how to set a fat (vfat) disk on key label in ubuntu linux

reference : https://help.ubuntu.com/community/RenameUSBDrive

FAT16 and FAT32

These filesystems are most often found on USB thumb drives, flash cards (like for a camera or cell phone), and older external USB hard drives.
Check the current label

sudo mlabel -i  -s ::

ex:

     sudo mlabel -i /dev/sdb1 -s ::

Note that we're using the special "::" drive which allows us to specify the device descriptor on the command line; otherwise we'd have to edit ~/.mtoolsrc to assign a drive letter (see Option 2 under "Change the label").

Change the label

Option 1

After unmounting and checking the current label (above), use

sudo mlabel -i  ::

ex:

     sudo mlabel -i /dev/sdb1 ::my_external

Ignore the "Volume label is XYZ" output as this is the old label. Jump to the Verify the Change section below.