systemd/extras/volume_id/README

vol_id - partition, filesystem, disklabel reader

This program is normally called from a udev rule, to provide udev with the
name, uuid or the filesystem type of a partition to name a device node.
vol_id opens the blockdevice node specified at the commandline.
The following commandline switches are supported to specify what vol_id
should print:

  --export prints all values
  -h       prints help text
  -l       prints the label of the partition
  -u       prints the uuid of the partition

vol_id will only return successful if the string asked for, is not
empty. All trailing whitespace will be removed, spaces replaced by underscore
and slashes ignored.

fstype                 probe  label  uuid  fsversion
----------------------------------------------------
ext                    *      *      *     *
reiserfs jr/3.5/3.6/4  *      *      *     *
fat (12, 16, 32)       *      *      *     *
ntfs                   *      *      *     *
jfs                    *      *      *     -
xfs                    *      *      *     -
hfs (plus, wrapped)    *      *      *     -
udf                    *      *      -     -
iso9660                *      *      n/a   -
ufs                    *      -      -     -
linux swap             *      *      *     *
LVM 1                  *      -      -     -
LVM 2                  *      -      -     *
linux raid             *      -      *     *
cramfs                 *      *      -     -
sysv                   *      *      -     *
luks                   *      -      *     -
hpfs                   *      -      -     -
romfs                  *
squashfs               *
minix                  *
highpoint              *
isw_raid               *
lsi_raid               *
nvidia_raid            *
promise_raid           *
silicon_raid           *
via_raid               *


If no label is found vol_id exits with nonzero and the rule will be
ignored.

To give it a try, you may call it on the commandline:
  $ extras/volume_id/vol_id --export /dev/sda6
  ID_FS_USAGE=filesystem
  ID_FS_TYPE=ext3
  ID_FS_VERSION=1.0
  ID_FS_UUID=3e999973-00c9-4917-9442-b7633bd95b9e
  ID_FS_LABEL=devel
  ID_FS_LABEL_SAFE=devel

  $ extras/volume_id/vol_id -l /dev/sda6
  devel

  $ extras/volume_id/vol_id -t /dev/sda6
  ext3


Any comment/questions/concerns to me:
  Kay Sievers <kay.sievers@vrfy.org>