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PERL(1)Perl Programmers Reference GuidePERL(1)

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 <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.

    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

    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    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    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

    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    perlgov             Perl Rules of Governance    perlgit             Using git with the Perl repository

    perlhist            Perl history records    perldelta           Perl changes since previous version    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

    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

    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)

    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

    perlboot                perlbot                 perlrepository    perltodo    perltooc                perltoot

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 "ENVIRONMENT" in perlrun.

Larry Wall <[email protected]>, 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 [email protected] .

 "@INC"                 locations of perl libraries

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

 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

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?

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.

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.

2025-04-12perl v5.36.0