Do you mean pass command-line arguments? If so, checkout the module Getopt::Long. Otherwise, are you looking for something like below?

#!/usr/bin/perl -w
use strict;
use IO::Dir;

my $oggdir = '/media/tmp/';
ParseDirectory($oggdir);

sub ParseDirectory
{
    my $dir = shift;
    my $d = IO::Dir->new($dir)
       or die "Can not open directory $dir for read!";

    while (defined(my $f = $d->read))
    {
        if ($f =~ /.*_+.*\.[Oo][Gg]{2}$/) {

            # matching files

            my $new_name = $f;
            $new_name =~ s/_//;    # remove _
            # rename $f to $new_name, etc.
        } else {

            # non-matching files

            # do whatever, set to default, etc.
        }
    }
}
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And an example of using Getopt::Long to parse command-line arguments:

#!/usr/local/bin/perl -w
use strict;
use Getopt::Long;

# Parse command line arguments and assign corresponding variables
GetOptions
(
    'i|init=s'   => \( my $INIT = undef ), # Specify the root director
+y
    'u|upload'   => \( my $UPLOAD = undef ),
    'v|verbose'  => \( my $VERBOSE  = 0 ),
);

unless ( defined $INIT )
{
    print <<EOF
Kapiti Exception Report
Usage: $0 [options]
Options:
-i|--init [file]    Specify the path to initialization file
-u|--upload         Upload the result into database
-v|--verbose        Let the report generator print more information

EOF
;
    exit(1);
}

# continue on...
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