1、切换centos源

cd /etc/yum.repos.d/

cp CentOS-Base.repo CentOS-Base.repo.bak

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

 yum clean all

 yum makecache

更新软件包

yum update -y

cat /etc/redhat-release

2、查看yum版本信息命令

yum repolist

 yum info yum

更新所有rpm包可以用yum update，若想根据某个具体的包，yum update 后加具体rpm包名即可

3、查看具体安装包信息

 rpm -qi centos-release-6-10.el6.centos.12.3.x86_64

4、查找yum可以安装的安装包

yum search ftp

修改centos8的源

 cd /etc/yum.repos.d/

创建新文件夹并将源文件备份为repo.bak

 mkdir backup && mv *repo backup/

下载国内yum文件

curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo

更新下载yum地址

 sed -i -e"s|mirrors.cloud.aliyuncs.com|mirrors.aliyun.com|g " /etc/yum.repos.d/CentOS-*

 sed -i -e "s|releasever|releasever-stream|g" /etc/yum.repos.d/CentOS-*

生成缓存

yum clean all && yum makecache