软件源就是一个应用程序安装库，很多很多的应用软件都在这个库里面。他可以是网络服务器，是光盘，甚至是硬盘上的一个目录。作为debian系的ubuntu,继承了debian的deb和apt系统，只要设定好软件源，就能很方便的安装软件了。ubuntu是基于debian的，debian使用的是一种後缀名为.deb的安装软件包。ubuntu的源，也就是一个个装着无数deb安装包的软件库。新立得和添加/删除就是一种帮我们找到所需要的deb包的方法。有时候，我们也会根据需要自己安装deb包。先下载deb包，然後双击，按提示输入密码，就可以轻轻松松的安装软件了。
默认的中国源速度非常不错，为了保证源内软件的齐全，建议电信用户添加cn99或台湾大学的源，建议网通用户添加UBNTU官方或台湾大学的源。
在终端输入并运行
sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup （备份当前的源列表，以便日後需要时恢复）
vi /etc/apt/sources.list （修改sources.list文件中源的列表）
sources.lis t文件中注释原有的并添加
#cn99.com 源更新服务器（江苏省常州市电信，推荐电信用户使用）：deb http://ubuntu.cn99.com/ubuntu/ gutsy main restricted universe multiversedeb http://ubuntu.cn99.com/ubuntu/ gutsy-security main restricted universe multiversedeb http://ubuntu.cn99.com/ubuntu/ gutsy-updates main restricted universe multiversedeb http://ubuntu.cn99.com/ubuntu/ gutsy-proposed main restricted universe multiversedeb http://ubuntu.cn99.com/ubuntu/ gutsy-backports main restricted universe multiversedeb-src http://ubuntu.cn99.com/ubuntu/ gutsy main restricted universe multiversedeb-src http://ubuntu.cn99.com/ubuntu/ gutsy-security main restricted universe multiversedeb-src http://ubuntu.cn99.com/ubuntu/ gutsy-updates main restricted universe multiversedeb-src http://ubuntu.cn99.com/ubuntu/ gutsy-proposed main restricted universe multiversedeb-src http://ubuntu.cn99.com/ubuntu/ gutsy-backports main restricted universe multiverse#Mirror.lupaworld.com 源更新服务器（浙江省杭州市双线服务器，网通同电信都可以用，亚洲地区官方更新服务器）：deb http://mirror.lupaworld.com/ubuntu gutsy main restricted universe multiversedeb http://mirror.lupaworld.com/ubuntu gutsy-security main restricted universe multiversedeb http://mirror.lupaworld.com/ubuntu gutsy-updates main restricted universe multiversedeb http://mirror.lupaworld.com/ubuntu gutsy-backports main restricted universe multiversedeb-src http://mirror.lupaworld.com/ubuntu gutsy main restricted universe multiversedeb-src http://mirror.lupaworld.com/ubuntu gutsy-security main restricted universe multiversedeb-src http://mirror.lupaworld.com/ubuntu gutsy-updates main restricted universe multiversedeb-src http://mirror.lupaworld.com/ubuntu gutsy-backports main restricted universe multiverse#Ubuntu 官方源 deb http://archive.ubuntu.com/ubuntu/ gutsy main restricted universe multiversedeb http://archive.ubuntu.com/ubuntu/ gutsy-security main restricted universe multiversedeb http://archive.ubuntu.com/ubuntu/ gutsy-updates main restricted universe multiversedeb http://archive.ubuntu.com/ubuntu/ gutsy-proposed main restricted universe multiversedeb http://archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiversedeb-src http://archive.ubuntu.com/ubuntu/ gutsy main restricted universe multiversedeb-src http://archive.ubuntu.com/ubuntu/ gutsy-security main restricted universe multiversedeb-src http://archive.ubuntu.com/ubuntu/ gutsy-updates main restricted universe multiversedeb-src http://archive.ubuntu.com/ubuntu/ gutsy-proposed main restricted universe multiversedeb-src http://archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse#台湾的官方源deb http://tw.archive.ubuntu.com/ubuntu gutsy main restricted universe multiversedeb http://tw.archive.ubuntu.com/ubuntu gutsy-security main restricted universe multiversedeb http://tw.archive.ubuntu.com/ubuntu gutsy-updates main restricted universe multiversedeb http://tw.archive.ubuntu.com/ubuntu gutsy-backports main restricted universe multiversedeb http://tw.archive.ubuntu.com/ubuntu gutsy-proposed main restricted universe multiversedeb-src http://tw.archive.ubuntu.com/ubuntu gutsy main restricted universe multiversedeb-src http://tw.archive.ubuntu.com/ubuntu gutsy-security main restricted universe multiversedeb-src http://tw.archive.ubuntu.com/ubuntu gutsy-updates main restricted universe multiversedeb-src http://tw.archive.ubuntu.com/ubuntu gutsy-backports main restricted universe multiversedeb-src http://tw.archive.ubuntu.com/ubuntu gutsy-proposed main restricted universe multiverse
自己变得跟水晶一般透明，
