usage.pm

mrtg 监控,请认真阅读您的文件包然后写出其具体功能

              -exitval => 2,
              -verbose => 0,
              -output  => \*STDERR);

Each of the following invocations of C<pod2usage()> will print the
"SYNOPSIS" section and any "OPTIONS" and/or "ARGUMENTS" sections to
C<STDOUT> and will exit with a status of 1:

    pod2usage(1);

    pod2usage(-verbose => 1);

    pod2usage(-exitval => 1);

    pod2usage({-exitval => 1, -output => \*STDOUT});

    pod2usage({-verbose => 1, -output => \*STDOUT});

    pod2usage(-exitval => 1, -verbose => 1);

    pod2usage(-exitval => 1, -verbose => 1, -output => \*STDOUT});

Each of the following invocations of C<pod2usage()> will print the
entire manual page to C<STDOUT> and will exit with a status of 1:

    pod2usage(-verbose  => 2);

    pod2usage({-verbose => 2, -output => \*STDOUT});

    pod2usage(-exitval  => 1, -verbose => 2);

    pod2usage({-exitval => 1, -verbose => 2, -output => \*STDOUT});

=head2 Recommended Use

Most scripts should print some type of usage message to C<STDERR> when a
command line syntax error is detected. They should also provide an
option (usually C<-H> or C<-help>) to print a (possibly more verbose)
usage message to C<STDOUT>. Some scripts may even wish to go so far as to
provide a means of printing their complete documentation to C<STDOUT>
(perhaps by allowing a C<-man> option). The following complete example
uses B<Pod::Usage> in combination with B<Getopt::Long> to do all of these
things:

    use Getopt::Long;
    use Pod::Usage;

    my $man = 0;
    my $help = 0;
    ## Parse options and print usage if there is a syntax error,
    ## or if usage was explicitly requested.
    GetOptions('help|?' => \$help, man => \$man) or pod2usage(2);
    pod2usage(1) if $help;
    pod2usage(-verbose => 2) if $man;

    ## If no arguments were given, then allow STDIN to be used only
    ## if it's not connected to a terminal (otherwise print usage)
    pod2usage("$0: No files given.")  if ((@ARGV == 0) && (-t STDIN));
    __END__

    =head1 NAME

    sample - Using GetOpt::Long and Pod::Usage

    =head1 SYNOPSIS

    sample [options] [file ...]

     Options:
       -help            brief help message
       -man             full documentation

    =head1 OPTIONS

    =over 8

    =item B<-help>

    Print a brief help message and exits.

    =item B<-man>

    Prints the manual page and exits.

    =back

    =head1 DESCRIPTION

    B<This program> will read the given input file(s) and do something
    useful with the contents thereof.

    =cut

=head1 CAVEATS

By default, B<pod2usage()> will use C<$0> as the path to the pod input
file.  Unfortunately, not all systems on which Perl runs will set C<$0>
properly (although if C<$0> isn't found, B<pod2usage()> will search
C<$ENV{PATH}> or else the list specified by the C<-pathlist> option).
If this is the case for your system, you may need to explicitly specify
the path to the pod docs for the invoking script using something
similar to the following:

    pod2usage(-exitval => 2, -input => "/path/to/your/pod/docs");

=head1 AUTHOR

Brad Appleton E<lt>[e-mail]<gt>

Based on code for B<Pod::Text::pod2text()> written by
Tom Christiansen E<lt>[e-mail]<gt>

=head1 ACKNOWLEDGEMENTS

Steven McDougall E<lt>[e-mail]<gt> for his help and patience
with re-writing this manpage.

=cut

#############################################################################

use strict;
#use diagnostics;
use Carp;
use Exporter;
use File::Spec;

use vars qw(@ISA @EXPORT);
@EXPORT = qw(&pod2usage);
BEGIN {
    if ( $] >= 5.005_58 ) {
       require Pod::Text;
       @ISA = qw( Pod::Text );
    }
    else {
       require Pod::PlainText;
       @ISA = qw( Pod::PlainText );
    }
}


##---------------------------------------------------------------------------

##---------------------------------
## Function definitions begin here
##---------------------------------

sub pod2usage {
    local($_) = shift || "";
    my %opts;
    ## Collect arguments
    if (@_ > 0) {
        ## Too many arguments - assume that this is a hash and
        ## the user forgot to pass a reference to it.
        %opts = ($_, @_);
    }
    elsif (ref $_) {
        ## User passed a ref to a hash
        %opts = %{$_}  if (ref($_) eq 'HASH');
    }
    elsif (/^[-+]?\d+$/) {
        ## User passed in the exit value to use
        $opts{"-exitval"} =  $_;
    }
    else {
        ## User passed in a message to print before issuing usage.
        $_  and  $opts{"-message"} = $_;
    }

    ## Need this for backward compatibility since we formerly used
    ## options that were all uppercase words rather than ones that
    ## looked like Unix command-line options.
    ## to be uppercase keywords)
    %opts = map {
        my $val = $opts{$_};
        s/^(?=\w)/-/;
        /^-msg/i   and  $_ = '-message';
        /^-exit/i  and  $_ = '-exitval';
        lc($_) => $val;    
    } (keys %opts);

    ## Now determine default -exitval and -verbose values to use
    if ((! defined $opts{"-exitval"}) && (! defined $opts{"-verbose"})) {
        $opts{"-exitval"} = 2;
        $opts{"-verbose"} = 0;
    }
    elsif (! defined $opts{"-exitval"}) {
        $opts{"-exitval"} = ($opts{"-verbose"} > 0) ? 1 : 2;
    }
    elsif (! defined $opts{"-verbose"}) {
        $opts{"-verbose"} = ($opts{"-exitval"} < 2);
    }

    ## Default the output file
    $opts{"-output"} = ($opts{"-exitval"} < 2) ? \*STDOUT : \*STDERR
            unless (defined $opts{"-output"});
    ## Default the input file
    $opts{"-input"} = $0  unless (defined $opts{"-input"});

    ## Look up input file in path if it doesnt exist.
    unless ((ref $opts{"-input"}) || (-e $opts{"-input"})) {
        my ($dirname, $basename) = ('', $opts{"-input"});
        my $pathsep = ($^O =~ /^(?:dos|os2|MSWin32)$/) ? ";"
                            : (($^O eq 'MacOS') ? ',' :  ":");
        my $pathspec = $opts{"-pathlist"} || $ENV{PATH} || $ENV{PERL5LIB};

        my @paths = (ref $pathspec) ? @$pathspec : split($pathsep, $pathspec);
        for $dirname (@paths) {
            $_ = File::Spec->catfile($dirname, $basename)  if length;
            last if (-e $_) && ($opts{"-input"} = $_);
        }
    }

    ## Now create a pod reader and constrain it to the desired sections.
    my $parser = new Pod::Usage(USAGE_OPTIONS => \%opts);
    if ($opts{"-verbose"} == 0) {
        $parser->select("SYNOPSIS");
    }
    elsif ($opts{"-verbose"} == 1) {
        my $opt_re = '(?i)' .
                     '(?:OPTIONS|ARGUMENTS)' .
                     '(?:\s*(?:AND|\/)\s*(?:OPTIONS|ARGUMENTS))?';
        $parser->select( 'SYNOPSIS', $opt_re, "DESCRIPTION/$opt_re" );
    }

    ## Now translate the pod document and then exit with the desired status
    $parser->parse_from_file($opts{"-input"}, $opts{"-output"});
    exit($opts{"-exitval"});
}

##---------------------------------------------------------------------------

##-------------------------------
## Method definitions begin here
##-------------------------------

sub new {
    my $this = shift;
    my $class = ref($this) || $this;
    my %params = @_;
    my $self = {%params};
    bless $self, $class;
    $self->initialize();
    return $self;
}

sub begin_pod {
    my $self = shift;
    $self->SUPER::begin_pod();  ## Have to call superclass
    my $msg = $self->{USAGE_OPTIONS}->{-message}  or  return 1;
    my $out_fh = $self->output_handle();
    print $out_fh "$msg\n";
}

sub preprocess_paragraph {
    my $self = shift;
    local $_ = shift;
    my $line = shift;
    ## See if this is a heading and we arent printing the entire manpage.
    if (($self->{USAGE_OPTIONS}->{-verbose} < 2) && /^=head/) {
        ## Change the title of the SYNOPSIS section to USAGE
        s/^=head1\s+SYNOPSIS\s*$/=head1 USAGE/;
        ## Try to do some lowercasing instead of all-caps in headings
        s{([A-Z])([A-Z]+)}{((length($2) > 2) ? $1 : lc($1)) . lc($2)}ge;
        ## Use a colon to end all headings
        s/\s*$/:/  unless (/:\s*$/);
        $_ .= "\n";
    }
    return  $self->SUPER::preprocess_paragraph($_);
}