ubuntu报错E:未找到软件包xxx的换源解决办法

Ubuntu系统自带的源都是国外的网址，国内用户在使用的时候网速比较慢。一个软件的下载是十分痛苦的，这里讲解一下如何将国外源更换为国内源，让你的网速Biu.Biu.Biu

1.备份原来的源

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

将以前的源备份一下，以防以后可以用的。

2.更换源

sudo gedit /etc/apt/sources.list

使用gedit打开文档，将下边的阿里源复制进去，然后点击保存关闭。

阿里源

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 

3.更新

更新源

sudo apt-get update

更新软件

 sudo apt-get upgrade