更改Yum安装源

备份原Yum源

备份当前的YUM源配置文件

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

修改数据源配置

方式1 (推荐)

如果你的电脑已经安装了wget，可以使用如下命令快速切换为阿里云的源

curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

方式2

在/etc/yum.repos.d/CentOS-Base.repo文件，修改文件内容为以下内容：

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

#released updates 
[updates]
name=CentOS-$releasever - Updates - Aliyun
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras - Aliyun
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - Aliyun
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7

更新缓存

保存文件后，运行以下命令清除缓存并生成新的缓存：

sudo yum clean all
sudo yum makecache

添加多个Yum源

继续添加网易163的数据源

curl -o /etc/yum.repos.d/CentOS7-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo

运行命令清除缓存并生成新的缓存

    yum clean all        # 清除缓存
    yum makecache        # 生成缓存