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。