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RedHat 9 (Linux i386) - man page for pcretest (redhat section 1)

PCRETEST(1)			     General Commands Manual			      PCRETEST(1)

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

SYNOPSIS
       pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [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  man  page	describes
       the  features  of the test program; for details of the regular expressions themselves, see
       the pcre man page.

OPTIONS
       -d	 Behave as if each regex had the /D modifier (see below); the  internal  form  is
		 output after compilation.

       -i	 Behave as if each regex had the /I modifier; information about the compiled pat-
		 tern 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 ear-
		 lier 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
		 to  be  osize.  The default value is 45, which is enough for 14 capturing subex-
		 pressions. The vector size can be  changed  for  individual  matching	calls  by
		 including \O in the data line (see below).

       -p	 Behave  as  if each regex has /P modifier; the POSIX wrapper API is used to call
		 PCRE. None of the other options has any effect when -p is set.

       -t	 Run each compile, study, and match 20000 times with a timer, and output  result-
		 ing  time per compile or match (in milliseconds). Do not set -t with -m, because
		 you will then get the size output 20000 times and the timing will be distorted.

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.

       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. 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.

PATTERN MODIFIERS
       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  asser-
       tion (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 modi-
       fier, 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  inter-
       nal 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.

       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
       the  (currently incomplete) support for UTF-8 character handling in PCRE, provided that it
       was compiled with this support enabled. This modifier also causes any non-printing charac-
       ters  in output strings to be printed using the \x{hh...} notation if they are valid UTF-8
       sequences.

DATA LINES
       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)
	 \x{hh...}  hexadecimal UTF-8 character

	 \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()

       When  \O  is  used,  it	may  be  higher  or  lower than the size set by the -O option (or
       defaulted to 45); \O applies only to the call of pcre_exec() for  the  line  in	which  it
       appears.

       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 0 causing
       REG_NOTBOL and REG_NOTEOL to be passed to regexec() respectively.

       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
       UTF-8 rules.

OUTPUT FROM PCRETEST
       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, or as
       \x{...} escapes if the /8 modifier was present on the pattern. 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  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 parenthe-
       ses 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.

AUTHOR
       Philip Hazel <ph10@cam.ac.uk>
       University Computing Service,
       New Museums Site,
       Cambridge CB2 3QG, England.
       Phone: +44 1223 334714

       Last updated: 15 August 2001
       Copyright (c) 1997-2001 University of Cambridge.

										      PCRETEST(1)


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