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