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 /<any> PCRE_NEWLINE_ANY
167 Those specifying line ending sequencess are literal strings as shown.
168 This example sets multiline matching with CRLF as the line ending
173 Details of the meanings of these PCRE options are given in the pcreapi
176 Finding all matches in a string
178 Searching for all possible matches within each subject string can be
179 requested by the /g or /G modifier. After finding a match, PCRE is
180 called again to search the remainder of the subject string. The differ-
181 ence between /g and /G is that the former uses the startoffset argument
182 to pcre_exec() to start searching at a new point within the entire
183 string (which is in effect what Perl does), whereas the latter passes
184 over a shortened substring. This makes a difference to the matching
185 process if the pattern begins with a lookbehind assertion (including \b
188 If any call to pcre_exec() in a /g or /G sequence matches an empty
189 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
190 flags set in order to search for another, non-empty, match at the same
191 point. If this second match fails, the start offset is advanced by
192 one, and the normal match is retried. This imitates the way Perl han-
193 dles such cases when using the /g modifier or the split() function.
197 There are yet more modifiers for controlling the way pcretest operates.
199 The /+ modifier requests that as well as outputting the substring that
200 matched the entire pattern, pcretest should in addition output the
201 remainder of the subject string. This is useful for tests where the
202 subject contains multiple copies of the same substring.
204 The /B modifier is a debugging feature. It requests that pcretest out-
205 put a representation of the compiled byte code after compilation.
207 The /L modifier must be followed directly by the name of a locale, for
212 For this reason, it must be the last modifier. The given locale is set,
213 pcre_maketables() is called to build a set of character tables for the
214 locale, and this is then passed to pcre_compile() when compiling the
215 regular expression. Without an /L modifier, NULL is passed as the
216 tables pointer; that is, /L applies only to the expression on which it
219 The /I modifier requests that pcretest output information about the
220 compiled pattern (whether it is anchored, has a fixed first character,
221 and so on). It does this by calling pcre_fullinfo() after compiling a
222 pattern. If the pattern is studied, the results of that are also out-
225 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
226 that is, both the /B and the /I modifiers.
228 The /F modifier causes pcretest to flip the byte order of the fields in
229 the compiled pattern that contain 2-byte and 4-byte numbers. This
230 facility is for testing the feature in PCRE that allows it to execute
231 patterns that were compiled on a host with a different endianness. This
232 feature is not available when the POSIX interface to PCRE is being
233 used, that is, when the /P pattern modifier is specified. See also the
234 section about saving and reloading compiled patterns below.
236 The /S modifier causes pcre_study() to be called after the expression
237 has been compiled, and the results used when the expression is matched.
239 The /M modifier causes the size of memory block used to hold the com-
240 piled pattern to be output.
242 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
243 rather than its native API. When this is done, all other modifiers
244 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
245 and REG_NEWLINE is set if /m is present. The wrapper functions force
246 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
248 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
249 set. This turns on support for UTF-8 character handling in PCRE, pro-
250 vided that it was compiled with this support enabled. This modifier
251 also causes any non-printing characters in output strings to be printed
252 using the \x{hh...} notation if they are valid UTF-8 sequences.
254 If the /? modifier is used with /8, it causes pcretest to call
255 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
256 checking of the string for UTF-8 validity.
261 Before each data line is passed to pcre_exec(), leading and trailing
262 whitespace is removed, and it is then scanned for \ escapes. Some of
263 these are pretty esoteric features, intended for checking out some of
264 the more complicated features of PCRE. If you are just testing "ordi-
265 nary" regular expressions, you probably don't need any of these. The
266 following escapes are recognized:
273 \qdd set the PCRE_MATCH_LIMIT limit to dd
274 (any number of digits)
275 \r carriage return (\x0d)
277 \v vertical tab (\x0b)
278 \nnn octal character (up to 3 octal digits)
279 \xhh hexadecimal character (up to 2 hex digits)
280 \x{hh...} hexadecimal character, any number of digits
282 \A pass the PCRE_ANCHORED option to pcre_exec()
284 \B pass the PCRE_NOTBOL option to pcre_exec()
286 \Cdd call pcre_copy_substring() for substring dd
287 after a successful match (number less than 32)
288 \Cname call pcre_copy_named_substring() for substring
289 "name" after a successful match (name termin-
290 ated by next non alphanumeric character)
291 \C+ show the current captured substrings at callout
293 \C- do not supply a callout function
294 \C!n return 1 instead of 0 when callout number n is
296 \C!n!m return 1 instead of 0 when callout number n is
297 reached for the nth time
298 \C*n pass the number n (may be negative) as callout
299 data; this is used as the callout return value
300 \D use the pcre_dfa_exec() match function
301 \F only shortest match for pcre_dfa_exec()
302 \Gdd call pcre_get_substring() for substring dd
303 after a successful match (number less than 32)
304 \Gname call pcre_get_named_substring() for substring
305 "name" after a successful match (name termin-
306 ated by next non-alphanumeric character)
307 \L call pcre_get_substringlist() after a
309 \M discover the minimum MATCH_LIMIT and
310 MATCH_LIMIT_RECURSION settings
311 \N pass the PCRE_NOTEMPTY option to pcre_exec()
313 \Odd set the size of the output vector passed to
314 pcre_exec() to dd (any number of digits)
315 \P pass the PCRE_PARTIAL option to pcre_exec()
317 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
318 (any number of digits)
319 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
320 \S output details of memory get/free calls during matching
321 \Z pass the PCRE_NOTEOL option to pcre_exec()
323 \? pass the PCRE_NO_UTF8_CHECK option to
324 pcre_exec() or pcre_dfa_exec()
325 \>dd start the match at offset dd (any number of digits);
326 this sets the startoffset argument for pcre_exec()
328 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
330 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
332 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
334 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
337 The escapes that specify line ending sequences are literal strings,
338 exactly as shown. No more than one newline setting should be present in
341 A backslash followed by anything else just escapes the anything else.
342 If the very last character is a backslash, it is ignored. This gives a
343 way of passing an empty line as data, since a real empty line termi-
344 nates the data input.
346 If \M is present, pcretest calls pcre_exec() several times, with dif-
347 ferent values in the match_limit and match_limit_recursion fields of
348 the pcre_extra data structure, until it finds the minimum numbers for
349 each parameter that allow pcre_exec() to complete. The match_limit num-
350 ber is a measure of the amount of backtracking that takes place, and
351 checking it out can be instructive. For most simple matches, the number
352 is quite small, but for patterns with very large numbers of matching
353 possibilities, it can become large very quickly with increasing length
354 of subject string. The match_limit_recursion number is a measure of how
355 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
356 memory is needed to complete the match attempt.
358 When \O is used, the value specified may be higher or lower than the
359 size set by the -O command line option (or defaulted to 45); \O applies
360 only to the call of pcre_exec() for the line in which it appears.
362 If the /P modifier was present on the pattern, causing the POSIX wrap-
363 per API to be used, the only option-setting sequences that have any
364 effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
365 to be passed to regexec().
367 The use of \x{hh...} to represent UTF-8 characters is not dependent on
368 the use of the /8 modifier on the pattern. It is recognized always.
369 There may be any number of hexadecimal digits inside the braces. The
370 result is from one to six bytes, encoded according to the UTF-8 rules.
373 THE ALTERNATIVE MATCHING FUNCTION
375 By default, pcretest uses the standard PCRE matching function,
376 pcre_exec() to match each data line. From release 6.0, PCRE supports an
377 alternative matching function, pcre_dfa_test(), which operates in a
378 different way, and has some restrictions. The differences between the
379 two functions are described in the pcrematching documentation.
381 If a data line contains the \D escape sequence, or if the command line
382 contains the -dfa option, the alternative matching function is called.
383 This function finds all possible matches at a given point. If, however,
384 the \F escape sequence is present in the data line, it stops after the
385 first match is found. This is always the shortest possible match.
388 DEFAULT OUTPUT FROM PCRETEST
390 This section describes the output when the normal matching function,
391 pcre_exec(), is being used.
393 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.
401 PCRE version 7.0 30-Nov-2006
410 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
422 If the pattern has the /g or /G modifier, the results of successive
423 matching attempts are output in sequence, like this:
434 "No match" is output only if the first match attempt fails.
436 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.
443 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).
449 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
451 When the alternative matching function, pcre_dfa_exec(), is used (by
452 means of the \D escape sequence or the -dfa command line option), the
453 output consists of a list of all the matches that start at the first
454 point in the subject where there is at least one match. For example:
456 re> /(tang|tangerine|tan)/
457 data> yellow tangerine\D
462 (Using the normal matching function on this data finds only "tang".)
463 The longest matching string is always given first (and numbered zero).
465 If /g is present on the pattern, the search for further matches resumes
466 at the end of the longest match. For example:
468 re> /(tang|tangerine|tan)/g
469 data> yellow tangerine and tangy sultana\D
477 Since the matching function does not support substring capture, the
478 escape sequences that are concerned with captured substrings are not
482 RESTARTING AFTER A PARTIAL MATCH
484 When the alternative matching function has given the PCRE_ERROR_PARTIAL
485 return, indicating that the subject partially matched the pattern, you
486 can restart the match with additional subject data by means of the \R
487 escape sequence. For example:
489 re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
495 For further information about partial matching, see the pcrepartial
501 If the pattern contains any callout requests, pcretest's callout func-
502 tion is called during matching. This works with both matching func-
503 tions. By default, the called function displays the callout number, the
504 start and current positions in the text at the callout time, and the
505 next pattern item to be tested. For example, the output
510 indicates that callout number 0 occurred for a match attempt starting
511 at the fourth character of the subject string, when the pointer was at
512 the seventh character of the data, and when the next pattern item was
513 \d. Just one circumflex is output if the start and current positions
516 Callouts numbered 255 are assumed to be automatic callouts, inserted as
517 a result of the /C pattern modifier. In this case, instead of showing
518 the callout number, the offset in the pattern, preceded by a plus, is
530 The callout function in pcretest returns zero (carry on matching) by
531 default, but you can use a \C item in a data line (as described above)
534 Inserting callouts can be helpful when using pcretest to check compli-
535 cated regular expressions. For further information about callouts, see
536 the pcrecallout documentation.
539 NON-PRINTING CHARACTERS
541 When pcretest is outputting text in the compiled version of a pattern,
542 bytes other than 32-126 are always treated as non-printing characters
543 are are therefore shown as hex escapes.
545 When pcretest is outputting text that is a matched part of a subject
546 string, it behaves in the same way, unless a different locale has been
547 set for the pattern (using the /L modifier). In this case, the
548 isprint() function to distinguish printing and non-printing characters.
551 SAVING AND RELOADING COMPILED PATTERNS
553 The facilities described in this section are not available when the
554 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
557 When the POSIX interface is not in use, you can cause pcretest to write
558 a compiled pattern to a file, by following the modifiers with > and a
559 file name. For example:
561 /pattern/im >/some/file
563 See the pcreprecompile documentation for a discussion about saving and
564 re-using compiled patterns.
566 The data that is written is binary. The first eight bytes are the
567 length of the compiled pattern data followed by the length of the
568 optional study data, each written as four bytes in big-endian order
569 (most significant byte first). If there is no study data (either the
570 pattern was not studied, or studying did not return any data), the sec-
571 ond length is zero. The lengths are followed by an exact copy of the
572 compiled pattern. If there is additional study data, this follows imme-
573 diately after the compiled pattern. After writing the file, pcretest
574 expects to read a new pattern.
576 A saved pattern can be reloaded into pcretest by specifing < and a file
577 name instead of a pattern. The name of the file must not contain a <
578 character, as otherwise pcretest will interpret the line as a pattern
579 delimited by < characters. For example:
582 Compiled regex loaded from /some/file
585 When the pattern has been loaded, pcretest proceeds to read data lines
588 You can copy a file written by pcretest to a different host and reload
589 it there, even if the new host has opposite endianness to the one on
590 which the pattern was compiled. For example, you can compile on an i86
591 machine and run on a SPARC machine.
593 File names for saving and reloading can be absolute or relative, but
594 note that the shell facility of expanding a file name that starts with
595 a tilde (~) is not available.
597 The ability to save and reload files in pcretest is intended for test-
598 ing and experimentation. It is not intended for production use because
599 only a single pattern can be written to a file. Furthermore, there is
600 no facility for supplying custom character tables for use with a
601 reloaded pattern. If the original pattern was compiled with custom
602 tables, an attempt to match a subject string using a reloaded pattern
603 is likely to cause pcretest to crash. Finally, if you attempt to load
604 a file that is not in the correct format, the result is undefined.
609 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
610 pcrepattern(3), pcreprecompile(3).
616 University Computing Service,
617 Cambridge CB2 3QH, England.
619 Last updated: 30 November 2006
620 Copyright (c) 1997-2006 University of Cambridge.
git://git.exim.org / exim.git / blob