program is the command-line interface to working with
library. It can determine the type of content (e.g. filesystem, swap)
a block device holds, and also attributes (tokens, NAME=value pairs)
from the content metadata (e.g. LABEL or UUID fields).
has two main forms of operation: either searching for a device with a
specific NAME=value pair, or displaying NAME=value pairs for one or
instead of reading from the default cache file
If you want to start with a clean cache (i.e. don't report devices previously
scanned but not necessarily available at this time), specify
Display a usage message and exit.
Probe all available devices. This is the default when displaying
tokens. When searching for a token normally the cache file is
used to locate the device and only that device is probed (to ensure
cache coherency) and all devices are probed only if the token cannot
be found in the cache.
is of the form
and the resulting token is shown for each (specified) device that has
such a tag. It is possible to specify multiple
options. If no tag is specified, then all tokens are shown for all
In order to just refresh the cache without showing any tokens use
with no other options.
is of the form
and that specific token is searched for in the cache or among all visible
block devices and additionally any specified devices. If that token is
not found, no output is shown. Common values for
Display version number and exit.
The UUID of the form 1b4e28ba-2fa1-11d2-883f-b9a761bde3fb (in
format "%08x-%04x-%04x-%04x-%012x") is output to the standard output.
Write the device cache to
instead of writing it to the default cache file
If you don't want to save the cache to the default file, specify
If not specified it will be the same file as that given by the
Display tokens from only the specified device. It is possible to
options on the command line. If none is given, all devices which
are shown, if they are recognized.
If the specified token was found, or if any tags were shown from (specified)
devices 0 is returned. If the specified token was not found, or no
(specified) devices could be identified return 2. For usage or other errors