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1 .TH PCRETEST 1
2 .SH NAME
3 pcretest - a program for testing Perl-compatible regular expressions.
4 .SH SYNOPSIS
5 .rs
6 .sp
7 .B pcretest "[-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]"
8 .ti +5n
9 .B "[destination]"
10 .P
11 \fBpcretest\fP was written as a test program for the PCRE regular expression
12 library itself, but it can also be used for experimenting with regular
13 expressions. This document describes the features of the test program; for
14 details of the regular expressions themselves, see the
15 .\" HREF
16 \fBpcrepattern\fP
17 .\"
18 documentation. For details of the PCRE library function calls and their
19 options, see the
20 .\" HREF
21 \fBpcreapi\fP
22 .\"
23 documentation.
24 .
25 .
26 .SH OPTIONS
27 .rs
28 .TP 10
29 \fB-C\fP
30 Output the version number of the PCRE library, and all available information
31 about the optional features that are included, and then exit.
32 .TP 10
33 \fB-d\fP
34 Behave as if each regex had the \fB/D\fP (debug) modifier; the internal
35 form is output after compilation.
36 .TP 10
37 \fB-i\fP
38 Behave as if each regex had the \fB/I\fP modifier; information about the
39 compiled pattern is given after compilation.
40 .TP 10
41 \fB-m\fP
42 Output the size of each compiled pattern after it has been compiled. This is
43 equivalent to adding \fB/M\fP to each regular expression. For compatibility
44 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
45 .TP 10
46 \fB-o\fP \fIosize\fP
47 Set the number of elements in the output vector that is used when calling
48 \fBpcre_exec()\fP to be \fIosize\fP. The default value is 45, which is enough
49 for 14 capturing subexpressions. The vector size can be changed for individual
50 matching calls by including \eO in the data line (see below).
51 .TP 10
52 \fB-p\fP
53 Behave as if each regex has \fB/P\fP modifier; the POSIX wrapper API is used
54 to call PCRE. None of the other options has any effect when \fB-p\fP is set.
55 .TP 10
56 \fB-t\fP
57 Run each compile, study, and match many times with a timer, and output
58 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
59 \fB-t\fP, because you will then get the size output a zillion times, and the
60 timing will be distorted.
61 .
62 .
63 .SH DESCRIPTION
64 .rs
65 .sp
66 If \fBpcretest\fP is given two filename arguments, it reads from the first and
67 writes to the second. If it is given only one filename argument, it reads from
68 that file and writes to stdout. Otherwise, it reads from stdin and writes to
69 stdout, and prompts for each line of input, using "re>" to prompt for regular
70 expressions, and "data>" to prompt for data lines.
71 .P
72 The program handles any number of sets of input on a single input file. Each
73 set starts with a regular expression, and continues with any number of data
74 lines to be matched against the pattern.
75 .P
76 Each data line is matched separately and independently. If you want to do
77 multiple-line matches, you have to use the \en escape sequence in a single line
78 of input to encode the newline characters. The maximum length of data line is
79 30,000 characters.
80 .P
81 An empty line signals the end of the data lines, at which point a new regular
82 expression is read. The regular expressions are given enclosed in any
83 non-alphanumeric delimiters other than backslash, for example
84 .sp
85 /(a|bc)x+yz/
86 .sp
87 White space before the initial delimiter is ignored. A regular expression may
88 be continued over several input lines, in which case the newline characters are
89 included within it. It is possible to include the delimiter within the pattern
90 by escaping it, for example
91 .sp
92 /abc\e/def/
93 .sp
94 If you do so, the escape and the delimiter form part of the pattern, but since
95 delimiters are always non-alphanumeric, this does not affect its interpretation.
96 If the terminating delimiter is immediately followed by a backslash, for
97 example,
98 .sp
99 /abc/\e
100 .sp
101 then a backslash is added to the end of the pattern. This is done to provide a
102 way of testing the error condition that arises if a pattern finishes with a
103 backslash, because
104 .sp
105 /abc\e/
106 .sp
107 is interpreted as the first line of a pattern that starts with "abc/", causing
108 pcretest to read the next line as a continuation of the regular expression.
109 .
110 .
111 .SH "PATTERN MODIFIERS"
112 .rs
113 .sp
114 A pattern may be followed by any number of modifiers, which are mostly single
115 characters. Following Perl usage, these are referred to below as, for example,
116 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
117 always be a slash, and no slash is used when writing modifiers. Whitespace may
118 appear between the final pattern delimiter and the first modifier, and between
119 the modifiers themselves.
120 .P
121 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
122 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
123 \fBpcre_compile()\fP is called. These four modifier letters have the same
124 effect as they do in Perl. For example:
125 .sp
126 /caseless/i
127 .sp
128 The following table shows additional modifiers for setting PCRE options that do
129 not correspond to anything in Perl:
130 .sp
131 \fB/A\fP PCRE_ANCHORED
132 \fB/C\fP PCRE_AUTO_CALLOUT
133 \fB/E\fP PCRE_DOLLAR_ENDONLY
134 \fB/N\fP PCRE_NO_AUTO_CAPTURE
135 \fB/U\fP PCRE_UNGREEDY
136 \fB/X\fP PCRE_EXTRA
137 .sp
138 Searching for all possible matches within each subject string can be requested
139 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
140 again to search the remainder of the subject string. The difference between
141 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
142 \fBpcre_exec()\fP to start searching at a new point within the entire string
143 (which is in effect what Perl does), whereas the latter passes over a shortened
144 substring. This makes a difference to the matching process if the pattern
145 begins with a lookbehind assertion (including \eb or \eB).
146 .P
147 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
148 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
149 flags set in order to search for another, non-empty, match at the same point.
150 If this second match fails, the start offset is advanced by one, and the normal
151 match is retried. This imitates the way Perl handles such cases when using the
152 \fB/g\fP modifier or the \fBsplit()\fP function.
153 .P
154 There are yet more modifiers for controlling the way \fBpcretest\fP
155 operates.
156 .P
157 The \fB/+\fP modifier requests that as well as outputting the substring that
158 matched the entire pattern, pcretest should in addition output the remainder of
159 the subject string. This is useful for tests where the subject contains
160 multiple copies of the same substring.
161 .P
162 The \fB/L\fP modifier must be followed directly by the name of a locale, for
163 example,
164 .sp
165 /pattern/Lfr_FR
166 .sp
167 For this reason, it must be the last modifier. The given locale is set,
168 \fBpcre_maketables()\fP is called to build a set of character tables for the
169 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
170 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
171 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
172 .P
173 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
174 compiled pattern (whether it is anchored, has a fixed first character, and
175 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
176 pattern. If the pattern is studied, the results of that are also output.
177 .P
178 The \fB/D\fP modifier is a PCRE debugging feature, which also assumes \fB/I\fP.
179 It causes the internal form of compiled regular expressions to be output after
180 compilation. If the pattern was studied, the information returned is also
181 output.
182 .P
183 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
184 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
185 facility is for testing the feature in PCRE that allows it to execute patterns
186 that were compiled on a host with a different endianness. This feature is not
187 available when the POSIX interface to PCRE is being used, that is, when the
188 \fB/P\fP pattern modifier is specified. See also the section about saving and
189 reloading compiled patterns below.
190 .P
191 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
192 expression has been compiled, and the results used when the expression is
193 matched.
194 .P
195 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
196 pattern to be output.
197 .P
198 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
199 API rather than its native API. When this is done, all other modifiers except
200 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
201 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
202 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
203 .P
204 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
205 option set. This turns on support for UTF-8 character handling in PCRE,
206 provided that it was compiled with this support enabled. This modifier also
207 causes any non-printing characters in output strings to be printed using the
208 \ex{hh...} notation if they are valid UTF-8 sequences.
209 .P
210 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
211 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
212 checking of the string for UTF-8 validity.
213 .
214 .
215 .SH "DATA LINES"
216 .rs
217 .sp
218 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
219 whitespace is removed, and it is then scanned for \e escapes. Some of these are
220 pretty esoteric features, intended for checking out some of the more
221 complicated features of PCRE. If you are just testing "ordinary" regular
222 expressions, you probably don't need any of these. The following escapes are
223 recognized:
224 .sp
225 \ea alarm (= BEL)
226 \eb backspace
227 \ee escape
228 \ef formfeed
229 \en newline
230 \er carriage return
231 \et tab
232 \ev vertical tab
233 \ennn octal character (up to 3 octal digits)
234 \exhh hexadecimal character (up to 2 hex digits)
235 .\" JOIN
236 \ex{hh...} hexadecimal character, any number of digits
237 in UTF-8 mode
238 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
239 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
240 .\" JOIN
241 \eCdd call pcre_copy_substring() for substring dd
242 after a successful match (number less than 32)
243 .\" JOIN
244 \eCname call pcre_copy_named_substring() for substring
245 "name" after a successful match (name termin-
246 ated by next non alphanumeric character)
247 .\" JOIN
248 \eC+ show the current captured substrings at callout
249 time
250 \eC- do not supply a callout function
251 .\" JOIN
252 \eC!n return 1 instead of 0 when callout number n is
253 reached
254 .\" JOIN
255 \eC!n!m return 1 instead of 0 when callout number n is
256 reached for the nth time
257 .\" JOIN
258 \eC*n pass the number n (may be negative) as callout
259 data; this is used as the callout return value
260 .\" JOIN
261 \eGdd call pcre_get_substring() for substring dd
262 after a successful match (number less than 32)
263 .\" JOIN
264 \eGname call pcre_get_named_substring() for substring
265 "name" after a successful match (name termin-
266 ated by next non-alphanumeric character)
267 .\" JOIN
268 \eL call pcre_get_substringlist() after a
269 successful match
270 \eM discover the minimum MATCH_LIMIT setting
271 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
272 .\" JOIN
273 \eOdd set the size of the output vector passed to
274 \fBpcre_exec()\fP to dd (any number of digits)
275 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
276 \eS output details of memory get/free calls during matching
277 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
278 .\" JOIN
279 \e? pass the PCRE_NO_UTF8_CHECK option to
280 \fBpcre_exec()\fP
281 \e>dd start the match at offset dd (any number of digits);
282 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
283 .sp
284 A backslash followed by anything else just escapes the anything else. If the
285 very last character is a backslash, it is ignored. This gives a way of passing
286 an empty line as data, since a real empty line terminates the data input.
287 .P
288 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
289 different values in the \fImatch_limit\fP field of the \fBpcre_extra\fP data
290 structure, until it finds the minimum number that is needed for
291 \fBpcre_exec()\fP to complete. This number is a measure of the amount of
292 recursion and backtracking that takes place, and checking it out can be
293 instructive. For most simple matches, the number is quite small, but for
294 patterns with very large numbers of matching possibilities, it can become large
295 very quickly with increasing length of subject string.
296 .P
297 When \eO is used, the value specified may be higher or lower than the size set
298 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
299 the call of \fBpcre_exec()\fP for the line in which it appears.
300 .P
301 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
302 API to be used, only \eB and \eZ have any effect, causing REG_NOTBOL and
303 REG_NOTEOL to be passed to \fBregexec()\fP respectively.
304 .P
305 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
306 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
307 any number of hexadecimal digits inside the braces. The result is from one to
308 six bytes, encoded according to the UTF-8 rules.
309 .
310 .
311 .SH "OUTPUT FROM PCRETEST"
312 .rs
313 .sp
314 When a match succeeds, pcretest outputs the list of captured substrings that
315 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
316 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
317 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
318 respectively, and otherwise the PCRE negative error number. Here is an example
319 of an interactive pcretest run.
320 .sp
321 $ pcretest
322 PCRE version 5.00 07-Sep-2004
323 .sp
324 re> /^abc(\ed+)/
325 data> abc123
326 0: abc123
327 1: 123
328 data> xyz
329 No match
330 .sp
331 If the strings contain any non-printing characters, they are output as \e0x
332 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
333 pattern. If the pattern has the \fB/+\fP modifier, the output for substring 0
334 is followed by the the rest of the subject string, identified by "0+" like
335 this:
336 .sp
337 re> /cat/+
338 data> cataract
339 0: cat
340 0+ aract
341 .sp
342 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
343 matching attempts are output in sequence, like this:
344 .sp
345 re> /\eBi(\ew\ew)/g
346 data> Mississippi
347 0: iss
348 1: ss
349 0: iss
350 1: ss
351 0: ipp
352 1: pp
353 .sp
354 "No match" is output only if the first match attempt fails.
355 .P
356 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
357 data line that is successfully matched, the substrings extracted by the
358 convenience functions are output with C, G, or L after the string number
359 instead of a colon. This is in addition to the normal full list. The string
360 length (that is, the return from the extraction function) is given in
361 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
362 .P
363 Note that while patterns can be continued over several lines (a plain ">"
364 prompt is used for continuations), data lines may not. However newlines can be
365 included in data by means of the \en escape.
366 .
367 .
368 .SH CALLOUTS
369 .rs
370 .sp
371 If the pattern contains any callout requests, \fBpcretest\fP's callout function
372 is called during matching. By default, it displays the callout number, the
373 start and current positions in the text at the callout time, and the next
374 pattern item to be tested. For example, the output
375 .sp
376 --->pqrabcdef
377 0 ^ ^ \ed
378 .sp
379 indicates that callout number 0 occurred for a match attempt starting at the
380 fourth character of the subject string, when the pointer was at the seventh
381 character of the data, and when the next pattern item was \ed. Just one
382 circumflex is output if the start and current positions are the same.
383 .P
384 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
385 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
386 callout number, the offset in the pattern, preceded by a plus, is output. For
387 example:
388 .sp
389 re> /\ed?[A-E]\e*/C
390 data> E*
391 --->E*
392 +0 ^ \ed?
393 +3 ^ [A-E]
394 +8 ^^ \e*
395 +10 ^ ^
396 0: E*
397 .sp
398 The callout function in \fBpcretest\fP returns zero (carry on matching) by
399 default, but you can use an \eC item in a data line (as described above) to
400 change this.
401 .P
402 Inserting callouts can be helpful when using \fBpcretest\fP to check
403 complicated regular expressions. For further information about callouts, see
404 the
405 .\" HREF
406 \fBpcrecallout\fP
407 .\"
408 documentation.
409 .
410 .
411 .SH "SAVING AND RELOADING COMPILED PATTERNS"
412 .rs
413 .sp
414 The facilities described in this section are not available when the POSIX
415 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
416 specified.
417 .P
418 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
419 compiled pattern to a file, by following the modifiers with > and a file name.
420 For example:
421 .sp
422 /pattern/im >/some/file
423 .sp
424 See the
425 .\" HREF
426 \fBpcreprecompile\fP
427 .\"
428 documentation for a discussion about saving and re-using compiled patterns.
429 .P
430 The data that is written is binary. The first eight bytes are the length of the
431 compiled pattern data followed by the length of the optional study data, each
432 written as four bytes in big-endian order (most significant byte first). If
433 there is no study data (either the pattern was not studied, or studying did not
434 return any data), the second length is zero. The lengths are followed by an
435 exact copy of the compiled pattern. If there is additional study data, this
436 follows immediately after the compiled pattern. After writing the file,
437 \fBpcretest\fP expects to read a new pattern.
438 .P
439 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
440 name instead of a pattern. The name of the file must not contain a < character,
441 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
442 characters.
443 For example:
444 .sp
445 re> </some/file
446 Compiled regex loaded from /some/file
447 No study data
448 .sp
449 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
450 the usual way.
451 .P
452 You can copy a file written by \fBpcretest\fP to a different host and reload it
453 there, even if the new host has opposite endianness to the one on which the
454 pattern was compiled. For example, you can compile on an i86 machine and run on
455 a SPARC machine.
456 .P
457 File names for saving and reloading can be absolute or relative, but note that
458 the shell facility of expanding a file name that starts with a tilde (~) is not
459 available.
460 .P
461 The ability to save and reload files in \fBpcretest\fP is intended for testing
462 and experimentation. It is not intended for production use because only a
463 single pattern can be written to a file. Furthermore, there is no facility for
464 supplying custom character tables for use with a reloaded pattern. If the
465 original pattern was compiled with custom tables, an attempt to match a subject
466 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
467 Finally, if you attempt to load a file that is not in the correct format, the
468 result is undefined.
469 .
470 .
471 .SH AUTHOR
472 .rs
473 .sp
474 Philip Hazel <ph10@cam.ac.uk>
475 .br
476 University Computing Service,
477 .br
478 Cambridge CB2 3QG, England.
479 .P
480 .in 0
481 Last updated: 10 September 2004
482 .br
483 Copyright (c) 1997-2004 University of Cambridge.

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