为了优化ubuntu软件安装/更新速度，我测试了国内几家apt源的速度，发现北京交大的apt源速度相对最快，然后可以通过以下步骤更新ubuntu源

1) 备份默认的apt源

1 $ cd /etc/apt
2 $ sudo cp

2) 编辑

$ sudo

复制粘贴以下列表：

1 deb http://archive.ubuntu.com/ubuntu/ raring main restricted universe multiverse
 2 deb http://archive.ubuntu.com/ubuntu/ raring-security main restricted universe multiverse
 3 deb http://archive.ubuntu.com/ubuntu/ raring-updates main restricted universe multiverse
 4 deb http://archive.ubuntu.com/ubuntu/ raring-proposed main restricted universe multiverse
 5 deb http://archive.ubuntu.com/ubuntu/ raring-backports main restricted universe multiverse
 6 deb-src http://archive.ubuntu.com/ubuntu/ raring main restricted universe multiverse
 7 deb-src http://archive.ubuntu.com/ubuntu/ raring-security main restricted universe multiverse
 8 deb-src http://archive.ubuntu.com/ubuntu/ raring-updates main restricted universe multiverse
 9 deb-src http://archive.ubuntu.com/ubuntu/ raring-proposed main restricted universe multiverse
10 deb-src http://archive.ubuntu.com/ubuntu/ raring-backports main restricted universe multiverse

 3) 注意，每次修改完apt源，一定要执行一下更新

$ sudo

大概花了几分钟，更新完成之后，就可以使用apt来安装应用程序了。

备注：ubuntu apt源列表 ​​http://wiki.ubuntu.org.cn/源列表​​