PCRETEST(1)                                                        PCRETEST(1)

NAME

       pcretest - a program for testing Perl-compatible regular expressions.

SYNOPSIS

       pcretest [options] [source] [destination]

       pcretest  was written as a test program for the PCRE regular expression

       library itself, but it can also be used for experimenting with  regular

       expressions.  This document describes the features of the test program;

       for details of the regular expressions themselves, see the  pcrepattern

       documentation. For details of the PCRE library function calls and their

       options, see the pcreapi documentation.

OPTIONS

       -b        Behave as if each regex has the /B (show bytecode)  modifier;

                 the internal form is output after compilation.

       -C        Output the version number of the PCRE library, and all avail-

                 able  information  about  the  optional  features  that   are

                 included, and then exit.

       -d        Behave  as  if  each  regex  has the /D (debug) modifier; the

                 internal form and information about the compiled  pattern  is

                 output after compilation; -d is equivalent to -b -i.

       -dfa      Behave  as if each data line contains the \D escape sequence;

                 this    causes    the    alternative    matching    function,

                 pcre_dfa_exec(),   to   be   used  instead  of  the  standard

                 pcre_exec() function (more detail is given below).

       -help     Output a brief summary these options and then exit.

       -i        Behave as if each regex  has  the  /I  modifier;  information

                 about the compiled pattern is given after compilation.

       -m        Output  the  size  of each compiled pattern after it has been

                 compiled. This is equivalent to adding  /M  to  each  regular

                 expression.   For  compatibility  with  earlier  versions  of

                 pcretest, -s is a synonym for -m.

       -o osize  Set the number of elements in the output vector that is  used

                 when  calling pcre_exec() or pcre_dfa_exec() to be osize. The

                 default value is 45, which is enough for 14 capturing  subex-

                 pressions   for  pcre_exec()  or  22  different  matches  for

                 pcre_dfa_exec(). The vector size can be changed for  individ-

                 ual  matching  calls  by  including  \O in the data line (see

                 below).

       -p        Behave as if each regex has the /P modifier; the POSIX  wrap-

                 per  API  is used to call PCRE. None of the other options has

                 any effect when -p is set.

       -q        Do not output the version number of pcretest at the start  of

                 execution.

       -S size   On  Unix-like  systems,  set the size of the runtime stack to

                 size megabytes.

       -t        Run each compile, study, and match many times with  a  timer,

                 and  output resulting time per compile or match (in millisec-

                 onds). Do not set -m with -t, because you will then  get  the

                 size  output  a  zillion  times,  and the timing will be dis-

                 torted. You can control the number  of  iterations  that  are

                 used  for timing by following -t with a number (as a separate

                 item on the command line). For example, "-t 1000" would iter-

                 ate 1000 times. The default is to iterate 500000 times.

       -tm       This is like -t except that it times only the matching phase,

                 not the compile or study phases.

DESCRIPTION

       If pcretest is given two filename arguments, it reads  from  the  first

       and writes to the second. If it is given only one filename argument, it

       reads from that file 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.

       When  pcretest  is  built,  a  configuration option can specify that it

       should be linked with the libreadline library. When this  is  done,  if

       the input is from a terminal, it is read using the readline() function.

       This provides line-editing and history facilities. The output from  the

       -help option states whether or not readline() will be used.

       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  num-

       ber of data lines to be matched against the pattern.

       Each  data line is matched separately and independently. If you want to

       do multi-line matches, you have to use the \n escape sequence (or \r or

       \r\n, etc., depending on the newline setting) in a single line of input

       to encode the newline sequences. There is no limit  on  the  length  of

       data  lines;  the  input  buffer is automatically extended if it is too

       small.

       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-alphanumeric delimiters other than backslash, for example:

         /(a|bc)x+yz/

       White space before the initial delimiter is ignored. A regular  expres-

       sion  may be continued over several input lines, in which case the new-

       line characters are included within it. 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-alphanumeric, this does not  affect

       its  interpretation.   If the terminating delimiter is immediately fol-

       lowed 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.

PATTERN MODIFIERS

       A pattern may be followed by any number of modifiers, which are  mostly

       single  characters.  Following  Perl usage, these are referred to below

       as, for example, "the /i modifier", even though the  delimiter  of  the

       pattern  need  not always be a slash, and no slash is used when writing

       modifiers. Whitespace may appear between the  final  pattern  delimiter

       and the first modifier, and between the modifiers themselves.

       The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,

       PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-

       pile()  is  called. These four modifier letters have the same effect as

       they do in Perl. For example:

         /caseless/i

       The following table shows additional modifiers for setting PCRE options

       that do not correspond to anything in Perl:

         /A              PCRE_ANCHORED

         /C              PCRE_AUTO_CALLOUT

         /E              PCRE_DOLLAR_ENDONLY

         /f              PCRE_FIRSTLINE

         /J              PCRE_DUPNAMES

         /N              PCRE_NO_AUTO_CAPTURE

         /U              PCRE_UNGREEDY

         /X              PCRE_EXTRA

         /<JS>           PCRE_JAVASCRIPT_COMPAT

         /<cr>           PCRE_NEWLINE_CR

         /<lf>           PCRE_NEWLINE_LF

         /<crlf>         PCRE_NEWLINE_CRLF

         /<anycrlf>      PCRE_NEWLINE_ANYCRLF

         /<any>          PCRE_NEWLINE_ANY

         /<bsr_anycrlf>  PCRE_BSR_ANYCRLF

         /<bsr_unicode>  PCRE_BSR_UNICODE

       Those  specifying  line  ending sequences are literal strings as shown,

       but the letters can be in either  case.  This  example  sets  multiline

       matching with CRLF as the line ending sequence:

         /^abc/m<crlf>

       Details  of the meanings of these PCRE options are given in the pcreapi

       documentation.

   Finding all matches in a string

       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 differ-

       ence 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  han-

       dles such cases when using the /g modifier or the split() function.

   Other modifiers

       There are yet more 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  /B modifier is a debugging feature. It requests that pcretest out-

       put a representation of the compiled byte code after compilation.  Nor-

       mally  this  information contains length and offset values; however, if

       /Z is also present, this data is replaced by spaces. This is a  special

       feature for use in the automatic test scripts; it ensures that the same

       output is generated for different internal link sizes.

       The /L modifier must be followed directly by the name of a locale,  for

       example,

         /pattern/Lfr_FR

       For this reason, it must be the last modifier. 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  pattern (whether it is anchored, has a fixed first character,

       and so on). It does this by calling pcre_fullinfo() after  compiling  a

       pattern.  If  the pattern is studied, the results of that are also out-

       put.

       The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,

       that is, both the /B and the /I modifiers.

       The /F modifier causes pcretest to flip the byte order of the fields in

       the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This

       facility  is  for testing the feature in PCRE that allows it to execute

       patterns that were compiled on a host with a different endianness. This

       feature  is  not  available  when  the POSIX interface to PCRE is being

       used, that is, when the /P pattern modifier is specified. See also  the

       section about saving and reloading compiled patterns below.

       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 com-

       piled pattern to be output.

       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.

       The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option

       set. This turns on support for UTF-8 character handling in  PCRE,  pro-

       vided  that  it  was  compiled with this support enabled. This modifier

       also causes any non-printing characters in output strings to be printed

       using the \x{hh...} notation if they are valid UTF-8 sequences.

       If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call

       pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the

       checking of the string for UTF-8 validity.

DATA LINES

       Before  each  data  line is passed to pcre_exec(), leading and trailing

       whitespace is removed, and it is then scanned for \  escapes.  Some  of

       these  are  pretty esoteric features, intended for checking out some of

       the more complicated features of PCRE. If you are just  testing  "ordi-

       nary"  regular  expressions,  you probably don't need any of these. The

       following escapes are recognized:

         \a         alarm (BEL, \x07)

         \b         backspace (\x08)

         \e         escape (\x27)

         \f         formfeed (\x0c)

         \n         newline (\x0a)

         \qdd       set the PCRE_MATCH_LIMIT limit to dd

                      (any number of digits)

         \r         carriage return (\x0d)

         \t         tab (\x09)

         \v         vertical tab (\x0b)

         \nnn       octal character (up to 3 octal digits)

         \xhh       hexadecimal character (up to 2 hex digits)

         \x{hh...}  hexadecimal character, any number of digits

                      in UTF-8 mode

         \A         pass the PCRE_ANCHORED option to pcre_exec()

                      or pcre_dfa_exec()

         \B         pass the PCRE_NOTBOL option to pcre_exec()

                      or pcre_dfa_exec()

         \Cdd       call pcre_copy_substring() for substring dd

                      after a successful match (number less than 32)

         \Cname     call pcre_copy_named_substring() for substring

                      "name" after a successful match (name termin-

                      ated by next non alphanumeric character)

         \C+        show the current captured substrings at callout

                      time

         \C-        do not supply a callout function

         \C!n       return 1 instead of 0 when callout number n is

                      reached

         \C!n!m     return 1 instead of 0 when callout number n is

                      reached for the nth time

         \C*n       pass the number n (may be negative) as callout

                      data; this is used as the callout return value

         \D         use the pcre_dfa_exec() match function

         \F         only shortest match for pcre_dfa_exec()

         \Gdd       call pcre_get_substring() for substring dd

                      after a successful match (number less than 32)

         \Gname     call pcre_get_named_substring() for substring

                      "name" after a successful match (name termin-

                      ated by next non-alphanumeric character)

         \L         call pcre_get_substringlist() after a

                      successful match

         \M         discover the minimum MATCH_LIMIT and

                      MATCH_LIMIT_RECURSION settings

         \N         pass the PCRE_NOTEMPTY option to pcre_exec()

                      or pcre_dfa_exec()

         \Odd       set the size of the output vector passed to

                      pcre_exec() to dd (any number of digits)

         \P         pass the PCRE_PARTIAL option to pcre_exec()

                      or pcre_dfa_exec()

         \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd

                      (any number of digits)

         \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()

         \S         output details of memory get/free calls during matching

         \Z         pass the PCRE_NOTEOL option to pcre_exec()

                      or pcre_dfa_exec()

         \?         pass the PCRE_NO_UTF8_CHECK option to

                      pcre_exec() or pcre_dfa_exec()

         \>dd       start the match at offset dd (any number of digits);

                      this sets the startoffset argument for pcre_exec()

                      or pcre_dfa_exec()

         \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()

                      or pcre_dfa_exec()

         \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()

                      or pcre_dfa_exec()

         \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()

                      or pcre_dfa_exec()

         \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()

                      or pcre_dfa_exec()

         \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()

                      or pcre_dfa_exec()

       The escapes that specify line ending  sequences  are  literal  strings,

       exactly as shown. No more than one newline setting should be present in

       any data line.

       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  termi-

       nates the data input.

       If  \M  is present, pcretest calls pcre_exec() several times, with dif-

       ferent values in the match_limit and  match_limit_recursion  fields  of

       the  pcre_extra  data structure, until it finds the minimum numbers for

       each parameter that allow pcre_exec() to complete. The match_limit num-

       ber  is  a  measure of the amount of backtracking that takes place, and

       checking it out can be instructive. For most simple matches, the number

       is  quite  small,  but for patterns with very large numbers of matching

       possibilities, it can become large very quickly with increasing  length

       of subject string. The match_limit_recursion number is a measure of how

       much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)

       memory is needed to complete the match attempt.

       When  \O  is  used, the value specified may be higher or lower than the

       size set by the -O command line option (or defaulted to 45); \O applies

       only to the call of pcre_exec() for the line in which it appears.

       If  the /P modifier was present on the pattern, causing the POSIX wrap-

       per API to be used, the only option-setting  sequences  that  have  any

       effect  are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,

       to be passed to regexec().

       The use of \x{hh...} to represent UTF-8 characters is not dependent  on

       the  use  of  the  /8 modifier on the pattern. It is recognized always.

       There may be any number of hexadecimal digits inside  the  braces.  The

       result  is  from  one  to  six bytes, encoded according to the original

       UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to

       0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,

       or indeed valid UTF-8 characters according to the later  rules  in  RFC

       3629.

THE ALTERNATIVE MATCHING FUNCTION

       By   default,  pcretest  uses  the  standard  PCRE  matching  function,

       pcre_exec() to match each data line. From release 6.0, PCRE supports an

       alternative  matching  function,  pcre_dfa_test(),  which operates in a

       different way, and has some restrictions. The differences  between  the

       two functions are described in the pcrematching documentation.

       If  a data line contains the \D escape sequence, or if the command line

       contains the -dfa option, the alternative matching function is  called.

       This function finds all possible matches at a given point. If, however,

       the \F escape sequence is present in the data line, it stops after  the

       first match is found. This is always the shortest possible match.

DEFAULT OUTPUT FROM PCRETEST

       This  section  describes  the output when the normal matching function,

       pcre_exec(), is being used.

       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. Otherwise, it outputs "No match" or "Partial

       match"  when  pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-

       TIAL, respectively, and otherwise the PCRE negative error number.  Here

       is an example of an interactive pcretest run.

         $ pcretest

         PCRE version 7.0 30-Nov-2006

           re> /^abc(\d+)/

         data> abc123

          0: abc123

          1: 123

         data> xyz

         No match

       Note  that unset capturing substrings that are not followed by one that

       is set are not returned by pcre_exec(), and are not shown by  pcretest.

       In  the following example, there are two capturing substrings, but when

       the first data line is matched, the  second,  unset  substring  is  not

       shown.  An "internal" unset substring is shown as "<unset>", as for the

       second data line.

           re> /(a)|(b)/

         data> a

          0: a

          1: a

         data> b

          0: b

          1: <unset>

          2: b

       If the strings contain any non-printing characters, they are output  as

       \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on

       the pattern. See below for the definition of  non-printing  characters.

       If  the pattern has the /+ modifier, the output for substring 0 is fol-

       lowed 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 the sequences \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  paren-

       theses after each string for \C and \G.

       Note that whereas patterns can be continued over several lines (a plain

       ">" prompt is used for continuations), data lines may not. However new-

       lines  can  be included in data by means of the \n escape (or \r, \r\n,

       etc., depending on the newline sequence setting).

OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION

       When the alternative matching function, pcre_dfa_exec(),  is  used  (by

       means  of  the \D escape sequence or the -dfa command line option), the

       output consists of a list of all the matches that start  at  the  first

       point in the subject where there is at least one match. For example:

           re> /(tang|tangerine|tan)/

         data> yellow tangerine\D

          0: tangerine

          1: tang

          2: tan

       (Using  the  normal  matching function on this data finds only "tang".)

       The longest matching string is always given first (and numbered  zero).

       If /g is present on the pattern, the search for further matches resumes

       at the end of the longest match. For example:

           re> /(tang|tangerine|tan)/g

         data> yellow tangerine and tangy sultana\D

          0: tangerine

          1: tang

          2: tan

          0: tang

          1: tan

          0: tan

       Since the matching function does not  support  substring  capture,  the

       escape  sequences  that  are concerned with captured substrings are not

       relevant.

RESTARTING AFTER A PARTIAL MATCH

       When the alternative matching function has given the PCRE_ERROR_PARTIAL

       return,  indicating that the subject partially matched the pattern, you

       can restart the match with additional subject data by means of  the  \R

       escape sequence. For example:

           re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/

         data> 23ja\P\D

         Partial match: 23ja

         data> n05\R\D

          0: n05

       For  further  information  about  partial matching, see the pcrepartial

       documentation.