更换阿里云源

CentOS

yum install wget
cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo  
wget -P /etc/yum.repos.d/ http://mirrors.aliyun.com/repo/epel-7.repo 
yum clean all
yum makecache

yum update -y

ubuntu

vim /etc/apt/source.list
# 编辑模式
:%s/us.archive.ubuntu/mirrors.aliyun/g

sudo apt update
sudo apt upgrade -y