Ubuntu安装完毕之后，默认的源是Ubuntu自己的，但毕竟Ubuntu服务器在国外，我们访问起来会比较慢，可以将软件源切换为国内源，比如：阿里源，清华源，中科大源等等。在这边以清华源为例，其它源也是一样的道理。
1 切换源之前先把配置文件备份一份：
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
2 找到清华源官网：
https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/
一定要选择与自己版本相对应的源，比如当前使用Ubuntu20.04，最好使用此版本的源，否则有可能会有意料不到的问题，良许就吃过这方面的亏。
网络上也有很多教你换源的帖子，但都是直接给出内容，有可能源与自己的版本不一致，所以最好自己去官网复制。
3.将之前的源全部删除
echo ” > sources.list
4.编辑新源文件
nano sources.list
5.加入新的数据源（清华数据源）
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释 deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse # 预发布软件源，不建议启用 # deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse
6.使用新源替换掉原来的源（一定要加sudo）：
sudo vi /etc/apt/sources.list
7.然后更新软件包缓存：
sudo apt update
这个命令，会访问源列表里的每个网址，并读取软件列表，然后保存在本地电脑。
8.通常我们会紧跟着再执行命令：
sudo apt-get upgrade
这个命令，会把本地已安装的软件，与刚下载的软件列表里对应软件进行对比，如果发现已安装的软件版本太低，就会提示你更新。
9.备用数据源【阿里】
在下面网站查找最新数据源
https://developer.aliyun.com/mirror/ubuntu?spm=a2c6h.13651102.0.0.b5371b11tio0iu
Ubuntu 14.04.5 LTS为例，最后的效果如下：
deb https://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse deb https://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse deb https://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse deb https://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse deb-src https://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse ## Not recommended # deb https://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse # deb-src https://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
ubuntu 16.04 配置如下
deb http://mirrors.aliyun.com/ubuntu/ xenial main deb-src http://mirrors.aliyun.com/ubuntu/ xenial main deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main deb http://mirrors.aliyun.com/ubuntu/ xenial universe deb-src http://mirrors.aliyun.com/ubuntu/ xenial universe deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates universe deb http://mirrors.aliyun.com/ubuntu/ xenial-security main deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security universe
ubuntu 18.04(bionic) 配置如下
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
ubuntu 20.04(focal) 配置如下
deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ focal-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ focal-backport
