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PERL(1)                Perl Programmers Reference Guide                PERL(1)



NAME
       perl - Practical Extraction and Report Language

SYNOPSIS
       perl [ -sTtuUWX ]      [ -hv ] [ -V[:configvar] ]      [ -cw ] [ -d[t][:debugger] ] [ -D[number/list] ]
            [ -pna ] [ -Fpattern ] [ -l[octal] ] [ -0[octal/hexadecimal] ]      [ -Idir ] [ -m[-]module ] [ -M[-]'mod-
       ule...' ] [ -f ]      [ -C [number/list] ]      [ -P ]      [ -S ]      [ -x[dir] ]      [ -i[extension] ]
            [ -e 'command' ] [ -- ] [ programfile ] [ argument ]...

       If you're new to Perl, you should start with perlintro, which is a general intro for beginners and provides
       some background to help you navigate the rest of Perl's extensive documentation.

       For ease of access, the Perl manual has been split up into several sections.

       Overview

           perl                Perl overview (this section)
           perlintro           Perl introduction for beginners
           perltoc             Perl documentation table of contents

       Tutorials

           perlreftut          Perl references short introduction
           perldsc             Perl data structures intro
           perllol             Perl data structures: arrays of arrays

           perlrequick         Perl regular expressions quick start
           perlretut           Perl regular expressions tutorial

           perlboot            Perl OO tutorial for beginners
           perltoot            Perl OO tutorial, part 1
           perltooc            Perl OO tutorial, part 2
           perlbot             Perl OO tricks and examples

           perlstyle           Perl style guide

           perlcheat           Perl cheat sheet
           perltrap            Perl traps for the unwary
           perldebtut          Perl debugging tutorial

           perlfaq             Perl frequently asked questions
             perlfaq1          General Questions About Perl
             perlfaq2          Obtaining and Learning about Perl
             perlfaq3          Programming Tools
             perlfaq4          Data Manipulation
             perlfaq5          Files and Formats
             perlfaq6          Regexes
             perlfaq7          Perl Language Issues
             perlfaq8          System Interaction
             perlfaq9          Networking

       Reference Manual

           perlsyn             Perl syntax
           perldata            Perl data structures
           perlop              Perl operators and precedence
           perlsub             Perl subroutines
           perlfunc            Perl built-in functions
             perlopentut       Perl open() tutorial
             perlpacktut       Perl pack() and unpack() tutorial
           perlpod             Perl plain old documentation
           perlpodspec         Perl plain old documentation format specification
           perlrun             Perl execution and options
           perldiag            Perl diagnostic messages
           perllexwarn         Perl warnings and their control
           perldebug           Perl debugging
           perlvar             Perl predefined variables
           perlre              Perl regular expressions, the rest of the story
           perlreref           Perl regular expressions quick reference
           perlref             Perl references, the rest of the story
           perlform            Perl formats
           perlobj             Perl objects
           perltie             Perl objects hidden behind simple variables
             perldbmfilter     Perl DBM filters

           perlipc             Perl interprocess communication
           perlfork            Perl fork() information
           perlnumber          Perl number semantics

           perlthrtut          Perl threads tutorial
             perlothrtut       Old Perl threads tutorial

           perlport            Perl portability guide
           perllocale          Perl locale support
           perluniintro        Perl Unicode introduction
           perlunicode         Perl Unicode support
           perlebcdic          Considerations for running Perl on EBCDIC platforms

           perlsec             Perl security

           perlmod             Perl modules: how they work
           perlmodlib          Perl modules: how to write and use
           perlmodstyle        Perl modules: how to write modules with style
           perlmodinstall      Perl modules: how to install from CPAN
           perlnewmod          Perl modules: preparing a new module for distribution

           perlutil            utilities packaged with the Perl distribution

           perlcompile         Perl compiler suite intro

           perlfilter          Perl source filters

           perlglossary        Perl Glossary

       Internals and C Language Interface

           perlembed           Perl ways to embed perl in your C or C++ application
           perldebguts         Perl debugging guts and tips
           perlxstut           Perl XS tutorial
           perlxs              Perl XS application programming interface
           perlclib            Internal replacements for standard C library functions
           perlguts            Perl internal functions for those doing extensions
           perlcall            Perl calling conventions from C

           perlapi             Perl API listing (autogenerated)
           perlintern          Perl internal functions (autogenerated)
           perliol             C API for Perl's implementation of IO in Layers
           perlapio            Perl internal IO abstraction interface

           perlhack            Perl hackers guide

       Miscellaneous

           perlbook            Perl book information
           perltodo            Perl things to do

           perldoc             Look up Perl documentation in Pod format

           perlhist            Perl history records
           perldelta           Perl changes since previous version
           perl587delta        Perl changes in version 5.8.7
           perl586delta        Perl changes in version 5.8.6
           perl585delta        Perl changes in version 5.8.5
           perl584delta        Perl changes in version 5.8.4
           perl583delta        Perl changes in version 5.8.3
           perl582delta        Perl changes in version 5.8.2
           perl581delta        Perl changes in version 5.8.1
           perl58delta         Perl changes in version 5.8.0
           perl573delta        Perl changes in version 5.7.3
           perl572delta        Perl changes in version 5.7.2
           perl571delta        Perl changes in version 5.7.1
           perl570delta        Perl changes in version 5.7.0
           perl561delta        Perl changes in version 5.6.1
           perl56delta         Perl changes in version 5.6
           perl5005delta       Perl changes in version 5.005
           perl5004delta       Perl changes in version 5.004

           perlartistic        Perl Artistic License
           perlgpl             GNU General Public License

       Language-Specific

           perlcn              Perl for Simplified Chinese (in EUC-CN)
           perljp              Perl for Japanese (in EUC-JP)
           perlko              Perl for Korean (in EUC-KR)
           perltw              Perl for Traditional Chinese (in Big5)

       Platform-Specific

           perlaix             Perl notes for AIX
           perlamiga           Perl notes for AmigaOS
           perlapollo          Perl notes for Apollo DomainOS
           perlbeos            Perl notes for BeOS
           perlbs2000          Perl notes for POSIX-BC BS2000
           perlce              Perl notes for WinCE
           perlcygwin          Perl notes for Cygwin
           perldgux            Perl notes for DG/UX
           perldos             Perl notes for DOS
           perlepoc            Perl notes for EPOC
           perlfreebsd         Perl notes for FreeBSD
           perlhpux            Perl notes for HP-UX
           perlhurd            Perl notes for Hurd
           perlirix            Perl notes for Irix
           perllinux           Perl notes for Linux
           perlmachten         Perl notes for Power MachTen
           perlmacos           Perl notes for Mac OS (Classic)
           perlmacosx          Perl notes for Mac OS X
           perlmint            Perl notes for MiNT
           perlmpeix           Perl notes for MPE/iX
           perlnetware         Perl notes for NetWare
           perlopenbsd         Perl notes for OpenBSD
           perlos2             Perl notes for OS/2
           perlos390           Perl notes for OS/390
           perlos400           Perl notes for OS/400
           perlplan9           Perl notes for Plan 9
           perlqnx             Perl notes for QNX
           perlsolaris         Perl notes for Solaris
           perltru64           Perl notes for Tru64
           perluts             Perl notes for UTS
           perlvmesa           Perl notes for VM/ESA
           perlvms             Perl notes for VMS
           perlvos             Perl notes for Stratus VOS
           perlwin32           Perl notes for Windows

       By default, the manpages listed above are installed in the /usr/local/man/ directory.

       Extensive additional documentation for Perl modules is available.  The default configuration for perl will
       place this additional documentation in the /usr/local/lib/perl5/man directory (or else in the man subdirectory
       of the Perl library directory).  Some of this additional documentation is distributed standard with Perl, but
       you'll also find documentation for third-party modules there.

       You should be able to view Perl's documentation with your man(1) program by including the proper directories in
       the appropriate start-up files, or in the MANPATH environment variable.  To find out where the configuration
       has installed the manpages, type:

           perl -V:man.dir

       If the directories have a common stem, such as /usr/local/man/man1 and /usr/local/man/man3, you need only to
       add that stem (/usr/local/man) to your man(1) configuration files or your MANPATH environment variable.  If
       they do not share a stem, you'll have to add both stems.

       If that doesn't work for some reason, you can still use the supplied perldoc script to view module information.
       You might also look into getting a replacement man program.

       If something strange has gone wrong with your program and you're not sure where you should look for help, try
       the -w switch first.  It will often point out exactly where the trouble is.

DESCRIPTION
       Perl is a language optimized for scanning arbitrary text files, extracting information from those text files,
       and printing reports based on that information.  It's also a good language for many system management tasks.
       The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, ele-
       gant, minimal).

       Perl combines (in the author's opinion, anyway) some of the best features of C, sed, awk, and sh, so people
       familiar with those languages should have little difficulty with it.  (Language historians will also note some
       vestiges of csh, Pascal, and even BASIC-PLUS.)  Expression syntax corresponds closely to C expression syntax.
       Unlike most Unix utilities, Perl does not arbitrarily limit the size of your data--if you've got the memory,
       Perl can slurp in your whole file as a single string.  Recursion is of unlimited depth.  And the tables used by
       hashes (sometimes called "associative arrays") grow as necessary to prevent degraded performance.  Perl can use
       sophisticated pattern matching techniques to scan large amounts of data quickly.  Although optimized for scan-
       ning text, Perl can also deal with binary data, and can make dbm files look like hashes.  Setuid Perl scripts
       are safer than C programs through a dataflow tracing mechanism that prevents many stupid security holes.

       If you have a problem that would ordinarily use sed or awk or sh, but it exceeds their capabilities or must run
       a little faster, and you don't want to write the silly thing in C, then Perl may be for you.  There are also
       translators to turn your sed and awk scripts into Perl scripts.

       But wait, there's more...

       Begun in 1993 (see perlhist), Perl version 5 is nearly a complete rewrite that provides the following addi-
       tional benefits:

       ?   modularity and reusability using innumerable modules

           Described in perlmod, perlmodlib, and perlmodinstall.

       ?   embeddable and extensible

           Described in perlembed, perlxstut, perlxs, perlcall, perlguts, and xsubpp.

       ?   roll-your-own magic variables (including multiple simultaneous DBM implementations)

           Described in perltie and AnyDBM_File.

       ?   subroutines can now be overridden, autoloaded, and prototyped

           Described in perlsub.

       ?   arbitrarily nested data structures and anonymous functions

           Described in perlreftut, perlref, perldsc, and perllol.

       ?   object-oriented programming

           Described in perlobj, perlboot, perltoot, perltooc, and perlbot.

       ?   support for light-weight processes (threads)

           Described in perlthrtut and threads.

       ?   support for Unicode, internationalization, and localization

           Described in perluniintro, perllocale and Locale::Maketext.

       ?   lexical scoping

           Described in perlsub.

       ?   regular expression enhancements

           Described in perlre, with additional examples in perlop.

       ?   enhanced debugger and interactive Perl environment, with integrated editor support

           Described in perldebtut, perldebug and perldebguts.

       ?   POSIX 1003.1 compliant library

           Described in POSIX.

       Okay, that's definitely enough hype.

AVAILABILITY
       Perl is available for most operating systems, including virtually all Unix-like platforms.  See "Supported
       Platforms" in perlport for a listing.

ENVIRONMENT
       See perlrun.

AUTHOR
       Larry Wall <larryATwall.org>, with the help of oodles of other folks.

       If your Perl success stories and testimonials may be of help to others who wish to advocate the use of Perl in
       their applications, or if you wish to simply express your gratitude to Larry and the Perl developers, please
       write to perl-thanksATperl.org .

FILES
        "@INC"                 locations of perl libraries

SEE ALSO
        a2p    awk to perl translator
        s2p    sed to perl translator

        http://www.perl.org/       the Perl homepage
        http://www.perl.com/       Perl articles (O'Reilly)
        http://www.cpan.org/       the Comprehensive Perl Archive
        http://www.pm.org/         the Perl Mongers

DIAGNOSTICS
       The "use warnings" pragma (and the -w switch) produces some lovely diagnostics.

       See perldiag for explanations of all Perl's diagnostics.  The "use diagnostics" pragma automatically turns
       Perl's normally terse warnings and errors into these longer forms.

       Compilation errors will tell you the line number of the error, with an indication of the next token or token
       type that was to be examined.  (In a script passed to Perl via -e switches, each -e is counted as one line.)

       Setuid scripts have additional constraints that can produce error messages such as "Insecure dependency".  See
       perlsec.

       Did we mention that you should definitely consider using the -w switch?

BUGS
       The -w switch is not mandatory.

       Perl is at the mercy of your machine's definitions of various operations such as type casting, atof(), and
       floating-point output with sprintf().

       If your stdio requires a seek or eof between reads and writes on a particular stream, so does Perl.  (This
       doesn't apply to sysread() and syswrite().)

       While none of the built-in data types have any arbitrary size limits (apart from memory size), there are still
       a few arbitrary limits:  a given variable name may not be longer than 251 characters.  Line numbers displayed
       by diagnostics are internally stored as short integers, so they are limited to a maximum of 65535 (higher num-
       bers usually being affected by wraparound).

       You may mail your bug reports (be sure to include full configuration information as output by the myconfig pro-
       gram in the perl source tree, or by "perl -V") to perlbugATperl.org .  If you've succeeded in compiling perl,
       the perlbug script in the utils/ subdirectory can be used to help mail in a bug report.

       Perl actually stands for Pathologically Eclectic Rubbish Lister, but don't tell anyone I said that.

NOTES
       The Perl motto is "There's more than one way to do it."  Divining how many more is left as an exercise to the
       reader.

       The three principal virtues of a programmer are Laziness, Impatience, and Hubris.  See the Camel Book for why.



perl v5.8.8                       2006-01-07                           PERL(1)