| 1 | =head1 NAME |
| 2 | |
| 3 | perl - The Perl language interpreter |
| 4 | |
| 5 | =head1 SYNOPSIS |
| 6 | |
| 7 | B<perl> S<[ B<-sTtuUWX> ]> |
| 8 | S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]> |
| 9 | S<[ B<-cw> ] [ B<-d>[B<t>][:I<debugger>] ] [ B<-D>[I<number/list>] ]> |
| 10 | S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal/hexadecimal>] ]> |
| 11 | S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ] [ B<-f> ]> |
| 12 | S<[ B<-C [I<number/list>] >]> |
| 13 | S<[ B<-S> ]> |
| 14 | S<[ B<-x>[I<dir>] ]> |
| 15 | S<[ B<-i>[I<extension>] ]> |
| 16 | S<[ [B<-e>|B<-E>] I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...> |
| 17 | |
| 18 | =head1 GETTING HELP |
| 19 | |
| 20 | The F<perldoc> program gives you access to all the documentation that comes |
| 21 | with Perl. You can get more documentation, tutorials and community support |
| 22 | online at L<http://www.perl.org/>. |
| 23 | |
| 24 | If you're new to Perl, you should start by running C<perldoc perlintro>, |
| 25 | which is a general intro for beginners and provides some background to help |
| 26 | you navigate the rest of Perl's extensive documentation. Run C<perldoc |
| 27 | perldoc> to learn more things you can do with F<perldoc>. |
| 28 | |
| 29 | For ease of access, the Perl manual has been split up into several sections. |
| 30 | |
| 31 | =head2 Overview |
| 32 | |
| 33 | perl Perl overview (this section) |
| 34 | perlintro Perl introduction for beginners |
| 35 | perltoc Perl documentation table of contents |
| 36 | |
| 37 | =head2 Tutorials |
| 38 | |
| 39 | perlreftut Perl references short introduction |
| 40 | perldsc Perl data structures intro |
| 41 | perllol Perl data structures: arrays of arrays |
| 42 | |
| 43 | perlrequick Perl regular expressions quick start |
| 44 | perlretut Perl regular expressions tutorial |
| 45 | |
| 46 | perlboot Perl OO tutorial for beginners |
| 47 | perltoot Perl OO tutorial, part 1 |
| 48 | perltooc Perl OO tutorial, part 2 |
| 49 | perlbot Perl OO tricks and examples |
| 50 | |
| 51 | perlperf Perl Performance and Optimization Techniques |
| 52 | |
| 53 | perlstyle Perl style guide |
| 54 | |
| 55 | perlcheat Perl cheat sheet |
| 56 | perltrap Perl traps for the unwary |
| 57 | perldebtut Perl debugging tutorial |
| 58 | |
| 59 | perlfaq Perl frequently asked questions |
| 60 | perlfaq1 General Questions About Perl |
| 61 | perlfaq2 Obtaining and Learning about Perl |
| 62 | perlfaq3 Programming Tools |
| 63 | perlfaq4 Data Manipulation |
| 64 | perlfaq5 Files and Formats |
| 65 | perlfaq6 Regexes |
| 66 | perlfaq7 Perl Language Issues |
| 67 | perlfaq8 System Interaction |
| 68 | perlfaq9 Networking |
| 69 | |
| 70 | =head2 Reference Manual |
| 71 | |
| 72 | perlsyn Perl syntax |
| 73 | perldata Perl data structures |
| 74 | perlop Perl operators and precedence |
| 75 | perlsub Perl subroutines |
| 76 | perlfunc Perl built-in functions |
| 77 | perlopentut Perl open() tutorial |
| 78 | perlpacktut Perl pack() and unpack() tutorial |
| 79 | perlpod Perl plain old documentation |
| 80 | perlpodspec Perl plain old documentation format specification |
| 81 | perlpodstyle Perl POD style guide |
| 82 | perlrun Perl execution and options |
| 83 | perldiag Perl diagnostic messages |
| 84 | perllexwarn Perl warnings and their control |
| 85 | perldebug Perl debugging |
| 86 | perlvar Perl predefined variables |
| 87 | perlre Perl regular expressions, the rest of the story |
| 88 | perlrebackslash Perl regular expression backslash sequences |
| 89 | perlrecharclass Perl regular expression character classes |
| 90 | perlreref Perl regular expressions quick reference |
| 91 | perlref Perl references, the rest of the story |
| 92 | perlform Perl formats |
| 93 | perlobj Perl objects |
| 94 | perltie Perl objects hidden behind simple variables |
| 95 | perldbmfilter Perl DBM filters |
| 96 | |
| 97 | perlipc Perl interprocess communication |
| 98 | perlfork Perl fork() information |
| 99 | perlnumber Perl number semantics |
| 100 | |
| 101 | perlthrtut Perl threads tutorial |
| 102 | |
| 103 | perlport Perl portability guide |
| 104 | perllocale Perl locale support |
| 105 | perluniintro Perl Unicode introduction |
| 106 | perlunicode Perl Unicode support |
| 107 | perlunifaq Perl Unicode FAQ |
| 108 | perluniprops Index of Unicode Version 5.2.0 properties in Perl |
| 109 | perlunitut Perl Unicode tutorial |
| 110 | perlebcdic Considerations for running Perl on EBCDIC platforms |
| 111 | |
| 112 | perlsec Perl security |
| 113 | |
| 114 | perlmod Perl modules: how they work |
| 115 | perlmodlib Perl modules: how to write and use |
| 116 | perlmodstyle Perl modules: how to write modules with style |
| 117 | perlmodinstall Perl modules: how to install from CPAN |
| 118 | perlnewmod Perl modules: preparing a new module for distribution |
| 119 | perlpragma Perl modules: writing a user pragma |
| 120 | |
| 121 | perlutil utilities packaged with the Perl distribution |
| 122 | |
| 123 | perlcompile Perl compiler suite intro |
| 124 | |
| 125 | perlfilter Perl source filters |
| 126 | |
| 127 | perlglossary Perl Glossary |
| 128 | |
| 129 | =head2 Internals and C Language Interface |
| 130 | |
| 131 | perlembed Perl ways to embed perl in your C or C++ application |
| 132 | perldebguts Perl debugging guts and tips |
| 133 | perlxstut Perl XS tutorial |
| 134 | perlxs Perl XS application programming interface |
| 135 | perlclib Internal replacements for standard C library functions |
| 136 | perlguts Perl internal functions for those doing extensions |
| 137 | perlcall Perl calling conventions from C |
| 138 | perlmroapi Perl method resolution plugin interface |
| 139 | perlreapi Perl regular expression plugin interface |
| 140 | perlreguts Perl regular expression engine internals |
| 141 | |
| 142 | perlapi Perl API listing (autogenerated) |
| 143 | perlintern Perl internal functions (autogenerated) |
| 144 | perliol C API for Perl's implementation of IO in Layers |
| 145 | perlapio Perl internal IO abstraction interface |
| 146 | |
| 147 | perlhack Perl hackers guide |
| 148 | perlpolicy Perl development policies |
| 149 | perlrepository Perl source repository |
| 150 | |
| 151 | =head2 Miscellaneous |
| 152 | |
| 153 | perlbook Perl book information |
| 154 | perlcommunity Perl community information |
| 155 | perltodo Perl things to do |
| 156 | |
| 157 | perldoc Look up Perl documentation in Pod format |
| 158 | |
| 159 | perlhist Perl history records |
| 160 | perldelta Perl changes since previous version |
| 161 | perl5136delta Perl changes in version 5.13.6 |
| 162 | perl5135delta Perl changes in version 5.13.5 |
| 163 | perl5134delta Perl changes in version 5.13.4 |
| 164 | perl5133delta Perl changes in version 5.13.3 |
| 165 | perl5132delta Perl changes in version 5.13.2 |
| 166 | perl5131delta Perl changes in version 5.13.1 |
| 167 | perl5130delta Perl changes in version 5.13.0 |
| 168 | perl5122delta Perl changes in version 5.12.2 |
| 169 | perl5121delta Perl changes in version 5.12.1 |
| 170 | perl5120delta Perl changes in version 5.12.0 |
| 171 | perl5115delta Perl changes in version 5.11.5 |
| 172 | perl5114delta Perl changes in version 5.11.4 |
| 173 | perl5113delta Perl changes in version 5.11.3 |
| 174 | perl5112delta Perl changes in version 5.11.2 |
| 175 | perl5111delta Perl changes in version 5.11.1 |
| 176 | perl5110delta Perl changes in version 5.11.0 |
| 177 | perl5101delta Perl changes in version 5.10.1 |
| 178 | perl5100delta Perl changes in version 5.10.0 |
| 179 | perl595delta Perl changes in version 5.9.5 |
| 180 | perl594delta Perl changes in version 5.9.4 |
| 181 | perl593delta Perl changes in version 5.9.3 |
| 182 | perl592delta Perl changes in version 5.9.2 |
| 183 | perl591delta Perl changes in version 5.9.1 |
| 184 | perl590delta Perl changes in version 5.9.0 |
| 185 | perl589delta Perl changes in version 5.8.9 |
| 186 | perl588delta Perl changes in version 5.8.8 |
| 187 | perl587delta Perl changes in version 5.8.7 |
| 188 | perl586delta Perl changes in version 5.8.6 |
| 189 | perl585delta Perl changes in version 5.8.5 |
| 190 | perl584delta Perl changes in version 5.8.4 |
| 191 | perl583delta Perl changes in version 5.8.3 |
| 192 | perl582delta Perl changes in version 5.8.2 |
| 193 | perl581delta Perl changes in version 5.8.1 |
| 194 | perl58delta Perl changes in version 5.8.0 |
| 195 | perl573delta Perl changes in version 5.7.3 |
| 196 | perl572delta Perl changes in version 5.7.2 |
| 197 | perl571delta Perl changes in version 5.7.1 |
| 198 | perl570delta Perl changes in version 5.7.0 |
| 199 | perl561delta Perl changes in version 5.6.1 |
| 200 | perl56delta Perl changes in version 5.6 |
| 201 | perl5005delta Perl changes in version 5.005 |
| 202 | perl5004delta Perl changes in version 5.004 |
| 203 | |
| 204 | perlartistic Perl Artistic License |
| 205 | perlgpl GNU General Public License |
| 206 | |
| 207 | =head2 Language-Specific |
| 208 | |
| 209 | perlcn Perl for Simplified Chinese (in EUC-CN) |
| 210 | perljp Perl for Japanese (in EUC-JP) |
| 211 | perlko Perl for Korean (in EUC-KR) |
| 212 | perltw Perl for Traditional Chinese (in Big5) |
| 213 | |
| 214 | =head2 Platform-Specific |
| 215 | |
| 216 | perlaix Perl notes for AIX |
| 217 | perlamiga Perl notes for AmigaOS |
| 218 | perlapollo Perl notes for Apollo DomainOS |
| 219 | perlbeos Perl notes for BeOS |
| 220 | perlbs2000 Perl notes for POSIX-BC BS2000 |
| 221 | perlce Perl notes for WinCE |
| 222 | perlcygwin Perl notes for Cygwin |
| 223 | perldgux Perl notes for DG/UX |
| 224 | perldos Perl notes for DOS |
| 225 | perlepoc Perl notes for EPOC |
| 226 | perlfreebsd Perl notes for FreeBSD |
| 227 | perlhaiku Perl notes for Haiku |
| 228 | perlhpux Perl notes for HP-UX |
| 229 | perlhurd Perl notes for Hurd |
| 230 | perlirix Perl notes for Irix |
| 231 | perllinux Perl notes for Linux |
| 232 | perlmacos Perl notes for Mac OS (Classic) |
| 233 | perlmacosx Perl notes for Mac OS X |
| 234 | perlmpeix Perl notes for MPE/iX |
| 235 | perlnetware Perl notes for NetWare |
| 236 | perlopenbsd Perl notes for OpenBSD |
| 237 | perlos2 Perl notes for OS/2 |
| 238 | perlos390 Perl notes for OS/390 |
| 239 | perlos400 Perl notes for OS/400 |
| 240 | perlplan9 Perl notes for Plan 9 |
| 241 | perlqnx Perl notes for QNX |
| 242 | perlriscos Perl notes for RISC OS |
| 243 | perlsolaris Perl notes for Solaris |
| 244 | perlsymbian Perl notes for Symbian |
| 245 | perltru64 Perl notes for Tru64 |
| 246 | perluts Perl notes for UTS |
| 247 | perlvmesa Perl notes for VM/ESA |
| 248 | perlvms Perl notes for VMS |
| 249 | perlvos Perl notes for Stratus VOS |
| 250 | perlwin32 Perl notes for Windows |
| 251 | |
| 252 | |
| 253 | On a Unix-like system, these documentation files will usually also be |
| 254 | available as manpages for use with the F<man> program. |
| 255 | |
| 256 | In general, if something strange has gone wrong with your program and you're |
| 257 | not sure where you should look for help, try the B<-w> switch first. It will |
| 258 | often point out exactly where the trouble is. |
| 259 | |
| 260 | =head1 DESCRIPTION |
| 261 | |
| 262 | Perl officially stands for Practical Extraction and Report Language, |
| 263 | except when it doesn't. |
| 264 | |
| 265 | Perl is a language optimized for scanning arbitrary |
| 266 | text files, extracting information from those text files, and printing |
| 267 | reports based on that information. It's also a good language for many |
| 268 | system management tasks. The language is intended to be practical |
| 269 | (easy to use, efficient, complete) rather than beautiful (tiny, |
| 270 | elegant, minimal). |
| 271 | |
| 272 | Perl combines (in the author's opinion, anyway) some of the best |
| 273 | features of C, B<sed>, B<awk>, and B<sh>, so people familiar with |
| 274 | those languages should have little difficulty with it. (Language |
| 275 | historians will also note some vestiges of B<csh>, Pascal, and even |
| 276 | BASIC-PLUS.) Expression syntax corresponds closely to C |
| 277 | expression syntax. Unlike most Unix utilities, Perl does not |
| 278 | arbitrarily limit the size of your data--if you've got the memory, |
| 279 | Perl can slurp in your whole file as a single string. Recursion is of |
| 280 | unlimited depth. And the tables used by hashes (sometimes called |
| 281 | "associative arrays") grow as necessary to prevent degraded |
| 282 | performance. Perl can use sophisticated pattern matching techniques to |
| 283 | scan large amounts of data quickly. Although optimized for |
| 284 | scanning text, Perl can also deal with binary data, and can make dbm |
| 285 | files look like hashes. Setuid Perl scripts are safer than C programs |
| 286 | through a dataflow tracing mechanism that prevents many stupid |
| 287 | security holes. |
| 288 | |
| 289 | If you have a problem that would ordinarily use B<sed> or B<awk> or |
| 290 | B<sh>, but it exceeds their capabilities or must run a little faster, |
| 291 | and you don't want to write the silly thing in C, then Perl may be for |
| 292 | you. There are also translators to turn your B<sed> and B<awk> |
| 293 | scripts into Perl scripts. |
| 294 | |
| 295 | But wait, there's more... |
| 296 | |
| 297 | Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete |
| 298 | rewrite that provides the following additional benefits: |
| 299 | |
| 300 | =over 4 |
| 301 | |
| 302 | =item * |
| 303 | |
| 304 | modularity and reusability using innumerable modules |
| 305 | |
| 306 | Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>. |
| 307 | |
| 308 | =item * |
| 309 | |
| 310 | embeddable and extensible |
| 311 | |
| 312 | Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>, |
| 313 | L<perlguts>, and L<xsubpp>. |
| 314 | |
| 315 | =item * |
| 316 | |
| 317 | roll-your-own magic variables (including multiple simultaneous DBM |
| 318 | implementations) |
| 319 | |
| 320 | Described in L<perltie> and L<AnyDBM_File>. |
| 321 | |
| 322 | =item * |
| 323 | |
| 324 | subroutines can now be overridden, autoloaded, and prototyped |
| 325 | |
| 326 | Described in L<perlsub>. |
| 327 | |
| 328 | =item * |
| 329 | |
| 330 | arbitrarily nested data structures and anonymous functions |
| 331 | |
| 332 | Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>. |
| 333 | |
| 334 | =item * |
| 335 | |
| 336 | object-oriented programming |
| 337 | |
| 338 | Described in L<perlobj>, L<perlboot>, L<perltoot>, L<perltooc>, |
| 339 | and L<perlbot>. |
| 340 | |
| 341 | =item * |
| 342 | |
| 343 | support for light-weight processes (threads) |
| 344 | |
| 345 | Described in L<perlthrtut> and L<threads>. |
| 346 | |
| 347 | =item * |
| 348 | |
| 349 | support for Unicode, internationalization, and localization |
| 350 | |
| 351 | Described in L<perluniintro>, L<perllocale> and L<Locale::Maketext>. |
| 352 | |
| 353 | =item * |
| 354 | |
| 355 | lexical scoping |
| 356 | |
| 357 | Described in L<perlsub>. |
| 358 | |
| 359 | =item * |
| 360 | |
| 361 | regular expression enhancements |
| 362 | |
| 363 | Described in L<perlre>, with additional examples in L<perlop>. |
| 364 | |
| 365 | =item * |
| 366 | |
| 367 | enhanced debugger and interactive Perl environment, |
| 368 | with integrated editor support |
| 369 | |
| 370 | Described in L<perldebtut>, L<perldebug> and L<perldebguts>. |
| 371 | |
| 372 | =item * |
| 373 | |
| 374 | POSIX 1003.1 compliant library |
| 375 | |
| 376 | Described in L<POSIX>. |
| 377 | |
| 378 | =back |
| 379 | |
| 380 | Okay, that's I<definitely> enough hype. |
| 381 | |
| 382 | =head1 AVAILABILITY |
| 383 | |
| 384 | Perl is available for most operating systems, including virtually |
| 385 | all Unix-like platforms. See L<perlport/"Supported Platforms"> |
| 386 | for a listing. |
| 387 | |
| 388 | =head1 ENVIRONMENT |
| 389 | |
| 390 | See L<perlrun>. |
| 391 | |
| 392 | =head1 AUTHOR |
| 393 | |
| 394 | Larry Wall <larry@wall.org>, with the help of oodles of other folks. |
| 395 | |
| 396 | If your Perl success stories and testimonials may be of help to others |
| 397 | who wish to advocate the use of Perl in their applications, |
| 398 | or if you wish to simply express your gratitude to Larry and the |
| 399 | Perl developers, please write to perl-thanks@perl.org . |
| 400 | |
| 401 | =head1 FILES |
| 402 | |
| 403 | "@INC" locations of perl libraries |
| 404 | |
| 405 | =head1 SEE ALSO |
| 406 | |
| 407 | a2p awk to perl translator |
| 408 | s2p sed to perl translator |
| 409 | |
| 410 | http://www.perl.org/ the Perl homepage |
| 411 | http://www.perl.com/ Perl articles (O'Reilly) |
| 412 | http://www.cpan.org/ the Comprehensive Perl Archive |
| 413 | http://www.pm.org/ the Perl Mongers |
| 414 | |
| 415 | =head1 DIAGNOSTICS |
| 416 | |
| 417 | The C<use warnings> pragma (and the B<-w> switch) produces some |
| 418 | lovely diagnostics. |
| 419 | |
| 420 | See L<perldiag> for explanations of all Perl's diagnostics. The C<use |
| 421 | diagnostics> pragma automatically turns Perl's normally terse warnings |
| 422 | and errors into these longer forms. |
| 423 | |
| 424 | Compilation errors will tell you the line number of the error, with an |
| 425 | indication of the next token or token type that was to be examined. |
| 426 | (In a script passed to Perl via B<-e> switches, each |
| 427 | B<-e> is counted as one line.) |
| 428 | |
| 429 | Setuid scripts have additional constraints that can produce error |
| 430 | messages such as "Insecure dependency". See L<perlsec>. |
| 431 | |
| 432 | Did we mention that you should definitely consider using the B<-w> |
| 433 | switch? |
| 434 | |
| 435 | =head1 BUGS |
| 436 | |
| 437 | The B<-w> switch is not mandatory. |
| 438 | |
| 439 | Perl is at the mercy of your machine's definitions of various |
| 440 | operations such as type casting, atof(), and floating-point |
| 441 | output with sprintf(). |
| 442 | |
| 443 | If your stdio requires a seek or eof between reads and writes on a |
| 444 | particular stream, so does Perl. (This doesn't apply to sysread() |
| 445 | and syswrite().) |
| 446 | |
| 447 | While none of the built-in data types have any arbitrary size limits |
| 448 | (apart from memory size), there are still a few arbitrary limits: a |
| 449 | given variable name may not be longer than 251 characters. Line numbers |
| 450 | displayed by diagnostics are internally stored as short integers, |
| 451 | so they are limited to a maximum of 65535 (higher numbers usually being |
| 452 | affected by wraparound). |
| 453 | |
| 454 | You may mail your bug reports (be sure to include full configuration |
| 455 | information as output by the myconfig program in the perl source |
| 456 | tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded |
| 457 | in compiling perl, the L<perlbug> script in the F<utils/> subdirectory |
| 458 | can be used to help mail in a bug report. |
| 459 | |
| 460 | Perl actually stands for Pathologically Eclectic Rubbish Lister, but |
| 461 | don't tell anyone I said that. |
| 462 | |
| 463 | =head1 NOTES |
| 464 | |
| 465 | The Perl motto is "There's more than one way to do it." Divining |
| 466 | how many more is left as an exercise to the reader. |
| 467 | |
| 468 | The three principal virtues of a programmer are Laziness, |
| 469 | Impatience, and Hubris. See the Camel Book for why. |
| 470 | |