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PERL(1) Perl Programmers Reference Guide PERL(1)
NAME
perl - The Perl 5 language interpreter
SYNOPSIS
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 ]...
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
<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.
Overview
perl Perl overview (this section)
perlintro Perl introduction for beginners
perltoc Perl documentation table of contents
Tutorials
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
perlrun Perl execution and options
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 Version 6.0.0 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
Miscellaneous
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
perl5162delta Perl changes in version 5.16.2
perl5161delta Perl changes in version 5.16.1
perl5160delta Perl changes in version 5.16.0
perl5160delta Perl changes in version 5.16.0
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
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
Language-Specific
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)
Platform-Specific
perlaix Perl notes for AIX
perlamiga Perl notes for AmigaOS
perlbeos Perl notes for BeOS
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
perlepoc Perl notes for EPOC
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
perlmpeix Perl notes for MPE/iX
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
perluts Perl notes for UTS
perlvmesa Perl notes for VM/ESA
perlvms Perl notes for VMS
perlvos Perl notes for Stratus VOS
perlwin32 Perl notes for Windows
Stubs for Deleted Documents
perlboot
perlbot
perltodo
perltooc
perltoot
On 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.
DESCRIPTION
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:
o modularity and reusability using innumerable modules
Described in perlmod, perlmodlib, and perlmodinstall.
o embeddable and extensible
Described in perlembed, perlxstut, perlxs, perlxstypemap, perlcall, perlguts, and
xsubpp.
o roll-your-own magic variables (including multiple simultaneous DBM implementations)
Described in perltie and AnyDBM_File.
o subroutines can now be overridden, autoloaded, and prototyped
Described in perlsub.
o arbitrarily nested data structures and anonymous functions
Described in perlreftut, perlref, perldsc, and perllol.
o object-oriented programming
Described in perlobj and perlootut.
o support for light-weight processes (threads)
Described in perlthrtut and threads.
o support for Unicode, internationalization, and localization
Described in perluniintro, perllocale and Locale::Maketext.
o lexical scoping
Described in perlsub.
o regular expression enhancements
Described in perlre, with additional examples in perlop.
o enhanced debugger and interactive Perl environment, with integrated editor support
Described in perldebtut, perldebug and perldebguts.
o POSIX 1003.1 compliant library
Described in POSIX.
Okay, that's definitely enough hype.
AVAILABILITY
Perl is available for most operating systems, including virtually all Unix-like platforms.
See "Supported Platforms" in perlport for a listing.
ENVIRONMENT
See perlrun.
AUTHOR
Larry Wall <larry AT 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 AT perl.org .
FILES
"@INC" locations of perl libraries
SEE ALSO
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 Mongers
DIAGNOSTICS
The "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?
BUGS
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 AT 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.
NOTES
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.
perl v5.16.3 2013-03-04 PERL(1)
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