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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 75 \fB-t\fP
63 nigel 63 Run each compile, study, and match many times with a timer, and output
64 nigel 75 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
65     \fB-t\fP, because you will then get the size output a zillion times, and the
66     timing will be distorted.
67     .
68     .
69 nigel 53 .SH DESCRIPTION
70 nigel 63 .rs
71     .sp
72 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
73 nigel 53 writes to the second. If it is given only one filename argument, it reads from
74     that file and writes to stdout. Otherwise, it reads from stdin and writes to
75     stdout, and prompts for each line of input, using "re>" to prompt for regular
76     expressions, and "data>" to prompt for data lines.
77 nigel 75 .P
78 nigel 53 The program handles any number of sets of input on a single input file. Each
79     set starts with a regular expression, and continues with any number of data
80 nigel 63 lines to be matched against the pattern.
81 nigel 75 .P
82     Each data line is matched separately and independently. If you want to do
83     multiple-line matches, you have to use the \en escape sequence in a single line
84 nigel 63 of input to encode the newline characters. The maximum length of data line is
85     30,000 characters.
86 nigel 75 .P
87 nigel 63 An empty line signals the end of the data lines, at which point a new regular
88     expression is read. The regular expressions are given enclosed in any
89 nigel 75 non-alphanumeric delimiters other than backslash, for example
90     .sp
91 nigel 53 /(a|bc)x+yz/
92 nigel 75 .sp
93 nigel 53 White space before the initial delimiter is ignored. A regular expression may
94     be continued over several input lines, in which case the newline characters are
95     included within it. It is possible to include the delimiter within the pattern
96     by escaping it, for example
97 nigel 75 .sp
98     /abc\e/def/
99     .sp
100 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
101 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
102 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
103     example,
104 nigel 75 .sp
105     /abc/\e
106     .sp
107 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
108     way of testing the error condition that arises if a pattern finishes with a
109     backslash, because
110 nigel 75 .sp
111     /abc\e/
112     .sp
113 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
114     pcretest to read the next line as a continuation of the regular expression.
115 nigel 75 .
116     .
117     .SH "PATTERN MODIFIERS"
118 nigel 63 .rs
119     .sp
120 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
121     characters. Following Perl usage, these are referred to below as, for example,
122     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
123     always be a slash, and no slash is used when writing modifiers. Whitespace may
124     appear between the final pattern delimiter and the first modifier, and between
125     the modifiers themselves.
126     .P
127     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
128     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
129     \fBpcre_compile()\fP is called. These four modifier letters have the same
130     effect as they do in Perl. For example:
131     .sp
132 nigel 53 /caseless/i
133 nigel 75 .sp
134     The following table shows additional modifiers for setting PCRE options that do
135     not correspond to anything in Perl:
136     .sp
137     \fB/A\fP PCRE_ANCHORED
138     \fB/C\fP PCRE_AUTO_CALLOUT
139     \fB/E\fP PCRE_DOLLAR_ENDONLY
140 nigel 77 \fB/f\fP PCRE_FIRSTLINE
141 nigel 75 \fB/N\fP PCRE_NO_AUTO_CAPTURE
142     \fB/U\fP PCRE_UNGREEDY
143     \fB/X\fP PCRE_EXTRA
144     .sp
145 nigel 53 Searching for all possible matches within each subject string can be requested
146 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
147 nigel 53 again to search the remainder of the subject string. The difference between
148 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
149     \fBpcre_exec()\fP to start searching at a new point within the entire string
150 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
151     substring. This makes a difference to the matching process if the pattern
152 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
153     .P
154     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
155 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
156     flags set in order to search for another, non-empty, match at the same point.
157     If this second match fails, the start offset is advanced by one, and the normal
158     match is retried. This imitates the way Perl handles such cases when using the
159 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
160     .P
161     There are yet more modifiers for controlling the way \fBpcretest\fP
162 nigel 53 operates.
163 nigel 75 .P
164     The \fB/+\fP modifier requests that as well as outputting the substring that
165 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
166     the subject string. This is useful for tests where the subject contains
167     multiple copies of the same substring.
168 nigel 75 .P
169     The \fB/L\fP modifier must be followed directly by the name of a locale, for
170 nigel 53 example,
171 nigel 75 .sp
172     /pattern/Lfr_FR
173     .sp
174     For this reason, it must be the last modifier. The given locale is set,
175     \fBpcre_maketables()\fP is called to build a set of character tables for the
176     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
177     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
178     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
179     .P
180     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
181     compiled pattern (whether it is anchored, has a fixed first character, and
182     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
183     pattern. If the pattern is studied, the results of that are also output.
184     .P
185     The \fB/D\fP modifier is a PCRE debugging feature, which also assumes \fB/I\fP.
186 nigel 53 It causes the internal form of compiled regular expressions to be output after
187 nigel 63 compilation. If the pattern was studied, the information returned is also
188     output.
189 nigel 75 .P
190     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
191     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
192     facility is for testing the feature in PCRE that allows it to execute patterns
193     that were compiled on a host with a different endianness. This feature is not
194     available when the POSIX interface to PCRE is being used, that is, when the
195     \fB/P\fP pattern modifier is specified. See also the section about saving and
196     reloading compiled patterns below.
197     .P
198     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
199 nigel 53 expression has been compiled, and the results used when the expression is
200     matched.
201 nigel 75 .P
202     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
203 nigel 53 pattern to be output.
204 nigel 75 .P
205     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
206 nigel 53 API rather than its native API. When this is done, all other modifiers except
207 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
208     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
209 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
210 nigel 75 .P
211     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
212 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
213     provided that it was compiled with this support enabled. This modifier also
214     causes any non-printing characters in output strings to be printed using the
215 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
216     .P
217     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
218     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
219 nigel 71 checking of the string for UTF-8 validity.
220 nigel 75 .
221     .
222     .SH "DATA LINES"
223 nigel 63 .rs
224     .sp
225 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
226     whitespace is removed, and it is then scanned for \e escapes. Some of these are
227 nigel 63 pretty esoteric features, intended for checking out some of the more
228     complicated features of PCRE. If you are just testing "ordinary" regular
229     expressions, you probably don't need any of these. The following escapes are
230 nigel 53 recognized:
231 nigel 75 .sp
232     \ea alarm (= BEL)
233     \eb backspace
234     \ee escape
235     \ef formfeed
236     \en newline
237     \er carriage return
238     \et tab
239     \ev vertical tab
240     \ennn octal character (up to 3 octal digits)
241     \exhh hexadecimal character (up to 2 hex digits)
242     .\" JOIN
243     \ex{hh...} hexadecimal character, any number of digits
244 nigel 63 in UTF-8 mode
245 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
246     \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
247     .\" JOIN
248     \eCdd call pcre_copy_substring() for substring dd
249     after a successful match (number less than 32)
250     .\" JOIN
251     \eCname call pcre_copy_named_substring() for substring
252 nigel 63 "name" after a successful match (name termin-
253     ated by next non alphanumeric character)
254 nigel 75 .\" JOIN
255     \eC+ show the current captured substrings at callout
256 nigel 63 time
257 nigel 75 \eC- do not supply a callout function
258     .\" JOIN
259     \eC!n return 1 instead of 0 when callout number n is
260 nigel 63 reached
261 nigel 75 .\" JOIN
262     \eC!n!m return 1 instead of 0 when callout number n is
263 nigel 63 reached for the nth time
264 nigel 75 .\" JOIN
265     \eC*n pass the number n (may be negative) as callout
266     data; this is used as the callout return value
267 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
268     \eF only shortest match for \fBpcre_dfa_exec()\fP
269 nigel 75 .\" JOIN
270     \eGdd call pcre_get_substring() for substring dd
271     after a successful match (number less than 32)
272     .\" JOIN
273     \eGname call pcre_get_named_substring() for substring
274 nigel 63 "name" after a successful match (name termin-
275     ated by next non-alphanumeric character)
276 nigel 75 .\" JOIN
277     \eL call pcre_get_substringlist() after a
278 nigel 63 successful match
279 nigel 75 \eM discover the minimum MATCH_LIMIT setting
280     \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
281     .\" JOIN
282     \eOdd set the size of the output vector passed to
283     \fBpcre_exec()\fP to dd (any number of digits)
284 nigel 77 .\" JOIN
285 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
286 nigel 77 or \fBpcre_dfa_exec()\fP
287     \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
288 nigel 75 \eS output details of memory get/free calls during matching
289     \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
290     .\" JOIN
291     \e? pass the PCRE_NO_UTF8_CHECK option to
292     \fBpcre_exec()\fP
293     \e>dd start the match at offset dd (any number of digits);
294     this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
295     .sp
296     A backslash followed by anything else just escapes the anything else. If the
297     very last character is a backslash, it is ignored. This gives a way of passing
298     an empty line as data, since a real empty line terminates the data input.
299     .P
300     If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
301     different values in the \fImatch_limit\fP field of the \fBpcre_extra\fP data
302 nigel 63 structure, until it finds the minimum number that is needed for
303 nigel 75 \fBpcre_exec()\fP to complete. This number is a measure of the amount of
304 nigel 63 recursion and backtracking that takes place, and checking it out can be
305     instructive. For most simple matches, the number is quite small, but for
306     patterns with very large numbers of matching possibilities, it can become large
307     very quickly with increasing length of subject string.
308 nigel 75 .P
309     When \eO is used, the value specified may be higher or lower than the size set
310     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
311     the call of \fBpcre_exec()\fP for the line in which it appears.
312     .P
313     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
314     API to be used, only \eB and \eZ have any effect, causing REG_NOTBOL and
315     REG_NOTEOL to be passed to \fBregexec()\fP respectively.
316     .P
317     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
318     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
319 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
320     six bytes, encoded according to the UTF-8 rules.
321 nigel 75 .
322     .
323 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
324 nigel 63 .rs
325     .sp
326 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
327     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
328     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
329     different way, and has some restrictions. The differences between the two
330     functions are described in the
331     .\" HREF
332     \fBpcrematching\fP
333     .\"
334     documentation.
335     .P
336     If a data line contains the \eD escape sequence, or if the command line
337     contains the \fB-dfa\fP option, the alternative matching function is called.
338     This function finds all possible matches at a given point. If, however, the \eF
339     escape sequence is present in the data line, it stops after the first match is
340     found. This is always the shortest possible match.
341     .
342     .
343     .SH "DEFAULT OUTPUT FROM PCRETEST"
344     .rs
345     .sp
346     This section describes the output when the normal matching function,
347     \fBpcre_exec()\fP, is being used.
348     .P
349 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
350 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
351     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
352     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
353     respectively, and otherwise the PCRE negative error number. Here is an example
354 nigel 77 of an interactive \fBpcretest\fP run.
355 nigel 75 .sp
356 nigel 53 $ pcretest
357 nigel 75 PCRE version 5.00 07-Sep-2004
358     .sp
359     re> /^abc(\ed+)/
360 nigel 53 data> abc123
361     0: abc123
362     1: 123
363     data> xyz
364     No match
365 nigel 75 .sp
366     If the strings contain any non-printing characters, they are output as \e0x
367     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
368     pattern. If the pattern has the \fB/+\fP modifier, the output for substring 0
369     is followed by the the rest of the subject string, identified by "0+" like
370     this:
371     .sp
372 nigel 53 re> /cat/+
373     data> cataract
374     0: cat
375     0+ aract
376 nigel 75 .sp
377     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
378 nigel 53 matching attempts are output in sequence, like this:
379 nigel 75 .sp
380     re> /\eBi(\ew\ew)/g
381 nigel 53 data> Mississippi
382     0: iss
383     1: ss
384     0: iss
385     1: ss
386     0: ipp
387     1: pp
388 nigel 75 .sp
389 nigel 53 "No match" is output only if the first match attempt fails.
390 nigel 75 .P
391     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
392 nigel 53 data line that is successfully matched, the substrings extracted by the
393     convenience functions are output with C, G, or L after the string number
394     instead of a colon. This is in addition to the normal full list. The string
395     length (that is, the return from the extraction function) is given in
396 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
397     .P
398 nigel 53 Note that while patterns can be continued over several lines (a plain ">"
399     prompt is used for continuations), data lines may not. However newlines can be
400 nigel 75 included in data by means of the \en escape.
401     .
402     .
403 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
404     .rs
405     .sp
406     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
407     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
408     output consists of a list of all the matches that start at the first point in
409     the subject where there is at least one match. For example:
410     .sp
411     re> /(tang|tangerine|tan)/
412     data> yellow tangerine\eD
413     0: tangerine
414     1: tang
415     2: tan
416     .sp
417     (Using the normal matching function on this data finds only "tang".) The
418     longest matching string is always given first (and numbered zero).
419     .P
420     If \fB/g\P is present on the pattern, the search for further matches resumes
421     at the end of the longest match. For example:
422     .sp
423     re> /(tang|tangerine|tan)/g
424     data> yellow tangerine and tangy sultana\eD
425     0: tangerine
426     1: tang
427     2: tan
428     0: tang
429     1: tan
430     0: tan
431     .sp
432     Since the matching function does not support substring capture, the escape
433     sequences that are concerned with captured substrings are not relevant.
434     .
435     .
436     .SH "RESTARTING AFTER A PARTIAL MATCH"
437     .rs
438     .sp
439     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
440     indicating that the subject partially matched the pattern, you can restart the
441     match with additional subject data by means of the \eR escape sequence. For
442     example:
443     .sp
444     re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
445     data> 23ja\eP\eD
446     Partial match: 23ja
447     data> n05\eR\eD
448     0: n05
449     .sp
450     For further information about partial matching, see the
451     .\" HREF
452     \fBpcrepartial\fP
453     .\"
454     documentation.
455     .
456     .
457 nigel 75 .SH CALLOUTS
458     .rs
459     .sp
460     If the pattern contains any callout requests, \fBpcretest\fP's callout function
461 nigel 77 is called during matching. This works with both matching functions. By default,
462     the called function displays the callout number, the start and current
463     positions in the text at the callout time, and the next pattern item to be
464     tested. For example, the output
465 nigel 75 .sp
466     --->pqrabcdef
467     0 ^ ^ \ed
468     .sp
469     indicates that callout number 0 occurred for a match attempt starting at the
470     fourth character of the subject string, when the pointer was at the seventh
471     character of the data, and when the next pattern item was \ed. Just one
472     circumflex is output if the start and current positions are the same.
473     .P
474     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
475     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
476     callout number, the offset in the pattern, preceded by a plus, is output. For
477     example:
478     .sp
479     re> /\ed?[A-E]\e*/C
480     data> E*
481     --->E*
482     +0 ^ \ed?
483     +3 ^ [A-E]
484     +8 ^^ \e*
485     +10 ^ ^
486     0: E*
487     .sp
488     The callout function in \fBpcretest\fP returns zero (carry on matching) by
489 nigel 77 default, but you can use a \eC item in a data line (as described above) to
490 nigel 75 change this.
491     .P
492     Inserting callouts can be helpful when using \fBpcretest\fP to check
493     complicated regular expressions. For further information about callouts, see
494     the
495     .\" HREF
496     \fBpcrecallout\fP
497     .\"
498     documentation.
499     .
500     .
501     .SH "SAVING AND RELOADING COMPILED PATTERNS"
502     .rs
503     .sp
504     The facilities described in this section are not available when the POSIX
505     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
506     specified.
507     .P
508     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
509     compiled pattern to a file, by following the modifiers with > and a file name.
510     For example:
511     .sp
512     /pattern/im >/some/file
513     .sp
514     See the
515     .\" HREF
516     \fBpcreprecompile\fP
517     .\"
518     documentation for a discussion about saving and re-using compiled patterns.
519     .P
520     The data that is written is binary. The first eight bytes are the length of the
521     compiled pattern data followed by the length of the optional study data, each
522     written as four bytes in big-endian order (most significant byte first). If
523     there is no study data (either the pattern was not studied, or studying did not
524     return any data), the second length is zero. The lengths are followed by an
525     exact copy of the compiled pattern. If there is additional study data, this
526     follows immediately after the compiled pattern. After writing the file,
527     \fBpcretest\fP expects to read a new pattern.
528     .P
529     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
530     name instead of a pattern. The name of the file must not contain a < character,
531     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
532     characters.
533     For example:
534     .sp
535     re> </some/file
536     Compiled regex loaded from /some/file
537     No study data
538     .sp
539     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
540     the usual way.
541     .P
542     You can copy a file written by \fBpcretest\fP to a different host and reload it
543     there, even if the new host has opposite endianness to the one on which the
544     pattern was compiled. For example, you can compile on an i86 machine and run on
545     a SPARC machine.
546     .P
547     File names for saving and reloading can be absolute or relative, but note that
548     the shell facility of expanding a file name that starts with a tilde (~) is not
549     available.
550     .P
551     The ability to save and reload files in \fBpcretest\fP is intended for testing
552     and experimentation. It is not intended for production use because only a
553     single pattern can be written to a file. Furthermore, there is no facility for
554     supplying custom character tables for use with a reloaded pattern. If the
555     original pattern was compiled with custom tables, an attempt to match a subject
556     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
557     Finally, if you attempt to load a file that is not in the correct format, the
558     result is undefined.
559     .
560     .
561 nigel 53 .SH AUTHOR
562 nigel 63 .rs
563     .sp
564 nigel 77 Philip Hazel
565 nigel 53 .br
566     University Computing Service,
567     .br
568     Cambridge CB2 3QG, England.
569 nigel 75 .P
570 nigel 63 .in 0
571 nigel 77 Last updated: 28 February 2005
572 nigel 53 .br
573 nigel 77 Copyright (c) 1997-2005 University of Cambridge.

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