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