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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 nigel 77 .B pcretest "[-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]"
8 nigel 75 .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 nigel 77 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
35 nigel 53 form is output after compilation.
36     .TP 10
37 nigel 77 \fB-dfa\fP
38     Behave as if each data line contains the \eD escape sequence; this causes the
39     alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
40     standard \fBpcre_exec()\fP function (more detail is given below).
41     .TP 10
42 nigel 75 \fB-i\fP
43 nigel 77 Behave as if each regex has the \fB/I\fP modifier; information about the
44 nigel 53 compiled pattern is given after compilation.
45     .TP 10
46 nigel 75 \fB-m\fP
47 nigel 53 Output the size of each compiled pattern after it has been compiled. This is
48 nigel 75 equivalent to adding \fB/M\fP to each regular expression. For compatibility
49     with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
50 nigel 53 .TP 10
51 nigel 75 \fB-o\fP \fIosize\fP
52     Set the number of elements in the output vector that is used when calling
53     \fBpcre_exec()\fP to be \fIosize\fP. The default value is 45, which is enough
54     for 14 capturing subexpressions. The vector size can be changed for individual
55     matching calls by including \eO in the data line (see below).
56 nigel 53 .TP 10
57 nigel 75 \fB-p\fP
58 nigel 77 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
59     used to call PCRE. None of the other options has any effect when \fB-p\fP is
60     set.
61 nigel 53 .TP 10
62 nigel 87 \fP-q\fP
63     Do not output the version number of \fBpcretest\fP at the start of execution.
64     .TP 10
65 nigel 75 \fB-t\fP
66 nigel 63 Run each compile, study, and match many times with a timer, and output
67 nigel 75 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
68     \fB-t\fP, because you will then get the size output a zillion times, and the
69     timing will be distorted.
70     .
71     .
72 nigel 53 .SH DESCRIPTION
73 nigel 63 .rs
74     .sp
75 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
76 nigel 53 writes to the second. If it is given only one filename argument, it reads from
77     that file and writes to stdout. Otherwise, it reads from stdin and writes to
78     stdout, and prompts for each line of input, using "re>" to prompt for regular
79     expressions, and "data>" to prompt for data lines.
80 nigel 75 .P
81 nigel 53 The program handles any number of sets of input on a single input file. Each
82     set starts with a regular expression, and continues with any number of data
83 nigel 63 lines to be matched against the pattern.
84 nigel 75 .P
85     Each data line is matched separately and independently. If you want to do
86     multiple-line matches, you have to use the \en escape sequence in a single line
87 nigel 63 of input to encode the newline characters. The maximum length of data line is
88     30,000 characters.
89 nigel 75 .P
90 nigel 63 An empty line signals the end of the data lines, at which point a new regular
91     expression is read. The regular expressions are given enclosed in any
92 nigel 75 non-alphanumeric delimiters other than backslash, for example
93     .sp
94 nigel 53 /(a|bc)x+yz/
95 nigel 75 .sp
96 nigel 53 White space before the initial delimiter is ignored. A regular expression may
97     be continued over several input lines, in which case the newline characters are
98     included within it. It is possible to include the delimiter within the pattern
99     by escaping it, for example
100 nigel 75 .sp
101     /abc\e/def/
102     .sp
103 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
104 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
105 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
106     example,
107 nigel 75 .sp
108     /abc/\e
109     .sp
110 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
111     way of testing the error condition that arises if a pattern finishes with a
112     backslash, because
113 nigel 75 .sp
114     /abc\e/
115     .sp
116 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
117     pcretest to read the next line as a continuation of the regular expression.
118 nigel 75 .
119     .
120     .SH "PATTERN MODIFIERS"
121 nigel 63 .rs
122     .sp
123 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
124     characters. Following Perl usage, these are referred to below as, for example,
125     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
126     always be a slash, and no slash is used when writing modifiers. Whitespace may
127     appear between the final pattern delimiter and the first modifier, and between
128     the modifiers themselves.
129     .P
130     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
131     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
132     \fBpcre_compile()\fP is called. These four modifier letters have the same
133     effect as they do in Perl. For example:
134     .sp
135 nigel 53 /caseless/i
136 nigel 75 .sp
137     The following table shows additional modifiers for setting PCRE options that do
138     not correspond to anything in Perl:
139     .sp
140     \fB/A\fP PCRE_ANCHORED
141     \fB/C\fP PCRE_AUTO_CALLOUT
142     \fB/E\fP PCRE_DOLLAR_ENDONLY
143 nigel 77 \fB/f\fP PCRE_FIRSTLINE
144 nigel 75 \fB/N\fP PCRE_NO_AUTO_CAPTURE
145     \fB/U\fP PCRE_UNGREEDY
146     \fB/X\fP PCRE_EXTRA
147     .sp
148 nigel 53 Searching for all possible matches within each subject string can be requested
149 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
150 nigel 53 again to search the remainder of the subject string. The difference between
151 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
152     \fBpcre_exec()\fP to start searching at a new point within the entire string
153 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
154     substring. This makes a difference to the matching process if the pattern
155 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
156     .P
157     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
158 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
159     flags set in order to search for another, non-empty, match at the same point.
160     If this second match fails, the start offset is advanced by one, and the normal
161     match is retried. This imitates the way Perl handles such cases when using the
162 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
163     .P
164     There are yet more modifiers for controlling the way \fBpcretest\fP
165 nigel 53 operates.
166 nigel 75 .P
167     The \fB/+\fP modifier requests that as well as outputting the substring that
168 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
169     the subject string. This is useful for tests where the subject contains
170     multiple copies of the same substring.
171 nigel 75 .P
172     The \fB/L\fP modifier must be followed directly by the name of a locale, for
173 nigel 53 example,
174 nigel 75 .sp
175     /pattern/Lfr_FR
176     .sp
177     For this reason, it must be the last modifier. The given locale is set,
178     \fBpcre_maketables()\fP is called to build a set of character tables for the
179     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
180     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
181     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
182     .P
183     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
184     compiled pattern (whether it is anchored, has a fixed first character, and
185     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
186     pattern. If the pattern is studied, the results of that are also output.
187     .P
188     The \fB/D\fP modifier is a PCRE debugging feature, which also assumes \fB/I\fP.
189 nigel 53 It causes the internal form of compiled regular expressions to be output after
190 nigel 63 compilation. If the pattern was studied, the information returned is also
191     output.
192 nigel 75 .P
193     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
194     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
195     facility is for testing the feature in PCRE that allows it to execute patterns
196     that were compiled on a host with a different endianness. This feature is not
197     available when the POSIX interface to PCRE is being used, that is, when the
198     \fB/P\fP pattern modifier is specified. See also the section about saving and
199     reloading compiled patterns below.
200     .P
201     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
202 nigel 53 expression has been compiled, and the results used when the expression is
203     matched.
204 nigel 75 .P
205     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
206 nigel 53 pattern to be output.
207 nigel 75 .P
208     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
209 nigel 53 API rather than its native API. When this is done, all other modifiers except
210 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
211     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
212 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
213 nigel 75 .P
214     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
215 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
216     provided that it was compiled with this support enabled. This modifier also
217     causes any non-printing characters in output strings to be printed using the
218 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
219     .P
220     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
221     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
222 nigel 71 checking of the string for UTF-8 validity.
223 nigel 75 .
224     .
225     .SH "DATA LINES"
226 nigel 63 .rs
227     .sp
228 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
229     whitespace is removed, and it is then scanned for \e escapes. Some of these are
230 nigel 63 pretty esoteric features, intended for checking out some of the more
231     complicated features of PCRE. If you are just testing "ordinary" regular
232     expressions, you probably don't need any of these. The following escapes are
233 nigel 53 recognized:
234 nigel 75 .sp
235     \ea alarm (= BEL)
236     \eb backspace
237     \ee escape
238     \ef formfeed
239     \en newline
240     \er carriage return
241     \et tab
242     \ev vertical tab
243     \ennn octal character (up to 3 octal digits)
244     \exhh hexadecimal character (up to 2 hex digits)
245     .\" JOIN
246     \ex{hh...} hexadecimal character, any number of digits
247 nigel 63 in UTF-8 mode
248 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
249     \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
250     .\" JOIN
251     \eCdd call pcre_copy_substring() for substring dd
252     after a successful match (number less than 32)
253     .\" JOIN
254     \eCname call pcre_copy_named_substring() for substring
255 nigel 63 "name" after a successful match (name termin-
256     ated by next non alphanumeric character)
257 nigel 75 .\" JOIN
258     \eC+ show the current captured substrings at callout
259 nigel 63 time
260 nigel 75 \eC- do not supply a callout function
261     .\" JOIN
262     \eC!n return 1 instead of 0 when callout number n is
263 nigel 63 reached
264 nigel 75 .\" JOIN
265     \eC!n!m return 1 instead of 0 when callout number n is
266 nigel 63 reached for the nth time
267 nigel 75 .\" JOIN
268     \eC*n pass the number n (may be negative) as callout
269     data; this is used as the callout return value
270 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
271     \eF only shortest match for \fBpcre_dfa_exec()\fP
272 nigel 75 .\" JOIN
273     \eGdd call pcre_get_substring() for substring dd
274     after a successful match (number less than 32)
275     .\" JOIN
276     \eGname call pcre_get_named_substring() for substring
277 nigel 63 "name" after a successful match (name termin-
278     ated by next non-alphanumeric character)
279 nigel 75 .\" JOIN
280     \eL call pcre_get_substringlist() after a
281 nigel 63 successful match
282 nigel 87 \eM discover the minimum MATCH_LIMIT and
283     MATCH_LIMIT_RECURSION settings
284 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
285     .\" JOIN
286     \eOdd set the size of the output vector passed to
287     \fBpcre_exec()\fP to dd (any number of digits)
288 nigel 77 .\" JOIN
289 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
290 nigel 77 or \fBpcre_dfa_exec()\fP
291     \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
292 nigel 75 \eS output details of memory get/free calls during matching
293     \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
294     .\" JOIN
295     \e? pass the PCRE_NO_UTF8_CHECK option to
296     \fBpcre_exec()\fP
297     \e>dd start the match at offset dd (any number of digits);
298     this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
299     .sp
300     A backslash followed by anything else just escapes the anything else. If the
301     very last character is a backslash, it is ignored. This gives a way of passing
302     an empty line as data, since a real empty line terminates the data input.
303     .P
304     If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
305 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
306     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
307     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
308     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
309     place, and checking it out can be instructive. For most simple matches, the
310     number is quite small, but for patterns with very large numbers of matching
311     possibilities, it can become large very quickly with increasing length of
312     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
313     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
314     to complete the match attempt.
315 nigel 75 .P
316     When \eO is used, the value specified may be higher or lower than the size set
317     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
318     the call of \fBpcre_exec()\fP for the line in which it appears.
319     .P
320     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
321 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
322     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
323     \fBregexec()\fP.
324 nigel 75 .P
325     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
326     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
327 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
328     six bytes, encoded according to the UTF-8 rules.
329 nigel 75 .
330     .
331 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
332 nigel 63 .rs
333     .sp
334 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
335     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
336     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
337     different way, and has some restrictions. The differences between the two
338     functions are described in the
339     .\" HREF
340     \fBpcrematching\fP
341     .\"
342     documentation.
343     .P
344     If a data line contains the \eD escape sequence, or if the command line
345     contains the \fB-dfa\fP option, the alternative matching function is called.
346     This function finds all possible matches at a given point. If, however, the \eF
347     escape sequence is present in the data line, it stops after the first match is
348     found. This is always the shortest possible match.
349     .
350     .
351     .SH "DEFAULT OUTPUT FROM PCRETEST"
352     .rs
353     .sp
354     This section describes the output when the normal matching function,
355     \fBpcre_exec()\fP, is being used.
356     .P
357 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
358 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
359     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
360     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
361     respectively, and otherwise the PCRE negative error number. Here is an example
362 nigel 77 of an interactive \fBpcretest\fP run.
363 nigel 75 .sp
364 nigel 53 $ pcretest
365 nigel 75 PCRE version 5.00 07-Sep-2004
366     .sp
367     re> /^abc(\ed+)/
368 nigel 53 data> abc123
369     0: abc123
370     1: 123
371     data> xyz
372     No match
373 nigel 75 .sp
374     If the strings contain any non-printing characters, they are output as \e0x
375     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
376     pattern. If the pattern has the \fB/+\fP modifier, the output for substring 0
377     is followed by the the rest of the subject string, identified by "0+" like
378     this:
379     .sp
380 nigel 53 re> /cat/+
381     data> cataract
382     0: cat
383     0+ aract
384 nigel 75 .sp
385     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
386 nigel 53 matching attempts are output in sequence, like this:
387 nigel 75 .sp
388     re> /\eBi(\ew\ew)/g
389 nigel 53 data> Mississippi
390     0: iss
391     1: ss
392     0: iss
393     1: ss
394     0: ipp
395     1: pp
396 nigel 75 .sp
397 nigel 53 "No match" is output only if the first match attempt fails.
398 nigel 75 .P
399     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
400 nigel 53 data line that is successfully matched, the substrings extracted by the
401     convenience functions are output with C, G, or L after the string number
402     instead of a colon. This is in addition to the normal full list. The string
403     length (that is, the return from the extraction function) is given in
404 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
405     .P
406 nigel 53 Note that while patterns can be continued over several lines (a plain ">"
407     prompt is used for continuations), data lines may not. However newlines can be
408 nigel 75 included in data by means of the \en escape.
409     .
410     .
411 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
412     .rs
413     .sp
414     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
415     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
416     output consists of a list of all the matches that start at the first point in
417     the subject where there is at least one match. For example:
418     .sp
419     re> /(tang|tangerine|tan)/
420     data> yellow tangerine\eD
421     0: tangerine
422     1: tang
423     2: tan
424     .sp
425     (Using the normal matching function on this data finds only "tang".) The
426     longest matching string is always given first (and numbered zero).
427     .P
428     If \fB/g\P is present on the pattern, the search for further matches resumes
429     at the end of the longest match. For example:
430     .sp
431     re> /(tang|tangerine|tan)/g
432     data> yellow tangerine and tangy sultana\eD
433     0: tangerine
434     1: tang
435     2: tan
436     0: tang
437     1: tan
438     0: tan
439     .sp
440     Since the matching function does not support substring capture, the escape
441     sequences that are concerned with captured substrings are not relevant.
442     .
443     .
444     .SH "RESTARTING AFTER A PARTIAL MATCH"
445     .rs
446     .sp
447     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
448     indicating that the subject partially matched the pattern, you can restart the
449     match with additional subject data by means of the \eR escape sequence. For
450     example:
451     .sp
452     re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
453     data> 23ja\eP\eD
454     Partial match: 23ja
455     data> n05\eR\eD
456     0: n05
457     .sp
458     For further information about partial matching, see the
459     .\" HREF
460     \fBpcrepartial\fP
461     .\"
462     documentation.
463     .
464     .
465 nigel 75 .SH CALLOUTS
466     .rs
467     .sp
468     If the pattern contains any callout requests, \fBpcretest\fP's callout function
469 nigel 77 is called during matching. This works with both matching functions. By default,
470     the called function displays the callout number, the start and current
471     positions in the text at the callout time, and the next pattern item to be
472     tested. For example, the output
473 nigel 75 .sp
474     --->pqrabcdef
475     0 ^ ^ \ed
476     .sp
477     indicates that callout number 0 occurred for a match attempt starting at the
478     fourth character of the subject string, when the pointer was at the seventh
479     character of the data, and when the next pattern item was \ed. Just one
480     circumflex is output if the start and current positions are the same.
481     .P
482     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
483     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
484     callout number, the offset in the pattern, preceded by a plus, is output. For
485     example:
486     .sp
487     re> /\ed?[A-E]\e*/C
488     data> E*
489     --->E*
490     +0 ^ \ed?
491     +3 ^ [A-E]
492     +8 ^^ \e*
493     +10 ^ ^
494     0: E*
495     .sp
496     The callout function in \fBpcretest\fP returns zero (carry on matching) by
497 nigel 77 default, but you can use a \eC item in a data line (as described above) to
498 nigel 75 change this.
499     .P
500     Inserting callouts can be helpful when using \fBpcretest\fP to check
501     complicated regular expressions. For further information about callouts, see
502     the
503     .\" HREF
504     \fBpcrecallout\fP
505     .\"
506     documentation.
507     .
508     .
509     .SH "SAVING AND RELOADING COMPILED PATTERNS"
510     .rs
511     .sp
512     The facilities described in this section are not available when the POSIX
513     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
514     specified.
515     .P
516     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
517     compiled pattern to a file, by following the modifiers with > and a file name.
518     For example:
519     .sp
520     /pattern/im >/some/file
521     .sp
522     See the
523     .\" HREF
524     \fBpcreprecompile\fP
525     .\"
526     documentation for a discussion about saving and re-using compiled patterns.
527     .P
528     The data that is written is binary. The first eight bytes are the length of the
529     compiled pattern data followed by the length of the optional study data, each
530     written as four bytes in big-endian order (most significant byte first). If
531     there is no study data (either the pattern was not studied, or studying did not
532     return any data), the second length is zero. The lengths are followed by an
533     exact copy of the compiled pattern. If there is additional study data, this
534     follows immediately after the compiled pattern. After writing the file,
535     \fBpcretest\fP expects to read a new pattern.
536     .P
537     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
538     name instead of a pattern. The name of the file must not contain a < character,
539     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
540     characters.
541     For example:
542     .sp
543     re> </some/file
544     Compiled regex loaded from /some/file
545     No study data
546     .sp
547     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
548     the usual way.
549     .P
550     You can copy a file written by \fBpcretest\fP to a different host and reload it
551     there, even if the new host has opposite endianness to the one on which the
552     pattern was compiled. For example, you can compile on an i86 machine and run on
553     a SPARC machine.
554     .P
555     File names for saving and reloading can be absolute or relative, but note that
556     the shell facility of expanding a file name that starts with a tilde (~) is not
557     available.
558     .P
559     The ability to save and reload files in \fBpcretest\fP is intended for testing
560     and experimentation. It is not intended for production use because only a
561     single pattern can be written to a file. Furthermore, there is no facility for
562     supplying custom character tables for use with a reloaded pattern. If the
563     original pattern was compiled with custom tables, an attempt to match a subject
564     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
565     Finally, if you attempt to load a file that is not in the correct format, the
566     result is undefined.
567     .
568     .
569 nigel 53 .SH AUTHOR
570 nigel 63 .rs
571     .sp
572 nigel 77 Philip Hazel
573 nigel 53 .br
574     University Computing Service,
575     .br
576     Cambridge CB2 3QG, England.
577 nigel 75 .P
578 nigel 63 .in 0
579 nigel 87 Last updated: 18 January 2006
580 nigel 53 .br
581 nigel 87 Copyright (c) 1997-2006 University of Cambridge.

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