protected function _exec($group, $subCmd, $args) {
        $keys = array_keys($args);
        $cmd = "aws $group $subCmd";
        foreach ($keys as $key) {
            $cmd .= is_numeric($key) ? ' ' : " --{$key}";
            $cmd .= true === $args[$key] ? '' : ' ' . $args[$key];
        }

        $cmd .= " --profile {$this->_profile}";
        return passthru($cmd);
    }