blkid — command−line utility to locate/print block device attributes
blkid −L label | −U uuid
blkid [−ghlv] [ −c file ] [ −w file ] [ −o format ] [ −s tag ] [ −t NAME=value ] device [ device...
]
blkid −p [ −O offset ] [ −S size ] [ −o format ] [ −s tag ] [ −u list ] device [ device... ]
The blkid program is the command-line interface to working with libblkid(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
cachefileRead 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 necessarily available at
this time), specify /dev/null.
−gPerform a garbage collection pass on the blkid cache to remove devices which no longer exist.
−hDisplay a usage message and exit.
−lLook up one device that matches the search parameter
specified using the −t option. If there are multiple
devices that match the specified search parameter, then
the device with the highest priority is returned,
and/or the first device found at a given priority.
Device types in order of decreasing priority are Device
Mapper, EVMS, LVM, MD, and finally regular block
devices. If this option is not specified, blkid will print all
of the devices that match the search parameter.
−L
labelLook up one device that uses the label (same as: -l
-o device -t LABEL=<label>). This look up method
is able to reliable use /dev/disk/by-label udev
symlinks (depends on setting in /etc/blkid.conf). Avoid
to use the symlinks directly. It is not reliable to use
the symlinks without verification. The −L option works on
systems with and without udev.
Unfortunately, the original blkid(8) from
e2fsprogs use the −L option as a
synonym to the −o
list option. For better portability use "-l -o
device -t LABEL=<label>" and "-o list" in your
scripts rather than -L option.
−u
listRestrict probing functions to defined (comma separated) list of "usage" types. Supported usage types are: filesystem, raid, crypto and other. The list can be prefixed with "no" to specify the usage types which should be ignored. For example:
blkid -p -u filesystem,other /dev/sda1
probes for all filesystems and others (e.g. swap) formats, and
blkid -p -u noraid /dev/sda1
probes for all supported formats exclude RAIDs. This
option is useful with −p only.
−U
uuidLook up one device that uses the uuid. For more
details see the −L option.
−o
formatDisplay blkid's output using
the specified format. The format parameter may
be:
- full
print all tags (the default)
- value
print the value of the tags
listprint the devices in a user-friendly format, this output format is unsupported for low-level probing (
−p)deviceprint the device name only, this output format is always enabled for
−Land−Uoptions- udev
vol_id compatible mode; usable in udev rules
−O
bytesProbe at the given offset (only useful with
−p).
−pSwitch to low-level probing mode (bypass cache)
−s
tagFor each (specified) device, show only the tags 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.
−S
bytesOverwrite device/file size (only useful with
−p).
−t
NAME=valueSearch 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 the specified devices are
searched.
−vDisplay version number and exit.
−w
writecachefileWrite 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.
deviceDisplay 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 (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.
blkid was written by Andreas Dilger for libblkid and improved by Theodore Ts'o and Karel Zak.
The blkid command is part of the util-linux-ng package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
libblkid(3) findfs(8) wipefs(8)
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Copyright 2000 Andreas Dilger (adilgerturbolinux.com) This man page was created for blkid from e2fsprogs-1.25. This file may be copied under the terms of the GNU Public License. Based on uuidgen, Mon Sep 17 10:42:12 2000, Andreas Dilger |