pcretest(1)
PCRETEST(1) USER COMMANDS PCRETEST(1)
NAME
pcretest - a program for testing Perl-compatible regular
expressions.
SYNOPSIS
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 reg-
ular 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 specifi-
cally 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 DATA FORMAT
Input to pcretest is processed line by line, either by cal-
ling the C library's fgets() function, or via the libread-
line library (see below). In Unix-like environments, fgets()
treats any bytes other than newline as data characters. How-
ever, 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 environ-
ments, fgets() treats any bytes other than newline as data
characters.
PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES
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,
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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".
COMMAND LINE OPTIONS
-8 If both the 8-bit library has been built, this
option causes the 8-bit library to be used (which
is the default); if the 8-bit library has not been
built, this option causes an error.
-16 If both the 8-bit or the 32-bit, and the 16-bit
libraries have been built, this option causes the
16-bit library to be used. If only the 16-bit
library has been built, this is the default (so
has no effect). If only the 8-bit or the 32-bit
library has been built, this option causes an
error.
-32 If both the 8-bit or the 16-bit, and the 32-bit
libraries have been built, this option causes the
32-bit library to be used. If only the 32-bit
library has been built, this is the default (so
has no effect). If only the 8-bit or the 16-bit
library has 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
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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() func-
tion (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 dif-
ferent limits.
-m Output the size of each compiled pattern after it
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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 pat-
terns.
-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 dif-
ferent 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.
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Note that there are pattern options that can over-
ride -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 identi-
cal, except when options that output information
about the actual running of a match are set.
The -M, -t, and -tm options, which give informa-
tion 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 dif-
ferent 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 com-
pile, 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 itera-
tions 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 com-
piles, studies, and matches are output.
DESCRIPTION
If pcretest is given two filename arguments, it reads from
the first and writes to the second. If it is given only one
filename argument, it reads from that file and writes to
stdout. Otherwise, it reads from stdin and writes to stdout,
and prompts for each line of input, using "re>" to prompt
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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 exam-
ple:
/(a|bc)x+yz/
White space before the initial delimiter is ignored. A regu-
lar 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 exam-
ple,
/abc/\
then a backslash is added to the end of the pattern. This is
done to provide a way of testing the error condition that
arises if a pattern finishes with a backslash, because
/abc\/
is interpreted as the first line of a pattern that starts
with "abc/", causing pcretest to read the next line as a
continuation of the regular expression.
PATTERN MODIFIERS
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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 modif-
ier", even though the delimiter of the pattern need not
always be a slash, and no slash is used when writing modif-
iers. White space may appear between the final pattern del-
imiter and the first modifier, and between the modifiers
themselves. For reference, here is a complete list of modif-
iers. 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
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/<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
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/<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. Other-
wise, 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 sub-
ject string. This is useful for tests where the subject con-
tains multiple copies of the same substring. If the + modif-
ier appears twice, the same action is taken for captured
substrings. In each case the remainder is output on the
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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. Nor-
mally this information contains length and offset values;
however, if /Z is also present, this data is replaced by
spaces. This is a special feature for use in the automatic
test scripts; it ensures that the same output is generated
for different internal link sizes. The /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 speci-
fied. See also the section about saving and reloading com-
piled 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
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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 exclama-
tion 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 dif-
ferent 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 nor-
mal 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 actu-
ally used. Note that there is also an independent /+ modif-
ier; 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
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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 modif-
ier 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 modif-
iers 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. Accord-
ingly, the standard tests are split up into a number of dif-
ferent 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 mis-
take; 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 facil-
ity for locking out specific modifiers. If an input line for
pcretest starts with the string "< forbid " the following
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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 char-
acter 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.
DATA LINES
Before each data line is passed to pcre[16|32]_exec(), lead-
ing 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 compli-
cated 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
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PCRETEST(1) USER COMMANDS PCRETEST(1)
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 sub-
string
"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
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PCRETEST(1) USER COMMANDS PCRETEST(1)
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 star-
toffset
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 inter-
preted as a UTF-8 character in UTF-8 mode, generating more
than one byte if the value is greater than 127. When test-
ing 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 new-
line setting should be present in any data line. A
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PCRETEST(1) USER COMMANDS PCRETEST(1)
backslash followed by anything else just escapes the any-
thing 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() execu-
tion, 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 backtrack-
ing that takes place, and checking it out can be instruc-
tive. For most simple matches, the number is quite small,
but for patterns with very large numbers of matching possi-
bilities, 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().
THE ALTERNATIVE MATCHING FUNCTION
By default, pcretest uses the standard PCRE matching func-
tion, 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.
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PCRETEST(1) USER COMMANDS PCRETEST(1)
DEFAULT OUTPUT FROM PCRETEST
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 sub-
string 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
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PCRETEST(1) USER COMMANDS PCRETEST(1)
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 func-
tions 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).
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
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 con-
sists 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
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PCRETEST(1) USER COMMANDS PCRETEST(1)
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 match-
ing substring. (Note that this is the entire substring that
was inspected during the partial match; it may include char-
acters before the actual match start if a lookbehind asser-
tion, \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 cap-
ture, the escape sequences that are concerned with captured
substrings are not relevant.
RESTARTING AFTER A PARTIAL MATCH
When the alternative matching function has given the
PCRE_ERROR_PARTIAL return, indicating that the subject par-
tially 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.
CALLOUTS
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
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PCRETEST(1) USER COMMANDS PCRETEST(1)
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 sub-
ject 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 compli-
cated regular expressions. For further information about
callouts, see the pcrecallout documentation.
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PCRETEST(1) USER COMMANDS PCRETEST(1)
NON-PRINTING CHARACTERS
When pcretest is outputting text in the compiled version of
a pattern, bytes other than 32-126 are always treated as
non-printing characters are are therefore shown as hex
escapes. When pcretest is outputting text that is a matched
part of a subject string, it behaves in the same way, unless
a different locale has been set for the pattern (using the
/L modifier). In this case, the isprint() function to dis-
tinguish printing and non-printing characters.
SAVING AND RELOADING COMPILED PATTERNS
The facilities described in this section are not available
when the POSIX interface to PCRE is being used, that is,
when the /P pattern modifier is specified. When the POSIX
interface is not in use, you can cause pcretest to write 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 addi-
tional 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 pat-
tern 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 optimiza-
tion, 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
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PCRETEST(1) USER COMMANDS PCRETEST(1)
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 rela-
tive, 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 produc-
tion use because only a single pattern can be written to a
file. Furthermore, there is no facility for supplying custom
character tables for use with a reloaded pattern. If the
original pattern was compiled with custom tables, an attempt
to match a subject string using a reloaded pattern is likely
to cause pcretest to crash. Finally, if you attempt to load
a file that is not in the correct format, the result is
undefined.
SEE ALSO
pcre(3), pcre16(3), pcre32(3), pcreapi(3), pcrecallout(3),
pcrejit, pcrematching(3), pcrepartial(d), pcrepattern(3),
pcreprecompile(3).
AUTHOR
Philip Hazel
University Computing Service
Cambridge CB2 3QH, England.
REVISION
Last updated: 23 February 2017
Copyright (c) 1997-2017 University of Cambridge.
PCRE 8.41 Last change: 23 February 2017 22
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