ubuntu 16.04 国内下载源更新（软件源更换）,下载源更换，更新apt 源，更新源sources.list
由于ubuntu自带的下载源主要是国外的，国内用户使用起来速度比较慢，现在将国内几个主要的ubuntu下载源列出来；你可以任选一个可用的下载源。本文更新下载源采用的是控制台命令行更换，ubuntu16.04中下载源文件source.list存放在/etc/apt/，直接vi /etc/apt/source.list就可以编辑文件。在更新下载源之前最好把官方的下载源进行备份。
备份原下载源：sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
可能之后安装一些软件需要使用官方的下载源。source.list文件编辑更新完之后执行一下更新源列表操作。
更新源列表：sudo apt-get update
然后安装需要更新的软件。
安装需更新的软件：sudo apt-get upgrade
需要注意一点就是以下列出的一小部分下载源只适用于ubuntu 16.04版本，如果需要下载其他版本请访问源列表原文（http://wiki.ubuntu.org.cn/Qref/Source）此链接内容已无。ubuntu各个版本分别对应18.04 为 bionic，17.10 为artful，16.04 为xenial ，14.04 为trusty。
维基百科ubuntu介绍(需要梯子)：https://zh.wikipedia.org/wiki/Ubuntu
下载源主要有教育网和非教育网的区别。
1.教育网用户可以更换的下载源：
清华大学镜像点：
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
浙江大学镜像点：
deb http://mirrors.zjustu.org/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.zjustu.org/ubuntu/ xenial-backports restricted universe multiverse
deb http://mirrors.zjustu.org/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://mirrors.zjustu.org/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.zjustu.org/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.zjustu.org/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.zjustu.org/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.zjustu.org/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://mirrors.zjustu.org/ubuntu/ xenial-security main restricted universe multiverse
中国科学技术大学镜像点：
deb https://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb http://download.virtualbox.org/virtualbox/debian xenial contrib
北京理工大学镜像点：
deb http://mirror.bjtu.edu.cn/ubuntu/ xenial main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ xenial-security main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ xenial-updates main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ xenial main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ xenial-backports main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ xenial-proposed main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ xenial-security main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ xenial-updates main multiverse restricted universe天津大学镜像点：
deb http://mirror.tju.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb http://mirror.tju.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirror.tju.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirror.tju.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb http://mirror.tju.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://mirror.tju.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirror.tju.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirror.tju.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirror.tju.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirror.tju.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse电子科技大学镜像点：
deb http://ubuntu.dormforce.net/ubuntu/ xenial main restricted universe multiverse
deb http://ubuntu.dormforce.net/ubuntu/ xenial-backports main restricted universe multiverse
deb http://ubuntu.dormforce.net/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://ubuntu.dormforce.net/ubuntu/ xenial-security main restricted universe multiverse
deb http://ubuntu.dormforce.net/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://ubuntu.dormforce.net/ubuntu/ xenial main restricted universe multiverse
deb-src http://ubuntu.dormforce.net/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://ubuntu.dormforce.net/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://ubuntu.dormforce.net/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://ubuntu.dormforce.net/ubuntu/ xenial-updates main restricted universe multiverse西安电子科技大学镜像点：
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial main restricted universe multiverse
deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial main restricted universe multiverse
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-security main restricted universe multiverse
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-updates main restricted universe multiverse
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-backports main restricted universe multiverse
deb http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://linux.xidian.edu.cn/mirrors/ubuntu/ xenial-proposed main restricted universe multiverse重庆大学镜像点：
deb http://mirrors.cqu.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.cqu.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.cqu.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.cqu.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://mirrors.cqu.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.cqu.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.cqu.edu.cn/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirrors.cqu.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.cqu.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://mirrors.cqu.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse1.非教育网用户可以更换的下载源：
网易163镜像点：
deb http://mirrors.163.com/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial-backports main restricted universe multiverse
阿里云镜像点：
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