blkid - command-line utility to locate/print block device attributes
blkid [ -hlv ] [ [ -c cachefile ] -w writecachefile ] [ -o format ] [
-s tag ] [ -t NAME=value ] [ device ... ]
The blkid program is the command-line interface to working with libu-
uid(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.
-c Read from cachefile instead of reading from the default cache
file /etc/blkid.tab. If you want to start with a clean cache
(i.e. don’t report devices previously scanned but not necessar-
ily 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
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
-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
-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.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.
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.
If the specified token was found, or if any tags were shown from (spec-
ified) 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.
blkid was written by Andreas Dilger for libblkid.
blkid is part the e2fsprogs package since version 1.26 and is available
E2fsprogs version 1.38 June 2005 BLKID(8)
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