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 ]...
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 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 perlbootPerl OO tutorial for beginners perltootPerl OO tutorial, part 1 perltoocPerl OO tutorial, part 2 perlbotPerl OO tricks and examples 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 perlrunPerl execution and options 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 perlunifaqPerl Unicode FAQ perlunipropsIndex of Unicode Version 6.0.0 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 perlcompile Perl compiler suite intro perlfilterPerl source filters 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 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 intepreter 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 perltodoPerl things to do perldocLook up Perl documentation in Pod format perlhistPerl history records perldeltaPerl changes since previous version perl5140deltaPerl changes in version 5.14.0 perl51311deltaPerl changes in version 5.13.11 perl51310deltaPerl changes in version 5.13.10 perl5139deltaPerl changes in version 5.13.9 perl5138deltaPerl changes in version 5.13.8 perl5137deltaPerl changes in version 5.13.7 perl5136deltaPerl changes in version 5.13.6 perl5135deltaPerl changes in version 5.13.5 perl5134deltaPerl changes in version 5.13.4 perl5133deltaPerl changes in version 5.13.3 perl5132deltaPerl changes in version 5.13.2 perl5131deltaPerl changes in version 5.13.1 perl5130deltaPerl changes in version 5.13.0 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 perl5115deltaPerl changes in version 5.11.5 perl5114deltaPerl changes in version 5.11.4 perl5113deltaPerl changes in version 5.11.3 perl5112deltaPerl changes in version 5.11.2 perl5111deltaPerl changes in version 5.11.1 perl5110deltaPerl changes in version 5.11.0 perl5101deltaPerl changes in version 5.10.1 perl5100deltaPerl changes in version 5.10.0 perl595deltaPerl changes in version 5.9.5 perl594deltaPerl changes in version 5.9.4 perl593deltaPerl changes in version 5.9.3 perl592deltaPerl changes in version 5.9.2 perl591deltaPerl changes in version 5.9.1 perl590deltaPerl changes in version 5.9.0 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 perl573deltaPerl changes in version 5.7.3 perl572deltaPerl changes in version 5.7.2 perl571deltaPerl changes in version 5.7.1 perl570deltaPerl changes in version 5.7.0 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 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 perlbeosPerl notes for BeOS perlbs2000Perl notes for POSIX-BC BS2000 perlcePerl notes for WinCE perlcygwinPerl notes for Cygwin perldguxPerl notes for DG/UX perldosPerl notes for DOS perlepocPerl notes for EPOC 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 perlmpeixPerl notes for MPE/iX 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 perltru64Perl notes for Tru64 perlutsPerl notes for UTS perlvmesaPerl notes for VM/ESA perlvmsPerl notes for VMS perlvosPerl notes for Stratus VOS perlwin32Perl notes for WindowsOn a Unix-like system, these documentation files will usually also be available as manpages for use with the man program.
In general, if something strange has gone wrong with your program and you're not sure where you should look for help, try the -w switch first. It 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).
Perl combines (in the author's opinion, anyway) some of the best features of C, sed, awk, and sh, so people familiar with those languages should have little difficulty with it. (Language historians will also note some vestiges of csh, Pascal, and even BASIC-PLUS.) Expression syntax corresponds closely to C expression syntax. Unlike most Unix utilities, Perl does not arbitrarily limit the size of your data--if you've got the memory, Perl can slurp in your whole file as a single string. Recursion is of unlimited depth. And the tables used by hashes (sometimes called "associative arrays") grow as necessary to prevent degraded performance. Perl can use sophisticated pattern matching techniques to scan large amounts of data quickly. Although optimized for scanning text, Perl also has many excellent tools for slicing and dicing binary data.
But wait, there's more...
Begun in 1993 (see perlhist), Perl version 5 is nearly a complete rewrite that provides the following additional benefits:
modularity and reusability using innumerable modules
Described in perlmod, perlmodlib, and perlmodinstall.
embeddable and extensible
Described in perlembed, perlxstut, perlxs, perlcall, perlguts, and xsubpp.
roll-your-own magic variables (including multiple simultaneous DBM implementations)
Described in perltie and AnyDBM_File.
subroutines can now be overridden, autoloaded, and prototyped
Described in perlsub.
arbitrarily nested data structures and anonymous functions
Described in perlreftut, perlref, perldsc, and perllol.
object-oriented programming
Described in perlobj, perlboot, perltoot, perltooc, and perlbot.
support for light-weight processes (threads)
Described in perlthrtut and threads.
support for Unicode, internationalization, and localization
Described in perluniintro, perllocale and Locale::Maketext.
lexical scoping
Described in perlsub.
regular expression enhancements
enhanced debugger and interactive Perl environment, with integrated editor support
Described in perldebtut, perldebug and perldebguts.
POSIX 1003.1 compliant library
Described in POSIX.
Okay, that's definitely enough hype.
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 librarieshttp://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 MongersThe use warnings pragma (and the -w switch) produces some lovely diagnostics.
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 -w switch?
The -w switch 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.