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1<html> 2<head> 3<title>pcrebuild specification</title> 4</head> 5<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"> 6<h1>pcrebuild man page</h1> 7<p> 8Return to the <a href="index.html">PCRE index page</a>. 9</p> 10<p> 11This page is part of the PCRE HTML documentation. It was generated automatically 12from the original man page. If there is any nonsense in it, please consult the 13man page, in case the conversion went wrong. 14<br> 15<ul> 16<li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a> 17<li><a name="TOC2" href="#SEC2">C++ SUPPORT</a> 18<li><a name="TOC3" href="#SEC3">UTF-8 SUPPORT</a> 19<li><a name="TOC4" href="#SEC4">UNICODE CHARACTER PROPERTY SUPPORT</a> 20<li><a name="TOC5" href="#SEC5">CODE VALUE OF NEWLINE</a> 21<li><a name="TOC6" href="#SEC6">WHAT \R MATCHES</a> 22<li><a name="TOC7" href="#SEC7">BUILDING SHARED AND STATIC LIBRARIES</a> 23<li><a name="TOC8" href="#SEC8">POSIX MALLOC USAGE</a> 24<li><a name="TOC9" href="#SEC9">HANDLING VERY LARGE PATTERNS</a> 25<li><a name="TOC10" href="#SEC10">AVOIDING EXCESSIVE STACK USAGE</a> 26<li><a name="TOC11" href="#SEC11">LIMITING PCRE RESOURCE USAGE</a> 27<li><a name="TOC12" href="#SEC12">CREATING CHARACTER TABLES AT BUILD TIME</a> 28<li><a name="TOC13" href="#SEC13">USING EBCDIC CODE</a> 29<li><a name="TOC14" href="#SEC14">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a> 30<li><a name="TOC15" href="#SEC15">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a> 31<li><a name="TOC16" href="#SEC16">SEE ALSO</a> 32<li><a name="TOC17" href="#SEC17">AUTHOR</a> 33<li><a name="TOC18" href="#SEC18">REVISION</a> 34</ul> 35<br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br> 36<P> 37This document describes the optional features of PCRE that can be selected when 38the library is compiled. It assumes use of the <b>configure</b> script, where 39the optional features are selected or deselected by providing options to 40<b>configure</b> before running the <b>make</b> command. However, the same 41options can be selected in both Unix-like and non-Unix-like environments using 42the GUI facility of <b>CMakeSetup</b> if you are using <b>CMake</b> instead of 43<b>configure</b> to build PCRE. 44</P> 45<P> 46The complete list of options for <b>configure</b> (which includes the standard 47ones such as the selection of the installation directory) can be obtained by 48running 49<pre> 50 ./configure --help 51</pre> 52The following sections include descriptions of options whose names begin with 53--enable or --disable. These settings specify changes to the defaults for the 54<b>configure</b> command. Because of the way that <b>configure</b> works, 55--enable and --disable always come in pairs, so the complementary option always 56exists as well, but as it specifies the default, it is not described. 57</P> 58<br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br> 59<P> 60By default, the <b>configure</b> script will search for a C++ compiler and C++ 61header files. If it finds them, it automatically builds the C++ wrapper library 62for PCRE. You can disable this by adding 63<pre> 64 --disable-cpp 65</pre> 66to the <b>configure</b> command. 67</P> 68<br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br> 69<P> 70To build PCRE with support for UTF-8 character strings, add 71<pre> 72 --enable-utf8 73</pre> 74to the <b>configure</b> command. Of itself, this does not make PCRE treat 75strings as UTF-8. As well as compiling PCRE with this option, you also have 76have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b> 77function. 78</P> 79<br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br> 80<P> 81UTF-8 support allows PCRE to process character values greater than 255 in the 82strings that it handles. On its own, however, it does not provide any 83facilities for accessing the properties of such characters. If you want to be 84able to use the pattern escapes \P, \p, and \X, which refer to Unicode 85character properties, you must add 86<pre> 87 --enable-unicode-properties 88</pre> 89to the <b>configure</b> command. This implies UTF-8 support, even if you have 90not explicitly requested it. 91</P> 92<P> 93Including Unicode property support adds around 30K of tables to the PCRE 94library. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are 95supported. Details are given in the 96<a href="pcrepattern.html"><b>pcrepattern</b></a> 97documentation. 98</P> 99<br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br> 100<P> 101By default, PCRE interprets character 10 (linefeed, LF) as indicating the end 102of a line. This is the normal newline character on Unix-like systems. You can 103compile PCRE to use character 13 (carriage return, CR) instead, by adding 104<pre> 105 --enable-newline-is-cr 106</pre> 107to the <b>configure</b> command. There is also a --enable-newline-is-lf option, 108which explicitly specifies linefeed as the newline character. 109<br> 110<br> 111Alternatively, you can specify that line endings are to be indicated by the two 112character sequence CRLF. If you want this, add 113<pre> 114 --enable-newline-is-crlf 115</pre> 116to the <b>configure</b> command. There is a fourth option, specified by 117<pre> 118 --enable-newline-is-anycrlf 119</pre> 120which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as 121indicating a line ending. Finally, a fifth option, specified by 122<pre> 123 --enable-newline-is-any 124</pre> 125causes PCRE to recognize any Unicode newline sequence. 126</P> 127<P> 128Whatever line ending convention is selected when PCRE is built can be 129overridden when the library functions are called. At build time it is 130conventional to use the standard for your operating system. 131</P> 132<br><a name="SEC6" href="#TOC1">WHAT \R MATCHES</a><br> 133<P> 134By default, the sequence \R in a pattern matches any Unicode newline sequence, 135whatever has been selected as the line ending sequence. If you specify 136<pre> 137 --enable-bsr-anycrlf 138</pre> 139the default is changed so that \R matches only CR, LF, or CRLF. Whatever is 140selected when PCRE is built can be overridden when the library functions are 141called. 142</P> 143<br><a name="SEC7" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br> 144<P> 145The PCRE building process uses <b>libtool</b> to build both shared and static 146Unix libraries by default. You can suppress one of these by adding one of 147<pre> 148 --disable-shared 149 --disable-static 150</pre> 151to the <b>configure</b> command, as required. 152</P> 153<br><a name="SEC8" href="#TOC1">POSIX MALLOC USAGE</a><br> 154<P> 155When PCRE is called through the POSIX interface (see the 156<a href="pcreposix.html"><b>pcreposix</b></a> 157documentation), additional working storage is required for holding the pointers 158to capturing substrings, because PCRE requires three integers per substring, 159whereas the POSIX interface provides only two. If the number of expected 160substrings is small, the wrapper function uses space on the stack, because this 161is faster than using <b>malloc()</b> for each call. The default threshold above 162which the stack is no longer used is 10; it can be changed by adding a setting 163such as 164<pre> 165 --with-posix-malloc-threshold=20 166</pre> 167to the <b>configure</b> command. 168</P> 169<br><a name="SEC9" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br> 170<P> 171Within a compiled pattern, offset values are used to point from one part to 172another (for example, from an opening parenthesis to an alternation 173metacharacter). By default, two-byte values are used for these offsets, leading 174to a maximum size for a compiled pattern of around 64K. This is sufficient to 175handle all but the most gigantic patterns. Nevertheless, some people do want to 176process enormous patterns, so it is possible to compile PCRE to use three-byte 177or four-byte offsets by adding a setting such as 178<pre> 179 --with-link-size=3 180</pre> 181to the <b>configure</b> command. The value given must be 2, 3, or 4. Using 182longer offsets slows down the operation of PCRE because it has to load 183additional bytes when handling them. 184</P> 185<br><a name="SEC10" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br> 186<P> 187When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking 188by making recursive calls to an internal function called <b>match()</b>. In 189environments where the size of the stack is limited, this can severely limit 190PCRE's operation. (The Unix environment does not usually suffer from this 191problem, but it may sometimes be necessary to increase the maximum stack size. 192There is a discussion in the 193<a href="pcrestack.html"><b>pcrestack</b></a> 194documentation.) An alternative approach to recursion that uses memory from the 195heap to remember data, instead of using recursive function calls, has been 196implemented to work round the problem of limited stack size. If you want to 197build a version of PCRE that works this way, add 198<pre> 199 --disable-stack-for-recursion 200</pre> 201to the <b>configure</b> command. With this configuration, PCRE will use the 202<b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory 203management functions. By default these point to <b>malloc()</b> and 204<b>free()</b>, but you can replace the pointers so that your own functions are 205used. 206</P> 207<P> 208Separate functions are provided rather than using <b>pcre_malloc</b> and 209<b>pcre_free</b> because the usage is very predictable: the block sizes 210requested are always the same, and the blocks are always freed in reverse 211order. A calling program might be able to implement optimized functions that 212perform better than <b>malloc()</b> and <b>free()</b>. PCRE runs noticeably more 213slowly when built in this way. This option affects only the <b>pcre_exec()</b> 214function; it is not relevant for the the <b>pcre_dfa_exec()</b> function. 215</P> 216<br><a name="SEC11" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br> 217<P> 218Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly 219(sometimes recursively) when matching a pattern with the <b>pcre_exec()</b> 220function. By controlling the maximum number of times this function may be 221called during a single matching operation, a limit can be placed on the 222resources used by a single call to <b>pcre_exec()</b>. The limit can be changed 223at run time, as described in the 224<a href="pcreapi.html"><b>pcreapi</b></a> 225documentation. The default is 10 million, but this can be changed by adding a 226setting such as 227<pre> 228 --with-match-limit=500000 229</pre> 230to the <b>configure</b> command. This setting has no effect on the 231<b>pcre_dfa_exec()</b> matching function. 232</P> 233<P> 234In some environments it is desirable to limit the depth of recursive calls of 235<b>match()</b> more strictly than the total number of calls, in order to 236restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion 237is specified) that is used. A second limit controls this; it defaults to the 238value that is set for --with-match-limit, which imposes no additional 239constraints. However, you can set a lower limit by adding, for example, 240<pre> 241 --with-match-limit-recursion=10000 242</pre> 243to the <b>configure</b> command. This value can also be overridden at run time. 244</P> 245<br><a name="SEC12" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br> 246<P> 247PCRE uses fixed tables for processing characters whose code values are less 248than 256. By default, PCRE is built with a set of tables that are distributed 249in the file <i>pcre_chartables.c.dist</i>. These tables are for ASCII codes 250only. If you add 251<pre> 252 --enable-rebuild-chartables 253</pre> 254to the <b>configure</b> command, the distributed tables are no longer used. 255Instead, a program called <b>dftables</b> is compiled and run. This outputs the 256source for new set of tables, created in the default locale of your C runtime 257system. (This method of replacing the tables does not work if you are cross 258compiling, because <b>dftables</b> is run on the local host. If you need to 259create alternative tables when cross compiling, you will have to do so "by 260hand".) 261</P> 262<br><a name="SEC13" href="#TOC1">USING EBCDIC CODE</a><br> 263<P> 264PCRE assumes by default that it will run in an environment where the character 265code is ASCII (or Unicode, which is a superset of ASCII). This is the case for 266most computer operating systems. PCRE can, however, be compiled to run in an 267EBCDIC environment by adding 268<pre> 269 --enable-ebcdic 270</pre> 271to the <b>configure</b> command. This setting implies 272--enable-rebuild-chartables. You should only use it if you know that you are in 273an EBCDIC environment (for example, an IBM mainframe operating system). 274</P> 275<br><a name="SEC14" href="#TOC1">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a><br> 276<P> 277By default, <b>pcregrep</b> reads all files as plain text. You can build it so 278that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads 279them with <b>libz</b> or <b>libbz2</b>, respectively, by adding one or both of 280<pre> 281 --enable-pcregrep-libz 282 --enable-pcregrep-libbz2 283</pre> 284to the <b>configure</b> command. These options naturally require that the 285relevant libraries are installed on your system. Configuration will fail if 286they are not. 287</P> 288<br><a name="SEC15" href="#TOC1">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a><br> 289<P> 290If you add 291<pre> 292 --enable-pcretest-libreadline 293</pre> 294to the <b>configure</b> command, <b>pcretest</b> is linked with the 295<b>libreadline</b> library, and when its input is from a terminal, it reads it 296using the <b>readline()</b> function. This provides line-editing and history 297facilities. Note that <b>libreadline</b> is GPL-licenced, so if you distribute a 298binary of <b>pcretest</b> linked in this way, there may be licensing issues. 299</P> 300<P> 301Setting this option causes the <b>-lreadline</b> option to be added to the 302<b>pcretest</b> build. In many operating environments with a sytem-installed 303<b>libreadline</b> this is sufficient. However, in some environments (e.g. 304if an unmodified distribution version of readline is in use), some extra 305configuration may be necessary. The INSTALL file for <b>libreadline</b> says 306this: 307<pre> 308 "Readline uses the termcap functions, but does not link with the 309 termcap or curses library itself, allowing applications which link 310 with readline the to choose an appropriate library." 311</pre> 312If your environment has not been set up so that an appropriate library is 313automatically included, you may need to add something like 314<pre> 315 LIBS="-ncurses" 316</pre> 317immediately before the <b>configure</b> command. 318</P> 319<br><a name="SEC16" href="#TOC1">SEE ALSO</a><br> 320<P> 321<b>pcreapi</b>(3), <b>pcre_config</b>(3). 322</P> 323<br><a name="SEC17" href="#TOC1">AUTHOR</a><br> 324<P> 325Philip Hazel 326<br> 327University Computing Service 328<br> 329Cambridge CB2 3QH, England. 330<br> 331</P> 332<br><a name="SEC18" href="#TOC1">REVISION</a><br> 333<P> 334Last updated: 13 April 2008 335<br> 336Copyright © 1997-2008 University of Cambridge. 337<br> 338<p> 339Return to the <a href="index.html">PCRE index page</a>. 340</p>