protected function processInputFiles()
    {
        $passwords = array();
        foreach ($this->_files as $handle => $file) {
            $this->addArg($handle.'=',$file['name']);
            if ($file['password']!==null) {
                $passwords[$handle] = $file['password'];
            }
        }
        if ($passwords!==array()) {
            $this->addArg('input_pw');
            foreach ($passwords as $handle => $password) {
                $this->addArg($handle.'=', $password);
            }
        }
    }