原本系統版本
$ cat /etc/debian_version
7.8
Bananian 15.08 (and later versions) will only be available for Debian 8/Jessie.
Debian 7/Wheezy is still supported and will receive kernel and security updates.
更新的方式：[@more@]
1.) 修改套件庫中的版本設定
$ sudo sed -i ‘s/wheezy/jessie/g’ /etc/apt/sources.list
2.) 更新套件庫來源
$ sudo apt-get update
3.) 更新套件
$ sudo apt-get upgrade
4.) 更新系統
$ sudo apt-get dist-upgrade
5.) 重新啟動電腦
$ sudo shutdown -r now
更新後版本
$ cat /etc/debian_version
8.1