TABLE OF CONTENTS

NAME

perl - The Perl 5 language interpreter

SYNOPSIS

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

For more information on these options, you can run perldoc perlrun.

GETTING HELP

The perldoc program gives you access to all the documentation that comes with Perl. You can get more documentation, tutorials and community support online at http://www.perl.org/.

If you're new to Perl, you should start by running perldoc perlintro, which is a general intro for beginners and provides some background to help you navigate the rest of Perl's extensive documentation. Run perldoc perldoc to learn more things you can do with perldoc.

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
perlrun         Perl execution and options
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

perlootut               Perl OO tutorial for beginners

perlperf                Perl Performance and Optimization Techniques

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
perlpodstyle    Perl POD style guide
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
perlrebackslash Perl regular expression backslash sequences
perlrecharclass Perl regular expression character classes
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

perlport                Perl portability guide
perllocale              Perl locale support
perluniintro    Perl Unicode introduction
perlunicode     Perl Unicode support
perlunifaq              Perl Unicode FAQ
perluniprops    Index of Unicode properties in Perl
perlunitut              Perl Unicode tutorial
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
perlpragma              Perl modules: writing a user pragma

perlutil                utilities packaged with the Perl distribution

perlfilter              Perl source filters

perldtrace              Perl's support for DTrace

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
perlxstypemap   Perl XS C/Perl type conversion tools
perlclib                Internal replacements for standard C library functions
perlguts                Perl internal functions for those doing extensions
perlcall                Perl calling conventions from C
perlmroapi              Perl method resolution plugin interface
perlreapi               Perl regular expression plugin interface
perlreguts              Perl regular expression engine internals

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
perlsource              Guide to the Perl source tree
perlinterp              Overview of the Perl interpreter source and how it works
perlhacktut     Walk through the creation of a simple C code patch
perlhacktips    Tips for Perl core C code hacking
perlpolicy              Perl development policies
perlgit         Using git with the Perl repository

Miscellaneous

perlbook                Perl book information
perlcommunity   Perl community information

perldoc         Look up Perl documentation in Pod format

perlhist                Perl history records
perldelta               Perl changes since previous version
perl5200delta   Perl changes in version 5.20.0
perl5182delta   Perl changes in version 5.18.2
perl5181delta   Perl changes in version 5.18.1
perl5180delta   Perl changes in version 5.18.0
perl5161delta   Perl changes in version 5.16.1
perl5162delta   Perl changes in version 5.16.2
perl5163delta   Perl changes in version 5.16.3
perl5160delta   Perl changes in version 5.16.0
perl5144delta   Perl changes in version 5.14.4
perl5143delta   Perl changes in version 5.14.3
perl5142delta   Perl changes in version 5.14.2
perl5141delta   Perl changes in version 5.14.1
perl5140delta   Perl changes in version 5.14.0
perl5125delta   Perl changes in version 5.12.5
perl5124delta   Perl changes in version 5.12.4
perl5123delta   Perl changes in version 5.12.3
perl5122delta   Perl changes in version 5.12.2
perl5121delta   Perl changes in version 5.12.1
perl5120delta   Perl changes in version 5.12.0
perl5101delta   Perl changes in version 5.10.1
perl5100delta   Perl changes in version 5.10.0
perl589delta    Perl changes in version 5.8.9
perl588delta    Perl changes in version 5.8.8
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
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

perlexperiment  A listing of experimental features in Perl

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
perlandroid             Perl notes for Android
perlbs2000              Perl notes for POSIX-BC BS2000
perlce          Perl notes for WinCE
perlcygwin              Perl notes for Cygwin
perldos         Perl notes for DOS
perlfreebsd     Perl notes for FreeBSD
perlhaiku               Perl notes for Haiku
perlhpux                Perl notes for HP-UX
perlhurd                Perl notes for Hurd
perlirix                Perl notes for Irix
perllinux               Perl notes for Linux
perlmacos               Perl notes for Mac OS (Classic)
perlmacosx              Perl notes for Mac OS X
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
perlriscos              Perl notes for RISC OS
perlsolaris     Perl notes for Solaris
perlsymbian     Perl notes for Symbian
perlsynology    Perl notes for Synology
perltru64               Perl notes for Tru64
perlvms         Perl notes for VMS
perlvos         Perl notes for Stratus VOS
perlwin32               Perl notes for Windows

Stubs for Deleted Documents

perlboot                
perlbot         
perlrepository
perltodo
perltooc                
perltoot                

On a Unix-like system, these documentation files will usually also be available as manpages for use with the man program.

Some documentation is not available as man pages, so if a cross-reference is not found by man, try it with perldoc. Perldoc can also take you directly to documentation for functions (with the -f switch). See perldoc --help (or perldoc perldoc or man perldoc) for other helpful options perldoc has to offer.

In general, if something strange has gone wrong with your program and you're not sure where you should look for help, try making your code comply with use strict and use warnings. These will often point out exactly where the trouble is.

DESCRIPTION

Perl officially stands for Practical Extraction and Report Language, except when it doesn't.

Perl was originally a language optimized for scanning arbitrary text files, extracting information from those text files, and printing reports based on that information. It quickly became a good language for many system management tasks. Over the years, Perl has grown into a general-purpose programming language. It's widely used for everything from quick "one-liners" to full-scale application development.

The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal). It combines (in the author's opinion, anyway) some of the best features of sed, awk, and sh, making it familiar and easy to use for Unix users to whip up quick solutions to annoying problems. Its general-purpose programming facilities support procedural, functional, and object-oriented programming paradigms, making Perl a comfortable language for the long haul on major projects, whatever your bent.

Perl's roots in text processing haven't been forgotten over the years. It still boasts some of the most powerful regular expressions to be found anywhere, and its support for Unicode text is world-class. It handles all kinds of structured text, too, through an extensive collection of extensions. Those libraries, collected in the CPAN, provide ready-made solutions to an astounding array of problems. When they haven't set the standard themselves, they steal from the best -- just like Perl itself.

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 <larry@wall.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-thanks@perl.org .

FILES

"@INC"                  locations of perl libraries

SEE ALSO

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

Using the use strict pragma ensures that all variables are properly declared and prevents other misuses of legacy Perl features.

The use warnings pragma produces some lovely diagnostics. One can also use the -w flag, but its use is normally discouraged, because it gets applied to all executed Perl code, including that not under your control.

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 use warnings pragma?

BUGS

The behavior implied by the use warnings pragma 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 numbers usually being affected by wraparound).

You may mail your bug reports (be sure to include full configuration information as output by the myconfig program in the perl source tree, or by perl -V) to perlbug@perl.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.