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

# Parse command line arguments and assign corresponding variables
GetOptions
(
    'a|add'     => \( my $ADD    = undef ),
    'r|remove'  => \( my $REMOVE = undef ),
    'd|delete'  => \( my $DELETE = undef ),
);

unless ( defined $ADD or defined $REMOVE or defined $DELETE )
{
    pod2usage( -exitval => 1, -output => \*STDERR );
}

if ($ADD) {
   ...
}

if ($REMOVE) {
   ...
}

if ($DELETE) {
   ...
}