-my $sudo = $params->{'no-sudo'} ? '' : 'sudo ';
-my $command = "$sudo $TW_CLI info c$params->{'controller'} u$params->{'unit'} status";
+for my $thing (qw{controller unit}) {
+ if ($params->{$thing} =~ m/^([0-9]+)$/) {
+ $params->{$thing} = $1;
+ } else {
+ die("Invalid $thing $1.\n");
+ }
+};
+
+my @command;
+push @command, "sudo" if $params->{'no-sudo'};
+push @command, ($TW_CLI, 'info', "c$params->{'controller'}", "u$params->{'unit'}", "status");
+my $command = join(' ', @command);