=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> ]...>
+
For ease of access, the Perl manual has been split up into a number
of sections:
- perl Perl overview (this section)
- perltoc Perl documentation table of contents
- perldata Perl data structures
- perlsyn Perl syntax
- perlop Perl operators and precedence
- perlre Perl regular expressions
- perlrun Perl execution and options
- perlfunc Perl builtin functions
- perlvar Perl predefined variables
- perlsub Perl subroutines
- perlmod Perl modules
- perlref Perl references
- perldsc Perl data structures intro
- perllol Perl data structures: lists of lists
- perlobj Perl objects
- perltie Perl objects hidden behind simple variables
- perlbot Perl OO tricks and examples
- perldebug Perl debugging
- perldiag Perl diagnostic messages
- perlform Perl formats
- perlipc Perl interprocess communication
- perlsec Perl security
- perltrap Perl traps for the unwary
- perlstyle Perl style guide
- perlxs Perl XS application programming interface
- perlxstut Perl XS tutorial
- perlguts Perl internal functions for those doing extensions
- perlcall Perl calling conventions from C
- perlembed Perl how to embed perl in your C or C++ app
- perlpod Perl plain old documentation
- perlbook Perl book information
+ perl Perl overview (this section)
+ perldelta Perl changes since previous version
+ perl5005delta Perl changes in version 5.005
+ perl5004delta Perl changes in version 5.004
+ perlfaq Perl frequently asked questions
+ perltoc Perl documentation table of contents
+
+ perldata Perl data structures
+ perlsyn Perl syntax
+ perlop Perl operators and precedence
+ perlre Perl regular expressions
+ perlrun Perl execution and options
+ perlfunc Perl builtin functions
+ perlvar Perl predefined variables
+ perlsub Perl subroutines
+ perlmod Perl modules: how they work
+ perlmodlib Perl modules: how to write and use
+ perlmodinstall Perl modules: how to install from CPAN
+ perlform Perl formats
+ perllocale Perl locale support
+
+ perlref Perl references
+ perlreftut Perl references short introduction
+ perldsc Perl data structures intro
+ perllol Perl data structures: lists of lists
+ perltoot Perl OO tutorial
+ perlobj Perl objects
+ perltie Perl objects hidden behind simple variables
+ perlbot Perl OO tricks and examples
+ perlipc Perl interprocess communication
+
+ perldebug Perl debugging
+ perldiag Perl diagnostic messages
+ perlsec Perl security
+ perltrap Perl traps for the unwary
+ perlport Perl portability guide
+ perlstyle Perl style guide
+
+ perlpod Perl plain old documentation
+ perlbook Perl book information
+
+ perlembed Perl ways to embed perl in your C or C++ application
+ perlapio Perl internal IO abstraction interface
+ perlxs Perl XS application programming interface
+ perlxstut Perl XS tutorial
+ perlguts Perl internal functions for those doing extensions
+ perlcall Perl calling conventions from C
+
+ perlhist Perl history records
(If you're intending to read these straight through for the first time,
the suggested order will tend to reduce the number of forward references.)
-Additional documentation for Perl modules is available in the
-F</usr/local/man/> directory. Some of this is distributed standard with
-Perl, but you'll also find third-party modules there. You should be able
-to view this with your man(1) program by including the proper directories
-in the appropriate start-up files. To find out where these are, type:
+By default, all of the above manpages 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 -le 'use Config; print "@Config{man1dir,man3dir}"'
+ perl -V:man.dir
-If the directories were F</usr/local/man/man1> and F</usr/local/man/man3>,
-you would only need to add F</usr/local/man> to your MANPATH. If
-they are different, you'll have to add both stems.
+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
=head1 DESCRIPTION
-Perl is an interpreted language optimized for scanning arbitrary
+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). It 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 quite closely to C
+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 quite 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 hash tables used by associative arrays
-grow as necessary to prevent degraded performance. Perl uses
-sophisticated pattern matching techniques to scan large amounts of data
-very quickly. Although optimized for scanning text, Perl can also
-deal with binary data, and can make dbm files look like associative
-arrays (where dbm is available). Setuid Perl scripts are safer than
-C programs through a dataflow tracing mechanism which 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.
+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 very 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 which 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...
Perl variables may now be declared within a lexical scope, like "auto"
variables in C. Not only is this more efficient, but it contributes
-to better privacy for "programming in the large".
+to better privacy for "programming in the large". Anonymous
+subroutines exhibit deep binding of lexical variables (closures).
=item * Arbitrarily nested data structures
virtual methods are supported in a straightforward manner and with very
little new syntax. Filehandles may now be treated as objects.
-=item * Embeddible and Extensible
+=item * Embeddable and Extensible
Perl may now be embedded easily in your C or C++ application, and can
either call or be called by your routines through a documented
interface. The XS preprocessor is provided to make it easy to glue
your C or C++ routines into Perl. Dynamic loading of modules is
-supported.
+supported, and Perl itself can be made into a dynamic library.
=item * POSIX compliant
=item * Subroutine definitions may now be autoloaded
In fact, the AUTOLOAD mechanism also allows you to define any arbitrary
-semantics for undefined subroutine calls. It's not just for autoloading.
+semantics for undefined subroutine calls. It's not for just autoloading.
=item * Regular expression enhancements
-You can now specify non-greedy quantifiers. You can now do grouping
+You can now specify nongreedy quantifiers. You can now do grouping
without creating a backreference. You can now write regular expressions
with embedded whitespace and comments for readability. A consistent
extensibility mechanism has been added that is upwardly compatible with
all old regular expressions.
-=back
-
-Ok, that's I<definitely> enough hype.
-
-=head1 ENVIRONMENT
-
-=over 12
-
-=item HOME
-
-Used if chdir has no argument.
-
-=item LOGDIR
+=item * Innumerable Unbundled Modules
-Used if chdir has no argument and HOME is not set.
+The Comprehensive Perl Archive Network described in L<perlmodlib>
+contains hundreds of plug-and-play modules full of reusable code.
+See F<http://www.perl.com/CPAN> for a site near you.
-=item PATH
+=item * Compilability
-Used in executing subprocesses, and in finding the script if B<-S> is
-used.
-
-=item PERL5LIB
-
-A colon-separated list of directories in which to look for Perl library
-files before looking in the standard library and the current
-directory. If PERL5LIB is not defined, PERLLIB is used. When running
-taint checks (because the script was running setuid or setgid, or the
-B<-T> switch was used), neither variable is used. The script should
-instead say
-
- use lib "/my/directory";
-
-=item PERL5DB
-
-The command used to get the debugger code. If unset, uses
-
- BEGIN { require 'perl5db.pl' }
-
-=item PERLLIB
-
-A colon-separated list of directories in which to look for Perl library
-files before looking in the standard library and the current
-directory. If PERL5LIB is defined, PERLLIB is not used.
+While not yet in full production mode, a working perl-to-C compiler
+does exist. It can generate portable byte code, simple C, or
+optimized C code.
=back
-Apart from these, Perl uses no other environment variables, except
-to make them available to the script being executed, and to child
-processes. However, scripts running setuid would do well to execute
-the following lines before doing anything else, just to keep people
-honest:
+Okay, that's I<definitely> enough hype.
+
+=head1 ENVIRONMENT
- $ENV{'PATH'} = '/bin:/usr/bin'; # or whatever you need
- $ENV{'SHELL'} = '/bin/sh' if defined $ENV{'SHELL'};
- $ENV{'IFS'} = '' if defined $ENV{'IFS'};
+See L<perlrun>.
=head1 AUTHOR
-Larry Wall E<lt><F<lwall@netlabs.com>E<gt>, with the help of oodles of other folks.
+Larry Wall <F<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 <F<perl-thanks@perl.org>>.
=head1 FILES
- "/tmp/perl-e$$" temporary file for -e commands
- "@INC" locations of perl 5 libraries
+ "@INC" locations of perl libraries
=head1 SEE ALSO
The B<-w> switch produces some lovely diagnostics.
-See L<perldiag> for explanations of all Perl's 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.
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 sprintf(). The latter
-can even trigger a coredump when passed ludicrous input values.
+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()
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 identifier may not be longer than 255 characters, and no
-component of your PATH may be longer than 255 if you use B<-S>. A regular
-expression may not compile to more than 32767 bytes internally.
-
-See the perl bugs database at F<http://perl.com/perl/bugs/>. You may
-mail your bug reports (be sure to include full configuration information
-as output by the myconfig program in the perl source tree) to
-F<perlbug@perl.com>.
+given variable name may not be longer than 251 characters.
+
+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 <F<perlbug@perl.com>>.
+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.
https://perl5.git.perl.org / perl5.git / blobdiff