将CentOS7的镜像源换成阿里云

1. 备份原来的配置文件

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2. 更换成阿里云的镜像源

# 下载阿里云的镜像源
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
# 修正版本号变量
sed -i 's/$releasever/7/g' /etc/yum.repos.d/CentOS-Base.repo

3. 清理缓存

yum clean all
yum makecache

4. 测试网络连接

ping -c 4 mirrors.aliyun.com