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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">BUILDING 8-BIT and 16-BIT LIBRARIES</a>
19 <li><a name="TOC4" href="#SEC4">C++ SUPPORT</a>
20 <li><a name="TOC5" href="#SEC5">UTF-8 and UTF-16 SUPPORT</a>
22 <li><a name="TOC7" href="#SEC7">JUST-IN-TIME COMPILER SUPPORT</a>
23 <li><a name="TOC8" href="#SEC8">CODE VALUE OF NEWLINE</a>
24 <li><a name="TOC9" href="#SEC9">WHAT \R MATCHES</a>
25 <li><a name="TOC10" href="#SEC10">POSIX MALLOC USAGE</a>
26 <li><a name="TOC11" href="#SEC11">HANDLING VERY LARGE PATTERNS</a>
27 <li><a name="TOC12" href="#SEC12">AVOIDING EXCESSIVE STACK USAGE</a>
28 <li><a name="TOC13" href="#SEC13">LIMITING PCRE RESOURCE USAGE</a>
29 <li><a name="TOC14" href="#SEC14">CREATING CHARACTER TABLES AT BUILD TIME</a>
30 <li><a name="TOC15" href="#SEC15">USING EBCDIC CODE</a>
32 <li><a name="TOC17" href="#SEC17">PCREGREP BUFFER SIZE</a>
34 <li><a name="TOC19" href="#SEC19">SEE ALSO</a>
35 <li><a name="TOC20" href="#SEC20">AUTHOR</a>
36 <li><a name="TOC21" href="#SEC21">REVISION</a>
37 </ul>
38 <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
39 <P>
40 This document describes the optional features of PCRE that can be selected when
41 the library is compiled. It assumes use of the <b>configure</b> script, where
42 the optional features are selected or deselected by providing options to
43 <b>configure</b> before running the <b>make</b> command. However, the same
44 options can be selected in both Unix-like and non-Unix-like environments using
45 the GUI facility of <b>cmake-gui</b> if you are using <b>CMake</b> instead of
46 <b>configure</b> to build PCRE.
47 </P>
48 <P>
49 There is a lot more information about building PCRE in non-Unix-like
50 environments in the file called <i>NON_UNIX_USE</i>, which is part of the PCRE
51 distribution. You should consult this file as well as the <i>README</i> file if
52 you are building in a non-Unix-like environment.
53 </P>
54 <P>
55 The complete list of options for <b>configure</b> (which includes the standard
56 ones such as the selection of the installation directory) can be obtained by
57 running
58 <pre>
59 ./configure --help
60 </pre>
61 The following sections include descriptions of options whose names begin with
62 --enable or --disable. These settings specify changes to the defaults for the
63 <b>configure</b> command. Because of the way that <b>configure</b> works,
64 --enable and --disable always come in pairs, so the complementary option always
65 exists as well, but as it specifies the default, it is not described.
66 </P>
67 <br><a name="SEC2" href="#TOC1">BUILDING 8-BIT and 16-BIT LIBRARIES</a><br>
68 <P>
69 By default, a library called <b>libpcre</b> is built, containing functions that
70 take string arguments contained in vectors of bytes, either as single-byte
71 characters, or interpreted as UTF-8 strings. You can also build a separate
72 library, called <b>libpcre16</b>, in which strings are contained in vectors of
73 16-bit data units and interpreted either as single-unit characters or UTF-16
74 strings, by adding
75 <pre>
76 --enable-pcre16
77 </pre>
78 to the <b>configure</b> command. If you do not want the 8-bit library, add
79 <pre>
80 --disable-pcre8
81 </pre>
82 as well. At least one of the two libraries must be built. Note that the C++ and
83 POSIX wrappers are for the 8-bit library only, and that <b>pcregrep</b> is an
84 8-bit program. None of these are built if you select only the 16-bit library.
85 </P>
86 <br><a name="SEC3" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
87 <P>
88 The PCRE building process uses <b>libtool</b> to build both shared and static
89 Unix libraries by default. You can suppress one of these by adding one of
90 <pre>
91 --disable-shared
92 --disable-static
93 </pre>
94 to the <b>configure</b> command, as required.
95 </P>
96 <br><a name="SEC4" href="#TOC1">C++ SUPPORT</a><br>
97 <P>
98 By default, if the 8-bit library is being built, the <b>configure</b> script
99 will search for a C++ compiler and C++ header files. If it finds them, it
100 automatically builds the C++ wrapper library (which supports only 8-bit
101 strings). You can disable this by adding
102 <pre>
103 --disable-cpp
104 </pre>
105 to the <b>configure</b> command.
106 </P>
107 <br><a name="SEC5" href="#TOC1">UTF-8 and UTF-16 SUPPORT</a><br>
108 <P>
109 To build PCRE with support for UTF Unicode character strings, add
110 <pre>
111 --enable-utf
112 </pre>
113 to the <b>configure</b> command. This setting applies to both libraries, adding
114 support for UTF-8 to the 8-bit library and support for UTF-16 to the 16-bit
115 library. There are no separate options for enabling UTF-8 and UTF-16
116 independently because that would allow ridiculous settings such as requesting
117 UTF-16 support while building only the 8-bit library. It is not possible to
118 build one library with UTF support and the other without in the same
119 configuration. (For backwards compatibility, --enable-utf8 is a synonym of
120 --enable-utf.)
121 </P>
122 <P>
123 Of itself, this setting does not make PCRE treat strings as UTF-8 or UTF-16. As
124 well as compiling PCRE with this option, you also have have to set the
125 PCRE_UTF8 or PCRE_UTF16 option when you call one of the pattern compiling
126 functions.
127 </P>
128 <P>
129 If you set --enable-utf when compiling in an EBCDIC environment, PCRE expects
130 its input to be either ASCII or UTF-8 (depending on the runtime option). It is
131 not possible to support both EBCDIC and UTF-8 codes in the same version of the
132 library. Consequently, --enable-utf and --enable-ebcdic are mutually
133 exclusive.
134 </P>
135 <br><a name="SEC6" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
136 <P>
137 UTF support allows the libraries to process character codepoints up to 0x10ffff
138 in the strings that they handle. On its own, however, it does not provide any
139 facilities for accessing the properties of such characters. If you want to be
140 able to use the pattern escapes \P, \p, and \X, which refer to Unicode
141 character properties, you must add
142 <pre>
143 --enable-unicode-properties
144 </pre>
145 to the <b>configure</b> command. This implies UTF support, even if you have
146 not explicitly requested it.
147 </P>
148 <P>
149 Including Unicode property support adds around 30K of tables to the PCRE
150 library. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are
151 supported. Details are given in the
152 <a href="pcrepattern.html"><b>pcrepattern</b></a>
153 documentation.
154 </P>
155 <br><a name="SEC7" href="#TOC1">JUST-IN-TIME COMPILER SUPPORT</a><br>
156 <P>
157 Just-in-time compiler support is included in the build by specifying
158 <pre>
159 --enable-jit
160 </pre>
161 This support is available only for certain hardware architectures. If this
162 option is set for an unsupported architecture, a compile time error occurs.
163 See the
164 <a href="pcrejit.html"><b>pcrejit</b></a>
165 documentation for a discussion of JIT usage. When JIT support is enabled,
166 pcregrep automatically makes use of it, unless you add
167 <pre>
168 --disable-pcregrep-jit
169 </pre>
170 to the "configure" command.
171 </P>
172 <br><a name="SEC8" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
173 <P>
174 By default, PCRE interprets the linefeed (LF) character as indicating the end
175 of a line. This is the normal newline character on Unix-like systems. You can
176 compile PCRE to use carriage return (CR) instead, by adding
177 <pre>
178 --enable-newline-is-cr
179 </pre>
180 to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
181 which explicitly specifies linefeed as the newline character.
182 <br>
183 <br>
184 Alternatively, you can specify that line endings are to be indicated by the two
185 character sequence CRLF. If you want this, add
186 <pre>
187 --enable-newline-is-crlf
188 </pre>
189 to the <b>configure</b> command. There is a fourth option, specified by
190 <pre>
191 --enable-newline-is-anycrlf
192 </pre>
193 which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as
194 indicating a line ending. Finally, a fifth option, specified by
195 <pre>
196 --enable-newline-is-any
197 </pre>
198 causes PCRE to recognize any Unicode newline sequence.
199 </P>
200 <P>
201 Whatever line ending convention is selected when PCRE is built can be
202 overridden when the library functions are called. At build time it is
203 conventional to use the standard for your operating system.
204 </P>
205 <br><a name="SEC9" href="#TOC1">WHAT \R MATCHES</a><br>
206 <P>
207 By default, the sequence \R in a pattern matches any Unicode newline sequence,
208 whatever has been selected as the line ending sequence. If you specify
209 <pre>
210 --enable-bsr-anycrlf
211 </pre>
212 the default is changed so that \R matches only CR, LF, or CRLF. Whatever is
213 selected when PCRE is built can be overridden when the library functions are
214 called.
215 </P>
216 <br><a name="SEC10" href="#TOC1">POSIX MALLOC USAGE</a><br>
217 <P>
218 When the 8-bit library is called through the POSIX interface (see the
219 <a href="pcreposix.html"><b>pcreposix</b></a>
220 documentation), additional working storage is required for holding the pointers
221 to capturing substrings, because PCRE requires three integers per substring,
222 whereas the POSIX interface provides only two. If the number of expected
223 substrings is small, the wrapper function uses space on the stack, because this
224 is faster than using <b>malloc()</b> for each call. The default threshold above
225 which the stack is no longer used is 10; it can be changed by adding a setting
226 such as
227 <pre>
228 --with-posix-malloc-threshold=20
229 </pre>
230 to the <b>configure</b> command.
231 </P>
232 <br><a name="SEC11" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
233 <P>
234 Within a compiled pattern, offset values are used to point from one part to
235 another (for example, from an opening parenthesis to an alternation
236 metacharacter). By default, two-byte values are used for these offsets, leading
237 to a maximum size for a compiled pattern of around 64K. This is sufficient to
238 handle all but the most gigantic patterns. Nevertheless, some people do want to
239 process truly enormous patterns, so it is possible to compile PCRE to use
240 three-byte or four-byte offsets by adding a setting such as
241 <pre>
242 --with-link-size=3
243 </pre>
244 to the <b>configure</b> command. The value given must be 2, 3, or 4. For the
245 16-bit library, a value of 3 is rounded up to 4. Using longer offsets slows
246 down the operation of PCRE because it has to load additional data when handling
247 them.
248 </P>
249 <br><a name="SEC12" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
250 <P>
251 When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
252 by making recursive calls to an internal function called <b>match()</b>. In
253 environments where the size of the stack is limited, this can severely limit
254 PCRE's operation. (The Unix environment does not usually suffer from this
255 problem, but it may sometimes be necessary to increase the maximum stack size.
256 There is a discussion in the
257 <a href="pcrestack.html"><b>pcrestack</b></a>
258 documentation.) An alternative approach to recursion that uses memory from the
259 heap to remember data, instead of using recursive function calls, has been
260 implemented to work round the problem of limited stack size. If you want to
261 build a version of PCRE that works this way, add
262 <pre>
263 --disable-stack-for-recursion
264 </pre>
265 to the <b>configure</b> command. With this configuration, PCRE will use the
266 <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory
267 management functions. By default these point to <b>malloc()</b> and
268 <b>free()</b>, but you can replace the pointers so that your own functions are
269 used instead.
270 </P>
271 <P>
272 Separate functions are provided rather than using <b>pcre_malloc</b> and
273 <b>pcre_free</b> because the usage is very predictable: the block sizes
274 requested are always the same, and the blocks are always freed in reverse
275 order. A calling program might be able to implement optimized functions that
276 perform better than <b>malloc()</b> and <b>free()</b>. PCRE runs noticeably more
277 slowly when built in this way. This option affects only the <b>pcre_exec()</b>
278 function; it is not relevant for <b>pcre_dfa_exec()</b>.
279 </P>
280 <br><a name="SEC13" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
281 <P>
282 Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
283 (sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
284 function. By controlling the maximum number of times this function may be
285 called during a single matching operation, a limit can be placed on the
286 resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
287 at run time, as described in the
288 <a href="pcreapi.html"><b>pcreapi</b></a>
289 documentation. The default is 10 million, but this can be changed by adding a
290 setting such as
291 <pre>
292 --with-match-limit=500000
293 </pre>
294 to the <b>configure</b> command. This setting has no effect on the
295 <b>pcre_dfa_exec()</b> matching function.
296 </P>
297 <P>
298 In some environments it is desirable to limit the depth of recursive calls of
299 <b>match()</b> more strictly than the total number of calls, in order to
300 restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
301 is specified) that is used. A second limit controls this; it defaults to the
302 value that is set for --with-match-limit, which imposes no additional
303 constraints. However, you can set a lower limit by adding, for example,
304 <pre>
305 --with-match-limit-recursion=10000
306 </pre>
307 to the <b>configure</b> command. This value can also be overridden at run time.
308 </P>
309 <br><a name="SEC14" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br>
310 <P>
311 PCRE uses fixed tables for processing characters whose code values are less
312 than 256. By default, PCRE is built with a set of tables that are distributed
313 in the file <i>pcre_chartables.c.dist</i>. These tables are for ASCII codes
314 only. If you add
315 <pre>
316 --enable-rebuild-chartables
317 </pre>
318 to the <b>configure</b> command, the distributed tables are no longer used.
319 Instead, a program called <b>dftables</b> is compiled and run. This outputs the
320 source for new set of tables, created in the default locale of your C runtime
321 system. (This method of replacing the tables does not work if you are cross
322 compiling, because <b>dftables</b> is run on the local host. If you need to
323 create alternative tables when cross compiling, you will have to do so "by
324 hand".)
325 </P>
326 <br><a name="SEC15" href="#TOC1">USING EBCDIC CODE</a><br>
327 <P>
328 PCRE assumes by default that it will run in an environment where the character
329 code is ASCII (or Unicode, which is a superset of ASCII). This is the case for
330 most computer operating systems. PCRE can, however, be compiled to run in an
331 EBCDIC environment by adding
332 <pre>
333 --enable-ebcdic
334 </pre>
335 to the <b>configure</b> command. This setting implies
336 --enable-rebuild-chartables. You should only use it if you know that you are in
337 an EBCDIC environment (for example, an IBM mainframe operating system). The
338 --enable-ebcdic option is incompatible with --enable-utf.
339 </P>
341 <P>
342 By default, <b>pcregrep</b> reads all files as plain text. You can build it so
343 that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads
344 them with <b>libz</b> or <b>libbz2</b>, respectively, by adding one or both of
345 <pre>
346 --enable-pcregrep-libz
347 --enable-pcregrep-libbz2
348 </pre>
349 to the <b>configure</b> command. These options naturally require that the
350 relevant libraries are installed on your system. Configuration will fail if
351 they are not.
352 </P>
353 <br><a name="SEC17" href="#TOC1">PCREGREP BUFFER SIZE</a><br>
354 <P>
355 <b>pcregrep</b> uses an internal buffer to hold a "window" on the file it is
356 scanning, in order to be able to output "before" and "after" lines when it
357 finds a match. The size of the buffer is controlled by a parameter whose
358 default value is 20K. The buffer itself is three times this size, but because
359 of the way it is used for holding "before" lines, the longest line that is
360 guaranteed to be processable is the parameter size. You can change the default
361 parameter value by adding, for example,
362 <pre>
363 --with-pcregrep-bufsize=50K
364 </pre>
365 to the <b>configure</b> command. The caller of \fPpcregrep\fP can, however,
366 override this value by specifying a run-time option.
367 </P>
368 <br><a name="SEC18" href="#TOC1">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a><br>
369 <P>
370 If you add
371 <pre>
372 --enable-pcretest-libreadline
373 </pre>
374 to the <b>configure</b> command, <b>pcretest</b> is linked with the
375 <b>libreadline</b> library, and when its input is from a terminal, it reads it
376 using the <b>readline()</b> function. This provides line-editing and history
377 facilities. Note that <b>libreadline</b> is GPL-licensed, so if you distribute a
378 binary of <b>pcretest</b> linked in this way, there may be licensing issues.
379 </P>
380 <P>
381 Setting this option causes the <b>-lreadline</b> option to be added to the
382 <b>pcretest</b> build. In many operating environments with a sytem-installed
383 <b>libreadline</b> this is sufficient. However, in some environments (e.g.
384 if an unmodified distribution version of readline is in use), some extra
385 configuration may be necessary. The INSTALL file for <b>libreadline</b> says
386 this:
387 <pre>
388 "Readline uses the termcap functions, but does not link with the
389 termcap or curses library itself, allowing applications which link
390 with readline the to choose an appropriate library."
391 </pre>
392 If your environment has not been set up so that an appropriate library is
393 automatically included, you may need to add something like
394 <pre>
395 LIBS="-ncurses"
396 </pre>
397 immediately before the <b>configure</b> command.
398 </P>
399 <br><a name="SEC19" href="#TOC1">SEE ALSO</a><br>
400 <P>
401 <b>pcreapi</b>(3), <b>pcre16</b>, <b>pcre_config</b>(3).
402 </P>
403 <br><a name="SEC20" href="#TOC1">AUTHOR</a><br>
404 <P>
405 Philip Hazel
406 <br>
407 University Computing Service
408 <br>
409 Cambridge CB2 3QH, England.
410 <br>
411 </P>
412 <br><a name="SEC21" href="#TOC1">REVISION</a><br>
413 <P>
414 Last updated: 07 January 2012
415 <br>
416 Copyright &copy; 1997-2012 University of Cambridge.
417 <br>
418 <p>
419 Return to the <a href="index.html">PCRE index page</a>.
420 </p>


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