1 This file contains the PCRE man page that described the pcretest program. Note
2 that not all of the features of PCRE are available in the limited version that
4 -------------------------------------------------------------------------------
6 PCRETEST(1) PCRETEST(1)
10 pcretest - a program for testing Perl-compatible regular expressions.
15 pcretest [options] [source] [destination]
17 pcretest was written as a test program for the PCRE regular expression
18 library itself, but it can also be used for experimenting with regular
19 expressions. This document describes the features of the test program;
20 for details of the regular expressions themselves, see the pcrepattern
21 documentation. For details of the PCRE library function calls and their
22 options, see the pcreapi documentation.
27 -b Behave as if each regex has the /B (show bytecode) modifier;
28 the internal form is output after compilation.
30 -C Output the version number of the PCRE library, and all avail-
31 able information about the optional features that are
32 included, and then exit.
34 -d Behave as if each regex has the /D (debug) modifier; the
35 internal form and information about the compiled pattern is
36 output after compilation; -d is equivalent to -b -i.
38 -dfa Behave as if each data line contains the \D escape sequence;
39 this causes the alternative matching function,
40 pcre_dfa_exec(), to be used instead of the standard
41 pcre_exec() function (more detail is given below).
43 -help Output a brief summary these options and then exit.
45 -i Behave as if each regex has the /I modifier; information
46 about the compiled pattern is given after compilation.
48 -m Output the size of each compiled pattern after it has been
49 compiled. This is equivalent to adding /M to each regular
50 expression. For compatibility with earlier versions of
51 pcretest, -s is a synonym for -m.
53 -o osize Set the number of elements in the output vector that is used
54 when calling pcre_exec() or pcre_dfa_exec() to be osize. The
55 default value is 45, which is enough for 14 capturing subex-
56 pressions for pcre_exec() or 22 different matches for
57 pcre_dfa_exec(). The vector size can be changed for individ-
58 ual matching calls by including \O in the data line (see
61 -p Behave as if each regex has the /P modifier; the POSIX wrap-
62 per API is used to call PCRE. None of the other options has
63 any effect when -p is set.
65 -q Do not output the version number of pcretest at the start of
68 -S size On Unix-like systems, set the size of the runtime stack to
71 -t Run each compile, study, and match many times with a timer,
72 and output resulting time per compile or match (in millisec-
73 onds). Do not set -m with -t, because you will then get the
74 size output a zillion times, and the timing will be dis-
75 torted. You can control the number of iterations that are
76 used for timing by following -t with a number (as a separate
77 item on the command line). For example, "-t 1000" would iter-
78 ate 1000 times. The default is to iterate 500000 times.
80 -tm This is like -t except that it times only the matching phase,
81 not the compile or study phases.
86 If pcretest is given two filename arguments, it reads from the first
87 and writes to the second. If it is given only one filename argument, it
88 reads from that file and writes to stdout. Otherwise, it reads from
89 stdin and writes to stdout, and prompts for each line of input, using
90 "re>" to prompt for regular expressions, and "data>" to prompt for data
93 The program handles any number of sets of input on a single input file.
94 Each set starts with a regular expression, and continues with any num-
95 ber of data lines to be matched against the pattern.
97 Each data line is matched separately and independently. If you want to
98 do multi-line matches, you have to use the \n escape sequence (or \r or
99 \r\n, etc., depending on the newline setting) in a single line of input
100 to encode the newline sequences. There is no limit on the length of
101 data lines; the input buffer is automatically extended if it is too
104 An empty line signals the end of the data lines, at which point a new
105 regular expression is read. The regular expressions are given enclosed
106 in any non-alphanumeric delimiters other than backslash, for example:
110 White space before the initial delimiter is ignored. A regular expres-
111 sion may be continued over several input lines, in which case the new-
112 line characters are included within it. It is possible to include the
113 delimiter within the pattern by escaping it, for example
117 If you do so, the escape and the delimiter form part of the pattern,
118 but since delimiters are always non-alphanumeric, this does not affect
119 its interpretation. If the terminating delimiter is immediately fol-
120 lowed by a backslash, for example,
124 then a backslash is added to the end of the pattern. This is done to
125 provide a way of testing the error condition that arises if a pattern
126 finishes with a backslash, because
130 is interpreted as the first line of a pattern that starts with "abc/",
131 causing pcretest to read the next line as a continuation of the regular
137 A pattern may be followed by any number of modifiers, which are mostly
138 single characters. Following Perl usage, these are referred to below
139 as, for example, "the /i modifier", even though the delimiter of the
140 pattern need not always be a slash, and no slash is used when writing
141 modifiers. Whitespace may appear between the final pattern delimiter
142 and the first modifier, and between the modifiers themselves.
144 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
145 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
146 pile() is called. These four modifier letters have the same effect as
147 they do in Perl. For example:
151 The following table shows additional modifiers for setting PCRE options
152 that do not correspond to anything in Perl:
156 /E PCRE_DOLLAR_ENDONLY
159 /N PCRE_NO_AUTO_CAPTURE
162 /<cr> PCRE_NEWLINE_CR
163 /<lf> PCRE_NEWLINE_LF
164 /<crlf> PCRE_NEWLINE_CRLF
165 /<anycrlf> PCRE_NEWLINE_ANYCRLF
166 /<any> PCRE_NEWLINE_ANY
168 Those specifying line ending sequencess are literal strings as shown.
169 This example sets multiline matching with CRLF as the line ending
174 Details of the meanings of these PCRE options are given in the pcreapi
177 Finding all matches in a string
179 Searching for all possible matches within each subject string can be
180 requested by the /g or /G modifier. After finding a match, PCRE is
181 called again to search the remainder of the subject string. The differ-
182 ence between /g and /G is that the former uses the startoffset argument
183 to pcre_exec() to start searching at a new point within the entire
184 string (which is in effect what Perl does), whereas the latter passes
185 over a shortened substring. This makes a difference to the matching
186 process if the pattern begins with a lookbehind assertion (including \b
189 If any call to pcre_exec() in a /g or /G sequence matches an empty
190 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
191 flags set in order to search for another, non-empty, match at the same
192 point. If this second match fails, the start offset is advanced by
193 one, and the normal match is retried. This imitates the way Perl han-
194 dles such cases when using the /g modifier or the split() function.
198 There are yet more modifiers for controlling the way pcretest operates.
200 The /+ modifier requests that as well as outputting the substring that
201 matched the entire pattern, pcretest should in addition output the
202 remainder of the subject string. This is useful for tests where the
203 subject contains multiple copies of the same substring.
205 The /B modifier is a debugging feature. It requests that pcretest out-
206 put a representation of the compiled byte code after compilation. Nor-
207 mally this information contains length and offset values; however, if
208 /Z is also present, this data is replaced by spaces. This is a special
209 feature for use in the automatic test scripts; it ensures that the same
210 output is generated for different internal link sizes.
212 The /L modifier must be followed directly by the name of a locale, for
217 For this reason, it must be the last modifier. The given locale is set,
218 pcre_maketables() is called to build a set of character tables for the
219 locale, and this is then passed to pcre_compile() when compiling the
220 regular expression. Without an /L modifier, NULL is passed as the
221 tables pointer; that is, /L applies only to the expression on which it
224 The /I modifier requests that pcretest output information about the
225 compiled pattern (whether it is anchored, has a fixed first character,
226 and so on). It does this by calling pcre_fullinfo() after compiling a
227 pattern. If the pattern is studied, the results of that are also out-
230 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
231 that is, both the /B and the /I modifiers.
233 The /F modifier causes pcretest to flip the byte order of the fields in
234 the compiled pattern that contain 2-byte and 4-byte numbers. This
235 facility is for testing the feature in PCRE that allows it to execute
236 patterns that were compiled on a host with a different endianness. This
237 feature is not available when the POSIX interface to PCRE is being
238 used, that is, when the /P pattern modifier is specified. See also the
239 section about saving and reloading compiled patterns below.
241 The /S modifier causes pcre_study() to be called after the expression
242 has been compiled, and the results used when the expression is matched.
244 The /M modifier causes the size of memory block used to hold the com-
245 piled pattern to be output.
247 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
248 rather than its native API. When this is done, all other modifiers
249 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
250 and REG_NEWLINE is set if /m is present. The wrapper functions force
251 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
253 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
254 set. This turns on support for UTF-8 character handling in PCRE, pro-
255 vided that it was compiled with this support enabled. This modifier
256 also causes any non-printing characters in output strings to be printed
257 using the \x{hh...} notation if they are valid UTF-8 sequences.
259 If the /? modifier is used with /8, it causes pcretest to call
260 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
261 checking of the string for UTF-8 validity.
266 Before each data line is passed to pcre_exec(), leading and trailing
267 whitespace is removed, and it is then scanned for \ escapes. Some of
268 these are pretty esoteric features, intended for checking out some of
269 the more complicated features of PCRE. If you are just testing "ordi-
270 nary" regular expressions, you probably don't need any of these. The
271 following escapes are recognized:
278 \qdd set the PCRE_MATCH_LIMIT limit to dd
279 (any number of digits)
280 \r carriage return (\x0d)
282 \v vertical tab (\x0b)
283 \nnn octal character (up to 3 octal digits)
284 \xhh hexadecimal character (up to 2 hex digits)
285 \x{hh...} hexadecimal character, any number of digits
287 \A pass the PCRE_ANCHORED option to pcre_exec()
289 \B pass the PCRE_NOTBOL option to pcre_exec()
291 \Cdd call pcre_copy_substring() for substring dd
292 after a successful match (number less than 32)
293 \Cname call pcre_copy_named_substring() for substring
294 "name" after a successful match (name termin-
295 ated by next non alphanumeric character)
296 \C+ show the current captured substrings at callout
298 \C- do not supply a callout function
299 \C!n return 1 instead of 0 when callout number n is
301 \C!n!m return 1 instead of 0 when callout number n is
302 reached for the nth time
303 \C*n pass the number n (may be negative) as callout
304 data; this is used as the callout return value
305 \D use the pcre_dfa_exec() match function
306 \F only shortest match for pcre_dfa_exec()
307 \Gdd call pcre_get_substring() for substring dd
308 after a successful match (number less than 32)
309 \Gname call pcre_get_named_substring() for substring
310 "name" after a successful match (name termin-
311 ated by next non-alphanumeric character)
312 \L call pcre_get_substringlist() after a
314 \M discover the minimum MATCH_LIMIT and
315 MATCH_LIMIT_RECURSION settings
316 \N pass the PCRE_NOTEMPTY option to pcre_exec()
318 \Odd set the size of the output vector passed to
319 pcre_exec() to dd (any number of digits)
320 \P pass the PCRE_PARTIAL option to pcre_exec()
322 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
323 (any number of digits)
324 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
325 \S output details of memory get/free calls during matching
326 \Z pass the PCRE_NOTEOL option to pcre_exec()
328 \? pass the PCRE_NO_UTF8_CHECK option to
329 pcre_exec() or pcre_dfa_exec()
330 \>dd start the match at offset dd (any number of digits);
331 this sets the startoffset argument for pcre_exec()
333 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
335 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
337 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
339 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
341 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
344 The escapes that specify line ending sequences are literal strings,
345 exactly as shown. No more than one newline setting should be present in
348 A backslash followed by anything else just escapes the anything else.
349 If the very last character is a backslash, it is ignored. This gives a
350 way of passing an empty line as data, since a real empty line termi-
351 nates the data input.
353 If \M is present, pcretest calls pcre_exec() several times, with dif-
354 ferent values in the match_limit and match_limit_recursion fields of
355 the pcre_extra data structure, until it finds the minimum numbers for
356 each parameter that allow pcre_exec() to complete. The match_limit num-
357 ber is a measure of the amount of backtracking that takes place, and
358 checking it out can be instructive. For most simple matches, the number
359 is quite small, but for patterns with very large numbers of matching
360 possibilities, it can become large very quickly with increasing length
361 of subject string. The match_limit_recursion number is a measure of how
362 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
363 memory is needed to complete the match attempt.
365 When \O is used, the value specified may be higher or lower than the
366 size set by the -O command line option (or defaulted to 45); \O applies
367 only to the call of pcre_exec() for the line in which it appears.
369 If the /P modifier was present on the pattern, causing the POSIX wrap-
370 per API to be used, the only option-setting sequences that have any
371 effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
372 to be passed to regexec().
374 The use of \x{hh...} to represent UTF-8 characters is not dependent on
375 the use of the /8 modifier on the pattern. It is recognized always.
376 There may be any number of hexadecimal digits inside the braces. The
377 result is from one to six bytes, encoded according to the UTF-8 rules.
380 THE ALTERNATIVE MATCHING FUNCTION
382 By default, pcretest uses the standard PCRE matching function,
383 pcre_exec() to match each data line. From release 6.0, PCRE supports an
384 alternative matching function, pcre_dfa_test(), which operates in a
385 different way, and has some restrictions. The differences between the
386 two functions are described in the pcrematching documentation.
388 If a data line contains the \D escape sequence, or if the command line
389 contains the -dfa option, the alternative matching function is called.
390 This function finds all possible matches at a given point. If, however,
391 the \F escape sequence is present in the data line, it stops after the
392 first match is found. This is always the shortest possible match.
395 DEFAULT OUTPUT FROM PCRETEST
397 This section describes the output when the normal matching function,
398 pcre_exec(), is being used.
400 When a match succeeds, pcretest outputs the list of captured substrings
401 that pcre_exec() returns, starting with number 0 for the string that
402 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
403 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
404 TIAL, respectively, and otherwise the PCRE negative error number. Here
405 is an example of an interactive pcretest run.
408 PCRE version 7.0 30-Nov-2006
417 If the strings contain any non-printing characters, they are output as
418 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
419 the pattern. See below for the definition of non-printing characters.
420 If the pattern has the /+ modifier, the output for substring 0 is fol-
421 lowed by the the rest of the subject string, identified by "0+" like
429 If the pattern has the /g or /G modifier, the results of successive
430 matching attempts are output in sequence, like this:
441 "No match" is output only if the first match attempt fails.
443 If any of the sequences \C, \G, or \L are present in a data line that
444 is successfully matched, the substrings extracted by the convenience
445 functions are output with C, G, or L after the string number instead of
446 a colon. This is in addition to the normal full list. The string length
447 (that is, the return from the extraction function) is given in paren-
448 theses after each string for \C and \G.
450 Note that whereas patterns can be continued over several lines (a plain
451 ">" prompt is used for continuations), data lines may not. However new-
452 lines can be included in data by means of the \n escape (or \r, \r\n,
453 etc., depending on the newline sequence setting).
456 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
458 When the alternative matching function, pcre_dfa_exec(), is used (by
459 means of the \D escape sequence or the -dfa command line option), the
460 output consists of a list of all the matches that start at the first
461 point in the subject where there is at least one match. For example:
463 re> /(tang|tangerine|tan)/
464 data> yellow tangerine\D
469 (Using the normal matching function on this data finds only "tang".)
470 The longest matching string is always given first (and numbered zero).
472 If /g is present on the pattern, the search for further matches resumes
473 at the end of the longest match. For example:
475 re> /(tang|tangerine|tan)/g
476 data> yellow tangerine and tangy sultana\D
484 Since the matching function does not support substring capture, the
485 escape sequences that are concerned with captured substrings are not
489 RESTARTING AFTER A PARTIAL MATCH
491 When the alternative matching function has given the PCRE_ERROR_PARTIAL
492 return, indicating that the subject partially matched the pattern, you
493 can restart the match with additional subject data by means of the \R
494 escape sequence. For example:
496 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
502 For further information about partial matching, see the pcrepartial
508 If the pattern contains any callout requests, pcretest's callout func-
509 tion is called during matching. This works with both matching func-
510 tions. By default, the called function displays the callout number, the
511 start and current positions in the text at the callout time, and the
512 next pattern item to be tested. For example, the output
517 indicates that callout number 0 occurred for a match attempt starting
518 at the fourth character of the subject string, when the pointer was at
519 the seventh character of the data, and when the next pattern item was
520 \d. Just one circumflex is output if the start and current positions
523 Callouts numbered 255 are assumed to be automatic callouts, inserted as
524 a result of the /C pattern modifier. In this case, instead of showing
525 the callout number, the offset in the pattern, preceded by a plus, is
537 The callout function in pcretest returns zero (carry on matching) by
538 default, but you can use a \C item in a data line (as described above)
541 Inserting callouts can be helpful when using pcretest to check compli-
542 cated regular expressions. For further information about callouts, see
543 the pcrecallout documentation.
546 NON-PRINTING CHARACTERS
548 When pcretest is outputting text in the compiled version of a pattern,
549 bytes other than 32-126 are always treated as non-printing characters
550 are are therefore shown as hex escapes.
552 When pcretest is outputting text that is a matched part of a subject
553 string, it behaves in the same way, unless a different locale has been
554 set for the pattern (using the /L modifier). In this case, the
555 isprint() function to distinguish printing and non-printing characters.
558 SAVING AND RELOADING COMPILED PATTERNS
560 The facilities described in this section are not available when the
561 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
564 When the POSIX interface is not in use, you can cause pcretest to write
565 a compiled pattern to a file, by following the modifiers with > and a
566 file name. For example:
568 /pattern/im >/some/file
570 See the pcreprecompile documentation for a discussion about saving and
571 re-using compiled patterns.
573 The data that is written is binary. The first eight bytes are the
574 length of the compiled pattern data followed by the length of the
575 optional study data, each written as four bytes in big-endian order
576 (most significant byte first). If there is no study data (either the
577 pattern was not studied, or studying did not return any data), the sec-
578 ond length is zero. The lengths are followed by an exact copy of the
579 compiled pattern. If there is additional study data, this follows imme-
580 diately after the compiled pattern. After writing the file, pcretest
581 expects to read a new pattern.
583 A saved pattern can be reloaded into pcretest by specifing < and a file
584 name instead of a pattern. The name of the file must not contain a <
585 character, as otherwise pcretest will interpret the line as a pattern
586 delimited by < characters. For example:
589 Compiled regex loaded from /some/file
592 When the pattern has been loaded, pcretest proceeds to read data lines
595 You can copy a file written by pcretest to a different host and reload
596 it there, even if the new host has opposite endianness to the one on
597 which the pattern was compiled. For example, you can compile on an i86
598 machine and run on a SPARC machine.
600 File names for saving and reloading can be absolute or relative, but
601 note that the shell facility of expanding a file name that starts with
602 a tilde (~) is not available.
604 The ability to save and reload files in pcretest is intended for test-
605 ing and experimentation. It is not intended for production use because
606 only a single pattern can be written to a file. Furthermore, there is
607 no facility for supplying custom character tables for use with a
608 reloaded pattern. If the original pattern was compiled with custom
609 tables, an attempt to match a subject string using a reloaded pattern
610 is likely to cause pcretest to crash. Finally, if you attempt to load
611 a file that is not in the correct format, the result is undefined.
616 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
617 pcrepattern(3), pcreprecompile(3).
623 University Computing Service
624 Cambridge CB2 3QH, England.
629 Last updated: 24 April 2007
630 Copyright (c) 1997-2007 University of Cambridge.
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