.TH PCRETEST 1

 .SH NAME

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

 .SH SYNOPSIS

 .rs

 .sp

 .B pcretest "[options] [source] [destination]"

 .sp

 \fBpcretest\fP 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

 .\" HREF

 \fBpcrepattern\fP

 .\"

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

 options, see the

 .\" HREF

 \fBpcreapi\fP

 .\"

 documentation.

 .

 .

 .SH OPTIONS

 .rs

 .TP 10

 \fB-b\fP

 Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal

 form is output after compilation.

 .TP 10

 \fB-C\fP

 Output the version number of the PCRE library, and all available information

 about the optional features that are included, and then exit.

 .TP 10

 \fB-d\fP

 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal

 form and information about the compiled pattern is output after compilation;

 \fB-d\fP is equivalent to \fB-b -i\fP.

 .TP 10

 \fB-dfa\fP

 Behave as if each data line contains the \eD escape sequence; this causes the

 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the

 standard \fBpcre_exec()\fP function (more detail is given below).

 .TP 10

 \fB-help\fP

 Output a brief summary these options and then exit.

 .TP 10

 \fB-i\fP

 Behave as if each regex has the \fB/I\fP modifier; information about the

 compiled pattern is given after compilation.

 .TP 10

 \fB-M\fP

 Behave as if each data line contains the \eM escape sequence; this causes

 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by

 calling \fBpcre_exec()\fP repeatedly with different limits.

 .TP 10

 \fB-m\fP

 Output the size of each compiled pattern after it has been compiled. This is

 equivalent to adding \fB/M\fP to each regular expression. For compatibility

 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.

 .TP 10

 \fB-o\fP \fIosize\fP

 Set the number of elements in the output vector that is used when calling

 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value

 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or

 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be

 changed for individual matching calls by including \eO in the data line (see

 below).

 .TP 10

 \fB-p\fP

 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is

 used to call PCRE. None of the other options has any effect when \fB-p\fP is

 set.

 .TP 10

 \fB-q\fP

 Do not output the version number of \fBpcretest\fP at the start of execution.

 .TP 10

 \fB-S\fP \fIsize\fP

 On Unix-like systems, set the size of the runtime stack to \fIsize\fP

 megabytes.

 .TP 10

 \fB-t\fP

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

 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with

 \fB-t\fP, because you will then get the size output a zillion times, and the

 timing will be distorted. You can control the number of iterations that are

 used for timing by following \fB-t\fP with a number (as a separate item on the

 command line). For example, "-t 1000" would iterate 1000 times. The default is

 to iterate 500000 times.

 .TP 10

 \fB-tm\fP

 This is like \fB-t\fP except that it times only the matching phase, not the

 compile or study phases.

 .

 .

 .SH DESCRIPTION

 .rs

 .sp

 If \fBpcretest\fP 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.

 .P

 When \fBpcretest\fP is built, a configuration option can specify that it should

 be linked with the \fBlibreadline\fP library. When this is done, if the input

 is from a terminal, it is read using the \fBreadline()\fP function. This

 provides line-editing and history facilities. The output from the \fB-help\fP

 option states whether or not \fBreadline()\fP will be used.

 .P

 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.

 .P

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

 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,

 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.

 .P

 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:

 .sp

   /(a|bc)x+yz/

 .sp

 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

 .sp

   /abc\e/def/

 .sp

 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 followed by a backslash, for

 example,

 .sp

   /abc/\e

 .sp

 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

 .sp

   /abc\e/

 .sp

 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.

 .

 .

 .SH "PATTERN MODIFIERS"

 .rs

 .sp

 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 \fB/i\fP 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.

 .P

 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,

 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when

 \fBpcre_compile()\fP is called. These four modifier letters have the same

 effect as they do in Perl. For example:

 .sp

   /caseless/i

 .sp

 The following table shows additional modifiers for setting PCRE options that do

 not correspond to anything in Perl:

 .sp

   \fB/A\fP              PCRE_ANCHORED

   \fB/C\fP              PCRE_AUTO_CALLOUT

   \fB/E\fP              PCRE_DOLLAR_ENDONLY

   \fB/f\fP              PCRE_FIRSTLINE

   \fB/J\fP              PCRE_DUPNAMES

   \fB/N\fP              PCRE_NO_AUTO_CAPTURE

   \fB/U\fP              PCRE_UNGREEDY

   \fB/X\fP              PCRE_EXTRA

   \fB/<JS>\fP           PCRE_JAVASCRIPT_COMPAT

   \fB/<cr>\fP           PCRE_NEWLINE_CR

   \fB/<lf>\fP           PCRE_NEWLINE_LF

   \fB/<crlf>\fP         PCRE_NEWLINE_CRLF

   \fB/<anycrlf>\fP      PCRE_NEWLINE_ANYCRLF

   \fB/<any>\fP          PCRE_NEWLINE_ANY

   \fB/<bsr_anycrlf>\fP  PCRE_BSR_ANYCRLF

   \fB/<bsr_unicode>\fP  PCRE_BSR_UNICODE

 .sp

 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:

 .sp

   /^abc/m<crlf>

 .sp

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

 .\" HREF

 \fBpcreapi\fP

 .\"

 documentation.

 .

 .

 .SS "Finding all matches in a string"

 .rs

 .sp

 Searching for all possible matches within each subject string can be requested

 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called

 again to search the remainder of the subject string. The difference between

 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to

 \fBpcre_exec()\fP 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 \eb or \eB).

 .P

 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP 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

 \fB/g\fP modifier or the \fBsplit()\fP function.

 .

 .

 .SS "Other modifiers"

 .rs

 .sp

 There are yet more modifiers for controlling the way \fBpcretest\fP

 operates.

 .P

 The \fB/+\fP 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.

 .P

 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP

 output a representation of the compiled byte code after compilation. Normally

 this information contains length and offset values; however, if \fB/Z\fP 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.

 .P

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

 example,

 .sp

   /pattern/Lfr_FR

 .sp

 For this reason, it must be the last modifier. The given locale is set,

 \fBpcre_maketables()\fP is called to build a set of character tables for the

 locale, and this is then passed to \fBpcre_compile()\fP when compiling the

 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables

 pointer; that is, \fB/L\fP applies only to the expression on which it appears.

 .P

 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the

 compiled pattern (whether it is anchored, has a fixed first character, and

 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a

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

 .P

 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to

 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.

 .P

 The \fB/F\fP modifier causes \fBpcretest\fP 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

 \fB/P\fP pattern modifier is specified. See also the section about saving and

 reloading compiled patterns below.

 .P

 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the

 expression has been compiled, and the results used when the expression is

 matched.

 .P

 The \fB/M\fP modifier causes the size of memory block used to hold the compiled

 pattern to be output.

 .P

 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper

 API rather than its native API. When this is done, all other modifiers except

 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is

 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions

 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.

 .P

 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8

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

 provided that it was compiled with this support enabled. This modifier also

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

 \ex{hh...} notation if they are valid UTF-8 sequences.

 .P

 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to

 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the

 checking of the string for UTF-8 validity.

 .

 .

 .SH "DATA LINES"

 .rs

 .sp

 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing

 whitespace is removed, and it is then scanned for \e 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 "ordinary" regular

 expressions, you probably don't need any of these. The following escapes are

 recognized:

 .sp

   \ea         alarm (BEL, \ex07)

   \eb         backspace (\ex08)

   \ee         escape (\ex27)

   \ef         formfeed (\ex0c)

   \en         newline (\ex0a)

 .\" JOIN

   \eqdd       set the PCRE_MATCH_LIMIT limit to dd

                (any number of digits)

   \er         carriage return (\ex0d)

   \et         tab (\ex09)

   \ev         vertical tab (\ex0b)

   \ennn       octal character (up to 3 octal digits)

   \exhh       hexadecimal character (up to 2 hex digits)

 .\" JOIN

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

                in UTF-8 mode

 .\" JOIN

   \eA         pass the PCRE_ANCHORED option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \eB         pass the PCRE_NOTBOL option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \eCdd       call pcre_copy_substring() for substring dd

                after a successful match (number less than 32)

 .\" JOIN

   \eCname     call pcre_copy_named_substring() for substring

                "name" after a successful match (name termin-

                ated by next non alphanumeric character)

 .\" JOIN

   \eC+        show the current captured substrings at callout

                time

   \eC-        do not supply a callout function

 .\" JOIN

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

                reached

 .\" JOIN

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

                reached for the nth time

 .\" JOIN

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

                data; this is used as the callout return value

   \eD         use the \fBpcre_dfa_exec()\fP match function

   \eF         only shortest match for \fBpcre_dfa_exec()\fP

 .\" JOIN

   \eGdd       call pcre_get_substring() for substring dd

                after a successful match (number less than 32)

 .\" JOIN

   \eGname     call pcre_get_named_substring() for substring

                "name" after a successful match (name termin-

                ated by next non-alphanumeric character)

 .\" JOIN

   \eL         call pcre_get_substringlist() after a

                successful match

 .\" JOIN

   \eM         discover the minimum MATCH_LIMIT and

                MATCH_LIMIT_RECURSION settings

 .\" JOIN

   \eN         pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \eOdd       set the size of the output vector passed to

                \fBpcre_exec()\fP to dd (any number of digits)

 .\" JOIN

   \eP         pass the PCRE_PARTIAL option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \eQdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd

                (any number of digits)

   \eR         pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP

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

 .\" JOIN

   \eZ         pass the PCRE_NOTEOL option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \e?         pass the PCRE_NO_UTF8_CHECK option to

                \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP

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

 .\" JOIN

                this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \e<cr>      pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \e<lf>      pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \e<crlf>    pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .\" JOIN

   \e<any>     pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP

                or \fBpcre_dfa_exec()\fP

 .sp

 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.

 .P

 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.

 .P

 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with

 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP

 fields of the \fBpcre_extra\fP data structure, until it finds the minimum

 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The

 \fImatch_limit\fP number 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 \fImatch_limit_recursion\fP 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.

 .P

 When \eO is used, the value specified may be higher or lower than the size set

 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to

 the call of \fBpcre_exec()\fP for the line in which it appears.

 .P

 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper

 API to be used, the only option-setting sequences that have any effect are \eB

 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to

 \fBregexec()\fP.

 .P

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

 of the \fB/8\fP 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.

 .

 .

 .SH "THE ALTERNATIVE MATCHING FUNCTION"

 .rs

 .sp

 By default, \fBpcretest\fP uses the standard PCRE matching function,

 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an

 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a

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

 functions are described in the

 .\" HREF

 \fBpcrematching\fP

 .\"

 documentation.

 .P

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

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

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

 escape sequence is present in the data line, it stops after the first match is

 found. This is always the shortest possible match.

 .

 .

 .SH "DEFAULT OUTPUT FROM PCRETEST"

 .rs

 .sp

 This section describes the output when the normal matching function,

 \fBpcre_exec()\fP, is being used.

 .P

 When a match succeeds, pcretest outputs the list of captured substrings that

 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched

 the whole pattern. Otherwise, it outputs "No match" or "Partial match"

 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,

 respectively, and otherwise the PCRE negative error number. Here is an example

 of an interactive \fBpcretest\fP run.

 .sp

   $ pcretest

   PCRE version 7.0 30-Nov-2006

 .sp

     re> /^abc(\ed+)/

   data> abc123

    0: abc123

    1: 123

   data> xyz

   No match

 .sp

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

 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. 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.

 .sp

     re> /(a)|(b)/

   data> a

    0: a

    1: a

   data> b

    0: b

    1: <unset>

    2: b

 .sp

 If the strings contain any non-printing characters, they are output as \e0x

 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the

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

 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by

 the the rest of the subject string, identified by "0+" like this:

 .sp

     re> /cat/+

   data> cataract

    0: cat

    0+ aract

 .sp

 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive

 matching attempts are output in sequence, like this:

 .sp

     re> /\eBi(\ew\ew)/g

   data> Mississippi

    0: iss

    1: ss

    0: iss

    1: ss

    0: ipp

    1: pp

 .sp

 "No match" is output only if the first match attempt fails.

 .P

 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP 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 \fB\eC\fP and \fB\eG\fP.

 .P

 Note that whereas 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 \en escape (or \er, \er\en, etc., depending on

 the newline sequence setting).

 .

 .

 .

 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"

 .rs

 .sp

 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by

 means of the \eD escape sequence or the \fB-dfa\fP 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:

 .sp

     re> /(tang|tangerine|tan)/

   data> yellow tangerine\eD

    0: tangerine

    1: tang

    2: tan

 .sp

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

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

 .P

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

 at the end of the longest match. For example:

 .sp

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

   data> yellow tangerine and tangy sultana\eD

    0: tangerine

    1: tang

    2: tan

    0: tang

    1: tan

    0: tan

 .sp

 Since the matching function does not support substring capture, the escape

 sequences that are concerned with captured substrings are not relevant.

 .

 .

 .SH "RESTARTING AFTER A PARTIAL MATCH"

 .rs

 .sp

 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 \eR escape sequence. For

 example:

 .sp

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

   data> 23ja\eP\eD

   Partial match: 23ja

   data> n05\eR\eD

    0: n05

 .sp

 For further information about partial matching, see the

 .\" HREF

 \fBpcrepartial\fP

 .\"

 documentation.

 .

 .

 .SH CALLOUTS

 .rs

 .sp

 If the pattern contains any callout requests, \fBpcretest\fP's callout function

 is called during matching. This works with both matching functions. By default,

 the called function displays the callout number, the start and current

 positions in the text at the callout time, and the next pattern item to be

 tested. For example, the output

 .sp

   --->pqrabcdef

     0    ^  ^     \ed

 .sp

 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 \ed. Just one

 circumflex is output if the start and current positions are the same.

 .P

 Callouts numbered 255 are assumed to be automatic callouts, inserted as a

 result of the \fB/C\fP pattern modifier. In this case, instead of showing the

 callout number, the offset in the pattern, preceded by a plus, is output. For

 example:

 .sp

     re> /\ed?[A-E]\e*/C

   data> E*

   --->E*

    +0 ^      \ed?

    +3 ^      [A-E]

    +8 ^^     \e*

   +10 ^ ^

    0: E*

 .sp

 The callout function in \fBpcretest\fP returns zero (carry on matching) by

 default, but you can use a \eC item in a data line (as described above) to

 change this.

 .P

 Inserting callouts can be helpful when using \fBpcretest\fP to check

 complicated regular expressions. For further information about callouts, see

 the

 .\" HREF

 \fBpcrecallout\fP

 .\"

 documentation.

 .

 .

 .

 .SH "NON-PRINTING CHARACTERS"

 .rs

 .sp

 When \fBpcretest\fP 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.

 .P

 When \fBpcretest\fP 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 \fB/L\fP modifier). In this case, the \fBisprint()\fP

 function to distinguish printing and non-printing characters.

 .

 .

 .

 .SH "SAVING AND RELOADING COMPILED PATTERNS"

 .rs

 .sp

 The facilities described in this section are not available when the POSIX

 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is

 specified.

 .P

 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a

 compiled pattern to a file, by following the modifiers with > and a file name.

 For example:

 .sp

   /pattern/im >/some/file

 .sp

 See the

 .\" HREF

 \fBpcreprecompile\fP

 .\"

 documentation for a discussion about saving and re-using compiled patterns.

 .P

 The data that is written is binary. The first eight bytes are the length of the

 compiled pattern data followed by the length of the optional study data, each

 written as four bytes in big-endian order (most significant byte first). If

 there is no study data (either the pattern was not studied, or studying did not

 return any data), the second length is zero. The lengths are followed by an

 exact copy of the compiled pattern. If there is additional study data, this

 follows immediately after the compiled pattern. After writing the file,

 \fBpcretest\fP expects to read a new pattern.

 .P

 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file

 name instead of a pattern. The name of the file must not contain a < character,

 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <

 characters.

 For example:

 .sp

    re> </some/file

   Compiled regex loaded from /some/file

   No study data

 .sp

 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in

 the usual way.

 .P

 You can copy a file written by \fBpcretest\fP 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.

 .P

 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.

 .P

 The ability to save and reload files in \fBpcretest\fP is intended for testing

 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 \fBpcretest\fP to crash.

 Finally, if you attempt to load a file that is not in the correct format, the

 result is undefined.

 .

 .

 .SH "SEE ALSO"

 .rs

 .sp

 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),

 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).

 .

 .

 .SH AUTHOR

 .rs

 .sp

 .nf

 Philip Hazel

 University Computing Service

 Cambridge CB2 3QH, England.

 .fi

 .

 .

 .SH REVISION

 .rs

 .sp

 .nf

 Last updated: 10 March 2009

 Copyright (c) 1997-2009 University of Cambridge.

 .fi