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".

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 <>.

       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.

           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
           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
           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

           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
           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
           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
           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 listing.


       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

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 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?


       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 .  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.