二、yum不能安装包

[root@localhost ~]# yum install dhcpd -y

Updating Subscription Management repositories.
Unable to read consumer identity
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Repository 'BaseOS' is missing name in configuration, using id.
Repository 'AppStream' is missing name in configuration, using id.
BaseOS                                                                                                                        0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'BaseOS':
  - Curl error (37): Couldn't read a file:// file for file:///mnt/BaseOS/repodata/repomd.xml [Couldn't open file /mnt/BaseOS/repodata/repomd.xml]								//出现错误
Error: Failed to download metadata for repo 'BaseOS': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried

解决方式

[root@localhost ~]# vim /etc/yum.repos.d/rhel8-2.repo<-----（自己本地的名称）					//进入此文件查看。