...
use Getopt::Long;
use Pod::Usage;
...
GetOptions(
           'd|dir=s'  =>  \( my $outDir  = '.'             ),
           'f|file=s' =>  \( my $inFile                    ),
           'l|log=s'  =>  \( my $logFile = './tu_log.conf' ),
    );

unless ( $inFile ) {
    pod2usage( -exitval => 1, -output => \*STDERR );
}
...
__END__
=pod

=head1 NAME

    Retail_PickList_Generator.pl - generate picklists for outstanding Retail orders.

=head1 SYNOPSIS

    Retail_PickList_Generator.pl --file <incoming retail order file> [--log <log config file> --dir <directory to write picklists to>]

 =cut