USB drive, TF card mount

When a USB flash drive or TF card is inserted, the storage device will
be recognized as a node similar to "/dev/sdb1" or "/dev/mmcblkp1",
which is the same as in the desktop PC Linux environment.

The file system supports FAT, FAT32, EXT2/3/4, NTFS. EC-A1684JD4 FD
does not support automatic mounting, so "mount" needs to be manually
mounted. After completing the data writing, please use "sync" or
"umount" in time, and please use the "sudo poweroff" command when
shutting down to avoid violent power-off and shutdown to avoid data
loss.

USB drive mount

Insert the USB drive, use "dmesg" to know the "sd" device
corresponding to the USB drive:

   [15460.953423] [5] sdb: sdb1

Mount the USB drive:

   # create mount directory
   mkdir disk
   # mount
   sudo mount /dev/sdb1 disk
   # View the files in the USB drive
   ls disk

TF card mount

The TF card mounting is similar to the USB drive, use "dmesg" to know
the "mmcblk" device corresponding to the TF card:

   [16220.776440] [4] mmcblk1: p1

Mount TF disk:

   # create mount directory
   mkdir media
   # mount
   sudo mount /dev/mmcblk1p1 media
   # View the files in the TF card
   ls media