CentOS 7更新yum源

备份原始文件

# 复制整个目录
cp -a /etc/yum.repos.d /etc/yum.repos.d.backup

# 或者复制单个文件
cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

编辑仓库配置文件

sudo vi /etc/yum.repos.d/CentOS-Base.repo

[base]
name=CentOS-$releasever - Base - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
        http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
        http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
        http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

# releasever变量会自动替换为当前系统的CentOS版本号，例如7

清除缓存并测试

sudo yum clean all
sudo yum makecache
sudo yum update

验证当前仓库配置

yum repolist