NAME
blkid - locate/print block device attributesSYNOPSIS
blkid --label label | --uuid uuidDESCRIPTION
The blkid program is the command-line interface to working with the libblkid(3) library. It can determine the type of content (e.g., filesystem or swap) that a block device holds, and also the attributes (tokens, NAME=value pairs) from the content metadata (e.g., LABEL or UUID fields).OPTIONS
The size and offset arguments may be followed by the multiplicative suffixes like KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning as "KiB"), or the suffixes KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.Read from cachefile instead of reading
from the default cache file (see the CONFIGURATION FILE section for
more details). 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.
Don’t encode non-printing characters.
The non-printing characters are encoded by ^ and M- notation by default. Note
that the --output udev output format uses a different encoding which
cannot be disabled.
Don’t print information (PART_ENTRY_*
tags) from partition table in low-level probing mode.
Perform a garbage collection pass on the blkid
cache to remove devices which no longer exist.
Set probing hint. The hints are an optional
way to force probing functions to check, for example, another location. The
currently supported is "session_offset= number" to set
session offset on multi-session UDF.
Display information about I/O Limits (aka I/O
topology). The 'export' output format is automatically enabled. This option
can be used together with the --probe option.
List all known filesystems and RAIDs and
exit.
Look up only one device that matches the
search parameter specified with the --match-token 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 (but see below note about udev). 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.
This option forces blkid to use udev when used for LABEL or UUID tokens
in --match-token. The goal is to provide output consistent with other
utils (like mount(8), etc.) on systems where the same tag is used for
multiple devices.
Look up the device that uses this filesystem
label; this is equal to --list-one --output device --match-token
LABEL= label. This lookup method is able to reliably use
/dev/disk/by-label udev symlinks (dependent on a setting in
/etc/blkid.conf). Avoid using the symlinks directly; it is not reliable
to use the symlinks without verification. The --label option works on
systems with and without udev.
Unfortunately, the original from e2fsprogs uses the -L
option as a synonym for -o list. For better portability, use -l -o
device -t LABEL= label and -o list in your scripts rather
than the -L option.
Restrict the probing functions to the
specified (comma-separated) list of superblock types (names). The list
items may be prefixed with "no" to specify the types which should be
ignored. For example:
blkid --probe --match-types vfat,ext3,ext4 /dev/sda1
probes for vfat, ext3 and ext4 filesystems, and
blkid --probe --match-types nominix /dev/sda1
probes for all supported formats except minix filesystems. This option is only
useful together with --probe.
Use the specified output format. Note that the
order of variables and devices is not fixed. See also option -s. The
format parameter may be:
full
value
list
device
udev
export
print all tags (the default)
print the value of the tags
print the devices in a user-friendly format;
this output format is unsupported for low-level probing ( --probe or
--info).
This output format is DEPRECATED in favour of the lsblk(8)
command.
print the device name only; this output format
is always enabled for the --label and --uuid options
print key="value" pairs for easy
import into the udev environment; the keys are prefixed by ID_FS_ or ID_PART_
prefixes. The value may be modified to be safe for udev environment; allowed
is plain ASCII, hex-escaping and valid UTF-8, everything else (including
whitespaces) is replaced with '_'. The keys with _ENC postfix use
hex-escaping for unsafe chars.
The udev output returns the ID_FS_AMBIVALENT tag if more superblocks are
detected, and ID_PART_ENTRY_* tags are always returned for all partitions
including empty partitions.
This output format is DEPRECATED.
print key=value pairs for easy import into the
environment; this output format is automatically enabled when I/O Limits (
--info option) are requested.
The non-printing characters are encoded by ^ and M- notation and all potentially
unsafe characters are escaped.
Probe at the given offset (only useful
with --probe). This option can be used together with the --info
option.
Switch to low-level superblock probing mode
(bypassing the cache).
Note that low-level probing also returns information about partition table type
(PTTYPE tag) and partitions (PART_ENTRY_* tags). The tag names produced by
low-level probing are based on names used internally by libblkid and it may be
different than when executed without --probe (for example
PART_ENTRY_UUID= vs PARTUUID=). See also --no-part-details.
For each (specified) device, show only the
tags that match tag. It is possible to specify multiple
--match-tag 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 --match-tag none with no other options.
Override the size of device/file (only useful
with --probe).
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 the specified devices are
searched.
Restrict the probing functions to the
specified (comma-separated) list of "usage" types. Supported
usage types are: filesystem, raid, crypto and other. The list items may be
prefixed with "no" to specify the usage types which should be
ignored. For example:
blkid --probe --usages filesystem,other /dev/sda1
probes for all filesystem and other (e.g., swap) formats, and
blkid --probe --usages noraid /dev/sda1
probes for all supported formats except RAIDs. This option is only useful
together with --probe.
Look up the device that uses this filesystem
uuid. For more details see the --label option.
Display help text and exit.
Print version and exit.
EXIT STATUS
If the specified device or device addressed by specified token (option --match-token) was found and it’s possible to gather any information about the device, an exit status 0 is returned. Note the option --match-tag filters output tags, but it does not affect exit status.CONFIGURATION FILE
The standard location of the /etc/blkid.conf config file can be overridden by the environment variable BLKID_CONF. The following options control the libblkid library:Sends uevent when
/dev/disk/by-{label,uuid,partuuid,partlabel}/ symlink does not match
with LABEL, UUID, PARTUUID or PARTLABEL on the device. Default is
"yes".
Overrides the standard location of the cache
file. This setting can be overridden by the environment variable
BLKID_FILE. Default is /run/blkid/blkid.tab, or
/etc/blkid.tab on systems without a /run directory.
Defines LABEL and UUID evaluation method(s).
Currently, the libblkid library supports the "udev" and
"scan" methods. More than one method may be specified in a
comma-separated list. Default is "udev,scan". The "udev"
method uses udev /dev/disk/by-* symlinks and the "scan"
method scans all block devices from the /proc/partitions file.
ENVIRONMENT
Setting LIBBLKID_DEBUG=all enables debug output.AUTHORS
blkid was written by Andreas Dilger for libblkid and improved by Theodore Ts’o and Karel Zak.SEE ALSO
libblkid(3), findfs(8), lsblk(8), wipefs(8)REPORTING BUGS
For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.AVAILABILITY
The blkid command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.2022-05-11 | util-linux 2.38.1 |