protected function validateServer($server)
    {
        if (in_array($server, array_keys($this->servers)))
        {
            // Get server options
            $options = $this->config->get($server);

            if (!$options || $options['host'] === 'yoursite') {
                throw new \Exception("Remote server \"{$server}\" not setup in remote.yml.");
            }

            if (shell_exec("which {$this->servers[$server]}") == '') {
                throw new \Exception("Shell command '' is required to publish using {$server}");
            }

            return true;
        }

        throw new \Exception("Unknown remote server: \"{$server}\"");
    }