执行更新数据(sudo apt-get update)提示:

Err http://mirrors.aliyun.com trusty Release.gpg
Could not resolve 'mirrors.aliyun.com'
Err http://mirrors.aliyun.com trusty-updates Release.gpg
Could not resolve 'mirrors.aliyun.com'
Err http://mirrors.aliyun.com trusty-backports Release.gpg
Could not resolve 'mirrors.aliyun.com'
Err http://mirrors.aliyun.com trusty-security Release.gpg

解法就是配置DNS文件

sudo gedit /etc/resolv.conf

加上下面两行
nameserver 8.8.8.8
nameserver 8.8.4.4

然后

sudo /etc/init.d/networking restart

sudo apt-get update

sudo apt-get upgrade