问题：U盘接入，系统可以识别，但在/dev目录下只有sda(或其他)，却无设备节点sda1(或其他)？

解决：

(1)查看U盘是否分区

#fdisk /dev/sda /*进入fdisk命令操作空间*/

#Command (m for help): m /*命令查看*/

Command action

a toggle a bootable flag #设置引导扇区

b edit bsd disklabel #编辑卷标(linux下使用的卷标bsd通用)

c toggle the dos compatibility flag

d delete a partition #删除分区

l list known partition types #列出已知的分区类型

m print this menu

n add a new partition #添加一个新的分区

o create a new empty DOS partition table #生成一个新的空DOS分区列表

p print the partition table #打印分区列表

q quit without saving changes #不保存退出

s create a new empty Sun disklabel

t change a partition's system id #改变一个分区列表的ID

u change display/entry units

v verify the partition table

w write table to disk and exit #写入列表到磁盘并退出

x extra functionality (experts only)

#Command (m for help): p

Disk /dev/sda: 8178 MB, 8178892800 bytes

252 heads, 62 sectors/track, 1022 cylinders

Units = cylinders of 15624 * 512 = 7999488 bytes

Device Boot Start End Blocks Id System /*可见U盘无分区*/

(2)若未分区，创建分区sda1，并格式化(也可以不进行格式化)

#fdisk /dev/sda

Command (m for help): m

Command Action

a toggle a bootable flag

b edit bsd disklabel

c toggle the dos compatibility flag

d delete a partition

l list known partition types

n add a new partition

o create a new empty DOS partition table

p print the partition table

q quit without saving changes

s create a new empty Sun disklabel

t change a partition's system id

u change display/entry units

v verify the partition table

w write table to disk and exit

x extra functionality (experts only)

Command (m for help): n /*n表示添加一个新的分区*/

Command action

e extended /*创建扩展分区*/

p primary partition (1-4) /*创建主分区*/

p

Partition number (1-4): 1 /*输入主分区号，这里设置为1*/

First cylinder (1-1022, default 1): Using default value 1 /*起始，回车使用默认值*/

Last cylinder or +size or +sizeM or +sizeK (1-1022, default 1022): Using default value 1022 /*结尾，回车使用默认值*/

Command (m for help): p /*p表示打印分区列表*/

Disk /dev/sda: 8178 MB, 8178892800 bytes

252 heads, 62 sectors/track, 1022 cylinders

Units = cylinders of 15624 * 512 = 7999488 bytes

Device Boot Start End Blocks Id System /*可见sda1分区已创建*/

/dev/sda1 1 1022 7983833 83 Linux

Command (m for help): w

The partition table has been altered.

Calling ioctl() to re-read partition table

#mkfs -t vfat /dev/sda1 /*对sda1进行格式化(也可以不进行这一步)*/

mkfs.vfat 3.0.12 (29 Oct 2011)

mkfs.vfat: /dev/sda1 contains a mounted file system.

#fsck -t vfat /dev/sda /*格式化完成后对U盘进行修复*/

fsck from util-linux 2.20.1

dosfsck 3.0.12, 29 Oct 2011, FAT32, LFN

Logical sector size (64543 bytes) is not a multiple of the physical sector size.

(3)前两步完成后，在/dev目录下将会出现设备节点sda1；如果没有，则手动创建设备节点sda1

#mknod /dev/sda1 b 8 1 /*手动创建设备节点sda1*/

#mount /dev/sda1 /mnt/udisk /*挂载U盘到/mnt/udisk目录下*/

#umount /mnt/udisk /*卸载U盘*/