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    Command:

    pcretest

    
    
    

    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 byte code) 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
           -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
           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
           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
    
             \a         alarm (BEL, \x07)
             \b         backspace (\x08)
             \e         escape (\x27)
             \f         form feed (\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 terminated
                          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 terminated
                          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)
                          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.
           matched the whole pattern. Otherwise, it outputs "No  match"  when  the
           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
           tially matching substring when pcre_exec() returns  PCRE_ERROR_PARTIAL.
           For  any  other return, pcretest outputs the PCRE negative error number
           and a short descriptive phrase. If the error is a failed  UTF-8  string
           check,  the  byte  offset of the start of the failing character and the
           reason code are also output, provided that the size of the output  vec-
           tor is at least two. 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
    
           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 fol-
           lowing 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
    
           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:
    
           the start and current positions in the text at the  callout  time,  and
           the next pattern item to be tested. For example, the output
    
             --->pqrabcdef
               0    ^  ^     \d
    
           indicates  that  callout number 0 occurred for a match attempt starting
           at the fourth character of the subject string, when the pointer was  at
           the  seventh  character of the data, and when the next pattern item was
           \d. Just one circumflex is output if the start  and  current  positions
           are the same.
    
           Callouts numbered 255 are assumed to be automatic callouts, inserted as
           a result of the /C pattern modifier. In this case, instead  of  showing
           the  callout  number, the offset in the pattern, preceded by a plus, is
           output. For example:
    
               re> /\d?[A-E]\*/C
             data> E*
             --->E*
              +0 ^      \d?
              +3 ^      [A-E]
              +8 ^^     \*
             +10 ^ ^
              0: E*
    
           The callout function in pcretest returns zero (carry  on  matching)  by
           default,  but you can use a \C item in a data line (as described above)
           to change this.
    
           Inserting callouts can be helpful when using pcretest to check  compli-
           cated  regular expressions. For further information about callouts, see
           the pcrecallout documentation.
    
    
    

    NON-PRINTING CHARACTERS

    
           When pcretest is outputting text in the compiled version of a  pattern,
           bytes  other  than 32-126 are always treated as non-printing characters
           are are therefore shown as hex escapes.
    
           When pcretest is outputting text that is a matched part  of  a  subject
           string,  it behaves in the same way, unless a different locale has been
           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
           isprint() function to distinguish printing and non-printing characters.
    
    
    

    SAVING AND RELOADING COMPILED PATTERNS

    
           The facilities described in this section are  not  available  when  the
           POSIX  interface  to  PCRE  is being used, that is, when the /P pattern
           modifier is specified.
    
           When the POSIX interface is not in use, you can cause pcretest to write
           compiled pattern. If there is additional study data, this follows imme-
           diately after the compiled pattern. After writing  the  file,  pcretest
           expects to read a new pattern.
    
           A  saved  pattern  can  be reloaded into pcretest by specifying < and a
           file name instead of a pattern. The name of the file must not contain a
           < character, as otherwise pcretest will interpret the line as a pattern
           delimited by < characters.  For example:
    
              re> </some/file
             Compiled regex loaded from /some/file
             No study data
    
           When the pattern has been loaded, pcretest proceeds to read data  lines
           in the usual way.
    
           You  can copy a file written by pcretest to a different host and reload
           it there, even if the new host has opposite endianness to  the  one  on
           which  the pattern was compiled. For example, you can compile on an i86
           machine and run on a SPARC machine.
    
           File names for saving and reloading can be absolute  or  relative,  but
           note  that the shell facility of expanding a file name that starts with
           a tilde (~) is not available.
    
           The ability to save and reload files in pcretest is intended for  test-
           ing  and experimentation. It is not intended for production use because
           only a single pattern can be written to a file. Furthermore,  there  is
           no  facility  for  supplying  custom  character  tables  for use with a
           reloaded pattern. If the original  pattern  was  compiled  with  custom
           tables,  an  attempt to match a subject string using a reloaded pattern
           is likely to cause pcretest to crash.  Finally, if you attempt to  load
           a file that is not in the correct format, the result is undefined.
    
    
    

    SEE ALSO

    
           pcre(3),  pcreapi(3),  pcrecallout(3), pcrematching(3), pcrepartial(d),
           pcrepattern(3), pcreprecompile(3).
    
    
    

    AUTHOR

    
           Philip Hazel
           University Computing Service
           Cambridge CB2 3QH, England.
    
    
    

    REVISION

    
           Last updated: 12 April 2008
           Copyright (c) 1997-2011 University of Cambridge.
    
    
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