The
blkid
program is the command-line interface to working with
libuuid(3)
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).
blkid
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
more devices.
OPTIONS
-c
Read from
cachefile
instead of reading from the default cache file
/etc/blkid/blkid.tab.
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
/dev/null.
-h
Display a usage message and exit.
-l
Look up the device that matches the search parameter specified using
the
-t
option, assuming that there is only one matching the search parameter.
For a system with a large number of disks, this will be more
efficient by avoiding the need to revalidate devices unless absolutely
necessary. If this option is not specified,
blkid
will use a less efficient approach, which allows
blkid
to print all of the devices that match the search parameter.
This option is best used for tag searches such as
LABEL=data_vol
or
UUID=e280469a-d06f-4c0b-b068-44f3b576029e.
If you want
blkid
to print all of the ext3 filesystems using a search parameter
such as
TYPE=ext3,
then this option should
not
be used.
-o
Display
blkid's
output using the specified format. The
format
parameter may be
full,
(the default),
value,
(only print the value of any tags printed by
blkid)
or
device
(only print the device name).
-s
Show only the tags for each (specified) device that match
tag.
It is possible to specify multiple
-s
options. If no tag is specified, then all tokens are shown for all
(specified) devices.
In order to just refresh the cache without showing any tokens use
-s none
with no other options.
-t
Search for block devices with tokens named
NAME
that have the value
value,
and display any devices which are found.
Common values for
NAME
include
TYPE,
LABEL,
and
UUID.
If there are no devices specified on the command line, all block devices
will be searched; otherwise, only search the devices specified by the user.
-v
Display version number and exit.
-w
<writecachefile>
Write the device cache to
writecachefile
instead of writing it to the default cache file
/etc/blkid/blkid.tab.
If you don't want to save the cache to the default file, specify
/dev/null.
If not specified it will be the same file as that given by the
-c
option.
<device>
Display tokens from only the specified device. It is possible to
give multiple
<device>
options on the command line. If none is given, all devices which
appear in
/proc/partitions
are shown, if they are recognized.
RETURN CODE
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, an exit code of 2 is returned.
For usage or other errors, an exit code of 4 is returned.
