在使用ubuntu进行开发，会有如下提示
Welcome to Ubuntu 12.04.5 LTS (GNU/Linux 3.4.0-030400-generic i686)
* Documentation: https://help.ubuntu.com/
New release '14.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.禁用方法：
vim /etc/update-manager/release-upgrades
设置Prompt=never