gpg：no valid openpgp data found

使用wget-q https://www.virtualbox.org/download/oracle_vbox_2016.asc -O- | sudo apt-key add - 时报错：gpg：no valid openpgp data found

解决办法：

　　wget-q https://www.virtualbox.org/download/oracle_vbox_2016.asc

　　sudo apt-key add oracle_vbox_2016.asc