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PERL(1)		       Perl Programmers	Reference Guide		       PERL(1)

       perl - Practical	Extraction and Report Language

       perl [ -sTuU ] [	-hv ] [	-V[:configvar] ]
	   [ -cw ] [ -d[:debugger] ] [ -D[number/list] ]
	   [ -pna ] [ -Fpattern	] [ -l[octal] ]	[ -0[octal] ]
	   [ -Idir ] [ -m[-]module ] [ -M[-]'module...'	]
	   [ -P	] [ -S ] [ -x[dir] ]
	   [ -i[extension] ] [ -e 'command' ] [	-- ] [ programfile ] [ argu-
       ment ]...

       If you're new to	Perl, you should start with perlintro, which is	a gen-
       eral intro for beginners	and provides some background to	help you navi-
       gate the	rest of	Perl's extensive documentation.

       For ease	of access, the Perl manual has been split up into several sec-


	   perl		       Perl overview (this section)
	   perlintro	       Perl introduction for beginners
	   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

	   perlboot	       Perl OO tutorial	for beginners
	   perltoot	       Perl OO tutorial, part 1
	   perltooc	       Perl OO tutorial, part 2
	   perlbot	       Perl OO tricks and examples

	   perlstyle	       Perl style guide

	   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
	   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
	   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
	     perlothrtut	 Old Perl threads tutorial

	   perlport	       Perl portability	guide
	   perllocale	       Perl locale support
	   perluniintro	       Perl Unicode introduction
	   perlunicode	       Perl Unicode support
	   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

	   perlutil	       utilities packaged with the Perl	distribution

	   perlcompile	       Perl compiler suite intro

	   perlfilter	       Perl source filters

       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
	   perlclib	       Internal	replacements for standard C library functions
	   perlguts	       Perl internal functions for those doing extensions
	   perlcall	       Perl calling conventions	from C

	   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


	   perlbook	       Perl book information
	   perltodo	       Perl things to do

	   perlhist	       Perl history records
	   perldelta	       Perl changes since previous version
	   perl573delta	       Perl changes in version 5.7.3
	   perl572delta	       Perl changes in version 5.7.2
	   perl571delta	       Perl changes in version 5.7.1
	   perl570delta	       Perl changes in version 5.7.0
	   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


	   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
	   perlapollo	       Perl notes for Apollo DomainOS
	   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
	   perlhpux	       Perl notes for HP-UX
	   perlhurd	       Perl notes for Hurd
	   perlirix	       Perl notes for Irix
	   perlmachten	       Perl notes for Power MachTen
	   perlmacos	       Perl notes for Mac OS (Classic)
	   perlmint	       Perl notes for MiNT
	   perlmpeix	       Perl notes for MPE/iX
	   perlnetware	       Perl notes for NetWare
	   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
	   perlsolaris	       Perl notes for Solaris
	   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

       By default, the manpages	listed above are installed in the /usr/lo-
       cal/man/	directory.

       Extensive additional documentation for Perl modules is available.  The
       default configuration for perl will place this additional documentation
       in the /usr/local/lib/perl5/man directory (or else in the man subdirec-
       tory of the Perl	library	directory).  Some of this additional documen-
       tation is distributed standard with Perl, but you'll also find documen-
       tation for third-party modules there.

       You should be able to view Perl's documentation with your man(1)	pro-
       gram by including the proper directories	in the appropriate start-up
       files, or in the	MANPATH	environment variable.  To find out where the
       configuration has installed the manpages, type:

	   perl	-V:man.dir

       If the directories have a common	stem, such as /usr/local/man/man1 and
       /usr/local/man/man3, you	need only to add that stem (/usr/local/man) to
       your man(1) configuration files or your MANPATH environment variable.
       If they do not share a stem, you'll have	to add both stems.

       If that doesn't work for	some reason, you can still use the supplied
       perldoc script to view module information.  You might also look into
       getting a replacement man program.

       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 is a language optimized for	scanning arbitrary text	files, ex-
       tracting	information from those text files, and printing	reports	based
       on that information.  It's also a good language for many	system manage-
       ment tasks.  The	language is intended to	be practical (easy to use, ef-
       ficient,	complete) rather than beautiful	(tiny, elegant,	minimal).

       Perl combines (in the author's opinion, anyway) some of the best	fea-
       tures 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 can also deal with binary data, and
       can make	dbm files look like hashes.  Setuid Perl scripts are safer
       than C programs through a dataflow tracing mechanism that prevents many
       stupid security holes.

       If you have a problem that would	ordinarily use sed or awk or sh, but
       it exceeds their	capabilities or	must run a little faster, and you
       don't want to write the silly thing in C, then Perl may be for you.
       There are also translators to turn your sed and awk scripts into	Perl

       But wait, there's more...

       Begun in	1993 (see perlhist), Perl version 5 is nearly a	complete re-
       write 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, perlcall,	perlguts, and

       o   roll-your-own magic variables (including multiple simultaneous DBM

	   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, perlboot, perltoot, perltooc, and perlbot.

       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.

       Perl is available for most operating systems, including virtually all
       Unix-like platforms.  See "Supported Platforms" in perlport for a list-

       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

	a2p    awk to perl translator
	s2p    sed to perl translator	   the Perl Home Page	   the Comprehensive Perl Archive	   Perl	Mongers	(Perl user groups)

       The "use	warnings" pragma (and the -w switch) produces some lovely di-

       See perldiag for	explanations of	all Perl's diagnostics.	 The "use di-
       agnostics" 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

       Setuid scripts have additional constraints that can produce error mes-
       sages 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 opera-
       tions such as type casting, atof(), and floating-point output with

       If your stdio requires a	seek or	eof between reads and writes on	a par-
       ticular stream, so does Perl.  (This doesn't apply to sysread() and

       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	num-
       bers 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 compil-
       ing 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.

perl v5.8.0			  2003-02-18			       PERL(1)


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