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1 nigel 53 .TH PCRETEST 1
2     .SH NAME
3     pcretest - a program for testing Perl-compatible regular expressions.
4     .SH SYNOPSIS
5 nigel 75 .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 nigel 53 library itself, but it can also be used for experimenting with regular
13 nigel 63 expressions. This document describes the features of the test program; for
14     details of the regular expressions themselves, see the
15     .\" HREF
16 nigel 75 \fBpcrepattern\fP
17 nigel 63 .\"
18 nigel 75 documentation. For details of the PCRE library function calls and their
19     options, see the
20 nigel 63 .\" HREF
21 nigel 75 \fBpcreapi\fP
22 nigel 63 .\"
23     documentation.
24 nigel 75 .
25     .
26 nigel 53 .SH OPTIONS
27 nigel 63 .rs
28 nigel 53 .TP 10
29 nigel 75 \fB-C\fP
30 nigel 63 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 nigel 75 \fB-d\fP
34     Behave as if each regex had the \fB/D\fP (debug) modifier; the internal
35 nigel 53 form is output after compilation.
36     .TP 10
37 nigel 75 \fB-i\fP
38     Behave as if each regex had the \fB/I\fP modifier; information about the
39 nigel 53 compiled pattern is given after compilation.
40     .TP 10
41 nigel 75 \fB-m\fP
42 nigel 53 Output the size of each compiled pattern after it has been compiled. This is
43 nigel 75 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 nigel 53 .TP 10
46 nigel 75 \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 nigel 53 .TP 10
52 nigel 75 \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 nigel 53 .TP 10
56 nigel 75 \fB-t\fP
57 nigel 63 Run each compile, study, and match many times with a timer, and output
58 nigel 75 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 nigel 53 .SH DESCRIPTION
64 nigel 63 .rs
65     .sp
66 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
67 nigel 53 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 nigel 75 .P
72 nigel 53 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 nigel 63 lines to be matched against the pattern.
75 nigel 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 nigel 63 of input to encode the newline characters. The maximum length of data line is
79     30,000 characters.
80 nigel 75 .P
81 nigel 63 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 nigel 75 non-alphanumeric delimiters other than backslash, for example
84     .sp
85 nigel 53 /(a|bc)x+yz/
86 nigel 75 .sp
87 nigel 53 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 nigel 75 .sp
92     /abc\e/def/
93     .sp
94 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
95 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
96 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
97     example,
98 nigel 75 .sp
99     /abc/\e
100     .sp
101 nigel 53 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 nigel 75 .sp
105     /abc\e/
106     .sp
107 nigel 53 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 nigel 75 .
110     .
111     .SH "PATTERN MODIFIERS"
112 nigel 63 .rs
113     .sp
114 nigel 75 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 nigel 53 /caseless/i
127 nigel 75 .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 nigel 53 Searching for all possible matches within each subject string can be requested
139 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
140 nigel 53 again to search the remainder of the subject string. The difference between
141 nigel 75 \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 nigel 53 (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 nigel 75 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 nigel 53 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 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
153     .P
154     There are yet more modifiers for controlling the way \fBpcretest\fP
155 nigel 53 operates.
156 nigel 75 .P
157     The \fB/+\fP modifier requests that as well as outputting the substring that
158 nigel 53 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 nigel 75 .P
162     The \fB/L\fP modifier must be followed directly by the name of a locale, for
163 nigel 53 example,
164 nigel 75 .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 nigel 53 It causes the internal form of compiled regular expressions to be output after
180 nigel 63 compilation. If the pattern was studied, the information returned is also
181     output.
182 nigel 75 .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 nigel 53 expression has been compiled, and the results used when the expression is
193     matched.
194 nigel 75 .P
195     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
196 nigel 53 pattern to be output.
197 nigel 75 .P
198     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
199 nigel 53 API rather than its native API. When this is done, all other modifiers except
200 nigel 75 \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 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
203 nigel 75 .P
204     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
205 nigel 63 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 nigel 75 \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 nigel 71 checking of the string for UTF-8 validity.
213 nigel 75 .
214     .
215     .SH "DATA LINES"
216 nigel 63 .rs
217     .sp
218 nigel 75 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 nigel 63 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 nigel 53 recognized:
224 nigel 75 .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 nigel 63 in UTF-8 mode
238 nigel 75 \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 nigel 63 "name" after a successful match (name termin-
246     ated by next non alphanumeric character)
247 nigel 75 .\" JOIN
248     \eC+ show the current captured substrings at callout
249 nigel 63 time
250 nigel 75 \eC- do not supply a callout function
251     .\" JOIN
252     \eC!n return 1 instead of 0 when callout number n is
253 nigel 63 reached
254 nigel 75 .\" JOIN
255     \eC!n!m return 1 instead of 0 when callout number n is
256 nigel 63 reached for the nth time
257 nigel 75 .\" 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 nigel 63 "name" after a successful match (name termin-
266     ated by next non-alphanumeric character)
267 nigel 75 .\" JOIN
268     \eL call pcre_get_substringlist() after a
269 nigel 63 successful match
270 nigel 75 \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 nigel 63 structure, until it finds the minimum number that is needed for
291 nigel 75 \fBpcre_exec()\fP to complete. This number is a measure of the amount of
292 nigel 63 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 nigel 75 .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 nigel 53 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 nigel 75 .
310     .
311     .SH "OUTPUT FROM PCRETEST"
312 nigel 63 .rs
313     .sp
314 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
315 nigel 75 \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 nigel 53 $ pcretest
322 nigel 75 PCRE version 5.00 07-Sep-2004
323     .sp
324     re> /^abc(\ed+)/
325 nigel 53 data> abc123
326     0: abc123
327     1: 123
328     data> xyz
329     No match
330 nigel 75 .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 nigel 53 re> /cat/+
338     data> cataract
339     0: cat
340     0+ aract
341 nigel 75 .sp
342     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
343 nigel 53 matching attempts are output in sequence, like this:
344 nigel 75 .sp
345     re> /\eBi(\ew\ew)/g
346 nigel 53 data> Mississippi
347     0: iss
348     1: ss
349     0: iss
350     1: ss
351     0: ipp
352     1: pp
353 nigel 75 .sp
354 nigel 53 "No match" is output only if the first match attempt fails.
355 nigel 75 .P
356     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
357 nigel 53 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 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
362     .P
363 nigel 53 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 nigel 75 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 nigel 53 .SH AUTHOR
472 nigel 63 .rs
473     .sp
474 nigel 53 Philip Hazel <ph10@cam.ac.uk>
475     .br
476     University Computing Service,
477     .br
478     Cambridge CB2 3QG, England.
479 nigel 75 .P
480 nigel 63 .in 0
481 nigel 75 Last updated: 10 September 2004
482 nigel 53 .br
483 nigel 75 Copyright (c) 1997-2004 University of Cambridge.

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