GPG error NO_PUBKEY

更新源/etc/apt/sources.list之后，sudo apt-get update，出现错误

W: GPG error: http://archive.raspbian.org wheezy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY ****************

解决方法：sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ****************

（****************代替出现的码）

参考http://askubuntu.com/questions/20725/gpg-error-the-following-signatures-couldnt-be-verified-because-the-public-key