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   1  =head1 NAME
   2  
   3  perl - Practical Extraction and Report Language
   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<-P> ]>
  14      S<[ B<-S> ]>
  15      S<[ B<-x>[I<dir>] ]>
  16      S<[ B<-i>[I<extension>] ]>
  17      S<[ B<-e> I<'command'> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...>
  18  
  19  If you're new to Perl, you should start with L<perlintro>, which is a 
  20  general intro for beginners and provides some background to help you
  21  navigate the rest of Perl's extensive documentation.
  22  
  23  For ease of access, the Perl manual has been split up into several sections.
  24  
  25  =head2 Overview
  26  
  27      perl        Perl overview (this section)
  28      perlintro        Perl introduction for beginners
  29      perltoc        Perl documentation table of contents
  30  
  31  =head2 Tutorials
  32  
  33      perlreftut        Perl references short introduction
  34      perldsc        Perl data structures intro
  35      perllol        Perl data structures: arrays of arrays
  36  
  37      perlrequick     Perl regular expressions quick start
  38      perlretut        Perl regular expressions tutorial
  39  
  40      perlboot        Perl OO tutorial for beginners
  41      perltoot        Perl OO tutorial, part 1
  42      perltooc        Perl OO tutorial, part 2
  43      perlbot        Perl OO tricks and examples
  44  
  45      perlstyle        Perl style guide
  46  
  47      perlcheat        Perl cheat sheet
  48      perltrap        Perl traps for the unwary
  49      perldebtut        Perl debugging tutorial
  50  
  51      perlfaq        Perl frequently asked questions
  52        perlfaq1        General Questions About Perl
  53        perlfaq2        Obtaining and Learning about Perl
  54        perlfaq3        Programming Tools
  55        perlfaq4        Data Manipulation
  56        perlfaq5        Files and Formats
  57        perlfaq6        Regexes
  58        perlfaq7        Perl Language Issues
  59        perlfaq8        System Interaction
  60        perlfaq9        Networking
  61  
  62  =head2 Reference Manual
  63  
  64      perlsyn        Perl syntax
  65      perldata        Perl data structures
  66      perlop        Perl operators and precedence
  67      perlsub        Perl subroutines
  68      perlfunc        Perl built-in functions
  69        perlopentut    Perl open() tutorial
  70        perlpacktut    Perl pack() and unpack() tutorial
  71      perlpod        Perl plain old documentation
  72      perlpodspec     Perl plain old documentation format specification
  73      perlrun        Perl execution and options
  74      perldiag        Perl diagnostic messages
  75      perllexwarn     Perl warnings and their control
  76      perldebug        Perl debugging
  77      perlvar        Perl predefined variables
  78      perlre        Perl regular expressions, the rest of the story
  79      perlrebackslash    Perl regular expression backslash sequences
  80      perlrecharclass    Perl regular expression character classes
  81      perlreref        Perl regular expressions quick reference
  82      perlref        Perl references, the rest of the story
  83      perlform        Perl formats
  84      perlobj        Perl objects
  85      perltie        Perl objects hidden behind simple variables
  86        perldbmfilter    Perl DBM filters
  87  
  88      perlipc        Perl interprocess communication
  89      perlfork        Perl fork() information
  90      perlnumber        Perl number semantics
  91  
  92      perlthrtut        Perl threads tutorial
  93        perlothrtut    Old Perl threads tutorial
  94  
  95      perlport        Perl portability guide
  96      perllocale        Perl locale support
  97      perluniintro    Perl Unicode introduction
  98      perlunicode     Perl Unicode support
  99      perlunifaq        Perl Unicode FAQ
 100      perlunitut        Perl Unicode tutorial
 101      perlebcdic        Considerations for running Perl on EBCDIC platforms
 102  
 103      perlsec        Perl security
 104  
 105      perlmod        Perl modules: how they work
 106      perlmodlib        Perl modules: how to write and use
 107      perlmodstyle    Perl modules: how to write modules with style
 108      perlmodinstall    Perl modules: how to install from CPAN
 109      perlnewmod        Perl modules: preparing a new module for distribution
 110      perlpragma        Perl modules: writing a user pragma
 111  
 112      perlutil        utilities packaged with the Perl distribution
 113  
 114      perlcompile     Perl compiler suite intro
 115  
 116      perlfilter        Perl source filters
 117  
 118      perlglossary    Perl Glossary
 119  
 120  =head2 Internals and C Language Interface
 121  
 122      perlembed        Perl ways to embed perl in your C or C++ application
 123      perldebguts     Perl debugging guts and tips
 124      perlxstut        Perl XS tutorial
 125      perlxs        Perl XS application programming interface
 126      perlclib        Internal replacements for standard C library functions
 127      perlguts        Perl internal functions for those doing extensions
 128      perlcall        Perl calling conventions from C
 129      perlreapi        Perl regular expression plugin interface
 130      perlreguts        Perl regular expression engine internals
 131  
 132      perlapi        Perl API listing (autogenerated)
 133      perlintern        Perl internal functions (autogenerated)
 134      perliol        C API for Perl's implementation of IO in Layers
 135      perlapio        Perl internal IO abstraction interface
 136  
 137      perlhack        Perl hackers guide
 138  
 139  =head2 Miscellaneous
 140  
 141      perlbook        Perl book information
 142      perlcommunity    Perl community information
 143      perltodo        Perl things to do
 144  
 145      perldoc        Look up Perl documentation in Pod format
 146  
 147      perlhist        Perl history records
 148      perldelta        Perl changes since previous version
 149      perl595delta    Perl changes in version 5.9.5
 150      perl594delta    Perl changes in version 5.9.4
 151      perl593delta    Perl changes in version 5.9.3
 152      perl592delta    Perl changes in version 5.9.2
 153      perl591delta    Perl changes in version 5.9.1
 154      perl590delta    Perl changes in version 5.9.0
 155      perl588delta    Perl changes in version 5.8.8
 156      perl587delta    Perl changes in version 5.8.7
 157      perl586delta    Perl changes in version 5.8.6
 158      perl585delta    Perl changes in version 5.8.5
 159      perl584delta    Perl changes in version 5.8.4
 160      perl583delta    Perl changes in version 5.8.3
 161      perl582delta    Perl changes in version 5.8.2
 162      perl581delta    Perl changes in version 5.8.1
 163      perl58delta     Perl changes in version 5.8.0
 164      perl573delta    Perl changes in version 5.7.3
 165      perl572delta    Perl changes in version 5.7.2
 166      perl571delta    Perl changes in version 5.7.1
 167      perl570delta    Perl changes in version 5.7.0
 168      perl561delta    Perl changes in version 5.6.1
 169      perl56delta     Perl changes in version 5.6
 170      perl5005delta    Perl changes in version 5.005
 171      perl5004delta    Perl changes in version 5.004
 172  
 173      perlartistic    Perl Artistic License
 174      perlgpl        GNU General Public License
 175  
 176  =head2 Language-Specific
 177  
 178      perlcn        Perl for Simplified Chinese (in EUC-CN)
 179      perljp        Perl for Japanese (in EUC-JP)
 180      perlko        Perl for Korean (in EUC-KR)
 181      perltw        Perl for Traditional Chinese (in Big5)
 182  
 183  =head2 Platform-Specific
 184  
 185      perlaix        Perl notes for AIX
 186      perlamiga        Perl notes for AmigaOS
 187      perlapollo        Perl notes for Apollo DomainOS
 188      perlbeos        Perl notes for BeOS
 189      perlbs2000        Perl notes for POSIX-BC BS2000
 190      perlce        Perl notes for WinCE
 191      perlcygwin        Perl notes for Cygwin
 192      perldgux        Perl notes for DG/UX
 193      perldos        Perl notes for DOS
 194      perlepoc        Perl notes for EPOC
 195      perlfreebsd     Perl notes for FreeBSD
 196      perlhpux        Perl notes for HP-UX
 197      perlhurd        Perl notes for Hurd
 198      perlirix        Perl notes for Irix
 199      perllinux        Perl notes for Linux
 200      perlmachten     Perl notes for Power MachTen
 201      perlmacos        Perl notes for Mac OS (Classic)
 202      perlmacosx        Perl notes for Mac OS X
 203      perlmint        Perl notes for MiNT
 204      perlmpeix        Perl notes for MPE/iX
 205      perlnetware     Perl notes for NetWare
 206      perlopenbsd     Perl notes for OpenBSD
 207      perlos2        Perl notes for OS/2
 208      perlos390        Perl notes for OS/390
 209      perlos400        Perl notes for OS/400
 210      perlplan9        Perl notes for Plan 9
 211      perlqnx        Perl notes for QNX
 212      perlriscos        Perl notes for RISC OS
 213      perlsolaris     Perl notes for Solaris
 214      perlsymbian     Perl notes for Symbian
 215      perltru64        Perl notes for Tru64
 216      perluts        Perl notes for UTS
 217      perlvmesa        Perl notes for VM/ESA
 218      perlvms        Perl notes for VMS
 219      perlvos        Perl notes for Stratus VOS
 220      perlwin32        Perl notes for Windows
 221  
 222  
 223  By default, the manpages listed above are installed in the 
 224  F</usr/local/man/> directory.  
 225  
 226  Extensive additional documentation for Perl modules is available.  The
 227  default configuration for perl will place this additional documentation
 228  in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
 229  subdirectory of the Perl library directory).  Some of this additional
 230  documentation is distributed standard with Perl, but you'll also find
 231  documentation for third-party modules there.
 232  
 233  You should be able to view Perl's documentation with your man(1)
 234  program by including the proper directories in the appropriate start-up
 235  files, or in the MANPATH environment variable.  To find out where the
 236  configuration has installed the manpages, type:
 237  
 238      perl -V:man.dir
 239  
 240  If the directories have a common stem, such as F</usr/local/man/man1>
 241  and F</usr/local/man/man3>, you need only to add that stem
 242  (F</usr/local/man>) to your man(1) configuration files or your MANPATH
 243  environment variable.  If they do not share a stem, you'll have to add
 244  both stems.
 245  
 246  If that doesn't work for some reason, you can still use the
 247  supplied F<perldoc> script to view module information.  You might
 248  also look into getting a replacement man program.
 249  
 250  If something strange has gone wrong with your program and you're not
 251  sure where you should look for help, try the B<-w> switch first.  It
 252  will often point out exactly where the trouble is.
 253  
 254  =head1 DESCRIPTION
 255  
 256  Perl is a language optimized for scanning arbitrary
 257  text files, extracting information from those text files, and printing
 258  reports based on that information.  It's also a good language for many
 259  system management tasks.  The language is intended to be practical
 260  (easy to use, efficient, complete) rather than beautiful (tiny,
 261  elegant, minimal).
 262  
 263  Perl combines (in the author's opinion, anyway) some of the best
 264  features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
 265  those languages should have little difficulty with it.  (Language
 266  historians will also note some vestiges of B<csh>, Pascal, and even
 267  BASIC-PLUS.)  Expression syntax corresponds closely to C
 268  expression syntax.  Unlike most Unix utilities, Perl does not
 269  arbitrarily limit the size of your data--if you've got the memory,
 270  Perl can slurp in your whole file as a single string.  Recursion is of
 271  unlimited depth.  And the tables used by hashes (sometimes called
 272  "associative arrays") grow as necessary to prevent degraded
 273  performance.  Perl can use sophisticated pattern matching techniques to
 274  scan large amounts of data quickly.  Although optimized for
 275  scanning text, Perl can also deal with binary data, and can make dbm
 276  files look like hashes.  Setuid Perl scripts are safer than C programs
 277  through a dataflow tracing mechanism that prevents many stupid
 278  security holes.
 279  
 280  If you have a problem that would ordinarily use B<sed> or B<awk> or
 281  B<sh>, but it exceeds their capabilities or must run a little faster,
 282  and you don't want to write the silly thing in C, then Perl may be for
 283  you.  There are also translators to turn your B<sed> and B<awk>
 284  scripts into Perl scripts.
 285  
 286  But wait, there's more...
 287  
 288  Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
 289  rewrite that provides the following additional benefits:
 290  
 291  =over 4
 292  
 293  =item *
 294  
 295  modularity and reusability using innumerable modules 
 296  
 297  Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
 298  
 299  =item *
 300  
 301  embeddable and extensible 
 302  
 303  Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
 304  L<perlguts>, and L<xsubpp>.
 305  
 306  =item *
 307  
 308  roll-your-own magic variables (including multiple simultaneous DBM
 309  implementations)
 310  
 311  Described in L<perltie> and L<AnyDBM_File>.
 312  
 313  =item *
 314  
 315  subroutines can now be overridden, autoloaded, and prototyped
 316  
 317  Described in L<perlsub>.
 318  
 319  =item *
 320  
 321  arbitrarily nested data structures and anonymous functions
 322  
 323  Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
 324  
 325  =item *
 326  
 327  object-oriented programming
 328  
 329  Described in L<perlobj>, L<perlboot>, L<perltoot>, L<perltooc>,
 330  and L<perlbot>.
 331  
 332  =item *
 333  
 334  support for light-weight processes (threads)
 335  
 336  Described in L<perlthrtut> and L<threads>.
 337  
 338  =item *
 339  
 340  support for Unicode, internationalization, and localization
 341  
 342  Described in L<perluniintro>, L<perllocale> and L<Locale::Maketext>.
 343  
 344  =item *
 345  
 346  lexical scoping
 347  
 348  Described in L<perlsub>.
 349  
 350  =item *
 351  
 352  regular expression enhancements
 353  
 354  Described in L<perlre>, with additional examples in L<perlop>.
 355  
 356  =item *
 357  
 358  enhanced debugger and interactive Perl environment,
 359  with integrated editor support
 360  
 361  Described in L<perldebtut>, L<perldebug> and L<perldebguts>.
 362  
 363  =item *
 364  
 365  POSIX 1003.1 compliant library
 366  
 367  Described in L<POSIX>.
 368  
 369  =back
 370  
 371  Okay, that's I<definitely> enough hype.
 372  
 373  =head1 AVAILABILITY
 374  
 375  Perl is available for most operating systems, including virtually
 376  all Unix-like platforms.  See L<perlport/"Supported Platforms">
 377  for a listing.
 378  
 379  =head1 ENVIRONMENT
 380  
 381  See L<perlrun>.
 382  
 383  =head1 AUTHOR
 384  
 385  Larry Wall <larry@wall.org>, with the help of oodles of other folks.
 386  
 387  If your Perl success stories and testimonials may be of help to others 
 388  who wish to advocate the use of Perl in their applications, 
 389  or if you wish to simply express your gratitude to Larry and the 
 390  Perl 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  
 408  The C<use warnings> pragma (and the B<-w> switch) produces some 
 409  lovely diagnostics.
 410  
 411  See L<perldiag> for explanations of all Perl's diagnostics.  The C<use
 412  diagnostics> pragma automatically turns Perl's normally terse warnings
 413  and errors into these longer forms.
 414  
 415  Compilation errors will tell you the line number of the error, with an
 416  indication of the next token or token type that was to be examined.
 417  (In a script passed to Perl via B<-e> switches, each
 418  B<-e> is counted as one line.)
 419  
 420  Setuid scripts have additional constraints that can produce error
 421  messages such as "Insecure dependency".  See L<perlsec>.
 422  
 423  Did we mention that you should definitely consider using the B<-w>
 424  switch?
 425  
 426  =head1 BUGS
 427  
 428  The B<-w> switch is not mandatory.
 429  
 430  Perl is at the mercy of your machine's definitions of various
 431  operations such as type casting, atof(), and floating-point
 432  output with sprintf().
 433  
 434  If your stdio requires a seek or eof between reads and writes on a
 435  particular stream, so does Perl.  (This doesn't apply to sysread()
 436  and syswrite().)
 437  
 438  While 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
 440  given variable name may not be longer than 251 characters.  Line numbers
 441  displayed by diagnostics are internally stored as short integers,
 442  so they are limited to a maximum of 65535 (higher numbers usually being
 443  affected by wraparound).
 444  
 445  You may mail your bug reports (be sure to include full configuration
 446  information as output by the myconfig program in the perl source
 447  tree, or by C<perl -V>) to perlbug@perl.org .  If you've succeeded
 448  in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
 449  can be used to help mail in a bug report.
 450  
 451  Perl actually stands for Pathologically Eclectic Rubbish Lister, but
 452  don't tell anyone I said that.
 453  
 454  =head1 NOTES
 455  
 456  The Perl motto is "There's more than one way to do it."  Divining
 457  how many more is left as an exercise to the reader.
 458  
 459  The three principal virtues of a programmer are Laziness,
 460  Impatience, and Hubris.  See the Camel Book for why.
 461