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1 nigel 63 <html>
2     <head>
3     <title>pcrebuild specification</title>
4     </head>
5     <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 nigel 75 <h1>pcrebuild man page</h1>
7     <p>
8     Return to the <a href="index.html">PCRE index page</a>.
9     </p>
10 ph10 111 <p>
11 nigel 75 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 ph10 111 <br>
15 nigel 63 <ul>
16     <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>
17 nigel 83 <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 ph10 231 <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 ph10 286 <li><a name="TOC14" href="#SEC14">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a>
30 ph10 289 <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 nigel 63 </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 ph10 261 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 ph10 453 the GUI facility of <b>cmake-gui</b> if you are using <b>CMake</b> instead of
43     <b>configure</b> to build PCRE.
44 ph10 261 </P>
45     <P>
46 ph10 453 There is a lot more information about building PCRE in non-Unix-like
47     environments in the file called <i>NON_UNIX_USE</i>, which is part of the PCRE
48     distribution. You should consult this file as well as the <i>README</i> file if
49     you are building in a non-Unix-like environment.
50     </P>
51     <P>
52 ph10 261 The complete list of options for <b>configure</b> (which includes the standard
53     ones such as the selection of the installation directory) can be obtained by
54     running
55 nigel 63 <pre>
56     ./configure --help
57 nigel 75 </pre>
58 ph10 128 The following sections include descriptions of options whose names begin with
59     --enable or --disable. These settings specify changes to the defaults for the
60 nigel 63 <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
62     exists as well, but as it specifies the default, it is not described.
63     </P>
64 nigel 83 <br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br>
65 nigel 63 <P>
66 nigel 83 By default, the <b>configure</b> script will search for a C++ compiler and C++
67     header files. If it finds them, it automatically builds the C++ wrapper library
68     for PCRE. You can disable this by adding
69     <pre>
70     --disable-cpp
71     </pre>
72     to the <b>configure</b> command.
73     </P>
74     <br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br>
75     <P>
76 ph10 392 To build PCRE with support for UTF-8 Unicode character strings, add
77 nigel 63 <pre>
78     --enable-utf8
79 nigel 75 </pre>
80 nigel 63 to the <b>configure</b> command. Of itself, this does not make PCRE treat
81     strings as UTF-8. As well as compiling PCRE with this option, you also have
82     have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>
83     function.
84     </P>
85 ph10 392 <P>
86     If you set --enable-utf8 when compiling in an EBCDIC environment, PCRE expects
87     its input to be either ASCII or UTF-8 (depending on the runtime option). It is
88     not possible to support both EBCDIC and UTF-8 codes in the same version of the
89     library. Consequently, --enable-utf8 and --enable-ebcdic are mutually
90     exclusive.
91     </P>
92 nigel 83 <br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
93 nigel 63 <P>
94 nigel 75 UTF-8 support allows PCRE to process character values greater than 255 in the
95     strings that it handles. On its own, however, it does not provide any
96     facilities for accessing the properties of such characters. If you want to be
97     able to use the pattern escapes \P, \p, and \X, which refer to Unicode
98     character properties, you must add
99     <pre>
100     --enable-unicode-properties
101     </pre>
102     to the <b>configure</b> command. This implies UTF-8 support, even if you have
103     not explicitly requested it.
104     </P>
105     <P>
106 ph10 128 Including Unicode property support adds around 30K of tables to the PCRE
107     library. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are
108     supported. Details are given in the
109 nigel 75 <a href="pcrepattern.html"><b>pcrepattern</b></a>
110     documentation.
111     </P>
112 nigel 83 <br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
113 nigel 75 <P>
114 ph10 392 By default, PCRE interprets the linefeed (LF) character as indicating the end
115 nigel 91 of a line. This is the normal newline character on Unix-like systems. You can
116 ph10 392 compile PCRE to use carriage return (CR) instead, by adding
117 nigel 63 <pre>
118     --enable-newline-is-cr
119 nigel 75 </pre>
120 nigel 91 to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
121     which explicitly specifies linefeed as the newline character.
122     <br>
123     <br>
124     Alternatively, you can specify that line endings are to be indicated by the two
125     character sequence CRLF. If you want this, add
126     <pre>
127     --enable-newline-is-crlf
128     </pre>
129 nigel 93 to the <b>configure</b> command. There is a fourth option, specified by
130     <pre>
131 ph10 150 --enable-newline-is-anycrlf
132     </pre>
133     which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as
134     indicating a line ending. Finally, a fifth option, specified by
135     <pre>
136 nigel 93 --enable-newline-is-any
137     </pre>
138 ph10 150 causes PCRE to recognize any Unicode newline sequence.
139 nigel 63 </P>
140 nigel 93 <P>
141     Whatever line ending convention is selected when PCRE is built can be
142     overridden when the library functions are called. At build time it is
143     conventional to use the standard for your operating system.
144     </P>
145 ph10 231 <br><a name="SEC6" href="#TOC1">WHAT \R MATCHES</a><br>
146 nigel 63 <P>
147 ph10 231 By default, the sequence \R in a pattern matches any Unicode newline sequence,
148     whatever has been selected as the line ending sequence. If you specify
149     <pre>
150     --enable-bsr-anycrlf
151     </pre>
152     the default is changed so that \R matches only CR, LF, or CRLF. Whatever is
153     selected when PCRE is built can be overridden when the library functions are
154     called.
155     </P>
156     <br><a name="SEC7" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
157     <P>
158 nigel 63 The PCRE building process uses <b>libtool</b> to build both shared and static
159     Unix libraries by default. You can suppress one of these by adding one of
160     <pre>
161     --disable-shared
162     --disable-static
163 nigel 75 </pre>
164 nigel 63 to the <b>configure</b> command, as required.
165     </P>
166 ph10 231 <br><a name="SEC8" href="#TOC1">POSIX MALLOC USAGE</a><br>
167 nigel 63 <P>
168 nigel 75 When PCRE is called through the POSIX interface (see the
169     <a href="pcreposix.html"><b>pcreposix</b></a>
170 nigel 63 documentation), additional working storage is required for holding the pointers
171 nigel 75 to capturing substrings, because PCRE requires three integers per substring,
172 nigel 63 whereas the POSIX interface provides only two. If the number of expected
173     substrings is small, the wrapper function uses space on the stack, because this
174     is faster than using <b>malloc()</b> for each call. The default threshold above
175     which the stack is no longer used is 10; it can be changed by adding a setting
176     such as
177     <pre>
178     --with-posix-malloc-threshold=20
179 nigel 75 </pre>
180 nigel 63 to the <b>configure</b> command.
181     </P>
182 ph10 231 <br><a name="SEC9" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
183 nigel 63 <P>
184     Within a compiled pattern, offset values are used to point from one part to
185     another (for example, from an opening parenthesis to an alternation
186 nigel 75 metacharacter). By default, two-byte values are used for these offsets, leading
187 nigel 63 to a maximum size for a compiled pattern of around 64K. This is sufficient to
188     handle all but the most gigantic patterns. Nevertheless, some people do want to
189     process enormous patterns, so it is possible to compile PCRE to use three-byte
190     or four-byte offsets by adding a setting such as
191     <pre>
192     --with-link-size=3
193 nigel 75 </pre>
194 nigel 63 to the <b>configure</b> command. The value given must be 2, 3, or 4. Using
195     longer offsets slows down the operation of PCRE because it has to load
196     additional bytes when handling them.
197     </P>
198 ph10 231 <br><a name="SEC10" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
199 nigel 63 <P>
200 nigel 77 When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
201     by making recursive calls to an internal function called <b>match()</b>. In
202     environments where the size of the stack is limited, this can severely limit
203     PCRE's operation. (The Unix environment does not usually suffer from this
204 nigel 91 problem, but it may sometimes be necessary to increase the maximum stack size.
205     There is a discussion in the
206     <a href="pcrestack.html"><b>pcrestack</b></a>
207     documentation.) An alternative approach to recursion that uses memory from the
208     heap to remember data, instead of using recursive function calls, has been
209     implemented to work round the problem of limited stack size. If you want to
210     build a version of PCRE that works this way, add
211 nigel 73 <pre>
212     --disable-stack-for-recursion
213 nigel 75 </pre>
214 nigel 73 to 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
216 ph10 182 management 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
218     used.
219 nigel 73 </P>
220 ph10 182 <P>
221     Separate 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
223     requested are always the same, and the blocks are always freed in reverse
224     order. A calling program might be able to implement optimized functions that
225     perform better than <b>malloc()</b> and <b>free()</b>. PCRE runs noticeably more
226     slowly when built in this way. This option affects only the <b>pcre_exec()</b>
227     function; it is not relevant for the the <b>pcre_dfa_exec()</b> function.
228     </P>
229 ph10 231 <br><a name="SEC11" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
230 nigel 91 <P>
231     Internally, 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>
233     function. By controlling the maximum number of times this function may be
234     called during a single matching operation, a limit can be placed on the
235     resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
236     at run time, as described in the
237     <a href="pcreapi.html"><b>pcreapi</b></a>
238     documentation. The default is 10 million, but this can be changed by adding a
239     setting such as
240     <pre>
241     --with-match-limit=500000
242     </pre>
243     to the <b>configure</b> command. This setting has no effect on the
244     <b>pcre_dfa_exec()</b> matching function.
245     </P>
246     <P>
247     In 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
249     restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
250     is specified) that is used. A second limit controls this; it defaults to the
251     value that is set for --with-match-limit, which imposes no additional
252     constraints. However, you can set a lower limit by adding, for example,
253     <pre>
254     --with-match-limit-recursion=10000
255     </pre>
256     to the <b>configure</b> command. This value can also be overridden at run time.
257     </P>
258 ph10 231 <br><a name="SEC12" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br>
259 nigel 73 <P>
260 ph10 128 PCRE uses fixed tables for processing characters whose code values are less
261     than 256. By default, PCRE is built with a set of tables that are distributed
262     in the file <i>pcre_chartables.c.dist</i>. These tables are for ASCII codes
263     only. If you add
264     <pre>
265     --enable-rebuild-chartables
266     </pre>
267     to the <b>configure</b> command, the distributed tables are no longer used.
268     Instead, a program called <b>dftables</b> is compiled and run. This outputs the
269     source for new set of tables, created in the default locale of your C runtime
270     system. (This method of replacing the tables does not work if you are cross
271     compiling, because <b>dftables</b> is run on the local host. If you need to
272     create alternative tables when cross compiling, you will have to do so "by
273     hand".)
274     </P>
275 ph10 231 <br><a name="SEC13" href="#TOC1">USING EBCDIC CODE</a><br>
276 ph10 128 <P>
277 nigel 73 PCRE assumes by default that it will run in an environment where the character
278 ph10 197 code is ASCII (or Unicode, which is a superset of ASCII). This is the case for
279     most computer operating systems. PCRE can, however, be compiled to run in an
280     EBCDIC environment by adding
281 nigel 73 <pre>
282     --enable-ebcdic
283 nigel 75 </pre>
284 ph10 128 to the <b>configure</b> command. This setting implies
285 ph10 197 --enable-rebuild-chartables. You should only use it if you know that you are in
286 ph10 392 an EBCDIC environment (for example, an IBM mainframe operating system). The
287     --enable-ebcdic option is incompatible with --enable-utf8.
288 nigel 73 </P>
289 ph10 286 <br><a name="SEC14" href="#TOC1">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a><br>
290 nigel 73 <P>
291 ph10 286 By default, <b>pcregrep</b> reads all files as plain text. You can build it so
292     that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads
293     them 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>
298     to the <b>configure</b> command. These options naturally require that the
299     relevant libraries are installed on your system. Configuration will fail if
300     they are not.
301     </P>
302 ph10 289 <br><a name="SEC15" href="#TOC1">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a><br>
303 ph10 286 <P>
304 ph10 289 If you add
305     <pre>
306     --enable-pcretest-libreadline
307     </pre>
308     to 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
310     using the <b>readline()</b> function. This provides line-editing and history
311     facilities. Note that <b>libreadline</b> is GPL-licenced, so if you distribute a
312     binary of <b>pcretest</b> linked in this way, there may be licensing issues.
313     </P>
314 ph10 345 <P>
315     Setting 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.
318     if an unmodified distribution version of readline is in use), some extra
319     configuration may be necessary. The INSTALL file for <b>libreadline</b> says
320     this:
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>
326     If your environment has not been set up so that an appropriate library is
327     automatically included, you may need to add something like
328     <pre>
329     LIBS="-ncurses"
330     </pre>
331     immediately before the <b>configure</b> command.
332     </P>
333 ph10 289 <br><a name="SEC16" href="#TOC1">SEE ALSO</a><br>
334     <P>
335 nigel 93 <b>pcreapi</b>(3), <b>pcre_config</b>(3).
336     </P>
337 ph10 289 <br><a name="SEC17" href="#TOC1">AUTHOR</a><br>
338 nigel 93 <P>
339 ph10 99 Philip Hazel
340 nigel 63 <br>
341 ph10 99 University Computing Service
342     <br>
343     Cambridge CB2 3QH, England.
344     <br>
345     </P>
346 ph10 289 <br><a name="SEC18" href="#TOC1">REVISION</a><br>
347 ph10 99 <P>
348 ph10 453 Last updated: 06 September 2009
349 ph10 99 <br>
350 ph10 392 Copyright &copy; 1997-2009 University of Cambridge.
351 ph10 99 <br>
352 nigel 75 <p>
353     Return to the <a href="index.html">PCRE index page</a>.
354     </p>


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