[perl5.git] / pod / perl.pod

=head1 NAME

perl - Practical Extraction and Report Language

=head1 SYNOPSIS

B<perl>	S<[ B<-sTuU> ]> S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]>
    S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]>
    S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]>
    S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]>
    S<[ B<-P> ]> S<[ B<-S> ]> S<[ B<-x>[I<dir>] ]>
    S<[ B<-i>[I<extension>] ]> S<[ B<-e> I<'command'> ] 
    [ B<--> ] [ I<programfile> ] [ I<argument> ]...>

If you're new to Perl, you should start with L<perlintro>, which is a 
general intro for beginners and provides some background to help you
navigate the rest of Perl's extensive documentation.

For ease of access, the Perl manual has been split up into several sections.

=head2 Overview

    perl		Perl overview (this section)
    perlintro		Perl introduction for beginners
    perltoc		Perl documentation table of contents


=head2 Tutorials

    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
  
    perlrequick		Perl regular expressions quick start
    perlretut		Perl regular expressions tutorial

    perlreftut		Perl references short introduction
    perldsc		Perl data structures intro
    perllol		Perl data structures: arrays of arrays

    perldebtut		Perl debugging tutorial

    perlopentut		Perl open() tutorial

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

=head2 Reference Manual
    perlsyn		Perl syntax
    perldata		Perl data structures
    perlop		Perl operators and precedence
    perlsub		Perl subroutines
    perlfunc		Perl built-in functions
    perlpod		Perl plain old documentation
    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		Perl threads tutorial

    perlport		Perl portability guide
    perllocale		Perl locale support
    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

=head2 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

=head2 Miscellaneous

    perlbook		Perl book information
    perlstyle		Perl style guide
    perltrap		Perl traps for the unwary
    perltodo		Perl things to do

    perlhist		Perl history records
    perldelta		Perl changes since previous version
    perl572delta	Perl changes in version 5.7.2
    perl571delta	Perl changes in version 5.7.1
    perl570delta	Perl changes in version 5.7.0
    perl56delta		Perl changes in version 5.6
    perl5005delta	Perl changes in version 5.005
    perl5004delta	Perl changes in version 5.004

=head2 Platform-Specific

    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
    perlhpux		Perl notes for HP-UX
    perlhurd		Perl notes for Hurd
    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
    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 
F</usr/local/man/> directory.  

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

You should be able to view Perl's documentation with your man(1)
program 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 F</usr/local/man/man1>
and F</usr/local/man/man3>, you need only to add that stem
(F</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 F<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 B<-w> switch first.  It
will often point out exactly where the trouble is.

=head1 DESCRIPTION

Perl is a language optimized for scanning arbitrary
text files, extracting information from those text files, and printing
reports based on that information.  It's also a good language for many
system management tasks.  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, B<sed>, B<awk>, and B<sh>, so people familiar with
those languages should have little difficulty with it.  (Language
historians will also note some vestiges of B<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 B<sed> or B<awk> or
B<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 B<sed> and B<awk>
scripts into Perl scripts.

But wait, there's more...

Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
rewrite that provides the following additional benefits:

=over 4

=item *

modularity and reusability using innumerable modules 

Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.

=item *

embeddable and extensible 

Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
L<perlguts>, and L<xsubpp>.

=item *

roll-your-own magic variables (including multiple simultaneous DBM implementations)

Described in L<perltie> and L<AnyDBM_File>.

=item *

subroutines can now be overridden, autoloaded, and prototyped

Described in L<perlsub>.

=item *

arbitrarily nested data structures and anonymous functions

Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.

=item *

object-oriented programming

Described in L<perlobj>, L<perltoot>, and L<perlbot>.

=item *

compilability into C code or Perl bytecode

Described in L<B> and L<B::Bytecode>.

=item *

support for light-weight processes (threads)

Described in L<perlthrtut> and L<Thread>.

=item *

support for internationalization, localization, and Unicode 

Described in L<perllocale> and L<utf8>.

=item *

lexical scoping

Described in L<perlsub>.

=item *

regular expression enhancements

Described in L<perlre>, with additional examples in L<perlop>.

=item *

enhanced debugger and interactive Perl environment,
with integrated editor support

Described in L<perldebug>.

=item *

POSIX 1003.1 compliant library

Described in L<POSIX>.

=back

Okay, that's I<definitely> enough hype.

=head1 AVAILABILITY

Perl is available for most operating systems, including virtually
all Unix-like platforms.  See L<perlport/"Supported Platforms">
for a listing.

=head1 ENVIRONMENT

See L<perlrun>.

=head1 AUTHOR

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 .

=head1 FILES

 "@INC"			locations of perl libraries

=head1 SEE ALSO

 a2p	awk to perl translator
 s2p	sed to perl translator

 http://www.perl.com/	    the Perl Home Page
 http://www.perl.com/CPAN   the Comprehensive Perl Archive

=head1 DIAGNOSTICS

The C<use warnings> pragma (and the B<-w> switch) produces some 
lovely diagnostics.

See L<perldiag> for explanations of all Perl's diagnostics.  The C<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 B<-e> switches, each
B<-e> is counted as one line.)

Setuid scripts have additional constraints that can produce error
messages such as "Insecure dependency".  See L<perlsec>.

Did we mention that you should definitely consider using the B<-w>
switch?

=head1 BUGS

The B<-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 C<perl -V>) to perlbug@perl.org .  If you've succeeded
in compiling perl, the B<perlbug> script in the F<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.

=head1 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.
Commit	Line	Data
a0d0e21e LW	1	=head1 NAME
	2
	3	perl - Practical Extraction and Report Language
	4
	5	=head1 SYNOPSIS
	6
19799a22 GS	7	B<perl> S<[ B<-sTuU> ]> S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]>
	8	S<[ B<-cw> ] [ B<-d>[:I<debugger>] ] [ B<-D>[I<number/list>] ]>
	9	S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal>] ]>
	10	S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<'module...'> ]>
	11	S<[ B<-P> ]> S<[ B<-S> ]> S<[ B<-x>[I<dir>] ]>
	12	S<[ B<-i>[I<extension>] ]> S<[ B<-e> I<'command'> ]
	13	[ B<--> ] [ I<programfile> ] [ I<argument> ]...>
c07a80fd	14
10151d09 JH	15	If you're new to Perl, you should start with L<perlintro>, which is a
	16	general intro for beginners and provides some background to help you
	17	navigate the rest of Perl's extensive documentation.
	18
	19	For ease of access, the Perl manual has been split up into several sections.
a0d0e21e	20
fd7b6849 MJD	21	=head2 Overview
fd7b6849 MJD	22
fb9cefb4	23	perl Perl overview (this section)
10151d09	24	perlintro Perl introduction for beginners
fb9cefb4	25	perltoc Perl documentation table of contents
760ac839	26
fd7b6849 MJD	27
	28	=head2 Tutorials
	29
	30	perlfaq Perl frequently asked questions
	31	perlfaq1 General Questions About Perl
	32	perlfaq2 Obtaining and Learning about Perl
	33	perlfaq3 Programming Tools
	34	perlfaq4 Data Manipulation
	35	perlfaq5 Files and Formats
	36	perlfaq6 Regexes
	37	perlfaq7 Perl Language Issues
	38	perlfaq8 System Interaction
	39	perlfaq9 Networking
	40
	41	perlrequick Perl regular expressions quick start
	42	perlretut Perl regular expressions tutorial
	43
	44	perlreftut Perl references short introduction
	45	perldsc Perl data structures intro
	46	perllol Perl data structures: arrays of arrays
	47
	48	perldebtut Perl debugging tutorial
	49
	50	perlopentut Perl open() tutorial
	51
	52	perlboot Perl OO tutorial for beginners
	53	perltoot Perl OO tutorial, part 1
	54	perltootc Perl OO tutorial, part 2
	55	perlbot Perl OO tricks and examples
	56
	57	=head2 Reference Manual
fb9cefb4	58	perlsyn Perl syntax
4755096e	59	perldata Perl data structures
fb9cefb4	60	perlop Perl operators and precedence
c2e66d9e	61	perlsub Perl subroutines
fd7b6849	62	perlfunc Perl built-in functions
c2e66d9e	63	perlpod Perl plain old documentation
c2e66d9e GS	64	perlrun Perl execution and options
c2e66d9e GS	65	perldiag Perl diagnostic messages
4755096e GS	66	perllexwarn Perl warnings and their control
4755096e GS	67	perldebug Perl debugging
fb9cefb4	68	perlvar Perl predefined variables
4755096e	69	perlre Perl regular expressions, the rest of the story
d396a558	70	perlref Perl references, the rest of the story
fb9cefb4	71	perlform Perl formats
d396a558	72	perlobj Perl objects
d396a558	73	perltie Perl objects hidden behind simple variables
fd7b6849	74	perldbmfilter Perl DBM filters
760ac839	75
c2e66d9e GS	76	perlipc Perl interprocess communication
	77	perlfork Perl fork() information
	78	perlnumber Perl number semantics
53d7eaa8	79
c2e66d9e	80	perlthrtut Perl threads tutorial
fd7b6849	81	perlothrtut Perl threads tutorial
c2e66d9e GS	82
c2e66d9e GS	83	perlport Perl portability guide
d396a558 JH	84	perllocale Perl locale support
	85	perlunicode Perl unicode support
	86	perlebcdic Considerations for running Perl on EBCDIC platforms
c2e66d9e	87
d396a558	88	perlsec Perl security
4755096e	89
c2e66d9e	90	perlmod Perl modules: how they work
35bf961c JH	91	perlmodlib Perl modules: how to write and use
35bf961c JH	92	perlmodstyle Perl modules: how to write modules with style
fd7b6849	93	perlmodinstall Perl modules: how to install from CPAN
c2e66d9e	94	perlnewmod Perl modules: preparing a new module for distribution
760ac839	95
fd7b6849	96	perlutil utilities packaged with the Perl distribution
760ac839	97
4755096e	98	perlcompile Perl compiler suite intro
760ac839	99
fd7b6849 MJD	100	perlfilter Perl source filters
	101
	102	=head2 Internals and C Language Interface
	103
fb9cefb4	104	perlembed Perl ways to embed perl in your C or C++ application
055fd3a9	105	perldebguts Perl debugging guts and tips
fb9cefb4	106	perlxstut Perl XS tutorial
4755096e	107	perlxs Perl XS application programming interface
f40a6c71	108	perlclib Internal replacements for standard C library functions
fb9cefb4 GS	109	perlguts Perl internal functions for those doing extensions
fb9cefb4 GS	110	perlcall Perl calling conventions from C
fd7b6849	111
954c1994 GS	112	perlapi Perl API listing (autogenerated)
954c1994 GS	113	perlintern Perl internal functions (autogenerated)
dc5c060f	114	perliol C API for Perl's implementation of IO in Layers
4755096e	115	perlapio Perl internal IO abstraction interface
fd7b6849	116
e8cd7eae	117	perlhack Perl hackers guide
4755096e	118
fd7b6849 MJD	119	=head2 Miscellaneous
	120
	121	perlbook Perl book information
	122	perlstyle Perl style guide
	123	perltrap Perl traps for the unwary
	124	perltodo Perl things to do
	125
fb9cefb4	126	perlhist Perl history records
4755096e	127	perldelta Perl changes since previous version
245d750e	128	perl572delta Perl changes in version 5.7.2
1db9e106 JH	129	perl571delta Perl changes in version 5.7.1
1db9e106 JH	130	perl570delta Perl changes in version 5.7.0
4755096e GS	131	perl56delta Perl changes in version 5.6
	132	perl5005delta Perl changes in version 5.005
	133	perl5004delta Perl changes in version 5.004
d516a115	134
fd7b6849 MJD	135	=head2 Platform-Specific
fd7b6849 MJD	136
37d4d706	137	perlaix Perl notes for AIX
a83b6f46 JH	138	perlamiga Perl notes for AmigaOS
	139	perlapollo Perl notes for Apollo DomainOS
	140	perlbeos Perl notes for BeOS
dc5c060f	141	perlbs2000 Perl notes for POSIX-BC BS2000
a1f19229	142	perlce Perl notes for WinCE
49877630	143	perlcygwin Perl notes for Cygwin
245d750e	144	perldgux Perl notes for DG/UX
49877630	145	perldos Perl notes for DOS
9a997319	146	perlepoc Perl notes for EPOC
49877630	147	perlhpux Perl notes for HP-UX
a83b6f46	148	perlhurd Perl notes for Hurd
da369004	149	perlmachten Perl notes for Power MachTen
26d9b02f	150	perlmacos Perl notes for Mac OS (Classic)
a83b6f46	151	perlmint Perl notes for MiNT
ab648d5e	152	perlmpeix Perl notes for MPE/iX
9038e305	153	perlnetware Perl notes for NetWare
49877630 GS	154	perlos2 Perl notes for OS/2
49877630 GS	155	perlos390 Perl notes for OS/390
a83b6f46 JH	156	perlplan9 Perl notes for Plan 9
a83b6f46 JH	157	perlqnx Perl notes for QNX
d420ca49	158	perlsolaris Perl notes for Solaris
772ff3b9	159	perltru64 Perl notes for Tru64
91144103	160	perluts Perl notes for UTS
cbe1151c	161	perlvmesa Perl notes for VM/ESA
49877630	162	perlvms Perl notes for VMS
9a997319	163	perlvos Perl notes for Stratus VOS
49877630 GS	164	perlwin32 Perl notes for Windows
49877630 GS	165
a0d0e21e	166
19799a22	167	By default, the manpages listed above are installed in the
fc952dec CS	168	F</usr/local/man/> directory.
	169
	170	Extensive additional documentation for Perl modules is available. The
	171	default configuration for perl will place this additional documentation
	172	in the F</usr/local/lib/perl5/man> directory (or else in the F<man>
	173	subdirectory of the Perl library directory). Some of this additional
	174	documentation is distributed standard with Perl, but you'll also find
	175	documentation for third-party modules there.
	176
	177	You should be able to view Perl's documentation with your man(1)
	178	program by including the proper directories in the appropriate start-up
	179	files, or in the MANPATH environment variable. To find out where the
	180	configuration has installed the manpages, type:
16d20bd9	181
760ac839	182	perl -V:man.dir
16d20bd9	183
fc952dec CS	184	If the directories have a common stem, such as F</usr/local/man/man1>
	185	and F</usr/local/man/man3>, you need only to add that stem
	186	(F</usr/local/man>) to your man(1) configuration files or your MANPATH
	187	environment variable. If they do not share a stem, you'll have to add
	188	both stems.
16d20bd9 AD	189
16d20bd9 AD	190	If that doesn't work for some reason, you can still use the
4633a7c4 LW	191	supplied F<perldoc> script to view module information. You might
4633a7c4 LW	192	also look into getting a replacement man program.
16d20bd9	193
a0d0e21e LW	194	If something strange has gone wrong with your program and you're not
	195	sure where you should look for help, try the B<-w> switch first. It
	196	will often point out exactly where the trouble is.
	197
	198	=head1 DESCRIPTION
	199
5f05dabc	200	Perl is a language optimized for scanning arbitrary
a0d0e21e LW	201	text files, extracting information from those text files, and printing
	202	reports based on that information. It's also a good language for many
	203	system management tasks. The language is intended to be practical
	204	(easy to use, efficient, complete) rather than beautiful (tiny,
94d58c47	205	elegant, minimal).
94d58c47	206
aa689395	207	Perl combines (in the author's opinion, anyway) some of the best
	208	features of C, B<sed>, B<awk>, and B<sh>, so people familiar with
	209	those languages should have little difficulty with it. (Language
	210	historians will also note some vestiges of B<csh>, Pascal, and even
14218588	211	BASIC-PLUS.) Expression syntax corresponds closely to C
a0d0e21e LW	212	expression syntax. Unlike most Unix utilities, Perl does not
a0d0e21e LW	213	arbitrarily limit the size of your data--if you've got the memory,
aa689395	214	Perl can slurp in your whole file as a single string. Recursion is of
0f31cffe	215	unlimited depth. And the tables used by hashes (sometimes called
aa689395	216	"associative arrays") grow as necessary to prevent degraded
0f31cffe	217	performance. Perl can use sophisticated pattern matching techniques to
14218588	218	scan large amounts of data quickly. Although optimized for
aa689395	219	scanning text, Perl can also deal with binary data, and can make dbm
aa689395	220	files look like hashes. Setuid Perl scripts are safer than C programs
14218588	221	through a dataflow tracing mechanism that prevents many stupid
aa689395	222	security holes.
	223
	224	If you have a problem that would ordinarily use B<sed> or B<awk> or
	225	B<sh>, but it exceeds their capabilities or must run a little faster,
	226	and you don't want to write the silly thing in C, then Perl may be for
	227	you. There are also translators to turn your B<sed> and B<awk>
	228	scripts into Perl scripts.
a0d0e21e LW	229
	230	But wait, there's more...
	231
19799a22 GS	232	Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
19799a22 GS	233	rewrite that provides the following additional benefits:
a0d0e21e	234
13a2d996	235	=over 4
a0d0e21e	236
551e1d92 RB	237	=item *
	238
	239	modularity and reusability using innumerable modules
a0d0e21e	240
19799a22	241	Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
a0d0e21e	242
551e1d92 RB	243	=item *
	244
	245	embeddable and extensible
a0d0e21e	246
19799a22 GS	247	Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlcall>,
19799a22 GS	248	L<perlguts>, and L<xsubpp>.
a0d0e21e	249
551e1d92 RB	250	=item *
	251
	252	roll-your-own magic variables (including multiple simultaneous DBM implementations)
a0d0e21e	253
19799a22	254	Described in L<perltie> and L<AnyDBM_File>.
a0d0e21e	255
551e1d92 RB	256	=item *
	257
	258	subroutines can now be overridden, autoloaded, and prototyped
a0d0e21e	259
19799a22	260	Described in L<perlsub>.
a0d0e21e	261
551e1d92 RB	262	=item *
	263
	264	arbitrarily nested data structures and anonymous functions
a0d0e21e	265
19799a22	266	Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
a0d0e21e	267
551e1d92 RB	268	=item *
	269
	270	object-oriented programming
a0d0e21e	271
19799a22	272	Described in L<perlobj>, L<perltoot>, and L<perlbot>.
a0d0e21e	273
551e1d92 RB	274	=item *
	275
	276	compilability into C code or Perl bytecode
a0d0e21e	277
19799a22	278	Described in L<B> and L<B::Bytecode>.
a0d0e21e	279
551e1d92 RB	280	=item *
	281
	282	support for light-weight processes (threads)
a0d0e21e	283
19799a22	284	Described in L<perlthrtut> and L<Thread>.
a0d0e21e	285
551e1d92 RB	286	=item *
	287
	288	support for internationalization, localization, and Unicode
a0d0e21e	289
19799a22	290	Described in L<perllocale> and L<utf8>.
a0d0e21e	291
551e1d92 RB	292	=item *
	293
	294	lexical scoping
a0d0e21e	295
19799a22	296	Described in L<perlsub>.
a0d0e21e	297
551e1d92 RB	298	=item *
	299
	300	regular expression enhancements
a0d0e21e	301
19799a22	302	Described in L<perlre>, with additional examples in L<perlop>.
a0d0e21e	303
551e1d92 RB	304	=item *
	305
	306	enhanced debugger and interactive Perl environment,
	307	with integrated editor support
a0d0e21e	308
19799a22	309	Described in L<perldebug>.
a0d0e21e	310
551e1d92 RB	311	=item *
	312
	313	POSIX 1003.1 compliant library
5f05dabc	314
19799a22	315	Described in L<POSIX>.
5f05dabc	316
a0d0e21e LW	317	=back
a0d0e21e LW	318
68dc0745	319	Okay, that's I<definitely> enough hype.
a0d0e21e	320
8e465e4e JH	321	=head1 AVAILABILITY
8e465e4e JH	322
14218588	323	Perl is available for most operating systems, including virtually
055fd3a9 GS	324	all Unix-like platforms. See L<perlport/"Supported Platforms">
055fd3a9 GS	325	for a listing.
8bc4a6bb	326
a0d0e21e LW	327	=head1 ENVIRONMENT
a0d0e21e LW	328
1e422769	329	See L<perlrun>.
a0d0e21e LW	330
	331	=head1 AUTHOR
	332
19799a22	333	Larry Wall <larry@wall.org>, with the help of oodles of other folks.
a0d0e21e	334
a99b1639 TP	335	If your Perl success stories and testimonials may be of help to others
	336	who wish to advocate the use of Perl in their applications,
	337	or if you wish to simply express your gratitude to Larry and the
19799a22	338	Perl developers, please write to perl-thanks@perl.org .
a99b1639	339
a0d0e21e LW	340	=head1 FILES
a0d0e21e LW	341
5f05dabc	342	"@INC" locations of perl libraries
a0d0e21e LW	343
	344	=head1 SEE ALSO
	345
	346	a2p awk to perl translator
	347	s2p sed to perl translator
	348
19799a22	349	http://www.perl.com/ the Perl Home Page
5a3e7812	350	http://www.perl.com/CPAN the Comprehensive Perl Archive
19799a22	351
a0d0e21e LW	352	=head1 DIAGNOSTICS
a0d0e21e LW	353
9f1b1f2d GS	354	The C<use warnings> pragma (and the B<-w> switch) produces some
9f1b1f2d GS	355	lovely diagnostics.
a0d0e21e	356
5a964f20 TC	357	See L<perldiag> for explanations of all Perl's diagnostics. The C<use
	358	diagnostics> pragma automatically turns Perl's normally terse warnings
	359	and errors into these longer forms.
a0d0e21e LW	360
	361	Compilation errors will tell you the line number of the error, with an
	362	indication of the next token or token type that was to be examined.
14218588	363	(In a script passed to Perl via B<-e> switches, each
a0d0e21e LW	364	B<-e> is counted as one line.)
	365
	366	Setuid scripts have additional constraints that can produce error
	367	messages such as "Insecure dependency". See L<perlsec>.
	368
	369	Did we mention that you should definitely consider using the B<-w>
	370	switch?
	371
	372	=head1 BUGS
	373
	374	The B<-w> switch is not mandatory.
	375
	376	Perl is at the mercy of your machine's definitions of various
1b3f7d21 CS	377	operations such as type casting, atof(), and floating-point
1b3f7d21 CS	378	output with sprintf().
a0d0e21e	379
748a9306	380	If your stdio requires a seek or eof between reads and writes on a
a0d0e21e LW	381	particular stream, so does Perl. (This doesn't apply to sysread()
	382	and syswrite().)
	383
	384	While none of the built-in data types have any arbitrary size limits
	385	(apart from memory size), there are still a few arbitrary limits: a
a30ac152 GS	386	given variable name may not be longer than 251 characters. Line numbers
	387	displayed by diagnostics are internally stored as short integers,
	388	so they are limited to a maximum of 65535 (higher numbers usually being
	389	affected by wraparound).
a0d0e21e	390
b0607b7a	391	You may mail your bug reports (be sure to include full configuration
19799a22	392	information as output by the myconfig program in the perl source
7f2de2d2	393	tree, or by C<perl -V>) to perlbug@perl.org . If you've succeeded
055fd3a9	394	in compiling perl, the B<perlbug> script in the F<utils/> subdirectory
19799a22	395	can be used to help mail in a bug report.
4633a7c4	396
a0d0e21e LW	397	Perl actually stands for Pathologically Eclectic Rubbish Lister, but
	398	don't tell anyone I said that.
	399
	400	=head1 NOTES
	401
	402	The Perl motto is "There's more than one way to do it." Divining
	403	how many more is left as an exercise to the reader.
	404
4633a7c4	405	The three principal virtues of a programmer are Laziness,
a0d0e21e	406	Impatience, and Hubris. See the Camel Book for why.
16d20bd9	407