整个过程可以分为三步：
第一步，准备一个8G的优盘，一台装有Linux系统的机器以及一个Linux系统的光盘镜像文件。
第二步，确定优盘的硬件位置（设备位置）
先将优盘插到Linux机器上，然后使用命令
fdisk -l
[root@trust ~]# fdisk -l
Disk /dev/sda: 200 GiB, 214748364800 bytes, 419430400 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xcd16d148
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 2099199 2097152 1G 83 Linux
/dev/sda2 2099200 419430399 417331200 199G 8e Linux LVM
Disk /dev/mapper/cl-root: 70 GiB, 75161927680 bytes, 146800640 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/mapper/cl-swap: 2 GiB, 2181038080 bytes, 4259840 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sdb: 28.8 GiB, 30943995904 bytes, 60437492 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x4a716bd3
Device Boot Start End Sectors Size Id Type
/dev/sdb1 * 63 60435647 60435585 28.8G b W95 FAT32
Disk /dev/mapper/cl-home: 127 GiB, 136327462912 bytes, 266264576 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
[root@trust ~]# dd if=/opt/CentOS-8.4.2105-x86_64-dvd1.iso of=/dev/sdb