#!/usr/bin/perl

use strict;
use warnings;
use Getopt::Long;

my $kill;
GetOptions('k:s' => \$kill,);

if(! defined $kill){
    print '$kill is not defined';
}
elsif($kill eq ''){
    print '$kill is ""';
}
elsif(defined $kill){
    print '$kill is defined and is not ""';
}
else{
    print "else";
}