Problem W: GPG 오류: http://shell.ninthgate.se/packages/debian wheezy InRelease: 다음 서명들은 공개키가 없기 때문에 인증할 수 없습니다: NO_PUBKEY 0B38CE01521D8275W: The repository 'http://shell.ninthgate.se/packages/debian wheezy InRelease' is not signed. Solution sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 0B38CE01521D8275