There are a number of ways to reduce some of this. The easiest way to get rid of the if's is probably something like:

Another simple way of setting defaults is to set them up before using Getopt::Long:

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

my ($lines, $cols) = (5, 16);

GetOptions ('line=s' => \$lines, 'col=s' => \$cols);

print "Lines: $lines Cols: $cols\n";
[download]

A very simple example I know, but it illustrates the point :)

Update: jcwren pointed out that I failed to mention this has a potential failure if you use '||' - if you want to set a value to '0', you won't be able to unless the default is also '0'. I advise pre-setting the defaults, and then letting the user override them - much simpler :) Thanks, jcwren.