制作镜像文件（这个需要等几分钟）
[root@localhost ~]# dd if=/dev/cdrom of=/root/centos7.7.ios 9109504+0 records in 9109504+0 records out 4664066048 bytes (4.7 GB) copied, 260.3 s, 17.9 MB/s
创建挂载目录
mkdir /dvd
挂载镜像文件
[root@localhost ~]# mount -o loop /root/centos7.7.ios /dvd/ mount: /dev/loop0 is write-protected, mounting read-only
查看挂载
sdb 8:16 0 10G 0 disk ├─sdb1 8:17 0 1G 0 part /part-ext4 ├─sdb2 8:18 0 2G 0 part /part-xfs ├─sdb3 8:19 0 2G 0 part [SWAP] ├─sdb4 8:20 0 512B 0 part └─sdb5 8:21 0 2G 0 part sr0 11:0 1 4.4G 0 rom /mnt/cdrom loop0 7:0 0 4.4G 0 loop /dvd