ubuntu14.04 报错 The following signatures couldn't be verified because the public key is not available

报错：

W: GPG error: http://repo.mysql.com trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8C718D3B5072E1F5

解决方法：

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv 8C718D3B5072E1F5

gpg -a --export 8C718D3B5072E1F5 | sudo apt-key add -

记录下。