1.vi /etc/yum.repos.d/redhat.repo

2.

[baseos]
name=baseos
baseurl=file:///mnt/BaseOS
#enabled:默认为1
enabled=1
gpgcheck=0

[appstream]
name=appstream
baseurl=file:///mnt/AppStream
enabled=1
gpgcheck=0

3. mount /dev/sr0 /mnt/

4.yum clean all 

5.yum makecache