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README file for PCRE (Perl-compatible regular expression library)
NOTE: This set of files relates to PCRE releases that use the original API,
with library names libpcre, libpcre16, and libpcre32. January 2015 saw the
first release of a new API, known as PCRE2, with release numbers starting at
10.00 and library names libpcre2-8, libpcre2-16, and libpcre2-32. The old
libraries (now called PCRE1) are now at end of life, and 8.45 is the final
release. New projects are advised to use the new PCRE2 libraries.
The latest release of PCRE1 is always available in three alternative formats
There is a mailing list for discussion about the development of PCRE at
pcre-dev@exim.org. You can access the archives and subscribe or manage your
subscription here:
Please read the NEWS file if you are upgrading from a previous release.
The contents of this README file are:
Documentation for PCRE
Contributions by users of PCRE
Building PCRE on non-Unix-like systems
Building PCRE without using autotools
Building PCRE using autotools
Retrieving configuration information
Shared libraries
Cross-compiling using autotools
Using HP's ANSI C++ compiler (aCC)
Compiling in Tru64 using native compilers
Using Sun's compilers for Solaris
Using PCRE from MySQL
Making new tarballs
Testing PCRE
Character tables
File manifest
PCRE is written in C, and it has its own API. There are three sets of
functions, one for the 8-bit library, which processes strings of bytes, one for
the 16-bit library, which processes strings of 16-bit values, and one for the
32-bit library, which processes strings of 32-bit values. The distribution also
includes a set of C++ wrapper functions (see the pcrecpp man page for details),
courtesy of Google Inc., which can be used to call the 8-bit PCRE library from
C++. Other C++ wrappers have been created from time to time. See, for example:
https://github.com/YasserAsmi/regexp, which aims to be simple and similar in
style to the C API.
The distribution also contains a set of C wrapper functions (again, just for
the 8-bit library) that are based on the POSIX regular expression API (see the
pcreposix man page). These end up in the library called libpcreposix. Note that
this just provides a POSIX calling interface to PCRE; the regular expressions
themselves still follow Perl syntax and semantics. The POSIX API is restricted,
and does not give full access to all of PCRE's facilities.
The header file for the POSIX-style functions is called pcreposix.h. The
official POSIX name is regex.h, but I did not want to risk possible problems
with existing files of that name by distributing it that way. To use PCRE with
an existing program that uses the POSIX API, pcreposix.h will have to be
renamed or pointed at by a link.
If you are using the POSIX interface to PCRE and there is already a POSIX regex
library installed on your system, as well as worrying about the regex.h header
file (as mentioned above), you must also take care when linking programs to
ensure that they link with PCRE's libpcreposix library. Otherwise they may pick
up the POSIX functions of the same name from the other library.
One way of avoiding this confusion is to compile PCRE with the addition of
-Dregcomp=PCREregcomp (and similarly for the other POSIX functions) to the
compiler flags (CFLAGS if you are using "configure" -- see below). This has the
effect of renaming the functions so that the names no longer clash. Of course,
you have to do the same thing for your applications, or write them using the
new names.
Documentation for PCRE
If you install PCRE in the normal way on a Unix-like system, you will end up
with a set of man pages whose names all start with "pcre". The one that is just
called "pcre" lists all the others. In addition to these man pages, the PCRE
documentation is supplied in two other forms:
1. There are files called doc/pcre.txt, doc/pcregrep.txt, and
doc/pcretest.txt in the source distribution. The first of these is a
concatenation of the text forms of all the section 3 man pages except
the listing of pcredemo.c and those that summarize individual functions.
The other two are the text forms of the section 1 man pages for the
pcregrep and pcretest commands. These text forms are provided for ease of
scanning with text editors or similar tools. They are installed in
<prefix>/share/doc/pcre, where <prefix> is the installation prefix
(defaulting to /usr/local).
2. A set of files containing all the documentation in HTML form, hyperlinked
in various ways, and rooted in a file called index.html, is distributed in
doc/html and installed in <prefix>/share/doc/pcre/html.
Users of PCRE have contributed files containing the documentation for various
releases in CHM format. These can be found in the Contrib directory of the FTP
site (see next section).
Contributions by users of PCRE
You can find contributions from PCRE users in the directory
There is a README file giving brief descriptions of what they are. Some are
complete in themselves; others are pointers to URLs containing relevant files.
Some of this material is likely to be well out-of-date. Several of the earlier
contributions provided support for compiling PCRE on various flavours of
Windows (I myself do not use Windows). Nowadays there is more Windows support
in the standard distribution, so these contibutions have been archived.
A PCRE user maintains downloadable Windows binaries of the pcregrep and
pcretest programs here:
Building PCRE on non-Unix-like systems
For a non-Unix-like system, please read the comments in the file
NON-AUTOTOOLS-BUILD, though if your system supports the use of "configure" and
"make" you may be able to build PCRE using autotools in the same way as for
many Unix-like systems.
PCRE can also be configured using the GUI facility provided by CMake's
cmake-gui command. This creates Makefiles, solution files, etc. The file
NON-AUTOTOOLS-BUILD has information about CMake.
PCRE has been compiled on many different operating systems. It should be
straightforward to build PCRE on any system that has a Standard C compiler and
library, because it uses only Standard C functions.
Building PCRE without using autotools
The use of autotools (in particular, libtool) is problematic in some
environments, even some that are Unix or Unix-like. See the NON-AUTOTOOLS-BUILD
file for ways of building PCRE without using autotools.
Building PCRE using autotools
If you are using HP's ANSI C++ compiler (aCC), please see the special note
in the section entitled "Using HP's ANSI C++ compiler (aCC)" below.
The following instructions assume the use of the widely used "configure; make;
make install" (autotools) process.
To build PCRE on system that supports autotools, first run the "configure"
command from the PCRE distribution directory, with your current directory set
to the directory where you want the files to be created. This command is a
standard GNU "autoconf" configuration script, for which generic instructions
are supplied in the file INSTALL.
Most commonly, people build PCRE within its own distribution directory, and in
this case, on many systems, just running "./configure" is sufficient. However,
the usual methods of changing standard defaults are available. For example:
CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
This command specifies that the C compiler should be run with the flags '-O2
-Wall' instead of the default, and that "make install" should install PCRE
under /opt/local instead of the default /usr/local.
If you want to build in a different directory, just run "configure" with that
directory as current. For example, suppose you have unpacked the PCRE source
into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
cd /build/pcre/pcre-xxx
PCRE is written in C and is normally compiled as a C library. However, it is
possible to build it as a C++ library, though the provided building apparatus
does not have any features to support this.
There are some optional features that can be included or omitted from the PCRE
library. They are also documented in the pcrebuild man page.
. By default, both shared and static libraries are built. You can change this
by adding one of these options to the "configure" command:
(See also "Shared libraries on Unix-like systems" below.)
. By default, only the 8-bit library is built. If you add --enable-pcre16 to
the "configure" command, the 16-bit library is also built. If you add
--enable-pcre32 to the "configure" command, the 32-bit library is also built.
If you want only the 16-bit or 32-bit library, use --disable-pcre8 to disable
building the 8-bit library.
. If you are building the 8-bit library and want to suppress the building of
the C++ wrapper library, you can add --disable-cpp to the "configure"
command. Otherwise, when "configure" is run without --disable-pcre8, it will
try to find a C++ compiler and C++ header files, and if it succeeds, it will
try to build the C++ wrapper.
. If you want to include support for just-in-time compiling, which can give
large performance improvements on certain platforms, add --enable-jit to the
"configure" command. This support is available only for certain hardware
architectures. If you try to enable it on an unsupported architecture, there
will be a compile time error.
. When JIT support is enabled, pcregrep automatically makes use of it, unless
you add --disable-pcregrep-jit to the "configure" command.
. If you want to make use of the support for UTF-8 Unicode character strings in
the 8-bit library, or UTF-16 Unicode character strings in the 16-bit library,
or UTF-32 Unicode character strings in the 32-bit library, you must add
--enable-utf to the "configure" command. Without it, the code for handling
UTF-8, UTF-16 and UTF-8 is not included in the relevant library. Even
when --enable-utf is included, the use of a UTF encoding still has to be
enabled by an option at run time. When PCRE is compiled with this option, its
input can only either be ASCII or UTF-8/16/32, even when running on EBCDIC
platforms. It is not possible to use both --enable-utf and --enable-ebcdic at
the same time.
. There are no separate options for enabling UTF-8, UTF-16 and UTF-32
independently because that would allow ridiculous settings such as requesting
UTF-16 support while building only the 8-bit library. However, the option
--enable-utf8 is retained for backwards compatibility with earlier releases
that did not support 16-bit or 32-bit character strings. It is synonymous with
--enable-utf. It is not possible to configure one library with UTF support
and the other without in the same configuration.
. If, in addition to support for UTF-8/16/32 character strings, you want to
include support for the \P, \p, and \X sequences that recognize Unicode
character properties, you must add --enable-unicode-properties to the
"configure" command. This adds about 30K to the size of the library (in the
form of a property table); only the basic two-letter properties such as Lu
are supported.
. You can build PCRE to recognize either CR or LF or the sequence CRLF or any
of the preceding, or any of the Unicode newline sequences as indicating the
end of a line. Whatever you specify at build time is the default; the caller
of PCRE can change the selection at run time. The default newline indicator
is a single LF character (the Unix standard). You can specify the default
newline indicator by adding --enable-newline-is-cr or --enable-newline-is-lf
or --enable-newline-is-crlf or --enable-newline-is-anycrlf or
--enable-newline-is-any to the "configure" command, respectively.
If you specify --enable-newline-is-cr or --enable-newline-is-crlf, some of
the standard tests will fail, because the lines in the test files end with
LF. Even if the files are edited to change the line endings, there are likely
to be some failures. With --enable-newline-is-anycrlf or
--enable-newline-is-any, many tests should succeed, but there may be some
. By default, the sequence \R in a pattern matches any Unicode line ending
sequence. This is independent of the option specifying what PCRE considers to
be the end of a line (see above). However, the caller of PCRE can restrict \R
to match only CR, LF, or CRLF. You can make this the default by adding
--enable-bsr-anycrlf to the "configure" command (bsr = "backslash R").
. When called via the POSIX interface, PCRE uses malloc() to get additional
storage for processing capturing parentheses if there are more than 10 of
them in a pattern. You can increase this threshold by setting, for example,
on the "configure" command.
. PCRE has a counter that limits the depth of nesting of parentheses in a
pattern. This limits the amount of system stack that a pattern uses when it
is compiled. The default is 250, but you can change it by setting, for
. PCRE has a counter that can be set to limit the amount of resources it uses
when matching a pattern. If the limit is exceeded during a match, the match
fails. The default is ten million. You can change the default by setting, for
on the "configure" command. This is just the default; individual calls to
pcre_exec() can supply their own value. There is more discussion on the
pcreapi man page.
. There is a separate counter that limits the depth of recursive function calls
during a matching process. This also has a default of ten million, which is
essentially "unlimited". You can change the default by setting, for example,
Recursive function calls use up the runtime stack; running out of stack can
cause programs to crash in strange ways. There is a discussion about stack
sizes in the pcrestack man page.
. The default maximum compiled pattern size is around 64K. You can increase
this by adding --with-link-size=3 to the "configure" command. In the 8-bit
library, PCRE then uses three bytes instead of two for offsets to different
parts of the compiled pattern. In the 16-bit library, --with-link-size=3 is
the same as --with-link-size=4, which (in both libraries) uses four-byte
offsets. Increasing the internal link size reduces performance. In the 32-bit
library, the only supported link size is 4.
. You can build PCRE so that its internal match() function that is called from
pcre_exec() does not call itself recursively. Instead, it uses memory blocks
obtained from the heap via the special functions pcre_stack_malloc() and
pcre_stack_free() to save data that would otherwise be saved on the stack. To
build PCRE like this, use
on the "configure" command. PCRE runs more slowly in this mode, but it may be
necessary in environments with limited stack sizes. This applies only to the
normal execution of the pcre_exec() function; if JIT support is being
successfully used, it is not relevant. Equally, it does not apply to
pcre_dfa_exec(), which does not use deeply nested recursion. There is a
discussion about stack sizes in the pcrestack man page.
. For speed, PCRE uses four tables for manipulating and identifying characters
whose code point values are less than 256. By default, it uses a set of
tables for ASCII encoding that is part of the distribution. If you specify
a program called dftables is compiled and run in the default C locale when
you obey "make". It builds a source file called pcre_chartables.c. If you do
not specify this option, pcre_chartables.c is created as a copy of
pcre_chartables.c.dist. See "Character tables" below for further information.
. It is possible to compile PCRE for use on systems that use EBCDIC as their
character code (as opposed to ASCII/Unicode) by specifying
This automatically implies --enable-rebuild-chartables (see above). However,
when PCRE is built this way, it always operates in EBCDIC. It cannot support
both EBCDIC and UTF-8/16/32. There is a second option, --enable-ebcdic-nl25,
which specifies that the code value for the EBCDIC NL character is 0x25
instead of the default 0x15.
. In environments where valgrind is installed, if you specify
PCRE will use valgrind annotations to mark certain memory regions as
unaddressable. This allows it to detect invalid memory accesses, and is
mostly useful for debugging PCRE itself.
. In environments where the gcc compiler is used and lcov version 1.6 or above
is installed, if you specify
the build process implements a code coverage report for the test suite. The
report is generated by running "make coverage". If ccache is installed on
your system, it must be disabled when building PCRE for coverage reporting.
You can do this by setting the environment variable CCACHE_DISABLE=1 before
running "make" to build PCRE. There is more information about coverage
reporting in the "pcrebuild" documentation.
. The pcregrep program currently supports only 8-bit data files, and so
requires the 8-bit PCRE library. It is possible to compile pcregrep to use
libz and/or libbz2, in order to read .gz and .bz2 files (respectively), by
specifying one or both of
Of course, the relevant libraries must be installed on your system.
. The default size (in bytes) of the internal buffer used by pcregrep can be
set by, for example:
The value must be a plain integer. The default is 20480.
. It is possible to compile pcretest so that it links with the libreadline
or libedit libraries, by specifying, respectively,
--enable-pcretest-libreadline or --enable-pcretest-libedit
If this is done, when pcretest's input is from a terminal, it reads it using
the readline() function. This provides line-editing and history facilities.
Note that libreadline is GPL-licenced, so if you distribute a binary of
pcretest linked in this way, there may be licensing issues. These can be
avoided by linking with libedit (which has a BSD licence) instead.
Enabling libreadline causes the -lreadline option to be added to the pcretest
build. In many operating environments with a sytem-installed readline
library this is sufficient. However, in some environments (e.g. if an
unmodified distribution version of readline is in use), it may be necessary
to specify something like LIBS="-lncurses" as well. This is because, to quote
the readline INSTALL, "Readline uses the termcap functions, but does not link
with the termcap or curses library itself, allowing applications which link
with readline the to choose an appropriate library." If you get error
messages about missing functions tgetstr, tgetent, tputs, tgetflag, or tgoto,
this is the problem, and linking with the ncurses library should fix it.
The "configure" script builds the following files for the basic C library:
. Makefile the makefile that builds the library
. config.h build-time configuration options for the library
. pcre.h the public PCRE header file
. pcre-config script that shows the building settings such as CFLAGS
that were set for "configure"
. libpcre.pc ) data for the pkg-config command
. libpcre16.pc )
. libpcre32.pc )
. libpcreposix.pc )
. libtool script that builds shared and/or static libraries
Versions of config.h and pcre.h are distributed in the PCRE tarballs under the
names config.h.generic and pcre.h.generic. These are provided for those who
have to built PCRE without using "configure" or CMake. If you use "configure"
or CMake, the .generic versions are not used.
When building the 8-bit library, if a C++ compiler is found, the following
files are also built:
. libpcrecpp.pc data for the pkg-config command
. pcrecpparg.h header file for calling PCRE via the C++ wrapper
. pcre_stringpiece.h header for the C++ "stringpiece" functions
The "configure" script also creates config.status, which is an executable
script that can be run to recreate the configuration, and config.log, which
contains compiler output from tests that "configure" runs.
Once "configure" has run, you can run "make". This builds the the libraries
libpcre, libpcre16 and/or libpcre32, and a test program called pcretest. If you
enabled JIT support with --enable-jit, a test program called pcre_jit_test is
built as well.
If the 8-bit library is built, libpcreposix and the pcregrep command are also
built, and if a C++ compiler was found on your system, and you did not disable
it with --disable-cpp, "make" builds the C++ wrapper library, which is called
libpcrecpp, as well as some test programs called pcrecpp_unittest,
pcre_scanner_unittest, and pcre_stringpiece_unittest.
The command "make check" runs all the appropriate tests. Details of the PCRE
tests are given below in a separate section of this document.
You can use "make install" to install PCRE into live directories on your
system. The following are installed (file names are all relative to the
<prefix> that is set when "configure" is run):
Commands (bin):
pcregrep (if 8-bit support is enabled)
Libraries (lib):
libpcre16 (if 16-bit support is enabled)
libpcre32 (if 32-bit support is enabled)
libpcre (if 8-bit support is enabled)
libpcreposix (if 8-bit support is enabled)
libpcrecpp (if 8-bit and C++ support is enabled)
Configuration information (lib/pkgconfig):
libpcrecpp.pc (if C++ support is enabled)
Header files (include):
pcre_scanner.h )
pcre_stringpiece.h ) if C++ support is enabled
pcrecpp.h )
pcrecpparg.h )
Man pages (share/man/man{1,3}):
pcre*.3 (lots more pages, all starting "pcre")
HTML documentation (share/doc/pcre/html):
*.html (lots more pages, hyperlinked from index.html)
Text file documentation (share/doc/pcre):
pcre.txt (a concatenation of the man(3) pages)
pcretest.txt the pcretest man page
pcregrep.txt the pcregrep man page
pcre-config.txt the pcre-config man page
If you want to remove PCRE from your system, you can run "make uninstall".
This removes all the files that "make install" installed. However, it does not
remove any directories, because these are often shared with other programs.
Retrieving configuration information
Running "make install" installs the command pcre-config, which can be used to
recall information about the PCRE configuration and installation. For example:
pcre-config --version
prints the version number, and
pcre-config --libs
outputs information about where the library is installed. This command can be
included in makefiles for programs that use PCRE, saving the programmer from
having to remember too many details.
The pkg-config command is another system for saving and retrieving information
about installed libraries. Instead of separate commands for each library, a
single command is used. For example:
pkg-config --cflags pcre
The data is held in *.pc files that are installed in a directory called
Shared libraries
The default distribution builds PCRE as shared libraries and static libraries,
as long as the operating system supports shared libraries. Shared library
support relies on the "libtool" script which is built as part of the
"configure" process.
The libtool script is used to compile and link both shared and static
libraries. They are placed in a subdirectory called .libs when they are newly
built. The programs pcretest and pcregrep are built to use these uninstalled
libraries (by means of wrapper scripts in the case of shared libraries). When
you use "make install" to install shared libraries, pcregrep and pcretest are
automatically re-built to use the newly installed shared libraries before being
installed themselves. However, the versions left in the build directory still
use the uninstalled libraries.
To build PCRE using static libraries only you must use --disable-shared when
configuring it. For example:
./configure --prefix=/usr/gnu --disable-shared
Then run "make" in the usual way. Similarly, you can use --disable-static to
build only shared libraries.
Cross-compiling using autotools
You can specify CC and CFLAGS in the normal way to the "configure" command, in
order to cross-compile PCRE for some other host. However, you should NOT
specify --enable-rebuild-chartables, because if you do, the dftables.c source
file is compiled and run on the local host, in order to generate the inbuilt
character tables (the pcre_chartables.c file). This will probably not work,
because dftables.c needs to be compiled with the local compiler, not the cross
When --enable-rebuild-chartables is not specified, pcre_chartables.c is created
by making a copy of pcre_chartables.c.dist, which is a default set of tables
that assumes ASCII code. Cross-compiling with the default tables should not be
a problem.
If you need to modify the character tables when cross-compiling, you should
move pcre_chartables.c.dist out of the way, then compile dftables.c by hand and
run it on the local host to make a new version of pcre_chartables.c.dist.
Then when you cross-compile PCRE this new version of the tables will be used.
Using HP's ANSI C++ compiler (aCC)
Unless C++ support is disabled by specifying the "--disable-cpp" option of the
"configure" script, you must include the "-AA" option in the CXXFLAGS
environment variable in order for the C++ components to compile correctly.
Also, note that the aCC compiler on PA-RISC platforms may have a defect whereby
needed libraries fail to get included when specifying the "-AA" compiler
option. If you experience unresolved symbols when linking the C++ programs,
use the workaround of specifying the following environment variable prior to
running the "configure" script:
CXXLDFLAGS="-lstd_v2 -lCsup_v2"
Compiling in Tru64 using native compilers
The following error may occur when compiling with native compilers in the Tru64
operating system:
CXX libpcrecpp_la-pcrecpp.lo
cxx: Error: /usr/lib/cmplrs/cxx/V7.1-006/include/cxx/iosfwd, line 58: #error
directive: "cannot include iosfwd -- define __USE_STD_IOSTREAM to
override default - see section 7.1.2 of the C++ Using Guide"
#error "cannot include iosfwd -- define __USE_STD_IOSTREAM to override default
- see section 7.1.2 of the C++ Using Guide"
This may be followed by other errors, complaining that 'namespace "std" has no
member'. The solution to this is to add the line
#define __USE_STD_IOSTREAM 1
to the config.h file.
Using Sun's compilers for Solaris
A user reports that the following configurations work on Solaris 9 sparcv9 and
Solaris 9 x86 (32-bit):
Solaris 9 sparcv9: ./configure --disable-cpp CC=/bin/cc CFLAGS="-m64 -g"
Solaris 9 x86: ./configure --disable-cpp CC=/bin/cc CFLAGS="-g"
Using PCRE from MySQL
On systems where both PCRE and MySQL are installed, it is possible to make use
of PCRE from within MySQL, as an alternative to the built-in pattern matching.
There is a web page that tells you how to do this:
Making new tarballs
The command "make dist" creates three PCRE tarballs, in tar.gz, tar.bz2, and
zip formats. The command "make distcheck" does the same, but then does a trial
build of the new distribution to ensure that it works.
If you have modified any of the man page sources in the doc directory, you
should first run the PrepareRelease script before making a distribution. This
script creates the .txt and HTML forms of the documentation from the man pages.
Testing PCRE
To test the basic PCRE library on a Unix-like system, run the RunTest script.
There is another script called RunGrepTest that tests the options of the
pcregrep command. If the C++ wrapper library is built, three test programs
called pcrecpp_unittest, pcre_scanner_unittest, and pcre_stringpiece_unittest
are also built. When JIT support is enabled, another test program called
pcre_jit_test is built.
Both the scripts and all the program tests are run if you obey "make check" or
"make test". For other environments, see the instructions in
The RunTest script runs the pcretest test program (which is documented in its
own man page) on each of the relevant testinput files in the testdata
directory, and compares the output with the contents of the corresponding
testoutput files. RunTest uses a file called testtry to hold the main output
from pcretest. Other files whose names begin with "test" are used as working
files in some tests.
Some tests are relevant only when certain build-time options were selected. For
example, the tests for UTF-8/16/32 support are run only if --enable-utf was
used. RunTest outputs a comment when it skips a test.
Many of the tests that are not skipped are run up to three times. The second
run forces pcre_study() to be called for all patterns except for a few in some
tests that are marked "never study" (see the pcretest program for how this is
done). If JIT support is available, the non-DFA tests are run a third time,
this time with a forced pcre_study() with the PCRE_STUDY_JIT_COMPILE option.
This testing can be suppressed by putting "nojit" on the RunTest command line.
The entire set of tests is run once for each of the 8-bit, 16-bit and 32-bit
libraries that are enabled. If you want to run just one set of tests, call
RunTest with either the -8, -16 or -32 option.
If valgrind is installed, you can run the tests under it by putting "valgrind"
on the RunTest command line. To run pcretest on just one or more specific test
files, give their numbers as arguments to RunTest, for example:
RunTest 2 7 11
You can also specify ranges of tests such as 3-6 or 3- (meaning 3 to the
end), or a number preceded by ~ to exclude a test. For example:
Runtest 3-15 ~10
This runs tests 3 to 15, excluding test 10, and just ~13 runs all the tests
except test 13. Whatever order the arguments are in, the tests are always run
in numerical order.
You can also call RunTest with the single argument "list" to cause it to output
a list of tests.
The first test file can be fed directly into the perltest.pl script to check
that Perl gives the same results. The only difference you should see is in the
first few lines, where the Perl version is given instead of the PCRE version.
The second set of tests check pcre_fullinfo(), pcre_study(),
pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
detection, and run-time flags that are specific to PCRE, as well as the POSIX
wrapper API. It also uses the debugging flags to check some of the internals of
If you build PCRE with a locale setting that is not the standard C locale, the
character tables may be different (see next paragraph). In some cases, this may
cause failures in the second set of tests. For example, in a locale where the
isprint() function yields TRUE for characters in the range 128-255, the use of
[:isascii:] inside a character class defines a different set of characters, and
this shows up in this test as a difference in the compiled code, which is being
listed for checking. Where the comparison test output contains [\x00-\x7f] the
test will contain [\x00-\xff], and similarly in some other cases. This is not a
bug in PCRE.
The third set of tests checks pcre_maketables(), the facility for building a
set of character tables for a specific locale and using them instead of the
default tables. The tests make use of the "fr_FR" (French) locale. Before
running the test, the script checks for the presence of this locale by running
the "locale" command. If that command fails, or if it doesn't include "fr_FR"
in the list of available locales, the third test cannot be run, and a comment
is output to say why. If running this test produces instances of the error
** Failed to set locale "fr_FR"
in the comparison output, it means that locale is not available on your system,
despite being listed by "locale". This does not mean that PCRE is broken.
[If you are trying to run this test on Windows, you may be able to get it to
work by changing "fr_FR" to "french" everywhere it occurs. Alternatively, use
RunTest.bat. The version of RunTest.bat included with PCRE 7.4 and above uses
Windows versions of test 2. More info on using RunTest.bat is included in the
document entitled NON-UNIX-USE.]
The fourth and fifth tests check the UTF-8/16/32 support and error handling and
internal UTF features of PCRE that are not relevant to Perl, respectively. The
sixth and seventh tests do the same for Unicode character properties support.
The eighth, ninth, and tenth tests check the pcre_dfa_exec() alternative
matching function, in non-UTF-8/16/32 mode, UTF-8/16/32 mode, and UTF-8/16/32
mode with Unicode property support, respectively.
The eleventh test checks some internal offsets and code size features; it is
run only when the default "link size" of 2 is set (in other cases the sizes
change) and when Unicode property support is enabled.
The twelfth test is run only when JIT support is available, and the thirteenth
test is run only when JIT support is not available. They test some JIT-specific
features such as information output from pcretest about JIT compilation.
The fourteenth, fifteenth, and sixteenth tests are run only in 8-bit mode, and
the seventeenth, eighteenth, and nineteenth tests are run only in 16/32-bit
mode. These are tests that generate different output in the two modes. They are
for general cases, UTF-8/16/32 support, and Unicode property support,
The twentieth test is run only in 16/32-bit mode. It tests some specific
16/32-bit features of the DFA matching engine.
The twenty-first and twenty-second tests are run only in 16/32-bit mode, when
the link size is set to 2 for the 16-bit library. They test reloading
pre-compiled patterns.
The twenty-third and twenty-fourth tests are run only in 16-bit mode. They are
for general cases, and UTF-16 support, respectively.
The twenty-fifth and twenty-sixth tests are run only in 32-bit mode. They are
for general cases, and UTF-32 support, respectively.
Character tables
For speed, PCRE uses four tables for manipulating and identifying characters
whose code point values are less than 256. The final argument of the
pcre_compile() function is a pointer to a block of memory containing the
concatenated tables. A call to pcre_maketables() can be used to generate a set
of tables in the current locale. If the final argument for pcre_compile() is
passed as NULL, a set of default tables that is built into the binary is used.
The source file called pcre_chartables.c contains the default set of tables. By
default, this is created as a copy of pcre_chartables.c.dist, which contains
tables for ASCII coding. However, if --enable-rebuild-chartables is specified
for ./configure, a different version of pcre_chartables.c is built by the
program dftables (compiled from dftables.c), which uses the ANSI C character
handling functions such as isalnum(), isalpha(), isupper(), islower(), etc. to
build the table sources. This means that the default C locale which is set for
your system will control the contents of these default tables. You can change
the default tables by editing pcre_chartables.c and then re-building PCRE. If
you do this, you should take care to ensure that the file does not get
automatically re-generated. The best way to do this is to move
pcre_chartables.c.dist out of the way and replace it with your customized
When the dftables program is run as a result of --enable-rebuild-chartables,
it uses the default C locale that is set on your system. It does not pay
attention to the LC_xxx environment variables. In other words, it uses the
system's default locale rather than whatever the compiling user happens to have
set. If you really do want to build a source set of character tables in a
locale that is specified by the LC_xxx variables, you can run the dftables
program by hand with the -L option. For example:
./dftables -L pcre_chartables.c.special
The first two 256-byte tables provide lower casing and case flipping functions,
respectively. The next table consists of three 32-byte bit maps which identify
digits, "word" characters, and white space, respectively. These are used when
building 32-byte bit maps that represent character classes for code points less
than 256.
The final 256-byte table has bits indicating various character types, as
1 white space character
2 letter
4 decimal digit
8 hexadecimal digit
16 alphanumeric or '_'
128 regular expression metacharacter or binary zero
You should not alter the set of characters that contain the 128 bit, as that
will cause PCRE to malfunction.
File manifest
The distribution should contain the files listed below. Where a file name is
given as pcre[16|32]_xxx it means that there are three files, one with the name
pcre_xxx, one with the name pcre16_xx, and a third with the name pcre32_xxx.
(A) Source files of the PCRE library functions and their headers:
dftables.c auxiliary program for building pcre_chartables.c
when --enable-rebuild-chartables is specified
pcre_chartables.c.dist a default set of character tables that assume ASCII
coding; used, unless --enable-rebuild-chartables is
specified, by copying to pcre[16]_chartables.c
pcreposix.c )
pcre[16|32]_byte_order.c )
pcre[16|32]_compile.c )
pcre[16|32]_config.c )
pcre[16|32]_dfa_exec.c )
pcre[16|32]_exec.c )
pcre[16|32]_fullinfo.c )
pcre[16|32]_get.c ) sources for the functions in the library,
pcre[16|32]_globals.c ) and some internal functions that they use
pcre[16|32]_jit_compile.c )
pcre[16|32]_maketables.c )
pcre[16|32]_newline.c )
pcre[16|32]_refcount.c )
pcre[16|32]_string_utils.c )
pcre[16|32]_study.c )
pcre[16|32]_tables.c )
pcre[16|32]_ucd.c )
pcre[16|32]_version.c )
pcre[16|32]_xclass.c )
pcre_ord2utf8.c )
pcre_valid_utf8.c )
pcre16_ord2utf16.c )
pcre16_utf16_utils.c )
pcre16_valid_utf16.c )
pcre32_utf32_utils.c )
pcre32_valid_utf32.c )
pcre[16|32]_printint.c ) debugging function that is used by pcretest,
) and can also be #included in pcre_compile()
pcre.h.in template for pcre.h when built by "configure"
pcreposix.h header for the external POSIX wrapper API
pcre_internal.h header for internal use
sljit/* 16 files that make up the JIT compiler
ucp.h header for Unicode property handling
config.h.in template for config.h, which is built by "configure"
pcrecpp.h public header file for the C++ wrapper
pcrecpparg.h.in template for another C++ header file
pcre_scanner.h public header file for C++ scanner functions
pcrecpp.cc )
pcre_scanner.cc ) source for the C++ wrapper library
pcre_stringpiece.h.in template for pcre_stringpiece.h, the header for the
C++ stringpiece functions
pcre_stringpiece.cc source for the C++ stringpiece functions
(B) Source files for programs that use PCRE:
pcredemo.c simple demonstration of coding calls to PCRE
pcregrep.c source of a grep utility that uses PCRE
pcretest.c comprehensive test program
(C) Auxiliary files:
132html script to turn "man" pages into HTML
AUTHORS information about the author of PCRE
ChangeLog log of changes to the code
CleanTxt script to clean nroff output for txt man pages
Detrail script to remove trailing spaces
HACKING some notes about the internals of PCRE
INSTALL generic installation instructions
LICENCE conditions for the use of PCRE
COPYING the same, using GNU's standard name
Makefile.in ) template for Unix Makefile, which is built by
) "configure"
Makefile.am ) the automake input that was used to create
) Makefile.in
NEWS important changes in this release
NON-UNIX-USE the previous name for NON-AUTOTOOLS-BUILD
NON-AUTOTOOLS-BUILD notes on building PCRE without using autotools
PrepareRelease script to make preparations for "make dist"
README this file
RunTest a Unix shell script for running tests
RunGrepTest a Unix shell script for pcregrep tests
aclocal.m4 m4 macros (generated by "aclocal")
config.guess ) files used by libtool,
config.sub ) used only when building a shared library
configure a configuring shell script (built by autoconf)
configure.ac ) the autoconf input that was used to build
) "configure" and config.h
depcomp ) script to find program dependencies, generated by
) automake
doc/*.3 man page sources for PCRE
doc/*.1 man page sources for pcregrep and pcretest
doc/index.html.src the base HTML page
doc/html/* HTML documentation
doc/pcre.txt plain text version of the man pages
doc/pcretest.txt plain text documentation of test program
doc/perltest.txt plain text documentation of Perl test program
install-sh a shell script for installing files
libpcre16.pc.in template for libpcre16.pc for pkg-config
libpcre32.pc.in template for libpcre32.pc for pkg-config
libpcre.pc.in template for libpcre.pc for pkg-config
libpcreposix.pc.in template for libpcreposix.pc for pkg-config
libpcrecpp.pc.in template for libpcrecpp.pc for pkg-config
ltmain.sh file used to build a libtool script
missing ) common stub for a few missing GNU programs while
) installing, generated by automake
mkinstalldirs script for making install directories
perltest.pl Perl test program
pcre-config.in source of script which retains PCRE information
pcre_jit_test.c test program for the JIT compiler
pcrecpp_unittest.cc )
pcre_scanner_unittest.cc ) test programs for the C++ wrapper
pcre_stringpiece_unittest.cc )
testdata/testinput* test data for main library tests
testdata/testoutput* expected test results
testdata/grep* input and output for pcregrep tests
testdata/* other supporting test files
(D) Auxiliary files for cmake support
(E) Auxiliary files for VPASCAL
(F) Auxiliary files for building PCRE "by hand"
pcre.h.generic ) a version of the public PCRE header file
) for use in non-"configure" environments
config.h.generic ) a version of config.h for use in non-"configure"
) environments
(F) Miscellaneous
RunTest.bat a script for running tests under Windows
Philip Hazel
Email local part: Philip.Hazel
Email domain: gmail.com
Last updated: 15 June 2021