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/Perl 5.26

perl

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
perlunicook 	Perl Unicode cookbook
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
perl52111delta	Perl changes in version 5.21.11
perl52110delta	Perl changes in version 5.21.10
perl5219delta	Perl changes in version 5.21.9
perl5218delta	Perl changes in version 5.21.8
perl5217delta	Perl changes in version 5.21.7
perl5216delta	Perl changes in version 5.21.6
perl5215delta	Perl changes in version 5.21.5
perl5214delta	Perl changes in version 5.21.4
perl5213delta	Perl changes in version 5.21.3
perl5212delta	Perl changes in version 5.21.2
perl5211delta	Perl changes in version 5.21.1
perl5210delta	Perl changes in version 5.21.0
perl5202delta	Perl changes in version 5.20.2
perl5201delta	Perl changes in version 5.20.1
perl5200delta	Perl changes in version 5.20.0
perl5184delta	Perl changes in version 5.18.4
perl5182delta	Perl changes in version 5.18.2
perl5181delta	Perl changes in version 5.18.1
perl5180delta	Perl changes in version 5.18.0
perl5163delta	Perl changes in version 5.16.3
perl5162delta	Perl changes in version 5.16.2
perl5161delta	Perl changes in version 5.16.1
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.

© 1993–2016 Larry Wall and others
Licensed under the GNU General Public License version 1 or later, or the Artistic License.
The Perl logo is a trademark of the Perl Foundation.
https://perldoc.perl.org/5.26.0/perl.html