Ubuntu 更换国内软件源，解决unable to locate package问题

以前记得直接在系统的软件中心里选择163或sohu的源就可以用了，但是今天却不行了，安装很多软件时提示 unable to locate package。

手动更换了阿里的软件源就顺畅了，速度也很快。

方法：

备份原文件

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

使用gedit打开，vi操作不太习惯

sudo gedit sudo cp /etc/apt/sources.list

全删掉，将下列内容复制进去，保存退出

deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse

更新源

sudo apt-get update