Feature request: accept dash in middle of --volume-id arg

[bjornfor]

The mkfs.fat --volume-id argument is currently a 32-bit hex number, but the Linux lsblk and mount commands use a dash in the middle of the (UUID - as they call it) number. The result is some impedance mismatch:

$ mkfs.fat -i 12345678 /dev/sdX1
(success)

$ lsblk -f
NAME     FSTYPE    LABEL    UUID           MOUNTPOINT
sdX1     vfat      BOOT     1234-5678

$ mkfs.fat -i 1234-5678 /dev/sdX1
mkfs.fat 4.1 (2017-01-24)
Volume ID must be a hexadecimal number
...

$ mount -U 12345678 /mnt
mount: /mnt: can't find UUID="12345678"

I would like to be able to copy the UUID/volume-id from lsblk/mount to mkfs.fat, since recreating disks with specific UUIDs is part of my backup restore process.

What do you think?

[bjornfor]

It appears that ntfs UUIDs are given without dash (both lsblk and mount emit/accept them). So perhaps the kind of compatibility I'm seeking is better implemented in lsblk/mount (stop using dash in vfat UUID fields). (My first thought was that UUIDs "must" have dash in them, but apparently not.)

[pali]

Windows's vol and dir commands print serial number (volume-id) with dash. Also UUIDs in /etc/fstab are written with dashes.

I'm for unification of usage of FAT volume-ids between Linux tools. So if other mount/blkid/... tools prints ids in one format they should be supported by mkfs.fat/fatlabel. Also if mkfs.fat/fatlabel prints ids in different format then it should be supported by mount/fsck/blkid wrappers too.