1、系统插入USB设备后，从控制台界面有如下提示：
从控制台信息可以看出插入的USB设备名。
从上图可以看出，插入的USB设备为sde4。
但是，如果是CRT工具远程连接过去，可以使用下面的命令来查看USB设备。
2、使用lsblk命令查找USB设备名
lsblk命令用于列出所有可用块设备的信息,而且还能显示他们之间的依赖关系,但是它不会列出RAM盘的信息。块设备有硬盘,闪存盘,cd-ROM等等。
如下所示：
[root@rhel7 ~]# lsblk --插入USB设备前的分区情况
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 19.5G 0 part
├─rhel-root 253:0 0 17.5G 0 lvm /
└─rhel-swap 253:1 0 2G 0 lvm [SWAP]
sdb 8:16 0 6G 0 disk
├─sdb1 8:17 0 100M 0 part
├─sdb2 8:18 0 110M 0 part
└─sdb3 8:19 0 120M 0 part
sdc 8:32 0 5G 0 disk
├─sdc1 8:33 0 100M 0 part
│ └─vgdate-lvvol1 253:2 0 292M 0 lvm /lvmFiles
├─sdc2 8:34 0 200M 0 part
│ └─vgdate-lvvol1 253:2 0 292M 0 lvm /lvmFiles
├─sdc3 8:35 0 200M 0 part
└─sdc4 8:36 0 250M 0 part
sdd 8:48 0 2G 0 disk
sr0 11:0 1 1024M 0 rom
[root@rhel7 ~]# lsblk --插入USB设备后的分区情况
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 20G 0 disk
├─sda1 8:1 0 500M 0 part /boot
└─sda2 8:2 0 19.5G 0 part
├─rhel-root 253:0 0 17.5G 0 lvm /
└─rhel-swap 253:1 0 2G 0 lvm [SWAP]
sdb 8:16 0 6G 0 disk
├─sdb1 8:17 0 100M 0 part
├─sdb2 8:18 0 110M 0 part
└─sdb3 8:19 0 120M 0 part
sdc 8:32 0 5G 0 disk
├─sdc1 8:33 0 100M 0 part
│ └─vgdate-lvvol1 253:2 0 292M 0 lvm /lvmFiles
├─sdc2 8:34 0 200M 0 part
│ └─vgdate-lvvol1 253:2 0 292M 0 lvm /lvmFiles
├─sdc3 8:35 0 200M 0 part
└─sdc4 8:36 0 250M 0 part
sdd 8:48 0 2G 0 disk
sde 8:64 1 7.5G 0 disk
└─sde4 8:68 1 7.5G 0 part
sr0 11:0 1 1024M 0 rom
[root@rhel7 ~]#
从上面的输出信息可以看出，设备为sde，为第一个分区sde4,大小为7.5GB
sde 8:64 1 7.5G 0 disk
└─sde4 8:68 1 7.5G 0 part
3、使用fdisk工具识别USB设备名
fdisk是一个功能强大的工具，用于查看你系统中的所有分区表，包括所有的USB设备，使用root权限执行如下命令：
[root@rhel7 ~]# fdisk -l Disk /dev/sda: 21.5 GB, 21474836480 bytes, 41943040 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 label type: dos
Disk identifier: 0x0006c7ae Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 41943039 20458496 8e Linux LVM Disk /dev/sdb: 6442 MB, 6442450944 bytes, 12582912 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 label type: dos
Disk identifier: 0xaa06e007 Device Boot Start End Blocks Id System
/dev/sdb1 2048 206847 102400 8e Linux LVM
/dev/sdb2 206848 432127 112640 8e Linux LVM
/dev/sdb3 432128 677887 122880 8e Linux LVM Disk /dev/sdc: 5368 MB, 5368709120 bytes, 10485760 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 label type: dos
Disk identifier: 0x0c16d904 Device Boot Start End Blocks Id System
/dev/sdc1 2048 206847 102400 8e Linux LVM
/dev/sdc2 206848 616447 204800 8e Linux LVM
/dev/sdc3 616448 1026047 204800 8e Linux LVM
/dev/sdc4 1026048 1538047 256000 8e Linux LVM Disk /dev/sdd: 2147 MB, 2147483648 bytes, 4194304 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 label type: dos
Disk identifier: 0x3990990c Device Boot Start End Blocks Id System Disk /dev/mapper/rhel-root: 18.8 GB, 18756927488 bytes, 36634624 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/rhel-swap: 2147 MB, 2147483648 bytes, 4194304 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/vgdate-lvvol1: 306 MB, 306184192 bytes, 598016 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/sde: 8022 MB, 8022654976 bytes, 15669248 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 label type: dos
Disk identifier: 0xcad4ebea Device Boot Start End Blocks Id System
/dev/sde4 * 63 15669184 7834561 7 HPFS/NTFS/exFAT
[root@rhel7 ~]#
从上图可以看出USB设备的信息如下：
Disk /dev/sde: 8022 MB, 8022654976 bytes, 15669248 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 label type: dos
Disk identifier: 0xcad4ebea Device Boot Start End Blocks Id System
/dev/sde4 * 63 15669184 7834561 7 HPFS/NTFS/exFAT
使用dmesg命令来识别出USB设备名
dmesg是一个重要的用于打印或者控制内核环形缓冲区的命令。环形缓冲区是一种数据结构，它存放着内核操作数据的信息。
运行如下的命令来查看内核操作信息，它同时也会打印出USB设备的信息：
……
[ 1055.720971] sde: sde4
[ 1055.816921] sd 6:0:0:0: [sde] Attached SCSI removable disk
[ 1168.185175] usb 1-1: USB disconnect, device number 6
[ 1250.915177] usb 1-1: new full-speed USB device number 7 using ohci-pci
[ 1251.361378] usb 1-1: New USB device found, idVendor=8644, idProduct=800b
[ 1251.364410] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 1251.367812] usb 1-1: Product: USB Flash Disk
[ 1251.370072] usb 1-1: Manufacturer: General
[ 1251.372505] usb 1-1: SerialNumber: 000000000000C4FC
[ 1251.378864] usb-storage 1-1:1.0: USB Mass Storage device detected
[ 1251.383180] scsi host7: usb-storage 1-1:1.0
[ 1252.415350] scsi 7:0:0:0: Direct-Access General USB Flash Disk 1.00 PQ: 0 ANSI: 2
[ 1252.424925] sd 7:0:0:0: Attached scsi generic sg5 type 0
[ 1252.451723] sd 7:0:0:0: [sde] 15669248 512-byte logical blocks: (8.02 GB/7.47 GiB)
[ 1252.481780] sd 7:0:0:0: [sde] Write Protect is off
[ 1252.484715] sd 7:0:0:0: [sde] Mode Sense: 03 00 00 00
[ 1252.507694] sd 7:0:0:0: [sde] No Caching mode page found
[ 1252.510073] sd 7:0:0:0: [sde] Assuming drive cache: write through
[ 1252.624206] sde: sde4
[ 1252.722176] sd 7:0:0:0: [sde] Attached SCSI removable disk
[root@rhel7 ~]#
其实上面的信息就是刚插入USB设备时服务器控制台上输出的信息。
查看USB设备内的文件：
从上面的信息可以看出，虽然USB设备已插入到Linux系统，但是挂载点mounted on是为空的，也就是还没有完成挂载，必须先挂载后才能使用。
[root@rhel7 ~]# mkdir -p /mnt/MyUSB [root@rhel7 ~]# mount /dev/sde4 /mnt/MyUSB/
mount: unknown filesystem type 'ntfs' [root@rhel7 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/rhel-root xfs 18G 4.6G 13G 26% /
devtmpfs devtmpfs 911M 0 911M 0% /dev
tmpfs tmpfs 921M 0 921M 0% /dev/shm
tmpfs tmpfs 921M 8.4M 912M 1% /run
tmpfs tmpfs 921M 0 921M 0% /sys/fs/cgroup
/dev/sda1 xfs 497M 124M 374M 25% /boot
/dev/mapper/vgdate-lvvol1 xfs 289M 16M 274M 6% /lvmFiles
tmpfs tmpfs 185M 0 185M 0% /run/user/0
重新格式化为ext4格式：
[root@rhel7 ~]# mkfs.ext4 /dev/sde4
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
490560 inodes, 1958640 blocks
97932 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=2006974464
60 block groups
32768 blocks per group, 32768 fragments per group
8176 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information:
done
重新挂载后就可以使用了：
[root@rhel7 ~]# mount /dev/sde4 /mnt/MyUSB/
[root@rhel7 ~]# cd /mnt/MyUSB/
[root@rhel7 MyUSB]# touch testMyUsb
[root@rhel7 MyUSB]# ls
lost+found testMyUsb
[root@rhel7 MyUSB]#
使用df -hT命令查看挂载的USB设备：
[root@rhel7 MyUSB]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/rhel-root xfs 18G 4.6G 13G 26% /
devtmpfs devtmpfs 911M 0 911M 0% /dev
tmpfs tmpfs 921M 0 921M 0% /dev/shm
tmpfs tmpfs 921M 8.4M 912M 1% /run
tmpfs tmpfs 921M 0 921M 0% /sys/fs/cgroup
/dev/sda1 xfs 497M 124M 374M 25% /boot
/dev/mapper/vgdate-lvvol1 xfs 289M 16M 274M 6% /lvmFiles
tmpfs tmpfs 185M 0 185M 0% /run/user/0
/dev/sde4 ext4 7.3G 34M 6.9G 1% /mnt/MyUSB //已挂载成功了，大小为7.3GB
[root@rhel7 MyUSB]#