PCRETEST(1) General Commands Manual PCRETEST(1)
pcretest - a program for testing Perl-compatible regular
expressions.
pcretest [options] [input file [output file]]
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 , pcre16 and pcre32 documentation.
The input for pcretest is a sequence of regular expression
patterns and strings to be matched, as described below. The
output shows the result of each match. Options on the command
line and the patterns control PCRE options and exactly what is
output.
As PCRE has evolved, it has acquired many different features, and
as a result, pcretest now has rather a lot of obscure options for
testing every possible feature. Some of these options are
specifically designed for use in conjunction with the test script
and data files that are distributed as part of PCRE, and are
unlikely to be of use otherwise. They are all documented here,
but without much justification.
Input to pcretest is processed line by line, either by calling
the C library's fgets() function, or via the libreadline library
(see below). In Unix-like environments, fgets() treats any bytes
other than newline as data characters. However, in some Windows
environments character 26 (hex 1A) causes an immediate end of
file, and no further data is read. For maximum portability,
therefore, it is safest to use only ASCII characters in pcretest
input files.
The input is processed using using C's string functions, so must
not contain binary zeroes, even though in Unix-like environments,
fgets() treats any bytes other than newline as data characters.
From release 8.30, two separate PCRE libraries can be built. The
original one supports 8-bit character strings, whereas the newer
16-bit library supports character strings encoded in 16-bit
units. From release 8.32, a third library can be built,
supporting character strings encoded in 32-bit units. The
pcretest program can be used to test all three libraries.
However, it is itself still an 8-bit program, reading 8-bit input
and writing 8-bit output. When testing the 16-bit or 32-bit
library, the patterns and data strings are converted to 16- or
32-bit format before being passed to the PCRE library functions.
Results are converted to 8-bit for output.
References to functions and structures of the form pcre[16|32]_xx
below mean "pcre_xx when using the 8-bit library, pcre16_xx when
using the 16-bit library, or pcre32_xx when using the 32-bit
library".
-8 If the 8-bit library has been built, this option causes it
to be used (this is the default). If the 8-bit library has
not been built, this option causes an error.
-16 If the 16-bit library has been built, this option causes
it to be used. If only the 16-bit library has been built,
this is the default. If the 16-bit library has not been
built, this option causes an error.
-32 If the 32-bit library has been built, this option causes
it to be used. If only the 32-bit library has been built,
this is the default. If the 32-bit library has not been
built, this option causes an error.
-b Behave as if each pattern 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
available information about the optional features that are
included, and then exit with zero exit code. All other
options are ignored.
-C option
Output information about a specific build-time option,
then exit. This functionality is intended for use in
scripts such as RunTest. The following options output the
value and set the exit code as indicated:
ebcdic-nl the code for LF (= NL) in an EBCDIC
environment:
0x15 or 0x25
0 if used in an ASCII environment
exit code is always 0
linksize the configured internal link size (2, 3, or
4)
exit code is set to the link size
newline the default newline setting:
CR, LF, CRLF, ANYCRLF, or ANY
exit code is always 0
bsr the default setting for what \R matches:
ANYCRLF or ANY
exit code is always 0
The following options output 1 for true or 0 for false,
and set the exit code to the same value:
ebcdic compiled for an EBCDIC environment
jit just-in-time support is available
pcre16 the 16-bit library was built
pcre32 the 32-bit library was built
pcre8 the 8-bit library was built
ucp Unicode property support is available
utf UTF-8 and/or UTF-16 and/or UTF-32 support
is available
If an unknown option is given, an error message is output;
the exit code is 0.
-d Behave as if each pattern 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[16|32]_dfa_exec(), to be used instead of the standard
pcre[16|32]_exec() function (more detail is given below).
-help Output a brief summary these options and then exit.
-i Behave as if each pattern has the /I modifier; information
about the compiled pattern is given after compilation.
-M Behave as if each data line contains the \M escape
sequence; this causes PCRE to discover the minimum
MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by calling
pcre[16|32]_exec() repeatedly with different limits.
-m Output the size of each compiled pattern after it has been
compiled. This is equivalent to adding /M to each regular
expression. The size is given in bytes for both libraries.
-O Behave as if each pattern has the /O modifier, that is
disable auto-possessification for all patterns.
-o osize
Set the number of elements in the output vector that is
used when calling pcre[16|32]_exec() or
pcre[16|32]_dfa_exec() to be osize. The default value is
45, which is enough for 14 capturing subexpressions for
pcre[16|32]_exec() or 22 different matches for
pcre[16|32]_dfa_exec(). The vector size can be changed
for individual matching calls by including \O in the data
line (see below).
-p Behave as if each pattern has the /P modifier; the POSIX
wrapper API is used to call PCRE. None of the other
options has any effect when -p is set. This option can be
used only with the 8-bit library.
-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 run-time stack
to size megabytes.
-s or -s+
Behave as if each pattern has the /S modifier; in other
words, force each pattern to be studied. If -s+ is used,
all the JIT compile options are passed to
pcre[16|32]_study(), causing just-in-time optimization to
be set up if it is available, for both full and partial
matching. Specific JIT compile options can be selected by
following -s+ with a digit in the range 1 to 7, which
selects the JIT compile modes as follows:
1 normal match only
2 soft partial match only
3 normal match and soft partial match
4 hard partial match only
6 soft and hard partial match
7 all three modes (default)
If -s++ is used instead of -s+ (with or without a
following digit), the text "(JIT)" is added to the first
output line after a match or no match when JIT-compiled
code was actually used.
Note that there are pattern options that can override -s,
either specifying no studying at all, or suppressing JIT
compilation.
If the /I or /D option is present on a pattern (requesting
output about the compiled pattern), information about the
result of studying is not included when studying is caused
only by -s and neither -i nor -d is present on the command
line. This behaviour means that the output from tests that
are run with and without -s should be identical, except
when options that output information about the actual
running of a match are set.
The -M, -t, and -tm options, which give information about
resources used, are likely to produce different output
with and without -s. Output may also differ if the /C
option is present on an individual pattern. This uses
callouts to trace the the matching process, and this may
be different between studied and non-studied patterns. If
the pattern contains (*MARK) items there may also be
differences, for the same reason. The -s command line
option can be overridden for specific patterns that should
never be studied (see the /S pattern modifier below).
-t Run each compile, study, and match many times with a
timer, and output the resulting times per compile, study,
or match (in milliseconds). Do not set -m with -t, 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 -t with a
number (as a separate item on the command line). For
example, "-t 1000" iterates 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.
-T -TM These behave like -t and -tm, but in addition, at the end
of a run, the total times for all compiles, studies, and
matches are output.
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 number of data lines to be matched against that 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
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-alphanumeric, 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.
A pattern may be followed by any number of modifiers, which are
mostly single characters, though some of these can be qualified
by further 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. White space may appear between
the final pattern delimiter and the first modifier, and between
the modifiers themselves. For reference, here is a complete list
of modifiers. They fall into several groups that are described in
detail in the following sections.
/8 set UTF mode
/9 set PCRE_NEVER_UTF (locks out UTF mode)
/? disable UTF validity check
/+ show remainder of subject after match
/= show all captures (not just those that are set)
/A set PCRE_ANCHORED
/B show compiled code
/C set PCRE_AUTO_CALLOUT
/D same as /B plus /I
/E set PCRE_DOLLAR_ENDONLY
/F flip byte order in compiled pattern
/f set PCRE_FIRSTLINE
/G find all matches (shorten string)
/g find all matches (use startoffset)
/I show information about pattern
/i set PCRE_CASELESS
/J set PCRE_DUPNAMES
/K show backtracking control names
/L set locale
/M show compiled memory size
/m set PCRE_MULTILINE
/N set PCRE_NO_AUTO_CAPTURE
/O set PCRE_NO_AUTO_POSSESS
/P use the POSIX wrapper
/Q test external stack check function
/S study the pattern after compilation
/s set PCRE_DOTALL
/T select character tables
/U set PCRE_UNGREEDY
/W set PCRE_UCP
/X set PCRE_EXTRA
/x set PCRE_EXTENDED
/Y set PCRE_NO_START_OPTIMIZE
/Z don't show lengths in /B output
/<any> set PCRE_NEWLINE_ANY
/<anycrlf> set PCRE_NEWLINE_ANYCRLF
/<cr> set PCRE_NEWLINE_CR
/<crlf> set PCRE_NEWLINE_CRLF
/<lf> set PCRE_NEWLINE_LF
/<bsr_anycrlf> set PCRE_BSR_ANYCRLF
/<bsr_unicode> set PCRE_BSR_UNICODE
/<JS> set PCRE_JAVASCRIPT_COMPAT
Perl-compatible modifiers
The /i, /m, /s, and /x modifiers set the PCRE_CASELESS,
PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options,
respectively, when pcre[16|32]_compile() is called. These four
modifier letters have the same effect as they do in Perl. For
example:
/caseless/i
Modifiers for other PCRE options
The following table shows additional modifiers for setting PCRE
compile-time options that do not correspond to anything in Perl:
/8 PCRE_UTF8 ) when using the 8-bit
/? PCRE_NO_UTF8_CHECK ) library
/8 PCRE_UTF16 ) when using the 16-bit
/? PCRE_NO_UTF16_CHECK ) library
/8 PCRE_UTF32 ) when using the 32-bit
/? PCRE_NO_UTF32_CHECK ) library
/9 PCRE_NEVER_UTF
/A PCRE_ANCHORED
/C PCRE_AUTO_CALLOUT
/E PCRE_DOLLAR_ENDONLY
/f PCRE_FIRSTLINE
/J PCRE_DUPNAMES
/N PCRE_NO_AUTO_CAPTURE
/O PCRE_NO_AUTO_POSSESS
/U PCRE_UNGREEDY
/W PCRE_UCP
/X PCRE_EXTRA
/Y PCRE_NO_START_OPTIMIZE
/<any> PCRE_NEWLINE_ANY
/<anycrlf> PCRE_NEWLINE_ANYCRLF
/<cr> PCRE_NEWLINE_CR
/<crlf> PCRE_NEWLINE_CRLF
/<lf> PCRE_NEWLINE_LF
/<bsr_anycrlf> PCRE_BSR_ANYCRLF
/<bsr_unicode> PCRE_BSR_UNICODE
/<JS> PCRE_JAVASCRIPT_COMPAT
The modifiers that are enclosed in angle brackets are literal
strings as shown, including the angle brackets, but the letters
within can be in either case. This example sets multiline
matching with CRLF as the line ending sequence:
/^abc/m<CRLF>
As well as turning on the PCRE_UTF8/16/32 option, the /8 modifier
causes all non-printing characters in output strings to be
printed using the \x{hh...} notation. Otherwise, those less than
0x100 are output in hex without the curly brackets.
Full details of the 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 difference between /g and /G is that the former uses
the startoffset argument to pcre[16|32]_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[16|32]_exec() in a /g or /G sequence matches
an empty string, the next call is done with the
PCRE_NOTEMPTY_ATSTART 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, and the normal
match is retried. This imitates the way Perl handles such cases
when using the /g modifier or the split() function. Normally, the
start offset is advanced by one character, but if the newline
convention recognizes CRLF as a newline, and the current
character is CR followed by LF, an advance of two is used.
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. If the + modifier appears twice, the same action is
taken for captured substrings. In each case the remainder is
output on the following line with a plus character following the
capture number. Note that this modifier must not immediately
follow the /S modifier because /S+ and /S++ have other meanings.
The /= modifier requests that the values of all potential
captured parentheses be output after a match. By default, only
those up to the highest one actually used in the match are output
(corresponding to the return code from pcre[16|32]_exec()).
Values in the offsets vector corresponding to higher numbers
should be set to -1, and these are output as "<unset>". This
modifier gives a way of checking that this is happening.
The /B modifier is a debugging feature. It requests that pcretest
output a representation of the compiled code after compilation.
Normally 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 /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
2-byte and 4-byte fields in the compiled pattern. 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 /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[16|32]_fullinfo() after compiling a pattern. If the pattern
is studied, the results of that are also output. In this output,
the word "char" means a non-UTF character, that is, the value of
a single data item (8-bit, 16-bit, or 32-bit, depending on the
library that is being tested).
The /K modifier requests pcretest to show names from backtracking
control verbs that are returned from calls to pcre[16|32]_exec().
It causes pcretest to create a pcre[16|32]_extra block if one has
not already been created by a call to pcre[16|32]_study(), and to
set the PCRE_EXTRA_MARK flag and the mark field within it, every
time that pcre[16|32]_exec() is called. If the variable that the
mark field points to is non-NULL for a match, non-match, or
partial match, pcretest prints the string to which it points. For
a match, this is shown on a line by itself, tagged with "MK:".
For a non-match it is added to the message.
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[16|32]_maketables() is called to build a set of
character tables for the locale, and this is then passed to
pcre[16|32]_compile() when compiling the regular expression.
Without an /L (or /T) modifier, NULL is passed as the tables
pointer; that is, /L applies only to the expression on which it
appears.
The /M modifier causes the size in bytes of the memory block used
to hold the compiled pattern to be output. This does not include
the size of the pcre[16|32] block; it is just the actual compiled
data. If the pattern is successfully studied with the
PCRE_STUDY_JIT_COMPILE option, the size of the JIT compiled code
is also output.
The /Q modifier is used to test the use of pcre_stack_guard. It
must be followed by '0' or '1', specifying the return code to be
given from an external function that is passed to PCRE and used
for stack checking during compilation (see the pcreapi
documentation for details).
The /S modifier causes pcre[16|32]_study() to be called after the
expression has been compiled, and the results used when the
expression is matched. There are a number of qualifying
characters that may follow /S. They may appear in any order.
If /S is followed by an exclamation mark, pcre[16|32]_study() is
called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always
to return a pcre_extra block, even when studying discovers no
useful information.
If /S is followed by a second S character, it suppresses
studying, even if it was requested externally by the -s command
line option. This makes it possible to specify that certain
patterns are always studied, and others are never studied,
independently of -s. This feature is used in the test files in a
few cases where the output is different when the pattern is
studied.
If the /S modifier is followed by a + character, the call to
pcre[16|32]_study() is made with all the JIT study options,
requesting just-in-time optimization support if it is available,
for both normal and partial matching. If you want to restrict the
JIT compiling modes, you can follow /S+ with a digit in the range
1 to 7:
1 normal match only
2 soft partial match only
3 normal match and soft partial match
4 hard partial match only
6 soft and hard partial match
7 all three modes (default)
If /S++ is used instead of /S+ (with or without a following
digit), the text "(JIT)" is added to the first output line after
a match or no match when JIT-compiled code was actually used.
Note that there is also an independent /+ modifier; it must not
be given immediately after /S or /S+ because this will be
misinterpreted.
If JIT studying is successful, the compiled JIT code will
automatically be used when pcre[16|32]_exec() is run, except when
incompatible run-time options are specified. For more details,
see the pcrejit documentation. See also the \J escape sequence
below for a way of setting the size of the JIT stack.
Finally, if /S is followed by a minus character, JIT compilation
is suppressed, even if it was requested externally by the -s
command line option. This makes it possible to specify that JIT
is never to be used for certain patterns.
The /T modifier must be followed by a single digit. It causes a
specific set of built-in character tables to be passed to
pcre[16|32]_compile(). It is used in the standard PCRE tests to
check behaviour with different character tables. The digit
specifies the tables as follows:
0 the default ASCII tables, as distributed in
pcre_chartables.c.dist
1 a set of tables defining ISO 8859 characters
In table 1, some characters whose codes are greater than 128 are
identified as letters, digits, spaces, etc.
Using the POSIX wrapper API
The /P modifier causes pcretest to call PCRE via the POSIX
wrapper API rather than its native API. This supports only the
8-bit library. When /P is set, the following modifiers set
options for the regcomp() function:
/i REG_ICASE
/m REG_NEWLINE
/N REG_NOSUB
/s REG_DOTALL )
/U REG_UNGREEDY ) These options are not part of
/W REG_UCP ) the POSIX standard
/8 REG_UTF8 )
The /+ modifier works as described above. All other modifiers are
ignored.
Locking out certain modifiers
PCRE can be compiled with or without support for certain features
such as UTF-8/16/32 or Unicode properties. Accordingly, the
standard tests are split up into a number of different files that
are selected for running depending on which features are
available. When updating the tests, it is all too easy to put a
new test into the wrong file by mistake; for example, to put a
test that requires UTF support into a file that is used when it
is not available. To help detect such mistakes as early as
possible, there is a facility for locking out specific modifiers.
If an input line for pcretest starts with the string "< forbid "
the following sequence of characters is taken as a list of
forbidden modifiers. For example, in the test files that must not
use UTF or Unicode property support, this line appears:
< forbid 8W
This locks out the /8 and /W modifiers. An immediate error is
given if they are subsequently encountered. If the character
string contains < but not >, all the multi-character modifiers
that begin with < are locked out. Otherwise, such modifiers must
be explicitly listed, for example:
< forbid <JS><cr>
There must be a single space between < and "forbid" for this
feature to be recognised. If there is not, the line is
interpreted either as a request to re-load a pre-compiled pattern
(see "SAVING AND RELOADING COMPILED PATTERNS" below) or, if there
is a another < character, as a pattern that uses < as its
delimiter.
Before each data line is passed to pcre[16|32]_exec(), leading
and trailing white space 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 "ordinary" 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 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); always
a byte unless > 255 in UTF-8 or 16-bit or 32-bit
mode
\o{dd...} octal character (any number of octal digits}
\xhh hexadecimal byte (up to 2 hex digits)
\x{hh...} hexadecimal character (any number of hex digits)
\A pass the PCRE_ANCHORED option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\B pass the PCRE_NOTBOL option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\Cdd call pcre[16|32]_copy_substring() for substring dd
after a successful match (number less than 32)
\Cname call pcre[16|32]_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[16|32]_dfa_exec() match function
\F only shortest match for pcre[16|32]_dfa_exec()
\Gdd call pcre[16|32]_get_substring() for substring dd
after a successful match (number less than 32)
\Gname call pcre[16|32]_get_named_substring() for substring
"name" after a successful match (name termin-
ated by next non-alphanumeric character)
\Jdd set up a JIT stack of dd kilobytes maximum (any
number of digits)
\L call pcre[16|32]_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[16|32]_exec()
or pcre[16|32]_dfa_exec(); if used twice, pass the
PCRE_NOTEMPTY_ATSTART option
\Odd set the size of the output vector passed to
pcre[16|32]_exec() to dd (any number of digits)
\P pass the PCRE_PARTIAL_SOFT option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec(); if used twice, pass the
PCRE_PARTIAL_HARD option
\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
(any number of digits)
\R pass the PCRE_DFA_RESTART option to
pcre[16|32]_dfa_exec()
\S output details of memory get/free calls during
matching
\Y pass the PCRE_NO_START_OPTIMIZE option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\Z pass the PCRE_NOTEOL option to pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\? pass the PCRE_NO_UTF[8|16|32]_CHECK option to
pcre[16|32]_exec() or pcre[16|32]_dfa_exec()
\>dd start the match at offset dd (optional "-"; then
any number of digits); this sets the startoffset
argument for pcre[16|32]_exec() or
pcre[16|32]_dfa_exec()
\<cr> pass the PCRE_NEWLINE_CR option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<lf> pass the PCRE_NEWLINE_LF option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<crlf> pass the PCRE_NEWLINE_CRLF option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
\<any> pass the PCRE_NEWLINE_ANY option to
pcre[16|32]_exec()
or pcre[16|32]_dfa_exec()
The use of \x{hh...} 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; invalid
values provoke error messages.
Note that \xhh specifies one byte rather than one character in
UTF-8 mode; this makes it possible to construct invalid UTF-8
sequences for testing purposes. On the other hand, \x{hh} is
interpreted as a UTF-8 character in UTF-8 mode, generating more
than one byte if the value is greater than 127. When testing the
8-bit library not in UTF-8 mode, \x{hh} generates one byte for
values less than 256, and causes an error for greater values.
In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This
makes it possible to construct invalid UTF-16 sequences for
testing purposes.
In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted.
This makes it possible to construct invalid UTF-32 sequences for
testing purposes.
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 terminates the data input.
The \J escape provides a way of setting the maximum stack size
that is used by the just-in-time optimization code. It is ignored
if JIT optimization is not being used. Providing a stack that is
larger than the default 32K is necessary only for very
complicated patterns.
If \M is present, pcretest calls pcre[16|32]_exec() several
times, with different values in the match_limit and
match_limit_recursion fields of the pcre[16|32]_extra data
structure, until it finds the minimum numbers for each parameter
that allow pcre[16|32]_exec() to complete without error. Because
this is testing a specific feature of the normal interpretive
pcre[16|32]_exec() execution, the use of any JIT optimization
that might have been set up by the /S+ qualifier of -s+ option is
disabled.
The match_limit 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
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[16|32]_exec() for the line in
which it appears.
If the /P modifier was present on the pattern, causing the POSIX
wrapper API to be used, the only option-setting sequences that
have any effect are \B, \N, and \Z, causing REG_NOTBOL,
REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to
regexec().
By default, pcretest uses the standard PCRE matching function,
pcre[16|32]_exec() to match each data line. PCRE also supports an
alternative matching function, pcre[16|32]_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 used. 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.
This section describes the output when the normal matching
function, pcre[16|32]_exec(), is being used.
When a match succeeds, pcretest outputs the list of captured
substrings that pcre[16|32]_exec() returns, starting with number
0 for the string that matched the whole pattern. Otherwise, it
outputs "No match" when the return is PCRE_ERROR_NOMATCH, and
"Partial match:" followed by the partially matching substring
when pcre[16|32]_exec() returns PCRE_ERROR_PARTIAL. (Note that
this is the entire substring that was inspected during the
partial match; it may include characters before the actual match
start if a lookbehind assertion, \K, \b, or \B was involved.) For
any other return, pcretest outputs the PCRE negative error number
and a short descriptive phrase. If the error is a failed UTF
string check, the offset of the start of the failing character
and the reason code are also output, provided that the size of
the output vector is at least two. Here is an example of an
interactive pcretest run.
$ pcretest
PCRE version 8.13 2011-04-30
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[16|32]_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 \xhh escapes if the value is less than 256 and UTF mode
is not set. Otherwise they are output as \x{hh...} escapes. See
below for the definition of non-printing characters. If the
pattern has the /+ modifier, 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. Here
is an example of a failure message (the offset 4 that is
specified by \>4 is past the end of the subject string):
re> /xyz/
data> xyz\>4
Error -24 (bad offset value)
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 parentheses 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 newlines can be included in data by means of the \n
escape (or \r, \r\n, etc., depending on the newline sequence
setting).
When the alternative matching function, pcre[16|32]_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). After a PCRE_ERROR_PARTIAL return, the output is
"Partial match:", followed by the partially matching substring.
(Note that this is the entire substring that was inspected during
the partial match; it may include characters before the actual
match start if a lookbehind assertion, \K, \b, or \B was
involved.)
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.
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.
If the pattern contains any callout requests, pcretest'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:
--->pqrabcdef
0 ^ ^ \d
This output 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*
If a pattern contains (*MARK) items, an additional line is output
whenever a change of latest mark is passed to the callout
function. For example:
re> /a(*MARK:X)bc/C
data> abc
--->abc
+0 ^ a
+1 ^^ (*MARK:X)
+10 ^^ b
Latest Mark: X
+11 ^ ^ c
+12 ^ ^
0: abc
The mark changes between matching "a" and "b", but stays the same
for the rest of the match, so nothing more is output. If, as a
result of backtracking, the mark reverts to being unset, the text
"<unset>" is output.
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 and other parameters of the
callout.
Inserting callouts can be helpful when using pcretest to check
complicated regular expressions. For further information about
callouts, see the pcrecallout documentation.
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.
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 a compiled pattern to a file, by following the modifiers
with > and a file name. For example:
/pattern/im >/some/file
See the pcreprecompile documentation for a discussion about
saving and re-using compiled patterns. Note that if the pattern
was successfully studied with JIT optimization, the JIT data
cannot be saved.
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 (excluding any JIT data) follows immediately
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. There must be no space between
< and the file name, which must not contain a < character, as
otherwise pcretest will interpret the line as a pattern delimited
by < characters. For example:
re> </some/file
Compiled pattern loaded from /some/file
No study data
If the pattern was previously studied with the JIT optimization,
the JIT information cannot be saved and restored, and so is lost.
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. When a
pattern is reloaded on a host with different endianness, the
confirmation message is changed to:
Compiled pattern (byte-inverted) loaded from /some/file
The test suite contains some saved pre-compiled patterns with
different endianness. These are reloaded using "<!" instead of
just "<". This suppresses the "(byte-inverted)" text so that the
output is the same on all hosts. It also forces debugging output
once the pattern has been reloaded.
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
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 pcretest to
crash. Finally, if you attempt to load a file that is not in the
correct format, the result is undefined.
pcre(3), pcre16(3), pcre32(3), pcreapi(3), pcrecallout(3),
pcrejit, pcrematching(3), pcrepartial(d), pcrepattern(3),
pcreprecompile(3).
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
Last updated: 10 February 2020
Copyright (c) 1997-2020 University of Cambridge.
This page is part of the PCRE (Perl Compatible Regular
Expressions) project. Information about the project can be found
at ⟨http://www.pcre.org/⟩. If you have a bug report for this
manual page, see
⟨http://bugs.exim.org/enter_bug.cgi?product=PCRE⟩. This page was
obtained from the tarball pcre-8.45.tar.gz fetched from
⟨ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/⟩ on
2021-08-27. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
PCRE 8.44 10 February 2020 PCRETEST(1)
Pages that refer to this page: pcregrep(1)
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