[perl #948] [PATCH] Allow tied $,

[perl5.git] / pod / perldoc.pod

=head1 NAME

perldoc - Look up Perl documentation in Pod format.

=head1 SYNOPSIS

B<perldoc> [B<-h>] [B<-D>] [B<-t>] [B<-u>] [B<-m>] [B<-l>] [B<-F>]
[B<-i>] [B<-V>] [B<-T>] [B<-r>]
[B<-dI<destination_file>>]
[B<-oI<formatname>>]
[B<-MI<FormatterClassName>>]
[B<-wI<formatteroption:value>>]
[B<-n>I<nroff-replacement>]
[B<-X>]
[B<-L> I<language_code>]
PageName|ModuleName|ProgramName

B<perldoc> B<-f> BuiltinFunction

B<perldoc> B<-L> it B<-f> BuiltinFunction

B<perldoc> B<-q> FAQ Keyword

B<perldoc> B<-L> fr B<-q> FAQ Keyword

B<perldoc> B<-v> PerlVariable

See below for more description of the switches.

=head1 DESCRIPTION

I<perldoc> looks up a piece of documentation in .pod format that is embedded
in the perl installation tree or in a perl script, and displays it via
C<pod2man | nroff -man | $PAGER>. (In addition, if running under HP-UX,
C<col -x> will be used.) This is primarily used for the documentation for
the perl library modules.

Your system may also have man pages installed for those modules, in
which case you can probably just use the man(1) command.

If you are looking for a table of contents to the Perl library modules
documentation, see the L<perltoc> page.

=head1 OPTIONS

=over 5

=item B<-h>

Prints out a brief B<h>elp message.

=item B<-D>

B<D>escribes search for the item in B<d>etail.

=item B<-t>

Display docs using plain B<t>ext converter, instead of nroff. This may be faster,
but it probably won't look as nice.

=item B<-u>

Skip the real Pod formatting, and just show the raw Pod source (B<U>nformatted)

=item B<-m> I<module>

Display the entire module: both code and unformatted pod documentation.
This may be useful if the docs don't explain a function in the detail
you need, and you'd like to inspect the code directly; perldoc will find
the file for you and simply hand it off for display.

=item B<-l>

Display onB<l>y the file name of the module found.

=item B<-F>

Consider arguments as file names; no search in directories will be performed.

=item B<-f> I<perlfunc>

The B<-f> option followed by the name of a perl built in function will
extract the documentation of this function from L<perlfunc>.

Example:

      perldoc -f sprintf


=item B<-q> I<perlfaq-search-regexp>

The B<-q> option takes a regular expression as an argument.  It will search
the B<q>uestion headings in perlfaq[1-9] and print the entries matching
the regular expression.

Example:

     perldoc -q shuffle


=item B<-v> I<perlvar>

The B<-v> option followed by the name of a Perl predefined variable will
extract the documentation of this variable from L<perlvar>.

Examples:

     perldoc -v '$"'
     perldoc -v @+
     perldoc -v DATA


=item B<-T>

This specifies that the output is not to be sent to a pager, but is to
be sent right to STDOUT.

=item B<-d> I<destination-filename>

This specifies that the output is to be sent neither to a pager nor
to STDOUT, but is to be saved to the specified filename.  Example:
C<perldoc -oLaTeX -dtextwrapdocs.tex Text::Wrap>

=item B<-o> I<output-formatname>

This specifies that you want Perldoc to try using a Pod-formatting
class for the output format that you specify.  For example:
C<-oman>.  This is actually just a wrapper around the C<-M> switch;
using C<-oI<formatname>> just looks for a loadable class by adding
that format name (with different capitalizations) to the end of
different classname prefixes.

For example, C<-oLaTeX> currently tries all of the following classes:
Pod::Perldoc::ToLaTeX Pod::Perldoc::Tolatex Pod::Perldoc::ToLatex
Pod::Perldoc::ToLATEX Pod::Simple::LaTeX Pod::Simple::latex
Pod::Simple::Latex Pod::Simple::LATEX Pod::LaTeX Pod::latex Pod::Latex
Pod::LATEX.

=item B<-M> I<module-name>

This specifies the module that you want to try using for formatting the
pod.  The class must at least provide a C<parse_from_file> method.
For example: C<perldoc -MPod::Perldoc::ToChecker>.

You can specify several classes to try by joining them with commas
or semicolons, as in C<-MTk::SuperPod;Tk::Pod>.

=item B<-w> I<option:value> or B<-w> I<option> 

This specifies an option to call the formatter B<w>ith.  For example,
C<-w textsize:15> will call
C<< $formatter->textsize(15) >> on the formatter object before it is
used to format the object.  For this to be valid, the formatter class
must provide such a method, and the value you pass should be valid.
(So if C<textsize> expects an integer, and you do C<-w textsize:big>,
expect trouble.)

You can use C<-w optionname> (without a value) as shorthand for
C<-w optionname:I<TRUE>>.  This is presumably useful in cases of on/off
features like: C<-w page_numbering>.

You can use a "=" instead of the ":", as in: C<-w textsize=15>.  This
might be more (or less) convenient, depending on what shell you use.

=item B<-X>

Use an index if it is present -- the B<-X> option looks for an entry
whose basename matches the name given on the command line in the file
C<$Config{archlib}/pod.idx>. The F<pod.idx> file should contain fully
qualified filenames, one per line.

=item B<-L> I<language_code>

This allows to specify the I<language code> for desired language translation.
If C<POD2::E<lt>language_codeE<gt>> package doesn't exist (or isn't installed
in your system), the switch will be ignored. 
All available translation packages should be found under the C<POD2::>
namespace. See L<POD2::IT> (or L<POD2::FR>) in order to see how to create and
integrate new localized C<POD2::*> pod documentation packages in
L<Pod::Perldoc>.

=item B<PageName|ModuleName|ProgramName>

The item you want to look up.  Nested modules (such as C<File::Basename>)
are specified either as C<File::Basename> or C<File/Basename>.  You may also
give a descriptive name of a page, such as C<perlfunc>.

For simple names like 'foo', when the normal search fails to find
a matching page, a search with the "perl" prefix is tried as well.
So "perldoc intro" is enough to find/render "perlintro.pod".

=item B<-n> I<some-formatter>

Specify replacement for nroff

=item B<-r>

Recursive search.

=item B<-i>

Ignore case.

=item B<-V>

Displays the version of perldoc you're running.

=back



=head1 SECURITY

Because B<perldoc> does not run properly tainted, and is known to
have security issues, when run as the superuser it will attempt to
drop privileges by setting the effective and real IDs to nobody's
or nouser's account, or -2 if unavailable.  If it cannot relinquish
its privileges, it will not run.  


=head1 ENVIRONMENT

Any switches in the C<PERLDOC> environment variable will be used before the
command line arguments.

Useful values for C<PERLDOC> include C<-oman>, C<-otext>, C<-otk>, C<-ortf>,
C<-oxml>, and so on, depending on what modules you have on hand; or
exactly specify the formatter class with C<-MPod::Perldoc::ToMan>
or the like.

C<perldoc> also searches directories
specified by the C<PERL5LIB> (or C<PERLLIB> if C<PERL5LIB> is not
defined) and C<PATH> environment variables.
(The latter is so that embedded pods for executables, such as
C<perldoc> itself, are available.)

C<perldoc> will use, in order of preference, the pager defined in
C<PERLDOC_PAGER>, C<MANPAGER>, or C<PAGER> before trying to find a pager
on its own. (C<MANPAGER> is not used if C<perldoc> was told to display
plain text or unformatted pod.)

One useful value for C<PERLDOC_PAGER> is C<less -+C -E>.

Having PERLDOCDEBUG set to a positive integer will make perldoc emit
even more descriptive output than the C<-v> switch does -- the higher the
number, the more it emits.


=head1 CHANGES

Up to 3.14_05, the switch B<-v> was used to produce verbose
messages of B<perldoc> operation, which is now enabled by B<-D>.


=head1 AUTHOR

Current maintainer: Adriano R. Ferreira <ferreira@cpan.org>

Past contributors are:
Sean M. Burke <sburke@cpan.org>,
Kenneth Albanowski <kjahds@kjahds.com>,
Andy Dougherty  <doughera@lafcol.lafayette.edu>,
and many others.

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