163 /<cr> PCRE_NEWLINE_CR
164 /<lf> PCRE_NEWLINE_LF
165 /<crlf> PCRE_NEWLINE_CRLF
166 /<anycrlf> PCRE_NEWLINE_ANYCRLF
167 /<any> PCRE_NEWLINE_ANY
168 /<bsr_anycrlf> PCRE_BSR_ANYCRLF
169 /<bsr_unicode> PCRE_BSR_UNICODE
171 Those specifying line ending sequences are literal strings as shown,
172 but the letters can be in either case. This example sets multiline
173 matching with CRLF as the line ending sequence:
177 Details of the meanings of these PCRE options are given in the pcreapi
180 Finding all matches in a string
182 Searching for all possible matches within each subject string can be
183 requested by the /g or /G modifier. After finding a match, PCRE is
184 called again to search the remainder of the subject string. The differ-
185 ence between /g and /G is that the former uses the startoffset argument
186 to pcre_exec() to start searching at a new point within the entire
187 string (which is in effect what Perl does), whereas the latter passes
188 over a shortened substring. This makes a difference to the matching
189 process if the pattern begins with a lookbehind assertion (including \b
192 If any call to pcre_exec() in a /g or /G sequence matches an empty
193 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
194 flags set in order to search for another, non-empty, match at the same
195 point. If this second match fails, the start offset is advanced by
196 one, and the normal match is retried. This imitates the way Perl han-
197 dles such cases when using the /g modifier or the split() function.
201 There are yet more modifiers for controlling the way pcretest operates.
203 The /+ modifier requests that as well as outputting the substring that
204 matched the entire pattern, pcretest should in addition output the
205 remainder of the subject string. This is useful for tests where the
206 subject contains multiple copies of the same substring.
208 The /B modifier is a debugging feature. It requests that pcretest out-
209 put a representation of the compiled byte code after compilation. Nor-
210 mally this information contains length and offset values; however, if
211 /Z is also present, this data is replaced by spaces. This is a special
212 feature for use in the automatic test scripts; it ensures that the same
213 output is generated for different internal link sizes.
215 The /L modifier must be followed directly by the name of a locale, for
220 For this reason, it must be the last modifier. The given locale is set,
221 pcre_maketables() is called to build a set of character tables for the
222 locale, and this is then passed to pcre_compile() when compiling the
223 regular expression. Without an /L modifier, NULL is passed as the
224 tables pointer; that is, /L applies only to the expression on which it
227 The /I modifier requests that pcretest output information about the
228 compiled pattern (whether it is anchored, has a fixed first character,
229 and so on). It does this by calling pcre_fullinfo() after compiling a
230 pattern. If the pattern is studied, the results of that are also out-
233 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
234 that is, both the /B and the /I modifiers.
236 The /F modifier causes pcretest to flip the byte order of the fields in
237 the compiled pattern that contain 2-byte and 4-byte numbers. This
238 facility is for testing the feature in PCRE that allows it to execute
239 patterns that were compiled on a host with a different endianness. This
240 feature is not available when the POSIX interface to PCRE is being
241 used, that is, when the /P pattern modifier is specified. See also the
242 section about saving and reloading compiled patterns below.
244 The /S modifier causes pcre_study() to be called after the expression
245 has been compiled, and the results used when the expression is matched.
247 The /M modifier causes the size of memory block used to hold the com-
248 piled pattern to be output.
250 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
251 rather than its native API. When this is done, all other modifiers
252 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
253 and REG_NEWLINE is set if /m is present. The wrapper functions force
254 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
256 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
257 set. This turns on support for UTF-8 character handling in PCRE, pro-
258 vided that it was compiled with this support enabled. This modifier
259 also causes any non-printing characters in output strings to be printed
260 using the \x{hh...} notation if they are valid UTF-8 sequences.
262 If the /? modifier is used with /8, it causes pcretest to call
263 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
264 checking of the string for UTF-8 validity.
269 Before each data line is passed to pcre_exec(), leading and trailing
270 whitespace is removed, and it is then scanned for \ escapes. Some of
271 these are pretty esoteric features, intended for checking out some of
272 the more complicated features of PCRE. If you are just testing "ordi-
273 nary" regular expressions, you probably don't need any of these. The
274 following escapes are recognized:
281 \qdd set the PCRE_MATCH_LIMIT limit to dd
282 (any number of digits)
283 \r carriage return (\x0d)
285 \v vertical tab (\x0b)
286 \nnn octal character (up to 3 octal digits)
287 \xhh hexadecimal character (up to 2 hex digits)
288 \x{hh...} hexadecimal character, any number of digits
290 \A pass the PCRE_ANCHORED option to pcre_exec()
292 \B pass the PCRE_NOTBOL option to pcre_exec()
294 \Cdd call pcre_copy_substring() for substring dd
295 after a successful match (number less than 32)
296 \Cname call pcre_copy_named_substring() for substring
297 "name" after a successful match (name termin-
298 ated by next non alphanumeric character)
299 \C+ show the current captured substrings at callout
301 \C- do not supply a callout function
302 \C!n return 1 instead of 0 when callout number n is
304 \C!n!m return 1 instead of 0 when callout number n is
305 reached for the nth time
306 \C*n pass the number n (may be negative) as callout
307 data; this is used as the callout return value
308 \D use the pcre_dfa_exec() match function
309 \F only shortest match for pcre_dfa_exec()
310 \Gdd call pcre_get_substring() for substring dd
311 after a successful match (number less than 32)
312 \Gname call pcre_get_named_substring() for substring
313 "name" after a successful match (name termin-
314 ated by next non-alphanumeric character)
315 \L call pcre_get_substringlist() after a
317 \M discover the minimum MATCH_LIMIT and
318 MATCH_LIMIT_RECURSION settings
319 \N pass the PCRE_NOTEMPTY option to pcre_exec()
321 \Odd set the size of the output vector passed to
322 pcre_exec() to dd (any number of digits)
323 \P pass the PCRE_PARTIAL option to pcre_exec()
325 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
326 (any number of digits)
327 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
328 \S output details of memory get/free calls during matching
329 \Z pass the PCRE_NOTEOL option to pcre_exec()
331 \? pass the PCRE_NO_UTF8_CHECK option to
332 pcre_exec() or pcre_dfa_exec()
333 \>dd start the match at offset dd (any number of digits);
334 this sets the startoffset argument for pcre_exec()
336 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
338 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
340 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
342 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
344 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
347 The escapes that specify line ending sequences are literal strings,
348 exactly as shown. No more than one newline setting should be present in
351 A backslash followed by anything else just escapes the anything else.
352 If the very last character is a backslash, it is ignored. This gives a
353 way of passing an empty line as data, since a real empty line termi-
354 nates the data input.
356 If \M is present, pcretest calls pcre_exec() several times, with dif-
357 ferent values in the match_limit and match_limit_recursion fields of
358 the pcre_extra data structure, until it finds the minimum numbers for
359 each parameter that allow pcre_exec() to complete. The match_limit num-
360 ber is a measure of the amount of backtracking that takes place, and
361 checking it out can be instructive. For most simple matches, the number
362 is quite small, but for patterns with very large numbers of matching
363 possibilities, it can become large very quickly with increasing length
364 of subject string. The match_limit_recursion number is a measure of how
365 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
366 memory is needed to complete the match attempt.
368 When \O is used, the value specified may be higher or lower than the
369 size set by the -O command line option (or defaulted to 45); \O applies
370 only to the call of pcre_exec() for the line in which it appears.
372 If the /P modifier was present on the pattern, causing the POSIX wrap-
373 per API to be used, the only option-setting sequences that have any
374 effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
375 to be passed to regexec().
377 The use of \x{hh...} to represent UTF-8 characters is not dependent on
378 the use of the /8 modifier on the pattern. It is recognized always.
379 There may be any number of hexadecimal digits inside the braces. The
380 result is from one to six bytes, encoded according to the original
381 UTF-8 rules of RFC 2279. This allows for values in the range 0 to
382 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
383 or indeed valid UTF-8 characters according to the later rules in RFC
387 THE ALTERNATIVE MATCHING FUNCTION
389 By default, pcretest uses the standard PCRE matching function,
390 pcre_exec() to match each data line. From release 6.0, PCRE supports an
391 alternative matching function, pcre_dfa_test(), which operates in a
392 different way, and has some restrictions. The differences between the
393 two functions are described in the pcrematching documentation.
395 If a data line contains the \D escape sequence, or if the command line
396 contains the -dfa option, the alternative matching function is called.
397 This function finds all possible matches at a given point. If, however,
398 the \F escape sequence is present in the data line, it stops after the
399 first match is found. This is always the shortest possible match.
402 DEFAULT OUTPUT FROM PCRETEST
404 This section describes the output when the normal matching function,
405 pcre_exec(), is being used.
407 When a match succeeds, pcretest outputs the list of captured substrings
408 that pcre_exec() returns, starting with number 0 for the string that
409 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
410 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
411 TIAL, respectively, and otherwise the PCRE negative error number. Here
412 is an example of an interactive pcretest run.
415 PCRE version 7.0 30-Nov-2006
424 Note that unset capturing substrings that are not followed by one that
425 is set are not returned by pcre_exec(), and are not shown by pcretest.
426 In the following example, there are two capturing substrings, but when
427 the first data line is matched, the second, unset substring is not
428 shown. An "internal" unset substring is shown as "<unset>", as for the
440 If the strings contain any non-printing characters, they are output as
441 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
442 the pattern. See below for the definition of non-printing characters.
443 If the pattern has the /+ modifier, the output for substring 0 is fol-
444 lowed by the the rest of the subject string, identified by "0+" like
452 If the pattern has the /g or /G modifier, the results of successive
453 matching attempts are output in sequence, like this:
464 "No match" is output only if the first match attempt fails.
466 If any of the sequences \C, \G, or \L are present in a data line that
467 is successfully matched, the substrings extracted by the convenience
468 functions are output with C, G, or L after the string number instead of
469 a colon. This is in addition to the normal full list. The string length
470 (that is, the return from the extraction function) is given in paren-
471 theses after each string for \C and \G.
473 Note that whereas patterns can be continued over several lines (a plain
474 ">" prompt is used for continuations), data lines may not. However new-
475 lines can be included in data by means of the \n escape (or \r, \r\n,
476 etc., depending on the newline sequence setting).
479 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
481 When the alternative matching function, pcre_dfa_exec(), is used (by
482 means of the \D escape sequence or the -dfa command line option), the
483 output consists of a list of all the matches that start at the first
484 point in the subject where there is at least one match. For example:
486 re> /(tang|tangerine|tan)/
487 data> yellow tangerine\D
492 (Using the normal matching function on this data finds only "tang".)
493 The longest matching string is always given first (and numbered zero).
495 If /g is present on the pattern, the search for further matches resumes
496 at the end of the longest match. For example:
498 re> /(tang|tangerine|tan)/g
499 data> yellow tangerine and tangy sultana\D
507 Since the matching function does not support substring capture, the
508 escape sequences that are concerned with captured substrings are not
512 RESTARTING AFTER A PARTIAL MATCH
514 When the alternative matching function has given the PCRE_ERROR_PARTIAL
515 return, indicating that the subject partially matched the pattern, you
516 can restart the match with additional subject data by means of the \R
517 escape sequence. For example:
519 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
525 For further information about partial matching, see the pcrepartial
531 If the pattern contains any callout requests, pcretest's callout func-
532 tion is called during matching. This works with both matching func-
533 tions. By default, the called function displays the callout number, the
534 start and current positions in the text at the callout time, and the
535 next pattern item to be tested. For example, the output
540 indicates that callout number 0 occurred for a match attempt starting
541 at the fourth character of the subject string, when the pointer was at
542 the seventh character of the data, and when the next pattern item was
543 \d. Just one circumflex is output if the start and current positions
546 Callouts numbered 255 are assumed to be automatic callouts, inserted as
547 a result of the /C pattern modifier. In this case, instead of showing
548 the callout number, the offset in the pattern, preceded by a plus, is
560 The callout function in pcretest returns zero (carry on matching) by
561 default, but you can use a \C item in a data line (as described above)
564 Inserting callouts can be helpful when using pcretest to check compli-
565 cated regular expressions. For further information about callouts, see
566 the pcrecallout documentation.
569 NON-PRINTING CHARACTERS
571 When pcretest is outputting text in the compiled version of a pattern,
572 bytes other than 32-126 are always treated as non-printing characters
573 are are therefore shown as hex escapes.
575 When pcretest is outputting text that is a matched part of a subject
576 string, it behaves in the same way, unless a different locale has been
577 set for the pattern (using the /L modifier). In this case, the
578 isprint() function to distinguish printing and non-printing characters.
581 SAVING AND RELOADING COMPILED PATTERNS
583 The facilities described in this section are not available when the
584 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
587 When the POSIX interface is not in use, you can cause pcretest to write
588 a compiled pattern to a file, by following the modifiers with > and a
589 file name. For example:
591 /pattern/im >/some/file
593 See the pcreprecompile documentation for a discussion about saving and
594 re-using compiled patterns.
596 The data that is written is binary. The first eight bytes are the
597 length of the compiled pattern data followed by the length of the
598 optional study data, each written as four bytes in big-endian order
599 (most significant byte first). If there is no study data (either the
600 pattern was not studied, or studying did not return any data), the sec-
601 ond length is zero. The lengths are followed by an exact copy of the
602 compiled pattern. If there is additional study data, this follows imme-
603 diately after the compiled pattern. After writing the file, pcretest
604 expects to read a new pattern.
606 A saved pattern can be reloaded into pcretest by specifing < and a file
607 name instead of a pattern. The name of the file must not contain a <
608 character, as otherwise pcretest will interpret the line as a pattern
609 delimited by < characters. For example:
612 Compiled regex loaded from /some/file
615 When the pattern has been loaded, pcretest proceeds to read data lines
618 You can copy a file written by pcretest to a different host and reload
619 it there, even if the new host has opposite endianness to the one on
620 which the pattern was compiled. For example, you can compile on an i86
621 machine and run on a SPARC machine.
623 File names for saving and reloading can be absolute or relative, but
624 note that the shell facility of expanding a file name that starts with
625 a tilde (~) is not available.
627 The ability to save and reload files in pcretest is intended for test-
628 ing and experimentation. It is not intended for production use because
629 only a single pattern can be written to a file. Furthermore, there is
630 no facility for supplying custom character tables for use with a
631 reloaded pattern. If the original pattern was compiled with custom
632 tables, an attempt to match a subject string using a reloaded pattern
633 is likely to cause pcretest to crash. Finally, if you attempt to load
634 a file that is not in the correct format, the result is undefined.
639 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
640 pcrepattern(3), pcreprecompile(3).
646 University Computing Service
647 Cambridge CB2 3QH, England.
652 Last updated: 18 December 2007
653 Copyright (c) 1997-2007 University of Cambridge.
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