Tristan Matthews | 0461646 | 2013-11-14 16:09:34 -0500 | [diff] [blame] | 1 | .TH PCREBUILD 3 |
| 2 | .SH NAME |
| 3 | PCRE - Perl-compatible regular expressions |
| 4 | . |
| 5 | . |
| 6 | .SH "PCRE BUILD-TIME OPTIONS" |
| 7 | .rs |
| 8 | .sp |
| 9 | This document describes the optional features of PCRE that can be selected when |
| 10 | the library is compiled. It assumes use of the \fBconfigure\fP script, where |
| 11 | the optional features are selected or deselected by providing options to |
| 12 | \fBconfigure\fP before running the \fBmake\fP command. However, the same |
| 13 | options can be selected in both Unix-like and non-Unix-like environments using |
| 14 | the GUI facility of \fBcmake-gui\fP if you are using \fBCMake\fP instead of |
| 15 | \fBconfigure\fP to build PCRE. |
| 16 | .P |
| 17 | There is a lot more information about building PCRE in non-Unix-like |
| 18 | environments in the file called \fINON_UNIX_USE\fP, which is part of the PCRE |
| 19 | distribution. You should consult this file as well as the \fIREADME\fP file if |
| 20 | you are building in a non-Unix-like environment. |
| 21 | .P |
| 22 | The complete list of options for \fBconfigure\fP (which includes the standard |
| 23 | ones such as the selection of the installation directory) can be obtained by |
| 24 | running |
| 25 | .sp |
| 26 | ./configure --help |
| 27 | .sp |
| 28 | The following sections include descriptions of options whose names begin with |
| 29 | --enable or --disable. These settings specify changes to the defaults for the |
| 30 | \fBconfigure\fP command. Because of the way that \fBconfigure\fP works, |
| 31 | --enable and --disable always come in pairs, so the complementary option always |
| 32 | exists as well, but as it specifies the default, it is not described. |
| 33 | . |
| 34 | . |
| 35 | .SH "BUILDING SHARED AND STATIC LIBRARIES" |
| 36 | .rs |
| 37 | .sp |
| 38 | The PCRE building process uses \fBlibtool\fP to build both shared and static |
| 39 | Unix libraries by default. You can suppress one of these by adding one of |
| 40 | .sp |
| 41 | --disable-shared |
| 42 | --disable-static |
| 43 | .sp |
| 44 | to the \fBconfigure\fP command, as required. |
| 45 | . |
| 46 | . |
| 47 | .SH "C++ SUPPORT" |
| 48 | .rs |
| 49 | .sp |
| 50 | By default, the \fBconfigure\fP script will search for a C++ compiler and C++ |
| 51 | header files. If it finds them, it automatically builds the C++ wrapper library |
| 52 | for PCRE. You can disable this by adding |
| 53 | .sp |
| 54 | --disable-cpp |
| 55 | .sp |
| 56 | to the \fBconfigure\fP command. |
| 57 | . |
| 58 | . |
| 59 | .SH "UTF-8 SUPPORT" |
| 60 | .rs |
| 61 | .sp |
| 62 | To build PCRE with support for UTF-8 Unicode character strings, add |
| 63 | .sp |
| 64 | --enable-utf8 |
| 65 | .sp |
| 66 | to the \fBconfigure\fP command. Of itself, this does not make PCRE treat |
| 67 | strings as UTF-8. As well as compiling PCRE with this option, you also have |
| 68 | have to set the PCRE_UTF8 option when you call the \fBpcre_compile()\fP |
| 69 | or \fBpcre_compile2()\fP functions. |
| 70 | .P |
| 71 | If you set --enable-utf8 when compiling in an EBCDIC environment, PCRE expects |
| 72 | its input to be either ASCII or UTF-8 (depending on the runtime option). It is |
| 73 | not possible to support both EBCDIC and UTF-8 codes in the same version of the |
| 74 | library. Consequently, --enable-utf8 and --enable-ebcdic are mutually |
| 75 | exclusive. |
| 76 | . |
| 77 | . |
| 78 | .SH "UNICODE CHARACTER PROPERTY SUPPORT" |
| 79 | .rs |
| 80 | .sp |
| 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 \eP, \ep, and \eX, which refer to Unicode |
| 85 | character properties, you must add |
| 86 | .sp |
| 87 | --enable-unicode-properties |
| 88 | .sp |
| 89 | to the \fBconfigure\fP command. This implies UTF-8 support, even if you have |
| 90 | not explicitly requested it. |
| 91 | .P |
| 92 | Including Unicode property support adds around 30K of tables to the PCRE |
| 93 | library. Only the general category properties such as \fILu\fP and \fINd\fP are |
| 94 | supported. Details are given in the |
| 95 | .\" HREF |
| 96 | \fBpcrepattern\fP |
| 97 | .\" |
| 98 | documentation. |
| 99 | . |
| 100 | . |
| 101 | .SH "JUST-IN-TIME COMPILER SUPPORT" |
| 102 | .rs |
| 103 | .sp |
| 104 | Just-in-time compiler support is included in the build by specifying |
| 105 | .sp |
| 106 | --enable-jit |
| 107 | .sp |
| 108 | This support is available only for certain hardware architectures. If this |
| 109 | option is set for an unsupported architecture, a compile time error occurs. |
| 110 | See the |
| 111 | .\" HREF |
| 112 | \fBpcrejit\fP |
| 113 | .\" |
| 114 | documentation for a discussion of JIT usage. When JIT support is enabled, |
| 115 | pcregrep automatically makes use of it, unless you add |
| 116 | .sp |
| 117 | --disable-pcregrep-jit |
| 118 | .sp |
| 119 | to the "configure" command. |
| 120 | . |
| 121 | . |
| 122 | .SH "CODE VALUE OF NEWLINE" |
| 123 | .rs |
| 124 | .sp |
| 125 | By default, PCRE interprets the linefeed (LF) character as indicating the end |
| 126 | of a line. This is the normal newline character on Unix-like systems. You can |
| 127 | compile PCRE to use carriage return (CR) instead, by adding |
| 128 | .sp |
| 129 | --enable-newline-is-cr |
| 130 | .sp |
| 131 | to the \fBconfigure\fP command. There is also a --enable-newline-is-lf option, |
| 132 | which explicitly specifies linefeed as the newline character. |
| 133 | .sp |
| 134 | Alternatively, you can specify that line endings are to be indicated by the two |
| 135 | character sequence CRLF. If you want this, add |
| 136 | .sp |
| 137 | --enable-newline-is-crlf |
| 138 | .sp |
| 139 | to the \fBconfigure\fP command. There is a fourth option, specified by |
| 140 | .sp |
| 141 | --enable-newline-is-anycrlf |
| 142 | .sp |
| 143 | which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as |
| 144 | indicating a line ending. Finally, a fifth option, specified by |
| 145 | .sp |
| 146 | --enable-newline-is-any |
| 147 | .sp |
| 148 | causes PCRE to recognize any Unicode newline sequence. |
| 149 | .P |
| 150 | Whatever line ending convention is selected when PCRE is built can be |
| 151 | overridden when the library functions are called. At build time it is |
| 152 | conventional to use the standard for your operating system. |
| 153 | . |
| 154 | . |
| 155 | .SH "WHAT \eR MATCHES" |
| 156 | .rs |
| 157 | .sp |
| 158 | By default, the sequence \eR in a pattern matches any Unicode newline sequence, |
| 159 | whatever has been selected as the line ending sequence. If you specify |
| 160 | .sp |
| 161 | --enable-bsr-anycrlf |
| 162 | .sp |
| 163 | the default is changed so that \eR matches only CR, LF, or CRLF. Whatever is |
| 164 | selected when PCRE is built can be overridden when the library functions are |
| 165 | called. |
| 166 | . |
| 167 | . |
| 168 | .SH "POSIX MALLOC USAGE" |
| 169 | .rs |
| 170 | .sp |
| 171 | When PCRE is called through the POSIX interface (see the |
| 172 | .\" HREF |
| 173 | \fBpcreposix\fP |
| 174 | .\" |
| 175 | documentation), additional working storage is required for holding the pointers |
| 176 | to capturing substrings, because PCRE requires three integers per substring, |
| 177 | whereas the POSIX interface provides only two. If the number of expected |
| 178 | substrings is small, the wrapper function uses space on the stack, because this |
| 179 | is faster than using \fBmalloc()\fP for each call. The default threshold above |
| 180 | which the stack is no longer used is 10; it can be changed by adding a setting |
| 181 | such as |
| 182 | .sp |
| 183 | --with-posix-malloc-threshold=20 |
| 184 | .sp |
| 185 | to the \fBconfigure\fP command. |
| 186 | . |
| 187 | . |
| 188 | .SH "HANDLING VERY LARGE PATTERNS" |
| 189 | .rs |
| 190 | .sp |
| 191 | Within a compiled pattern, offset values are used to point from one part to |
| 192 | another (for example, from an opening parenthesis to an alternation |
| 193 | metacharacter). By default, two-byte values are used for these offsets, leading |
| 194 | to a maximum size for a compiled pattern of around 64K. This is sufficient to |
| 195 | handle all but the most gigantic patterns. Nevertheless, some people do want to |
| 196 | process truyl enormous patterns, so it is possible to compile PCRE to use |
| 197 | three-byte or four-byte offsets by adding a setting such as |
| 198 | .sp |
| 199 | --with-link-size=3 |
| 200 | .sp |
| 201 | to the \fBconfigure\fP command. The value given must be 2, 3, or 4. Using |
| 202 | longer offsets slows down the operation of PCRE because it has to load |
| 203 | additional bytes when handling them. |
| 204 | . |
| 205 | . |
| 206 | .SH "AVOIDING EXCESSIVE STACK USAGE" |
| 207 | .rs |
| 208 | .sp |
| 209 | When matching with the \fBpcre_exec()\fP function, PCRE implements backtracking |
| 210 | by making recursive calls to an internal function called \fBmatch()\fP. In |
| 211 | environments where the size of the stack is limited, this can severely limit |
| 212 | PCRE's operation. (The Unix environment does not usually suffer from this |
| 213 | problem, but it may sometimes be necessary to increase the maximum stack size. |
| 214 | There is a discussion in the |
| 215 | .\" HREF |
| 216 | \fBpcrestack\fP |
| 217 | .\" |
| 218 | documentation.) An alternative approach to recursion that uses memory from the |
| 219 | heap to remember data, instead of using recursive function calls, has been |
| 220 | implemented to work round the problem of limited stack size. If you want to |
| 221 | build a version of PCRE that works this way, add |
| 222 | .sp |
| 223 | --disable-stack-for-recursion |
| 224 | .sp |
| 225 | to the \fBconfigure\fP command. With this configuration, PCRE will use the |
| 226 | \fBpcre_stack_malloc\fP and \fBpcre_stack_free\fP variables to call memory |
| 227 | management functions. By default these point to \fBmalloc()\fP and |
| 228 | \fBfree()\fP, but you can replace the pointers so that your own functions are |
| 229 | used instead. |
| 230 | .P |
| 231 | Separate functions are provided rather than using \fBpcre_malloc\fP and |
| 232 | \fBpcre_free\fP because the usage is very predictable: the block sizes |
| 233 | requested are always the same, and the blocks are always freed in reverse |
| 234 | order. A calling program might be able to implement optimized functions that |
| 235 | perform better than \fBmalloc()\fP and \fBfree()\fP. PCRE runs noticeably more |
| 236 | slowly when built in this way. This option affects only the \fBpcre_exec()\fP |
| 237 | function; it is not relevant for \fBpcre_dfa_exec()\fP. |
| 238 | . |
| 239 | . |
| 240 | .SH "LIMITING PCRE RESOURCE USAGE" |
| 241 | .rs |
| 242 | .sp |
| 243 | Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly |
| 244 | (sometimes recursively) when matching a pattern with the \fBpcre_exec()\fP |
| 245 | function. By controlling the maximum number of times this function may be |
| 246 | called during a single matching operation, a limit can be placed on the |
| 247 | resources used by a single call to \fBpcre_exec()\fP. The limit can be changed |
| 248 | at run time, as described in the |
| 249 | .\" HREF |
| 250 | \fBpcreapi\fP |
| 251 | .\" |
| 252 | documentation. The default is 10 million, but this can be changed by adding a |
| 253 | setting such as |
| 254 | .sp |
| 255 | --with-match-limit=500000 |
| 256 | .sp |
| 257 | to the \fBconfigure\fP command. This setting has no effect on the |
| 258 | \fBpcre_dfa_exec()\fP matching function. |
| 259 | .P |
| 260 | In some environments it is desirable to limit the depth of recursive calls of |
| 261 | \fBmatch()\fP more strictly than the total number of calls, in order to |
| 262 | restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion |
| 263 | is specified) that is used. A second limit controls this; it defaults to the |
| 264 | value that is set for --with-match-limit, which imposes no additional |
| 265 | constraints. However, you can set a lower limit by adding, for example, |
| 266 | .sp |
| 267 | --with-match-limit-recursion=10000 |
| 268 | .sp |
| 269 | to the \fBconfigure\fP command. This value can also be overridden at run time. |
| 270 | . |
| 271 | . |
| 272 | .SH "CREATING CHARACTER TABLES AT BUILD TIME" |
| 273 | .rs |
| 274 | .sp |
| 275 | PCRE uses fixed tables for processing characters whose code values are less |
| 276 | than 256. By default, PCRE is built with a set of tables that are distributed |
| 277 | in the file \fIpcre_chartables.c.dist\fP. These tables are for ASCII codes |
| 278 | only. If you add |
| 279 | .sp |
| 280 | --enable-rebuild-chartables |
| 281 | .sp |
| 282 | to the \fBconfigure\fP command, the distributed tables are no longer used. |
| 283 | Instead, a program called \fBdftables\fP is compiled and run. This outputs the |
| 284 | source for new set of tables, created in the default locale of your C runtime |
| 285 | system. (This method of replacing the tables does not work if you are cross |
| 286 | compiling, because \fBdftables\fP is run on the local host. If you need to |
| 287 | create alternative tables when cross compiling, you will have to do so "by |
| 288 | hand".) |
| 289 | . |
| 290 | . |
| 291 | .SH "USING EBCDIC CODE" |
| 292 | .rs |
| 293 | .sp |
| 294 | PCRE assumes by default that it will run in an environment where the character |
| 295 | code is ASCII (or Unicode, which is a superset of ASCII). This is the case for |
| 296 | most computer operating systems. PCRE can, however, be compiled to run in an |
| 297 | EBCDIC environment by adding |
| 298 | .sp |
| 299 | --enable-ebcdic |
| 300 | .sp |
| 301 | to the \fBconfigure\fP command. This setting implies |
| 302 | --enable-rebuild-chartables. You should only use it if you know that you are in |
| 303 | an EBCDIC environment (for example, an IBM mainframe operating system). The |
| 304 | --enable-ebcdic option is incompatible with --enable-utf8. |
| 305 | . |
| 306 | . |
| 307 | .SH "PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT" |
| 308 | .rs |
| 309 | .sp |
| 310 | By default, \fBpcregrep\fP reads all files as plain text. You can build it so |
| 311 | that it recognizes files whose names end in \fB.gz\fP or \fB.bz2\fP, and reads |
| 312 | them with \fBlibz\fP or \fBlibbz2\fP, respectively, by adding one or both of |
| 313 | .sp |
| 314 | --enable-pcregrep-libz |
| 315 | --enable-pcregrep-libbz2 |
| 316 | .sp |
| 317 | to the \fBconfigure\fP command. These options naturally require that the |
| 318 | relevant libraries are installed on your system. Configuration will fail if |
| 319 | they are not. |
| 320 | . |
| 321 | . |
| 322 | .SH "PCREGREP BUFFER SIZE" |
| 323 | .rs |
| 324 | .sp |
| 325 | \fBpcregrep\fP uses an internal buffer to hold a "window" on the file it is |
| 326 | scanning, in order to be able to output "before" and "after" lines when it |
| 327 | finds a match. The size of the buffer is controlled by a parameter whose |
| 328 | default value is 20K. The buffer itself is three times this size, but because |
| 329 | of the way it is used for holding "before" lines, the longest line that is |
| 330 | guaranteed to be processable is the parameter size. You can change the default |
| 331 | parameter value by adding, for example, |
| 332 | .sp |
| 333 | --with-pcregrep-bufsize=50K |
| 334 | .sp |
| 335 | to the \fBconfigure\fP command. The caller of \fPpcregrep\fP can, however, |
| 336 | override this value by specifying a run-time option. |
| 337 | . |
| 338 | . |
| 339 | .SH "PCRETEST OPTION FOR LIBREADLINE SUPPORT" |
| 340 | .rs |
| 341 | .sp |
| 342 | If you add |
| 343 | .sp |
| 344 | --enable-pcretest-libreadline |
| 345 | .sp |
| 346 | to the \fBconfigure\fP command, \fBpcretest\fP is linked with the |
| 347 | \fBlibreadline\fP library, and when its input is from a terminal, it reads it |
| 348 | using the \fBreadline()\fP function. This provides line-editing and history |
| 349 | facilities. Note that \fBlibreadline\fP is GPL-licensed, so if you distribute a |
| 350 | binary of \fBpcretest\fP linked in this way, there may be licensing issues. |
| 351 | .P |
| 352 | Setting this option causes the \fB-lreadline\fP option to be added to the |
| 353 | \fBpcretest\fP build. In many operating environments with a sytem-installed |
| 354 | \fBlibreadline\fP this is sufficient. However, in some environments (e.g. |
| 355 | if an unmodified distribution version of readline is in use), some extra |
| 356 | configuration may be necessary. The INSTALL file for \fBlibreadline\fP says |
| 357 | this: |
| 358 | .sp |
| 359 | "Readline uses the termcap functions, but does not link with the |
| 360 | termcap or curses library itself, allowing applications which link |
| 361 | with readline the to choose an appropriate library." |
| 362 | .sp |
| 363 | If your environment has not been set up so that an appropriate library is |
| 364 | automatically included, you may need to add something like |
| 365 | .sp |
| 366 | LIBS="-ncurses" |
| 367 | .sp |
| 368 | immediately before the \fBconfigure\fP command. |
| 369 | . |
| 370 | . |
| 371 | .SH "SEE ALSO" |
| 372 | .rs |
| 373 | .sp |
| 374 | \fBpcreapi\fP(3), \fBpcre_config\fP(3). |
| 375 | . |
| 376 | . |
| 377 | .SH AUTHOR |
| 378 | .rs |
| 379 | .sp |
| 380 | .nf |
| 381 | Philip Hazel |
| 382 | University Computing Service |
| 383 | Cambridge CB2 3QH, England. |
| 384 | .fi |
| 385 | . |
| 386 | . |
| 387 | .SH REVISION |
| 388 | .rs |
| 389 | .sp |
| 390 | .nf |
| 391 | Last updated: 06 September 2011 |
| 392 | Copyright (c) 1997-2011 University of Cambridge. |
| 393 | .fi |