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


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