=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)
+ perldelta Perl changes since previous version
+
perldata Perl data structures
perlsyn Perl syntax
perlop Perl operators and precedence
perlvar Perl predefined variables
perlsub Perl subroutines
perlmod Perl modules
- perlref Perl references and nested data structures
+ perlform Perl formats
+ perllocale Perl locale support
+
+ perlref Perl references
+ 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
- perlform Perl formats
- perlipc Perl interprocess communication
perlsec Perl security
perltrap Perl traps for the unwary
perlstyle Perl style guide
- perlapi Perl application programming interface
+
+ perlpod Perl plain old documentation
+ perlbook Perl book information
+
+ perlembed Perl how to embed perl in your C or C++ app
+ 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
- perlovl Perl overloading semantics
- perlbook Perl book information
(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:
+
+ perl -V:man.dir
+
+If the directories were F</usr/local/man/man1> and F</usr/local/man/man3>,
+you would need to add only F</usr/local/man> to your MANPATH. If
+they are different, 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 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
+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,
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
+arrays. 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
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
extensibility mechanism has been added that is upwardly compatible with
all old regular expressions.
+=item * Innumerable Unbundled Modules
+
+The Comprehensive Perl Archive Network described in L<perlmod>
+contains hundreds of plug-and-play modules full of reusable
+code. See F<http://www.perl.com/CPAN> for a site near you.
+
+=item * Compilability
+
+While not yet in full production mode, a working perl-to-C compiler
+does exist. It can generate portable bytecode, simple C, or
+optimized C code.
+
=back
Ok, that's I<definitely> enough hype.
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.
+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
BEGIN { require 'perl5db.pl' }
+=item PERL_DESTRUCT_LEVEL
+
+Relevant only if your perl executable was built with B<-DDEBUGGING>,
+this controls the behavior of global destruction of objects and other
+references.
+
=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.
-
=back
+Perl also has environment variables that control how Perl handles data
+specific to particular natural languages. See L<perllocale>.
+
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
=head1 AUTHOR
-Larry Wall <F<lwall@netlabs.com.>, with the help of oodles of other folks.
+Larry Wall E<lt>F<larry@wall.org>E<gt>, with the help of oodles of other folks.
=head1 FILES
"/tmp/perl-e$$" temporary file for -e commands
- "@INC" locations of perl 5 libraries
+ "@INC" locations of perl libraries
=head1 SEE ALSO
a2p awk to perl translator
+
s2p sed to perl translator
=head1 DIAGNOSTICS
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().
+operations such as type casting, atof(), and sprintf(). The latter
+can even trigger a core dump when passed ludicrous input values.
-If your stdio requires an seek or eof between reads and writes on a
+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 identifier may not be longer than 255 characters, and no
+given variable name 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.
+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.
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 principle virtues of a programmer are Laziness,
+The three principal virtues of a programmer are Laziness,
Impatience, and Hubris. See the Camel Book for why.
+
https://perl5.git.perl.org / perl5.git / blobdiff