centos8.5.2111更换yum源

要更换 CentOS 8.5.2111 的 yum 源，可以按照以下步骤进行操作：

1. 打开终端，使用 root 权限登录。

2. 备份原始的 yum 源文件，以防止操作不当造成问题：

   cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak

3. 使用编辑器（如 vi 或 nano）打开 yum 源文件：

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

4. 注释掉原始的镜像源配置，将其内容修改为如下所示：

   [BaseOS]
   name=CentOS-$releasever - Base
   baseurl=https://mirrors.cloud.tencent.com/centos/$releasever/BaseOS/$basearch/os/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

   #released updates
   [AppStream]
   name=CentOS-$releasever - AppStream
   baseurl=https://mirrors.cloud.tencent.com/centos/$releasever/AppStream/$basearch/os/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

   #additional packages that may be useful
   [Extras]
   name=CentOS-$releasever - Extras
   baseurl=https://mirrors.cloud.tencent.com/centos/$releasever/Extras/$basearch/os/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

   #additional packages that extend functionality of existing packages
   [PowerTools]
   name=CentOS-$releasever - PowerTools
   baseurl=https://mirrors.cloud.tencent.com/centos/$releasever/PowerTools/$basearch/os/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

   #contrib - packages by Centos Users
   [Contrib]
   name=CentOS-$releasever - Contrib
   baseurl=https://mirrors.cloud.tencent.com/centos/$releasever/Contrib/$basearch/os/
   gpgcheck=1
   gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

这里使用了腾讯云的镜像源，你也可以选择其他可靠的源。

5. 保存并关闭文件。

6. 清除缓存并生成新的缓存：

   yum clean all
   yum makecache

7. 完成后，你应该已经成功更换了 CentOS 的 yum 源。