following signatures couldn't be verified because the public key is not available: NO_PUBKEY 2F7F0DA5FD5B64B9具体来说,我得到了错误
nik@nik:~$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 2F7F0DA5FD5B64B9Executing: /tmp/apt-key-gpghome.uWb8bIzMR8/