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>cmake-gui</b> if you are using <b>CMake</b> instead of 43<b>configure</b> to build PCRE. 44</P> 45<P> 46There is a lot more information about building PCRE in non-Unix-like 47environments in the file called <i>NON_UNIX_USE</i>, which is part of the PCRE 48distribution. You should consult this file as well as the <i>README</i> file if 49you are building in a non-Unix-like environment. 50</P> 51<P> 52The complete list of options for <b>configure</b> (which includes the standard 53ones such as the selection of the installation directory) can be obtained by 54running 55<pre> 56 /configure --help 57</pre> 58The following sections include descriptions of options whose names begin with 59--enable or --disable. These settings specify changes to the defaults for the 60<b>configure</b> command. Because of the way that <b>configure</b> works, 61--enable and --disable always come in pairs, so the complementary option always 62exists as well, but as it specifies the default, it is not described. 63</P> 64<br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br> 65<P> 66By default, the <b>configure</b> script will search for a C++ compiler and C++ 67header files. If it finds them, it automatically builds the C++ wrapper library 68for PCRE. You can disable this by adding 69<pre> 70 --disable-cpp 71</pre> 72to the <b>configure</b> command. 73</P> 74<br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br> 75<P> 76To build PCRE with support for UTF-8 Unicode character strings, add 77<pre> 78 --enable-utf8 79</pre> 80to the <b>configure</b> command. Of itself, this does not make PCRE treat 81strings as UTF-8. As well as compiling PCRE with this option, you also have 82have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b> 83or <b>pcre_compile2()</b> functions. 84</P> 85<P> 86If you set --enable-utf8 when compiling in an EBCDIC environment, PCRE expects 87its input to be either ASCII or UTF-8 (depending on the runtime option). It is 88not possible to support both EBCDIC and UTF-8 codes in the same version of the 89library. Consequently, --enable-utf8 and --enable-ebcdic are mutually 90exclusive. 91</P> 92<br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br> 93<P> 94UTF-8 support allows PCRE to process character values greater than 255 in the 95strings that it handles. On its own, however, it does not provide any 96facilities for accessing the properties of such characters. If you want to be 97able to use the pattern escapes \P, \p, and \X, which refer to Unicode 98character properties, you must add 99<pre> 100 --enable-unicode-properties 101</pre> 102to the <b>configure</b> command. This implies UTF-8 support, even if you have 103not explicitly requested it. 104</P> 105<P> 106Including Unicode property support adds around 30K of tables to the PCRE 107library. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are 108supported. Details are given in the 109<a href="pcrepattern.html"><b>pcrepattern</b></a> 110documentation. 111</P> 112<br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br> 113<P> 114By default, PCRE interprets the linefeed (LF) character as indicating the end 115of a line. This is the normal newline character on Unix-like systems. You can 116compile PCRE to use carriage return (CR) instead, by adding 117<pre> 118 --enable-newline-is-cr 119</pre> 120to the <b>configure</b> command. There is also a --enable-newline-is-lf option, 121which explicitly specifies linefeed as the newline character. 122<br> 123<br> 124Alternatively, you can specify that line endings are to be indicated by the two 125character sequence CRLF. If you want this, add 126<pre> 127 --enable-newline-is-crlf 128</pre> 129to the <b>configure</b> command. There is a fourth option, specified by 130<pre> 131 --enable-newline-is-anycrlf 132</pre> 133which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as 134indicating a line ending. Finally, a fifth option, specified by 135<pre> 136 --enable-newline-is-any 137</pre> 138causes PCRE to recognize any Unicode newline sequence. 139</P> 140<P> 141Whatever line ending convention is selected when PCRE is built can be 142overridden when the library functions are called. At build time it is 143conventional to use the standard for your operating system. 144</P> 145<br><a name="SEC6" href="#TOC1">WHAT \R MATCHES</a><br> 146<P> 147By default, the sequence \R in a pattern matches any Unicode newline sequence, 148whatever has been selected as the line ending sequence. If you specify 149<pre> 150 --enable-bsr-anycrlf 151</pre> 152the default is changed so that \R matches only CR, LF, or CRLF. Whatever is 153selected when PCRE is built can be overridden when the library functions are 154called. 155</P> 156<br><a name="SEC7" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br> 157<P> 158The PCRE building process uses <b>libtool</b> to build both shared and static 159Unix libraries by default. You can suppress one of these by adding one of 160<pre> 161 --disable-shared 162 --disable-static 163</pre> 164to the <b>configure</b> command, as required. 165</P> 166<br><a name="SEC8" href="#TOC1">POSIX MALLOC USAGE</a><br> 167<P> 168When PCRE is called through the POSIX interface (see the 169<a href="pcreposix.html"><b>pcreposix</b></a> 170documentation), additional working storage is required for holding the pointers 171to capturing substrings, because PCRE requires three integers per substring, 172whereas the POSIX interface provides only two. If the number of expected 173substrings is small, the wrapper function uses space on the stack, because this 174is faster than using <b>malloc()</b> for each call. The default threshold above 175which the stack is no longer used is 10; it can be changed by adding a setting 176such as 177<pre> 178 --with-posix-malloc-threshold=20 179</pre> 180to the <b>configure</b> command. 181</P> 182<br><a name="SEC9" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br> 183<P> 184Within a compiled pattern, offset values are used to point from one part to 185another (for example, from an opening parenthesis to an alternation 186metacharacter). By default, two-byte values are used for these offsets, leading 187to a maximum size for a compiled pattern of around 64K. This is sufficient to 188handle all but the most gigantic patterns. Nevertheless, some people do want to 189process truyl enormous patterns, so it is possible to compile PCRE to use 190three-byte or four-byte offsets by adding a setting such as 191<pre> 192 --with-link-size=3 193</pre> 194to the <b>configure</b> command. The value given must be 2, 3, or 4. Using 195longer offsets slows down the operation of PCRE because it has to load 196additional bytes when handling them. 197</P> 198<br><a name="SEC10" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br> 199<P> 200When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking 201by making recursive calls to an internal function called <b>match()</b>. In 202environments where the size of the stack is limited, this can severely limit 203PCRE's operation. (The Unix environment does not usually suffer from this 204problem, but it may sometimes be necessary to increase the maximum stack size. 205There is a discussion in the 206<a href="pcrestack.html"><b>pcrestack</b></a> 207documentation.) An alternative approach to recursion that uses memory from the 208heap to remember data, instead of using recursive function calls, has been 209implemented to work round the problem of limited stack size. If you want to 210build a version of PCRE that works this way, add 211<pre> 212 --disable-stack-for-recursion 213</pre> 214to the <b>configure</b> command. With this configuration, PCRE will use the 215<b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory 216management functions. By default these point to <b>malloc()</b> and 217<b>free()</b>, but you can replace the pointers so that your own functions are 218used instead. 219</P> 220<P> 221Separate functions are provided rather than using <b>pcre_malloc</b> and 222<b>pcre_free</b> because the usage is very predictable: the block sizes 223requested are always the same, and the blocks are always freed in reverse 224order. A calling program might be able to implement optimized functions that 225perform better than <b>malloc()</b> and <b>free()</b>. PCRE runs noticeably more 226slowly when built in this way. This option affects only the <b>pcre_exec()</b> 227function; it is not relevant for <b>pcre_dfa_exec()</b>. 228</P> 229<br><a name="SEC11" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br> 230<P> 231Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly 232(sometimes recursively) when matching a pattern with the <b>pcre_exec()</b> 233function. By controlling the maximum number of times this function may be 234called during a single matching operation, a limit can be placed on the 235resources used by a single call to <b>pcre_exec()</b>. The limit can be changed 236at run time, as described in the 237<a href="pcreapi.html"><b>pcreapi</b></a> 238documentation. The default is 10 million, but this can be changed by adding a 239setting such as 240<pre> 241 --with-match-limit=500000 242</pre> 243to the <b>configure</b> command. This setting has no effect on the 244<b>pcre_dfa_exec()</b> matching function. 245</P> 246<P> 247In some environments it is desirable to limit the depth of recursive calls of 248<b>match()</b> more strictly than the total number of calls, in order to 249restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion 250is specified) that is used. A second limit controls this; it defaults to the 251value that is set for --with-match-limit, which imposes no additional 252constraints. However, you can set a lower limit by adding, for example, 253<pre> 254 --with-match-limit-recursion=10000 255</pre> 256to the <b>configure</b> command. This value can also be overridden at run time. 257</P> 258<br><a name="SEC12" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br> 259<P> 260PCRE uses fixed tables for processing characters whose code values are less 261than 256. By default, PCRE is built with a set of tables that are distributed 262in the file <i>pcre_chartables.c.dist</i>. These tables are for ASCII codes 263only. If you add 264<pre> 265 --enable-rebuild-chartables 266</pre> 267to the <b>configure</b> command, the distributed tables are no longer used. 268Instead, a program called <b>dftables</b> is compiled and run. This outputs the 269source for new set of tables, created in the default locale of your C runtime 270system. (This method of replacing the tables does not work if you are cross 271compiling, because <b>dftables</b> is run on the local host. If you need to 272create alternative tables when cross compiling, you will have to do so "by 273hand".) 274</P> 275<br><a name="SEC13" href="#TOC1">USING EBCDIC CODE</a><br> 276<P> 277PCRE assumes by default that it will run in an environment where the character 278code is ASCII (or Unicode, which is a superset of ASCII). This is the case for 279most computer operating systems. PCRE can, however, be compiled to run in an 280EBCDIC environment by adding 281<pre> 282 --enable-ebcdic 283</pre> 284to the <b>configure</b> command. This setting implies 285--enable-rebuild-chartables. You should only use it if you know that you are in 286an EBCDIC environment (for example, an IBM mainframe operating system). The 287--enable-ebcdic option is incompatible with --enable-utf8. 288</P> 289<br><a name="SEC14" href="#TOC1">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a><br> 290<P> 291By default, <b>pcregrep</b> reads all files as plain text. You can build it so 292that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads 293them with <b>libz</b> or <b>libbz2</b>, respectively, by adding one or both of 294<pre> 295 --enable-pcregrep-libz 296 --enable-pcregrep-libbz2 297</pre> 298to the <b>configure</b> command. These options naturally require that the 299relevant libraries are installed on your system. Configuration will fail if 300they are not. 301</P> 302<br><a name="SEC15" href="#TOC1">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a><br> 303<P> 304If you add 305<pre> 306 --enable-pcretest-libreadline 307</pre> 308to the <b>configure</b> command, <b>pcretest</b> is linked with the 309<b>libreadline</b> library, and when its input is from a terminal, it reads it 310using the <b>readline()</b> function. This provides line-editing and history 311facilities. Note that <b>libreadline</b> is GPL-licensed, so if you distribute a 312binary of <b>pcretest</b> linked in this way, there may be licensing issues. 313</P> 314<P> 315Setting this option causes the <b>-lreadline</b> option to be added to the 316<b>pcretest</b> build. In many operating environments with a sytem-installed 317<b>libreadline</b> this is sufficient. However, in some environments (e.g. 318if an unmodified distribution version of readline is in use), some extra 319configuration may be necessary. The INSTALL file for <b>libreadline</b> says 320this: 321<pre> 322 "Readline uses the termcap functions, but does not link with the 323 termcap or curses library itself, allowing applications which link 324 with readline the to choose an appropriate library." 325</pre> 326If your environment has not been set up so that an appropriate library is 327automatically included, you may need to add something like 328<pre> 329 LIBS="-ncurses" 330</pre> 331immediately before the <b>configure</b> command. 332</P> 333<br><a name="SEC16" href="#TOC1">SEE ALSO</a><br> 334<P> 335<b>pcreapi</b>(3), <b>pcre_config</b>(3). 336</P> 337<br><a name="SEC17" href="#TOC1">AUTHOR</a><br> 338<P> 339Philip Hazel 340<br> 341University Computing Service 342<br> 343Cambridge CB2 3QH, England. 344<br> 345</P> 346<br><a name="SEC18" href="#TOC1">REVISION</a><br> 347<P> 348Last updated: 29 September 2009 349<br> 350Copyright © 1997-2009 University of Cambridge. 351<br> 352<p> 353Return to the <a href="index.html">PCRE index page</a>. 354</p> 355