1、前言
在Ubuntu系统上使用"apt-get install"进行软件安装更新的时候，由于使用的源是国外的，网络速度非常缓慢，本文记录在Ubuntu系统上进行更换国内源。
2、Ubuntu换源
首先需要将原始的源文件进行备份，命令行如下：
$ sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
接下来，修改源文件/etc/apt/sources.list，添加国内源：
$ sudo vim /etc/apt/sources.list
先将原文件的内容进行删除，然后添加国内源，常用的国内源有如下：
（1）阿里源
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
（2）清华源
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
将上面给出的源复制到文件/etc/apt/sources.list即可。
最后，使用下面命令进行源更新：
$ sudo apt-get update
源更新完成后，安装自己需要的软件就可以了。