$ sudo apt-get update $ sudo apt-get upgrade $ sudo apt-get dist-upgrade $ sudo apt-get install update-manager-core $ sudo do-release-upgrade $ sudo apt-get update Hit http://security.ubuntu.com precise-security Release.gpg Hit http://ap-northeast-1.ec2.archive.ubuntu.com precise Release.gpg Hit http://security.ubuntu.com precise-security Release Get:1 http://ap-northeast-1.ec2.archive.ubuntu.com