更换ubuntu apt-get 源

1. 备份默认的apt源

$ cd /etc/apt
$ sudo cp sources.list sources.list.backup

2. 编辑

$ sudo gedit sources.list

deb http://archive.ubuntu.com/ubuntu/ raring main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ raring-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ raring-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ raring-proposed main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ raring-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ raring main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ raring-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ raring-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ raring-proposed main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ raring-backports main restricted universe multiverse

3)更新

$ sudo apt-get update