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

# 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 <https://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: declarations, statements, comments
        perldata            Perl data structures
        perlop              Perl expressions: operators, precedence, string literals
        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
        perldocstyle        Perl style guide for core docs
        perlpodstyle        Perl POD style guide
        perldiag            Perl diagnostic messages
        perldeprecation     Perl deprecations
        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
        perlclass           Perl class syntax
        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
        perlsecpolicy       Perl security report handling policy
        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            Interacting with 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
        perlclassguts       Internals of class syntax
        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
        perlgov             Perl Rules of Governance
        perlgit             Using git with the Perl repository

## History

        perlhist            Perl history records
        perldelta           Perl changes since previous version
        perl5400delta       Perl changes in version 5.40.0
        perl5382delta       Perl changes in version 5.38.2
        perl5381delta       Perl changes in version 5.38.1
        perl5380delta       Perl changes in version 5.38.0
        perl5363delta       Perl changes in version 5.36.3
        perl5362delta       Perl changes in version 5.36.2
        perl5361delta       Perl changes in version 5.36.1
        perl5360delta       Perl changes in version 5.36.0
        perl5343delta       Perl changes in version 5.34.3
        perl5342delta       Perl changes in version 5.34.2
        perl5341delta       Perl changes in version 5.34.1
        perl5340delta       Perl changes in version 5.34.0
        perl5321delta       Perl changes in version 5.32.1
        perl5320delta       Perl changes in version 5.32.0
        perl5303delta       Perl changes in version 5.30.3
        perl5302delta       Perl changes in version 5.30.2
        perl5301delta       Perl changes in version 5.30.1
        perl5300delta       Perl changes in version 5.30.0
        perl5283delta       Perl changes in version 5.28.3
        perl5282delta       Perl changes in version 5.28.2
        perl5281delta       Perl changes in version 5.28.1
        perl5280delta       Perl changes in version 5.28.0
        perl5263delta       Perl changes in version 5.26.3
        perl5262delta       Perl changes in version 5.26.2
        perl5261delta       Perl changes in version 5.26.1
        perl5260delta       Perl changes in version 5.26.0
        perl5244delta       Perl changes in version 5.24.4
        perl5243delta       Perl changes in version 5.24.3
        perl5242delta       Perl changes in version 5.24.2
        perl5241delta       Perl changes in version 5.24.1
        perl5240delta       Perl changes in version 5.24.0
        perl5224delta       Perl changes in version 5.22.4
        perl5223delta       Perl changes in version 5.22.3
        perl5222delta       Perl changes in version 5.22.2
        perl5221delta       Perl changes in version 5.22.1
        perl5220delta       Perl changes in version 5.22.0
        perl5203delta       Perl changes in version 5.20.3
        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

## Miscellaneous

        perlbook            Perl book information
        perlcommunity       Perl community information
        perldoc             Look up Perl documentation in Pod format
        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 UTF-8)
        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
        perlcygwin          Perl notes for Cygwin
        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
        perlmacosx          Perl notes for Mac OS X
        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
        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 "ENVIRONMENT" in 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

"@INC" above is a reference to the built-in variable of the same name; see perlvar for more information.

# SEE ALSO

<https://www.perl.org/>
  the Perl homepage
<https://www.perl.com/>
  Perl articles
<https://www.cpan.org/>
  the Comprehensive Perl Archive
<https://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. These are enabled by default within the scope of "use v5.12" (or higher).

The "use warnings" pragma produces some lovely diagnostics. It is enabled by default when you say "use v5.35" (or higher). 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 submit 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 <https://github.com/Perl/perl5/issues>.

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.

2025-01-28 | perl v5.40.1