my @stamp_files = qw(/var/lib/apt/update_success /var/lib/apt/periodic/update-stamp /var/lib/apt/lists/lock);
my $last_update;
foreach my $stamp_file (@stamp_files) {
	$last_update = -M $stamp_file;
	last if $last_update;
}

my $updatecolor;
if ($last_update >= 7) {
	$updatecolor = 'red';
} elsif ($last_update >= 1.5) {
	$updatecolor = 'yellow';
} else {
	$updatecolor = 'green';
}