1 files changed, 49 insertions, 0 deletions
diff --git a/extras/volume_id/README b/extras/volume_id/README
new file mode 100644
index 0000000000..9d881a1a05
--- /dev/null
+++ b/extras/volume_id/README
@@ -0,0 +1,49 @@
+
+udev_volume_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.
+udev_volume_id opens the blockdevice specified by the environment variable
+DEVPATH and searches for a filesystem superblock to read the label. The
+following commandline switches are supported to specify what udev_volume_id
+should print to stdout:
+
+       no option prints all values
+  -h   prints help text
+  -l   prints the label of the partition
+  -u   prints the uuid of the partition
+  -d   read disk instead of partition
+
+If -d is specified udev_volume_id tries to read the label from the main
+block device where the partition belongs to. For now this is only useful
+for s390 dasd labels.
+
+udev_volume_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.
+
+The following rule will create a symlink named with the label string:
+  KERNEL="[hs]d*", PROGRAM="/sbin/udev_volume_id -l", SYMLINK="%c"
+
+If no label is found udev_volume_id exits with nonzero and the rule will be
+ignored.
+
+To give it a try, you may call it on the commandline:
+
+  [root@pim udev.kay]# DEVPATH=/block/hda/hda3 extras/volume_id/udev_volume_id
+  T:ext3
+  L:Music Store
+  N:Music_Store
+  U:d2da42b5-bbd9-44eb-a72c-cc4542fcb71e
+
+  [root@pim udev.kay]# DEVPATH=/block/hda/hda3 extras/volume_id/udev_volume_id -l
+  Music_Store
+
+  [root@pim udev.kay]# DEVPATH=/block/hda/hda1 extras/volume_id/udev_volume_id -t
+  swap
+
+
+Please send any comment/questions/concerns to me or:
+	linux-hotplug-devel@lists.sourceforge.net
+
+Kay Sievers <kay.sievers@vrfy.org>