Linux "blkid" Command Line Options and Examples
locate/print block device attributes

The blkid program is the command-line interface to working with the libblkid(3) library. It can determine the type of content (e.g.


Usage:

blkid --label label | --uuid uuid






Command Line Options:

-c
Read from cachefile instead of reading from the default cache file (see the CONFIGURATION FILE section for more details). Ifyou want to start with a clean cache (i.e. don't report devices previously scanned but not necessarily available at thistime), specify /dev/null.
blkid -c ...
-d
Don't encode non-printing characters. The non-printing characters are encoded by ^ and M- notation by default. Note that the
blkid -d ...
--output
udev output format uses a different encoding which cannot be disabled.
blkid --output ...
-g
Perform a garbage collection pass on the blkid cache to remove devices which no longer exist.
blkid -g ...
-h
Display a usage message and exit.
blkid -h ...
-i
Display information about I/O Limits (aka I/O topology). The 'export' output format is automatically enabled. This optioncan be used together with the --probe option.
blkid -i ...
-k
List all known filesystems and RAIDs and exit.
blkid -k ...
-l
Look up only one device that matches the search parameter specified with the --match-token option. If there are multipledevices that match the specified search parameter, then the device with the highest priority is returned, and/or the firstdevice found at a given priority. Device types in order of decreasing priority are: Device Mapper, EVMS, LVM, MD, and finallyregular block devices. If this option is not specified, blkid will print all of the devices that match the search parameter.
blkid -l ...
-L
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 onsystems with and without udev.Unfortunately, the original blkid(8) from e2fsprogs uses the -L option as a synonym for -o list. For better portability, use
blkid -L ...
-n
Restrict the probing functions to the specified (comma-separated) list of superblock types (names). The list items may beprefixed with "no" to specify the types which should be ignored. For example:blkid --probe --match-types vfat,ext3,ext4 /dev/sda1probes for vfat, ext3 and ext4 filesystems, andblkid --probe --match-types nominix /dev/sda1probes for all supported formats except minix filesystems. This option is only useful together with --probe.
blkid -n ...
-o
Use the specified output format. Note that the order of variables and devices is not fixed. See also option -s. The formatparameter may be:full print all tags (the default)value print the value of the tagslist print the devices in a user-friendly format; this output format is unsupported for low-level probing (--probe or
blkid -o ...
--info).
This output format is DEPRECATED in favour of the lsblk(8) command.device print the device name only; this output format is always enabled for the --label and --uuid optionsudev print key="value" pairs for easy import into the udev environment; the keys are prefixed by ID_FS_ or ID_PART_ prefixesThe udev output returns the ID_FS_AMBIVALENT tag if more superblocks are detected, and ID_PART_ENTRY_* tags are alwaysreturned for all partitions including empty partitions. This output format is DEPRECATED.export print key=value pairs for easy import into the environment; this output format is automatically enabled when I/O Limits
blkid --info). ...
--info
The non-printing characters are encoded by ^ and M- notation and all potentially unsafe characters are escaped.
blkid --info ...
-O
Probe at the given offset (only useful with --probe). This option can be used together with the --info option.
blkid -O ...
-p
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 thanwhen executed without --probe (for example PART_ENTRY_UUID= vs PARTUUID=).
blkid -p ...
-s
For each (specified) device, show only the tags that match tag. It is possible to specify multiple --match-tag options. Ifno tag is specified, then all tokens are shown for all (specified) devices. In order to just refresh the cache without show‐ing any tokens, use --match-tag none with no other options.
blkid -s ...
-S
Override the size of device/file (only useful with --probe).
blkid -S ...
-t
Search for block devices with tokens named NAME that have the value value, and display any devices which are found. Commonvalues for NAME include TYPE, LABEL, and UUID. If there are no devices specified on the command line, all block devices willbe searched; otherwise only the specified devices are searched.
blkid -t ...
-u
Restrict the probing functions to the specified (comma-separated) list of "usage" types. Supported usage types are: filesys‐tem, 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/sda1probes for all filesystem and other (e.g. swap) formats, andblkid --probe --usages noraid /dev/sda1probes for all supported formats except RAIDs. This option is only useful together with --probe.
blkid -u ...
-U
Look up the device that uses this filesystem uuid. For more details see the --label option.
blkid -U ...
-V
Display version number and exit.RETURN CODEIf the specified device or device addressed by specified token (option --match-token) was found and it's possible to gather anyinformation about the device, an exit code 0 is returned. Note the option --match-tag filters output tags, but it does not affectreturn code.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.If an ambivalent probing result was detected by low-level probing mode (-p), an exit code of 8 is returned.CONFIGURATION FILEThe standard location of the /etc/blkid.conf config file can be overridden by the environment variable BLKID_CONF. The followingoptions control the libblkid library:SEND_UEVENT=<yes|not>Sends uevent when /dev/disk/by-{label,uuid,partuuid,partlabel}/ symlink does not match with LABEL, UUID, PARTUUID or PARTLABELon the device. Default is "yes".CACHE_FILE=<path>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.EVALUATE=<methods>Defines LABEL and UUID evaluation method(s). Currently, the libblkid library supports the "udev" and "scan" methods. Morethan 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.AUTHORblkid was written by Andreas Dilger for libblkid and improved by Theodore Ts'o and Karel Zak.ENVIRONMENTSetting LIBBLKID_DEBUG=all enables debug output.
blkid -V ...