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1  The pcretest program  PCRETEST(1)                                                        PCRETEST(1)
 --------------------  
2    
 This program is intended for testing PCRE, but it can also be used for  
 experimenting with regular expressions.  
3    
4  If it is given two filename arguments, it reads from the first and writes to  NAME
5  the second. If it is given only one filename argument, it reads from that file         pcretest - a program for testing Perl-compatible regular expressions.
 and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and  
 prompts for each line of input, using "re>" to prompt for regular expressions,  
 and "data>" to prompt for data lines.  
   
 The program handles any number of sets of input on a single input file. Each  
 set starts with a regular expression, and continues with any number of data  
 lines to be matched against the pattern. An empty line signals the end of the  
 data lines, at which point a new regular expression is read. The regular  
 expressions are given enclosed in any non-alphameric delimiters other than  
 backslash, for example  
   
   /(a|bc)x+yz/  
   
 White space before the initial delimiter is ignored. A regular expression may  
 be continued over several input lines, in which case the newline characters are  
 included within it. See the test input files in the testdata directory for many  
 examples. It is possible to include the delimiter within the pattern by  
 escaping it, for example  
   
   /abc\/def/  
   
 If you do so, the escape and the delimiter form part of the pattern, but since  
 delimiters are always non-alphameric, this does not affect its interpretation.  
 If the terminating delimiter is immediately followed by a backslash, for  
 example,  
   
   /abc/\  
   
 then a backslash is added to the end of the pattern. This is done to provide a  
 way of testing the error condition that arises if a pattern finishes with a  
 backslash, because  
   
   /abc\/  
   
 is interpreted as the first line of a pattern that starts with "abc/", causing  
 pcretest to read the next line as a continuation of the regular expression.  
   
 The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,  
 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For  
 example:  
   
   /caseless/i  
   
 These modifier letters have the same effect as they do in Perl. There are  
 others which set PCRE options that do not correspond to anything in Perl: /A,  
 /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
   
 Searching for all possible matches within each subject string can be requested  
 by the /g or /G modifier. After finding a match, PCRE is called again to search  
 the remainder of the subject string. The difference between /g and /G is that  
 the former uses the startoffset argument to pcre_exec() to start searching at  
 a new point within the entire string (which is in effect what Perl does),  
 whereas the latter passes over a shortened substring. This makes a difference  
 to the matching process if the pattern begins with a lookbehind assertion  
 (including \b or \B).  
   
 If any call to pcre_exec() in a /g or /G sequence matches an empty string, the  
 next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set in order  
 to search for another, non-empty, match at the same point. If this second match  
 fails, the start offset is advanced by one, and the normal match is retried.  
 This imitates the way Perl handles such cases when using the /g modifier or the  
 split() function.  
   
 There are a number of other modifiers for controlling the way pcretest  
 operates.  
   
 The /+ modifier requests that as well as outputting the substring that matched  
 the entire pattern, pcretest should in addition output the remainder of the  
 subject string. This is useful for tests where the subject contains multiple  
 copies of the same substring.  
   
 The /L modifier must be followed directly by the name of a locale, for example,  
   
   /pattern/Lfr  
   
 For this reason, it must be the last modifier letter. The given locale is set,  
 pcre_maketables() is called to build a set of character tables for the locale,  
 and this is then passed to pcre_compile() when compiling the regular  
 expression. Without an /L modifier, NULL is passed as the tables pointer; that  
 is, /L applies only to the expression on which it appears.  
   
 The /I modifier requests that pcretest output information about the compiled  
 expression (whether it is anchored, has a fixed first character, and so on). It  
 does this by calling pcre_fullinfo() after compiling an expression, and  
 outputting the information it gets back. If the pattern is studied, the results  
 of that are also output.  
   
 The /D modifier is a PCRE debugging feature, which also assumes /I. It causes  
 the internal form of compiled regular expressions to be output after  
 compilation.  
   
 The /S modifier causes pcre_study() to be called after the expression has been  
 compiled, and the results used when the expression is matched.  
   
 The /M modifier causes the size of memory block used to hold the compiled  
 pattern to be output.  
   
 Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API  
 rather than its native API. When this is done, all other modifiers except /i,  
 /m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is  
 set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,  
 and PCRE_DOTALL unless REG_NEWLINE is set.  
   
 Before each data line is passed to pcre_exec(), leading and trailing whitespace  
 is removed, and it is then scanned for \ escapes. The following are recognized:  
   
   \a     alarm (= BEL)  
   \b     backspace  
   \e     escape  
   \f     formfeed  
   \n     newline  
   \r     carriage return  
   \t     tab  
   \v     vertical tab  
   \nnn   octal character (up to 3 octal digits)  
   \xhh   hexadecimal character (up to 2 hex digits)  
   
   \A     pass the PCRE_ANCHORED option to pcre_exec()  
   \B     pass the PCRE_NOTBOL option to pcre_exec()  
   \Cdd   call pcre_copy_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \Gdd   call pcre_get_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \L     call pcre_get_substringlist() after a successful match  
   \N     pass the PCRE_NOTEMPTY option to pcre_exec()  
   \Odd   set the size of the output vector passed to pcre_exec() to dd  
            (any number of decimal digits)  
   \Z     pass the PCRE_NOTEOL option to pcre_exec()  
   
 A backslash followed by anything else just escapes the anything else. If the  
 very last character is a backslash, it is ignored. This gives a way of passing  
 an empty line as data, since a real empty line terminates the data input.  
   
 If /P was present on the regex, causing the POSIX wrapper API to be used, only  
 \B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL to be passed to  
 regexec() respectively.  
   
 When a match succeeds, pcretest outputs the list of captured substrings that  
 pcre_exec() returns, starting with number 0 for the string that matched the  
 whole pattern. Here is an example of an interactive pcretest run.  
   
   $ pcretest  
   PCRE version 2.06 08-Jun-1999  
   
     re> /^abc(\d+)/  
   data> abc123  
    0: abc123  
    1: 123  
   data> xyz  
   No match  
   
 If the strings contain any non-printing characters, they are output as \0x  
 escapes. If the pattern has the /+ modifier, then the output for substring 0 is  
 followed by the the rest of the subject string, identified by "0+" like this:  
   
     re> /cat/+  
   data> cataract  
    0: cat  
    0+ aract  
   
 If the pattern has the /g or /G modifier, the results of successive matching  
 attempts are output in sequence, like this:  
   
     re> /\Bi(\w\w)/g  
   data> Mississippi  
    0: iss  
    1: ss  
    0: iss  
    1: ss  
    0: ipp  
    1: pp  
   
 "No match" is output only if the first match attempt fails.  
   
 If any of \C, \G, or \L are present in a data line that is successfully  
 matched, the substrings extracted by the convenience functions are output with  
 C, G, or L after the string number instead of a colon. This is in addition to  
 the normal full list. The string length (that is, the return from the  
 extraction function) is given in parentheses after each string for \C and \G.  
   
 Note that while patterns can be continued over several lines (a plain ">"  
 prompt is used for continuations), data lines may not. However newlines can be  
 included in data by means of the \n escape.  
   
 If the -p option is given to pcretest, it is equivalent to adding /P to each  
 regular expression: the POSIX wrapper API is used to call PCRE. None of the  
 following flags has any effect in this case.  
   
 If the option -d is given to pcretest, it is equivalent to adding /D to each  
 regular expression: the internal form is output after compilation.  
   
 If the option -i is given to pcretest, it is equivalent to adding /I to each  
 regular expression: information about the compiled pattern is given after  
 compilation.  
   
 If the option -m is given to pcretest, it outputs the size of each compiled  
 pattern after it has been compiled. It is equivalent to adding /M to each  
 regular expression. For compatibility with earlier versions of pcretest, -s is  
 a synonym for -m.  
   
 If the -t option is given, each compile, study, and match is run 20000 times  
 while being timed, and the resulting time per compile or match is output in  
 milliseconds. Do not set -t with -s, because you will then get the size output  
 20000 times and the timing will be distorted. If you want to change the number  
 of repetitions used for timing, edit the definition of LOOPREPEAT at the top of  
 pcretest.c  
6    
7  Philip Hazel <ph10@cam.ac.uk>  
8  January 2000  SYNOPSIS
9    
10           pcretest [options] [input file [output file]]
11    
12           pcretest  was written as a test program for the PCRE regular expression
13           library itself, but it can also be used for experimenting with  regular
14           expressions.  This document describes the features of the test program;
15           for details of the regular expressions themselves, see the  pcrepattern
16           documentation. For details of the PCRE library function calls and their
17           options, see the pcreapi documentation. The input  for  pcretest  is  a
18           sequence  of  regular expression patterns and strings to be matched, as
19           described below. The output shows the result of each match. Options  on
20           the command line and the patterns control PCRE options and exactly what
21           is output.
22    
23    
24    COMMAND LINE OPTIONS
25    
26           -b        Behave as if each pattern has the /B (show byte  code)  modi-
27                     fier; the internal form is output after compilation.
28    
29           -C        Output the version number of the PCRE library, and all avail-
30                     able  information  about  the  optional  features  that   are
31                     included, and then exit.
32    
33           -d        Behave  as  if  each pattern has the /D (debug) modifier; the
34                     internal form and information about the compiled  pattern  is
35                     output after compilation; -d is equivalent to -b -i.
36    
37           -dfa      Behave  as if each data line contains the \D escape sequence;
38                     this    causes    the    alternative    matching    function,
39                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
40                     pcre_exec() function (more detail is given below).
41    
42           -help     Output a brief summary these options and then exit.
43    
44           -i        Behave as if each pattern has the  /I  modifier;  information
45                     about the compiled pattern is given after compilation.
46    
47           -M        Behave  as if each data line contains the \M escape sequence;
48                     this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
49                     MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
50                     edly with different limits.
51    
52           -m        Output the size of each compiled pattern after  it  has  been
53                     compiled.  This  is  equivalent  to adding /M to each regular
54                     expression.
55    
56           -o osize  Set the number of elements in the output vector that is  used
57                     when  calling pcre_exec() or pcre_dfa_exec() to be osize. The
58                     default value is 45, which is enough for 14 capturing  subex-
59                     pressions   for  pcre_exec()  or  22  different  matches  for
60                     pcre_dfa_exec(). The vector size can be changed for  individ-
61                     ual  matching  calls  by  including  \O in the data line (see
62                     below).
63    
64           -p        Behave as if each pattern has  the  /P  modifier;  the  POSIX
65                     wrapper  API  is used to call PCRE. None of the other options
66                     has any effect when -p is set.
67    
68           -q        Do not output the version number of pcretest at the start  of
69                     execution.
70    
71           -S size   On  Unix-like  systems, set the size of the run-time stack to
72                     size megabytes.
73    
74           -s        Behave as if each pattern  has  the  /S  modifier;  in  other
75                     words,  force  each  pattern  to  be studied. If the /I or /D
76                     option is present on a pattern (requesting output  about  the
77                     compiled  pattern),  information about the result of studying
78                     is not included when studying is caused only by -s  and  nei-
79                     ther -i nor -d is present on the command line. This behaviour
80                     means that the output from tests that are run with and  with-
81                     out  -s  should be identical, except when options that output
82                     information about the actual running of a match are set.  The
83                     -M,  -t,  and  -tm  options,  which  give  information  about
84                     resources used, are likely to produce different  output  with
85                     and  without  -s.  Output may also differ if the /C option is
86                     present on an individual pattern. This uses callouts to trace
87                     the  the  matching process, and this may be different between
88                     studied and non-studied patterns.  If  the  pattern  contains
89                     (*MARK)  items  there  may  also be differences, for the same
90                     reason. The -s command line option can be overridden for spe-
91                     cific  patterns  that  should  never  be  studied (see the /S
92                     option below).
93    
94           -t        Run each compile, study, and match many times with  a  timer,
95                     and  output resulting time per compile or match (in millisec-
96                     onds). Do not set -m with -t, because you will then  get  the
97                     size  output  a  zillion  times,  and the timing will be dis-
98                     torted. You can control the number  of  iterations  that  are
99                     used  for timing by following -t with a number (as a separate
100                     item on the command line). For example, "-t 1000" would iter-
101                     ate 1000 times. The default is to iterate 500000 times.
102    
103           -tm       This is like -t except that it times only the matching phase,
104                     not the compile or study phases.
105    
106    
107    DESCRIPTION
108    
109           If pcretest is given two filename arguments, it reads  from  the  first
110           and writes to the second. If it is given only one filename argument, it
111           reads from that file and writes to stdout.  Otherwise,  it  reads  from
112           stdin  and  writes to stdout, and prompts for each line of input, using
113           "re>" to prompt for regular expressions, and "data>" to prompt for data
114           lines.
115    
116           When  pcretest  is  built,  a  configuration option can specify that it
117           should be linked with the libreadline library. When this  is  done,  if
118           the input is from a terminal, it is read using the readline() function.
119           This provides line-editing and history facilities. The output from  the
120           -help option states whether or not readline() will be used.
121    
122           The program handles any number of sets of input on a single input file.
123           Each set starts with a regular expression, and continues with any  num-
124           ber of data lines to be matched against the pattern.
125    
126           Each  data line is matched separately and independently. If you want to
127           do multi-line matches, you have to use the \n escape sequence (or \r or
128           \r\n, etc., depending on the newline setting) in a single line of input
129           to encode the newline sequences. There is no limit  on  the  length  of
130           data  lines;  the  input  buffer is automatically extended if it is too
131           small.
132    
133           An empty line signals the end of the data lines, at which point  a  new
134           regular  expression is read. The regular expressions are given enclosed
135           in any non-alphanumeric delimiters other than backslash, for example:
136    
137             /(a|bc)x+yz/
138    
139           White space before the initial delimiter is ignored. A regular  expres-
140           sion  may be continued over several input lines, in which case the new-
141           line characters are included within it. It is possible to  include  the
142           delimiter within the pattern by escaping it, for example
143    
144             /abc\/def/
145    
146           If  you  do  so, the escape and the delimiter form part of the pattern,
147           but since delimiters are always non-alphanumeric, this does not  affect
148           its  interpretation.   If the terminating delimiter is immediately fol-
149           lowed by a backslash, for example,
150    
151             /abc/\
152    
153           then a backslash is added to the end of the pattern. This  is  done  to
154           provide  a  way of testing the error condition that arises if a pattern
155           finishes with a backslash, because
156    
157             /abc\/
158    
159           is interpreted as the first line of a pattern that starts with  "abc/",
160           causing pcretest to read the next line as a continuation of the regular
161           expression.
162    
163    
164    PATTERN MODIFIERS
165    
166           A pattern may be followed by any number of modifiers, which are  mostly
167           single  characters.  Following  Perl usage, these are referred to below
168           as, for example, "the /i modifier", even though the  delimiter  of  the
169           pattern  need  not always be a slash, and no slash is used when writing
170           modifiers. White space may appear between the final  pattern  delimiter
171           and the first modifier, and between the modifiers themselves.
172    
173           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
174           PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-
175           pile()  is  called. These four modifier letters have the same effect as
176           they do in Perl. For example:
177    
178             /caseless/i
179    
180           The following table shows additional modifiers for  setting  PCRE  com-
181           pile-time options that do not correspond to anything in Perl:
182    
183             /8              PCRE_UTF8
184             /?              PCRE_NO_UTF8_CHECK
185             /A              PCRE_ANCHORED
186             /C              PCRE_AUTO_CALLOUT
187             /E              PCRE_DOLLAR_ENDONLY
188             /f              PCRE_FIRSTLINE
189             /J              PCRE_DUPNAMES
190             /N              PCRE_NO_AUTO_CAPTURE
191             /U              PCRE_UNGREEDY
192             /W              PCRE_UCP
193             /X              PCRE_EXTRA
194             /Y              PCRE_NO_START_OPTIMIZE
195             /<JS>           PCRE_JAVASCRIPT_COMPAT
196             /<cr>           PCRE_NEWLINE_CR
197             /<lf>           PCRE_NEWLINE_LF
198             /<crlf>         PCRE_NEWLINE_CRLF
199             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
200             /<any>          PCRE_NEWLINE_ANY
201             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
202             /<bsr_unicode>  PCRE_BSR_UNICODE
203    
204           The  modifiers  that are enclosed in angle brackets are literal strings
205           as shown, including the angle brackets, but the letters within  can  be
206           in  either case.  This example sets multiline matching with CRLF as the
207           line ending sequence:
208    
209             /^abc/m<CRLF>
210    
211           As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
212           any  non-printing  characters in output strings to be printed using the
213           \x{hh...} notation if they are valid UTF-8 sequences. Full  details  of
214           the PCRE options are given in the pcreapi documentation.
215    
216       Finding all matches in a string
217    
218           Searching  for  all  possible matches within each subject string can be
219           requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
220           called again to search the remainder of the subject string. The differ-
221           ence between /g and /G is that the former uses the startoffset argument
222           to  pcre_exec()  to  start  searching  at a new point within the entire
223           string (which is in effect what Perl does), whereas the  latter  passes
224           over  a  shortened  substring.  This makes a difference to the matching
225           process if the pattern begins with a lookbehind assertion (including \b
226           or \B).
227    
228           If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty
229           string, the next  call  is  done  with  the  PCRE_NOTEMPTY_ATSTART  and
230           PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
231           match at the same point. If this second match fails, the  start  offset
232           is  advanced,  and  the  normal match is retried. This imitates the way
233           Perl handles such cases when using the /g modifier or the split() func-
234           tion.  Normally,  the start offset is advanced by one character, but if
235           the newline convention recognizes CRLF as a newline,  and  the  current
236           character is CR followed by LF, an advance of two is used.
237    
238       Other modifiers
239    
240           There are yet more modifiers for controlling the way pcretest operates.
241    
242           The  /+ modifier requests that as well as outputting the substring that
243           matched the entire pattern, pcretest  should  in  addition  output  the
244           remainder  of  the  subject  string. This is useful for tests where the
245           subject contains multiple copies of the same substring. If the +  modi-
246           fier  appears  twice, the same action is taken for captured substrings.
247           In each case the remainder is output on the following line with a  plus
248           character following the capture number.
249    
250           The  /=  modifier  requests  that  the values of all potential captured
251           parentheses be output after a match by pcre_exec().  By  default,  only
252           those up to the highest one actually used in the match are output (cor-
253           responding to the return code from pcre_exec()). Values in the  offsets
254           vector  corresponding  to higher numbers should be set to -1, and these
255           are output as "<unset>". This modifier gives a  way  of  checking  that
256           this is happening.
257    
258           The  /B modifier is a debugging feature. It requests that pcretest out-
259           put a representation of the compiled byte code after compilation.  Nor-
260           mally  this  information contains length and offset values; however, if
261           /Z is also present, this data is replaced by spaces. This is a  special
262           feature for use in the automatic test scripts; it ensures that the same
263           output is generated for different internal link sizes.
264    
265           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
266           that is, both the /B and the /I modifiers.
267    
268           The /F modifier causes pcretest to flip the byte order of the fields in
269           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
270           facility  is  for testing the feature in PCRE that allows it to execute
271           patterns that were compiled on a host with a different endianness. This
272           feature  is  not  available  when  the POSIX interface to PCRE is being
273           used, that is, when the /P pattern modifier is specified. See also  the
274           section about saving and reloading compiled patterns below.
275    
276           The  /I  modifier  requests  that pcretest output information about the
277           compiled pattern (whether it is anchored, has a fixed first  character,
278           and  so  on). It does this by calling pcre_fullinfo() after compiling a
279           pattern. If the pattern is studied, the results of that are  also  out-
280           put.
281    
282           The  /K modifier requests pcretest to show names from backtracking con-
283           trol verbs that are returned  from  calls  to  pcre_exec().  It  causes
284           pcretest  to create a pcre_extra block if one has not already been cre-
285           ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
286           the mark field within it, every time that pcre_exec() is called. If the
287           variable that the mark field points to is non-NULL for  a  match,  non-
288           match, or partial match, pcretest prints the string to which it points.
289           For a match, this is shown on a line by itself, tagged with "MK:".  For
290           a non-match it is added to the message.
291    
292           The  /L modifier must be followed directly by the name of a locale, for
293           example,
294    
295             /pattern/Lfr_FR
296    
297           For this reason, it must be the last modifier. The given locale is set,
298           pcre_maketables()  is called to build a set of character tables for the
299           locale, and this is then passed to pcre_compile()  when  compiling  the
300           regular  expression.  Without an /L (or /T) modifier, NULL is passed as
301           the tables pointer; that is, /L applies only to the expression on which
302           it appears.
303    
304           The  /M  modifier causes the size of memory block used to hold the com-
305           piled pattern to be output.
306    
307           If the /S modifier appears once, it causes pcre_study()  to  be  called
308           after  the  expression has been compiled, and the results used when the
309           expression is matched. If /S appears  twice,  it  suppresses  studying,
310           even if it was requested externally by the -s command line option. This
311           makes it possible to specify that certain patterns are always  studied,
312           and others are never studied, independently of -s. This feature is used
313           in the test files in a few cases where the output is different when the
314           pattern is studied.
315    
316           The  /T  modifier  must be followed by a single digit. It causes a spe-
317           cific set of built-in character tables to be passed to  pcre_compile().
318           It is used in the standard PCRE tests to check behaviour with different
319           character tables. The digit specifies the tables as follows:
320    
321             0   the default ASCII tables, as distributed in
322                   pcre_chartables.c.dist
323             1   a set of tables defining ISO 8859 characters
324    
325           In table 1, some characters whose codes are greater than 128 are  iden-
326           tified as letters, digits, spaces, etc.
327    
328       Using the POSIX wrapper API
329    
330           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
331           rather than its native API. When /P is set, the following modifiers set
332           options for the regcomp() function:
333    
334             /i    REG_ICASE
335             /m    REG_NEWLINE
336             /N    REG_NOSUB
337             /s    REG_DOTALL     )
338             /U    REG_UNGREEDY   ) These options are not part of
339             /W    REG_UCP        )   the POSIX standard
340             /8    REG_UTF8       )
341    
342           The  /+  modifier  works  as  described  above. All other modifiers are
343           ignored.
344    
345    
346    DATA LINES
347    
348           Before each data line is passed to pcre_exec(),  leading  and  trailing
349           white  space  is removed, and it is then scanned for \ escapes. Some of
350           these are pretty esoteric features, intended for checking out  some  of
351           the  more  complicated features of PCRE. If you are just testing "ordi-
352           nary" regular expressions, you probably don't need any  of  these.  The
353           following escapes are recognized:
354    
355             \a         alarm (BEL, \x07)
356             \b         backspace (\x08)
357             \e         escape (\x27)
358             \f         form feed (\x0c)
359             \n         newline (\x0a)
360             \qdd       set the PCRE_MATCH_LIMIT limit to dd
361                          (any number of digits)
362             \r         carriage return (\x0d)
363             \t         tab (\x09)
364             \v         vertical tab (\x0b)
365             \nnn       octal character (up to 3 octal digits)
366                          always a byte unless > 255 in UTF-8 mode
367             \xhh       hexadecimal byte (up to 2 hex digits)
368             \x{hh...}  hexadecimal character, any number of digits
369                          in UTF-8 mode
370             \A         pass the PCRE_ANCHORED option to pcre_exec()
371                          or pcre_dfa_exec()
372             \B         pass the PCRE_NOTBOL option to pcre_exec()
373                          or pcre_dfa_exec()
374             \Cdd       call pcre_copy_substring() for substring dd
375                          after a successful match (number less than 32)
376             \Cname     call pcre_copy_named_substring() for substring
377                          "name" after a successful match (name termin-
378                          ated by next non alphanumeric character)
379             \C+        show the current captured substrings at callout
380                          time
381             \C-        do not supply a callout function
382             \C!n       return 1 instead of 0 when callout number n is
383                          reached
384             \C!n!m     return 1 instead of 0 when callout number n is
385                          reached for the nth time
386             \C*n       pass the number n (may be negative) as callout
387                          data; this is used as the callout return value
388             \D         use the pcre_dfa_exec() match function
389             \F         only shortest match for pcre_dfa_exec()
390             \Gdd       call pcre_get_substring() for substring dd
391                          after a successful match (number less than 32)
392             \Gname     call pcre_get_named_substring() for substring
393                          "name" after a successful match (name termin-
394                          ated by next non-alphanumeric character)
395             \L         call pcre_get_substringlist() after a
396                          successful match
397             \M         discover the minimum MATCH_LIMIT and
398                          MATCH_LIMIT_RECURSION settings
399             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
400                          or pcre_dfa_exec(); if used twice, pass the
401                          PCRE_NOTEMPTY_ATSTART option
402             \Odd       set the size of the output vector passed to
403                          pcre_exec() to dd (any number of digits)
404             \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
405                          or pcre_dfa_exec(); if used twice, pass the
406                          PCRE_PARTIAL_HARD option
407             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
408                          (any number of digits)
409             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
410             \S         output details of memory get/free calls during matching
411             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
412                          or pcre_dfa_exec()
413             \Z         pass the PCRE_NOTEOL option to pcre_exec()
414                          or pcre_dfa_exec()
415             \?         pass the PCRE_NO_UTF8_CHECK option to
416                          pcre_exec() or pcre_dfa_exec()
417             \>dd       start the match at offset dd (optional "-"; then
418                          any number of digits); this sets the startoffset
419                          argument for pcre_exec() or pcre_dfa_exec()
420             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
421                          or pcre_dfa_exec()
422             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
423                          or pcre_dfa_exec()
424             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
425                          or pcre_dfa_exec()
426             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
427                          or pcre_dfa_exec()
428             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
429                          or pcre_dfa_exec()
430    
431           Note  that  \xhh  always  specifies  one byte, even in UTF-8 mode; this
432           makes it possible to construct invalid UTF-8 sequences for testing pur-
433           poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
434           UTF-8 mode, generating more than one byte if the value is greater  than
435           127. When not in UTF-8 mode, it generates one byte for values less than
436           256, and causes an error for greater values.
437    
438           The escapes that specify line ending  sequences  are  literal  strings,
439           exactly as shown. No more than one newline setting should be present in
440           any data line.
441    
442           A backslash followed by anything else just escapes the  anything  else.
443           If  the very last character is a backslash, it is ignored. This gives a
444           way of passing an empty line as data, since a real  empty  line  termi-
445           nates the data input.
446    
447           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
448           ferent values in the match_limit and  match_limit_recursion  fields  of
449           the  pcre_extra  data structure, until it finds the minimum numbers for
450           each parameter that allow pcre_exec() to complete. The match_limit num-
451           ber  is  a  measure of the amount of backtracking that takes place, and
452           checking it out can be instructive. For most simple matches, the number
453           is  quite  small,  but for patterns with very large numbers of matching
454           possibilities, it can become large very quickly with increasing  length
455           of subject string. The match_limit_recursion number is a measure of how
456           much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)
457           memory is needed to complete the match attempt.
458    
459           When  \O  is  used, the value specified may be higher or lower than the
460           size set by the -O command line option (or defaulted to 45); \O applies
461           only to the call of pcre_exec() for the line in which it appears.
462    
463           If  the /P modifier was present on the pattern, causing the POSIX wrap-
464           per API to be used, the only option-setting  sequences  that  have  any
465           effect  are  \B,  \N,  and  \Z,  causing  REG_NOTBOL, REG_NOTEMPTY, and
466           REG_NOTEOL, respectively, to be passed to regexec().
467    
468           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
469           the  use  of  the  /8 modifier on the pattern. It is recognized always.
470           There may be any number of hexadecimal digits inside  the  braces.  The
471           result  is  from  one  to  six bytes, encoded according to the original
472           UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to
473           0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
474           or indeed valid UTF-8 characters according to the later  rules  in  RFC
475           3629.
476    
477    
478    THE ALTERNATIVE MATCHING FUNCTION
479    
480           By   default,  pcretest  uses  the  standard  PCRE  matching  function,
481           pcre_exec() to match each data line. From release 6.0, PCRE supports an
482           alternative  matching  function,  pcre_dfa_test(),  which operates in a
483           different way, and has some restrictions. The differences  between  the
484           two functions are described in the pcrematching documentation.
485    
486           If  a data line contains the \D escape sequence, or if the command line
487           contains the -dfa option, the alternative matching function is  called.
488           This function finds all possible matches at a given point. If, however,
489           the \F escape sequence is present in the data line, it stops after  the
490           first match is found. This is always the shortest possible match.
491    
492    
493    DEFAULT OUTPUT FROM PCRETEST
494    
495           This  section  describes  the output when the normal matching function,
496           pcre_exec(), is being used.
497    
498           When a match succeeds, pcretest outputs the list of captured substrings
499           that  pcre_exec()  returns,  starting with number 0 for the string that
500           matched the whole pattern. Otherwise, it outputs "No  match"  when  the
501           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
502           tially matching substring when pcre_exec() returns  PCRE_ERROR_PARTIAL.
503           (Note  that  this is the entire substring that was inspected during the
504           partial match; it may include characters before the actual match  start
505           if  a  lookbehind assertion, \K, \b, or \B was involved.) For any other
506           return, pcretest outputs the PCRE negative error  number  and  a  short
507           descriptive  phrase.  If  the error is a failed UTF-8 string check, the
508           byte offset of the start of the failing character and the  reason  code
509           are  also  output,  provided  that  the size of the output vector is at
510           least two. Here is an example of an interactive pcretest run.
511    
512             $ pcretest
513             PCRE version 8.13 2011-04-30
514    
515               re> /^abc(\d+)/
516             data> abc123
517              0: abc123
518              1: 123
519             data> xyz
520             No match
521    
522           Unset capturing substrings that are not followed by one that is set are
523           not returned by pcre_exec(), and are not shown by pcretest. In the fol-
524           lowing example, there are two capturing substrings, but when the  first
525           data  line  is  matched,  the  second, unset substring is not shown. An
526           "internal" unset substring is shown as "<unset>",  as  for  the  second
527           data line.
528    
529               re> /(a)|(b)/
530             data> a
531              0: a
532              1: a
533             data> b
534              0: b
535              1: <unset>
536              2: b
537    
538           If  the strings contain any non-printing characters, they are output as
539           \0x escapes, or as \x{...} escapes if the /8 modifier  was  present  on
540           the  pattern.  See below for the definition of non-printing characters.
541           If the pattern has the /+ modifier, the output for substring 0 is  fol-
542           lowed  by  the  the rest of the subject string, identified by "0+" like
543           this:
544    
545               re> /cat/+
546             data> cataract
547              0: cat
548              0+ aract
549    
550           If the pattern has the /g or /G modifier,  the  results  of  successive
551           matching attempts are output in sequence, like this:
552    
553               re> /\Bi(\w\w)/g
554             data> Mississippi
555              0: iss
556              1: ss
557              0: iss
558              1: ss
559              0: ipp
560              1: pp
561    
562           "No  match" is output only if the first match attempt fails. Here is an
563           example of a failure message (the offset 4 that is specified by \>4  is
564           past the end of the subject string):
565    
566               re> /xyz/
567             data> xyz\>4
568             Error -24 (bad offset value)
569    
570           If  any  of the sequences \C, \G, or \L are present in a data line that
571           is successfully matched, the substrings extracted  by  the  convenience
572           functions are output with C, G, or L after the string number instead of
573           a colon. This is in addition to the normal full list. The string length
574           (that  is,  the return from the extraction function) is given in paren-
575           theses after each string for \C and \G.
576    
577           Note that whereas patterns can be continued over several lines (a plain
578           ">" prompt is used for continuations), data lines may not. However new-
579           lines can be included in data by means of the \n escape (or  \r,  \r\n,
580           etc., depending on the newline sequence setting).
581    
582    
583    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
584    
585           When  the  alternative  matching function, pcre_dfa_exec(), is used (by
586           means of the \D escape sequence or the -dfa command line  option),  the
587           output  consists  of  a list of all the matches that start at the first
588           point in the subject where there is at least one match. For example:
589    
590               re> /(tang|tangerine|tan)/
591             data> yellow tangerine\D
592              0: tangerine
593              1: tang
594              2: tan
595    
596           (Using the normal matching function on this data  finds  only  "tang".)
597           The  longest matching string is always given first (and numbered zero).
598           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
599           lowed  by  the  partially  matching  substring.  (Note that this is the
600           entire substring that was inspected during the partial  match;  it  may
601           include characters before the actual match start if a lookbehind asser-
602           tion, \K, \b, or \B was involved.)
603    
604           If /g is present on the pattern, the search for further matches resumes
605           at the end of the longest match. For example:
606    
607               re> /(tang|tangerine|tan)/g
608             data> yellow tangerine and tangy sultana\D
609              0: tangerine
610              1: tang
611              2: tan
612              0: tang
613              1: tan
614              0: tan
615    
616           Since  the  matching  function  does not support substring capture, the
617           escape sequences that are concerned with captured  substrings  are  not
618           relevant.
619    
620    
621    RESTARTING AFTER A PARTIAL MATCH
622    
623           When the alternative matching function has given the PCRE_ERROR_PARTIAL
624           return, indicating that the subject partially matched the pattern,  you
625           can  restart  the match with additional subject data by means of the \R
626           escape sequence. For example:
627    
628               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
629             data> 23ja\P\D
630             Partial match: 23ja
631             data> n05\R\D
632              0: n05
633    
634           For further information about partial  matching,  see  the  pcrepartial
635           documentation.
636    
637    
638    CALLOUTS
639    
640           If  the pattern contains any callout requests, pcretest's callout func-
641           tion is called during matching. This works  with  both  matching  func-
642           tions. By default, the called function displays the callout number, the
643           start and current positions in the text at the callout  time,  and  the
644           next pattern item to be tested. For example, the output
645    
646             --->pqrabcdef
647               0    ^  ^     \d
648    
649           indicates  that  callout number 0 occurred for a match attempt starting
650           at the fourth character of the subject string, when the pointer was  at
651           the  seventh  character of the data, and when the next pattern item was
652           \d. Just one circumflex is output if the start  and  current  positions
653           are the same.
654    
655           Callouts numbered 255 are assumed to be automatic callouts, inserted as
656           a result of the /C pattern modifier. In this case, instead  of  showing
657           the  callout  number, the offset in the pattern, preceded by a plus, is
658           output. For example:
659    
660               re> /\d?[A-E]\*/C
661             data> E*
662             --->E*
663              +0 ^      \d?
664              +3 ^      [A-E]
665              +8 ^^     \*
666             +10 ^ ^
667              0: E*
668    
669           If a pattern contains (*MARK) items, an additional line is output when-
670           ever  a  change  of  latest mark is passed to the callout function. For
671           example:
672    
673               re> /a(*MARK:X)bc/C
674             data> abc
675             --->abc
676              +0 ^       a
677              +1 ^^      (*MARK:X)
678             +10 ^^      b
679             Latest Mark: X
680             +11 ^ ^     c
681             +12 ^  ^
682              0: abc
683    
684           The mark changes between matching "a" and "b", but stays the  same  for
685           the  rest  of  the match, so nothing more is output. If, as a result of
686           backtracking, the mark reverts to being unset, the  text  "<unset>"  is
687           output.
688    
689           The  callout  function  in pcretest returns zero (carry on matching) by
690           default, but you can use a \C item in a data line (as described  above)
691           to change this and other parameters of the callout.
692    
693           Inserting  callouts can be helpful when using pcretest to check compli-
694           cated regular expressions. For further information about callouts,  see
695           the pcrecallout documentation.
696    
697    
698    NON-PRINTING CHARACTERS
699    
700           When  pcretest is outputting text in the compiled version of a pattern,
701           bytes other than 32-126 are always treated as  non-printing  characters
702           are are therefore shown as hex escapes.
703    
704           When  pcretest  is  outputting text that is a matched part of a subject
705           string, it behaves in the same way, unless a different locale has  been
706           set  for  the  pattern  (using  the  /L  modifier).  In  this case, the
707           isprint() function to distinguish printing and non-printing characters.
708    
709    
710    SAVING AND RELOADING COMPILED PATTERNS
711    
712           The facilities described in this section are  not  available  when  the
713           POSIX  interface  to  PCRE  is being used, that is, when the /P pattern
714           modifier is specified.
715    
716           When the POSIX interface is not in use, you can cause pcretest to write
717           a  compiled  pattern to a file, by following the modifiers with > and a
718           file name.  For example:
719    
720             /pattern/im >/some/file
721    
722           See the pcreprecompile documentation for a discussion about saving  and
723           re-using compiled patterns.
724    
725           The  data  that  is  written  is  binary. The first eight bytes are the
726           length of the compiled pattern data  followed  by  the  length  of  the
727           optional  study  data,  each  written as four bytes in big-endian order
728           (most significant byte first). If there is no study  data  (either  the
729           pattern was not studied, or studying did not return any data), the sec-
730           ond length is zero. The lengths are followed by an exact  copy  of  the
731           compiled pattern. If there is additional study data, this follows imme-
732           diately after the compiled pattern. After writing  the  file,  pcretest
733           expects to read a new pattern.
734    
735           A  saved  pattern  can  be reloaded into pcretest by specifying < and a
736           file name instead of a pattern. The name of the file must not contain a
737           < character, as otherwise pcretest will interpret the line as a pattern
738           delimited by < characters.  For example:
739    
740              re> </some/file
741             Compiled pattern loaded from /some/file
742             No study data
743    
744           When the pattern has been loaded, pcretest proceeds to read data  lines
745           in the usual way.
746    
747           You  can copy a file written by pcretest to a different host and reload
748           it there, even if the new host has opposite endianness to  the  one  on
749           which  the pattern was compiled. For example, you can compile on an i86
750           machine and run on a SPARC machine.
751    
752           File names for saving and reloading can be absolute  or  relative,  but
753           note  that the shell facility of expanding a file name that starts with
754           a tilde (~) is not available.
755    
756           The ability to save and reload files in pcretest is intended for  test-
757           ing  and experimentation. It is not intended for production use because
758           only a single pattern can be written to a file. Furthermore,  there  is
759           no  facility  for  supplying  custom  character  tables  for use with a
760           reloaded pattern. If the original  pattern  was  compiled  with  custom
761           tables,  an  attempt to match a subject string using a reloaded pattern
762           is likely to cause pcretest to crash.  Finally, if you attempt to  load
763           a file that is not in the correct format, the result is undefined.
764    
765    
766    SEE ALSO
767    
768           pcre(3),  pcreapi(3),  pcrecallout(3), pcrematching(3), pcrepartial(d),
769           pcrepattern(3), pcreprecompile(3).
770    
771    
772    AUTHOR
773    
774           Philip Hazel
775           University Computing Service
776           Cambridge CB2 3QH, England.
777    
778    
779    REVISION
780    
781           Last updated: 01 August 2011
782           Copyright (c) 1997-2011 University of Cambridge.

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