#!/usr/bin/perl -w
 
use strict;
 
my $sudo_binary     = "/usr/bin/sudo";
my $apt_get_binary  = "/usr/bin/apt-get";
my $command         = "$sudo_binary $apt_get_binary update";
my $output          = `$command`;
 
$command            = "$sudo_binary $apt_get_binary -s upgrade";
$output             = `$command`;
my @lines           = split(/\n/,$output);
 
foreach(@lines){
    if($_ =~ /^([0-9]+)\s+upgraded/){
        if($1 > 0){
            print "CRITICAL - There are $1 updates available\n";
            exit 2;
        }
        else{
            print "OK - System up to date";
            exit 0;
        }
    }
}
print "UNKNOWN - Unable to run apt-get update/upgrade";
exit 3;