一、Ubantu

1、备份系统源文件

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

2、编辑源文件

sudo vi /etc/apt/sources.list

3、直接输入49dd，清除所有内容
4、粘贴国内源

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-backports main restricted universe multiverse

5、更新源

sudo apt-get -y update && sudo apt-get -y upgrade

二、CentOS 7

1、备份系统源文件

sudo cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2、下载清华大学镜像源文件

sudo wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.tuna.tsinghua.edu.cn/help/centos/

3、清理缓存并更新软件包

sudo yum clean all
sudo yum makecache

三、CentOS 8

sudo cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2、下载清华大学镜像源文件

sudo wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.tuna.tsinghua.edu.cn/help/centos/

3、清理缓存并更新软件包

sudo dnf clean all
sudo dnf makecache