將 ftp.us.debian.org 設為軟體來源 , Debian 8 ( Jessie )

在 Terminal (終端機) 依次執行以下指令 :
su
nano /etc/apt/sources.list


將 /etc/apt/sources.list 內容更改如下 :

deb http://ftp.us.debian.org/debian/ jessie main contrib non-free
deb-src http://ftp.us.debian.org/debian/ jessie main contrib non-free

deb http://security.debian.org/ jessie/updates main contrib non-free
deb-src http://security.debian.org/ jessie/updates main contrib non-free

deb http://ftp.us.debian.org/debian/ jessie-updates main contrib non-free
deb-src http://ftp.us.debian.org/debian/ jessie-updates main contrib non-free


儲存改好的 /etc/apt/sources.list  檔

(  Ctrl + O  儲存檔案
   Ctrl + X  離開           )

之後在 Terminal (終端機) 依次執行以下指令 :
su
aptitude clean
aptitude update
aptitude full-upgrade
aptitude clean
exit
(   或
su
aptitude clean; aptitude update; aptitude full-upgrade; aptitude clean
exit
或
su
apt-get clean; apt-get update; apt-get upgrade; apt-get dist-upgrade; apt-get clean
exit      )

參考文章 :
https://www.debian.org/doc/manuals/debian-faq/ch-uptodate.en.html