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 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.
perl Perl overview (this section) perlintroPerl introduction for beginners perlrunPerl execution and options perltocPerl documentation table of contentsperlreftutPerl references short introduction perldscPerl data structures intro perllolPerl data structures: arrays of arrays perlrequick Perl regular expressions quick start perlretutPerl regular expressions tutorial perlootutPerl OO tutorial for beginners perlperfPerl Performance and Optimization Techniques perlstylePerl style guide perlcheatPerl cheat sheet perltrapPerl traps for the unwary perldebtutPerl debugging tutorial perlfaqPerl frequently asked questions perlfaq1General Questions About Perl perlfaq2Obtaining and Learning about Perl perlfaq3Programming Tools perlfaq4Data Manipulation perlfaq5Files and Formats perlfaq6Regexes perlfaq7Perl Language Issues perlfaq8System Interaction perlfaq9NetworkingperlsynPerl syntax perldataPerl data structures perlopPerl operators and precedence perlsubPerl subroutines perlfuncPerl built-in functions perlopentutPerl open() tutorial perlpacktutPerl pack() and unpack() tutorial perlpodPerl plain old documentation perlpodspec Perl plain old documentation format specification perlpodstylePerl POD style guide perldiagPerl diagnostic messages perllexwarn Perl warnings and their control perldebugPerl debugging perlvarPerl predefined variables perlrePerl regular expressions, the rest of the story perlrebackslashPerl regular expression backslash sequences perlrecharclassPerl regular expression character classes perlrerefPerl regular expressions quick reference perlrefPerl references, the rest of the story perlformPerl formats perlobjPerl objects perltiePerl objects hidden behind simple variables perldbmfilterPerl DBM filters perlipcPerl interprocess communication perlforkPerl fork() information perlnumberPerl number semantics perlthrtutPerl threads tutorial perlportPerl portability guide perllocalePerl locale support perluniintroPerl Unicode introduction perlunicode Perl Unicode support perlunicook Perl Unicode cookbook perlunifaqPerl Unicode FAQ perlunipropsIndex of Unicode properties in Perl perlunitutPerl Unicode tutorial perlebcdicConsiderations for running Perl on EBCDIC platforms perlsecPerl security perlmodPerl modules: how they work perlmodlibPerl modules: how to write and use perlmodstylePerl modules: how to write modules with style perlmodinstallPerl modules: how to install from CPAN perlnewmodPerl modules: preparing a new module for distribution perlpragmaPerl modules: writing a user pragma perlutilutilities packaged with the Perl distribution perlfilterPerl source filters perldtracePerl's support for DTrace perlglossaryPerl GlossaryperlembedPerl ways to embed perl in your C or C++ application perldebguts Perl debugging guts and tips perlxstutPerl XS tutorial perlxsPerl XS application programming interface perlxstypemapPerl XS C/Perl type conversion tools perlclibInternal replacements for standard C library functions perlgutsPerl internal functions for those doing extensions perlcallPerl calling conventions from C perlmroapiPerl method resolution plugin interface perlreapiPerl regular expression plugin interface perlregutsPerl regular expression engine internals perlapiPerl API listing (autogenerated) perlinternPerl internal functions (autogenerated) perliolC API for Perl's implementation of IO in Layers perlapioPerl internal IO abstraction interface perlhackPerl hackers guide perlsourceGuide to the Perl source tree perlinterpOverview of the Perl interpreter source and how it works perlhacktut Walk through the creation of a simple C code patch perlhacktipsTips for Perl core C code hacking perlpolicyPerl development policies perlgitUsing git with the Perl repositoryperlbookPerl book information perlcommunityPerl community information perldocLook up Perl documentation in Pod format perlhistPerl history records perldeltaPerl changes since previous version perl5240deltaPerl changes in version 5.24.0 perl5222deltaPerl changes in version 5.22.2 perl5221deltaPerl changes in version 5.22.1 perl5220deltaPerl changes in version 5.22.0 perl5203deltaPerl changes in version 5.20.3 perl5202deltaPerl changes in version 5.20.2 perl5201deltaPerl changes in version 5.20.1 perl5200deltaPerl changes in version 5.20.0 perl5184deltaPerl changes in version 5.18.4 perl5182deltaPerl changes in version 5.18.2 perl5181deltaPerl changes in version 5.18.1 perl5180deltaPerl changes in version 5.18.0 perl5163deltaPerl changes in version 5.16.3 perl5162deltaPerl changes in version 5.16.2 perl5161deltaPerl changes in version 5.16.1 perl5160deltaPerl changes in version 5.16.0 perl5144deltaPerl changes in version 5.14.4 perl5143deltaPerl changes in version 5.14.3 perl5142deltaPerl changes in version 5.14.2 perl5141deltaPerl changes in version 5.14.1 perl5140deltaPerl changes in version 5.14.0 perl5125deltaPerl changes in version 5.12.5 perl5124deltaPerl changes in version 5.12.4 perl5123deltaPerl changes in version 5.12.3 perl5122deltaPerl changes in version 5.12.2 perl5121deltaPerl changes in version 5.12.1 perl5120deltaPerl changes in version 5.12.0 perl5101deltaPerl changes in version 5.10.1 perl5100deltaPerl changes in version 5.10.0 perl589deltaPerl changes in version 5.8.9 perl588deltaPerl changes in version 5.8.8 perl587deltaPerl changes in version 5.8.7 perl586deltaPerl changes in version 5.8.6 perl585deltaPerl changes in version 5.8.5 perl584deltaPerl changes in version 5.8.4 perl583deltaPerl changes in version 5.8.3 perl582deltaPerl changes in version 5.8.2 perl581deltaPerl changes in version 5.8.1 perl58delta Perl changes in version 5.8.0 perl561deltaPerl changes in version 5.6.1 perl56delta Perl changes in version 5.6 perl5005deltaPerl changes in version 5.005 perl5004deltaPerl changes in version 5.004 perlexperimentA listing of experimental features in Perl perlartisticPerl Artistic License perlgplGNU General Public LicenseperlcnPerl for Simplified Chinese (in EUC-CN) perljpPerl for Japanese (in EUC-JP) perlkoPerl for Korean (in EUC-KR) perltwPerl for Traditional Chinese (in Big5)perlaixPerl notes for AIX perlamigaPerl notes for AmigaOS perlandroidPerl notes for Android perlbs2000Perl notes for POSIX-BC BS2000 perlcePerl notes for WinCE perlcygwinPerl notes for Cygwin perldosPerl notes for DOS perlfreebsd Perl notes for FreeBSD perlhaikuPerl notes for Haiku perlhpuxPerl notes for HP-UX perlhurdPerl notes for Hurd perlirixPerl notes for Irix perllinuxPerl notes for Linux perlmacosPerl notes for Mac OS (Classic) perlmacosxPerl notes for Mac OS X perlnetware Perl notes for NetWare perlopenbsd Perl notes for OpenBSD perlos2Perl notes for OS/2 perlos390Perl notes for OS/390 perlos400Perl notes for OS/400 perlplan9Perl notes for Plan 9 perlqnxPerl notes for QNX perlriscosPerl notes for RISC OS perlsolaris Perl notes for Solaris perlsymbian Perl notes for Symbian perlsynology Perl notes for Synology perltru64Perl notes for Tru64 perlvmsPerl notes for VMS perlvosPerl notes for Stratus VOS perlwin32Perl notes for Windowsperlboot perlbot perlrepository perltodo perltooc perltootOn 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.
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 <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 .
"@INC" locations of perl libraries"@INC" above is a reference to the built-in variable of the same name; see perlvar for more information.
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 MongersUsing 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 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.
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.