perl - The Perl 5 language interpreter


   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".


   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 <>.

   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

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

       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

       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
       perl5240delta       Perl changes in version 5.24.0
       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

       perlexperiment      A listing of experimental features in Perl

       perlartistic        Perl Artistic License
       perlgpl             GNU General Public License

       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)

       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

   On Debian systems, you need to install the perl-doc package which
   contains the majority of the standard Perl documentation and the
   perldoc program.

   Extensive additional documentation for Perl modules is available, both
   those distributed with Perl and third-party modules which are packaged
   or locally installed.

   You should be able to view Perl's documentation with your man(1)
   program or perldoc(1).

   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.


   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.


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


   See perlrun.


   Larry Wall <>, 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 .


    "@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       the Perl homepage       Perl articles (O'Reilly)       the Comprehensive Perl Archive         the Perl Mongers


   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

   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

   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?


   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

   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

   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 .  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.


   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.


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.

Free Software

Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.

Free Books

The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.