前言：
在使用Linux安装一些应用的时候经常会遇到速度 按B算的尴尬情况，特别是安装ROS等文件时1G多的包可能要下载好几天，有时候还会因为不小心断网前功尽弃。为了解决这个问题，我们需要更换系统的源，我们选用阿里的源
流程：
1、备份sources.list文件
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
2、修改sources.list文件，将复制后面“阿里云源”里的源地址覆盖原来的内容
sudo gedit /etc/apt/sources.list
阿里云源
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、修改完成后，更新源
sudo apt-get update
到此，你便能大幅度提高你的Linux系统的下载速度