.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

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