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LSBLK(8) System Administration LSBLK(8)

NAME

lsblk - list block devices

SYNOPSIS

lsblk [options] [device...]

DESCRIPTION

lsblk lists information about all available or the specified block devices. The lsblk command reads the sysfs filesystem and udev db to gather information. If the udev db is not available or lsblk is compiled without udev support, then it tries to read LABELs, UUIDs and filesystem types from the block device. In this case root permissions are necessary.

By default, the command prints all block devices (except RAM disks) in a tree-like format. The same device can be repeated in the tree if it relates to other devices. The --merge option is recommended for more complicated setups to gather groups of devices and describe complex N:M relationships.

The tree-like output (or children[] array in the JSON output) is enabled only if NAME column it present in the output or when --tree command line option is used. See also --nodeps and --list to control the tree formatting.

The default output, as well as the default output from options like --fs and --topology, is subject to change. So whenever possible, you should avoid using default outputs in your scripts. Always explicitly define expected columns by using --output columns-list and --list in environments where a stable output is required.

Use lsblk --list-columns to get a list of all available columns.

Note that lsblk might be executed in time when udev does not have all information about recently added or modified devices yet. In this case it is recommended to use udevadm settle before lsblk to synchronize with udev.

The relationship between block devices and filesystems is not always one-to-one. The filesystem may use more block devices, or the same filesystem may be accessible by more paths. This is the reason why lsblk provides MOUNTPOINT and MOUNTPOINTS (pl.) columns. The column MOUNTPOINT displays only one mount point (usually the last mounted instance of the filesystem), and the column MOUNTPOINTS displays by multi-line cell all mount points associated with the device.

OPTIONS

-A, --noempty

Don’t print empty devices.

-a, --all

Disable all built-in filters and list all empty devices and RAM disk devices too.

-b, --bytes

Print the sizes in bytes rather than in a human-readable format.

By default, the unit, sizes are expressed in, is byte, and unit prefixes are in power of 2^10 (1024). Abbreviations of symbols are exhibited truncated in order to reach a better readability, by exhibiting alone the first letter of them; examples: "1 KiB" and "1 MiB" are respectively exhibited as "1 K" and "1 M", then omitting on purpose the mention "iB", which is part of these abbreviations.

-H, --list-columns

List the available columns, use with --json or --raw to get output in machine-readable format.

-D, --discard

Print information about the discarding capabilities (TRIM, UNMAP) for each device.

-d, --nodeps

Do not print holder devices or slaves. For example, lsblk --nodeps /dev/sda prints information about the sda device only.

-E, --dedup column

Use column as a de-duplication key to de-duplicate output tree. If the key is not available for the device, or the device is a partition and parental whole-disk device provides the same key than the device is always printed.

The usual use case is to de-duplicate output on system multi-path devices, for example by -E WWN.

-e, --exclude list

Exclude the devices specified by the comma-separated list of major device numbers. Note that RAM disks (major=1) are excluded by default if --all is not specified. The filter is applied to the top-level devices only. This may be confusing for --list output format where hierarchy of the devices is not obvious.

-f, --fs

Output info about filesystems. This option is equivalent to -o NAME,FSTYPE,FSVER,LABEL,UUID,FSAVAIL,FSUSE%,MOUNTPOINTS. The authoritative information about filesystems and raids is provided by the blkid(8) command.

-I, --include list

Include devices specified by the comma-separated list of major device numbers. The filter is applied to the top-level devices only. This may be confusing for --list output format where hierarchy of the devices is not obvious.

-i, --ascii

Use ASCII characters for tree formatting.

-J, --json

Use JSON output format. It’s strongly recommended to use --output and also --tree if necessary. Note that children[] is used only if NAME column or --tree is used.

-l, --list

Produce output in the form of a list. The output does not provide information about relationships between devices and since version 2.34 every device is printed only once if --pairs or --raw not specified (the parsable outputs are maintained in backwardly compatible way).

-M, --merge

Group parents of sub-trees to provide more readable output for RAIDs and Multi-path devices. The tree-like output is required.

-m, --perms

Output info about device owner, group and mode. This option is equivalent to -o NAME,SIZE,OWNER,GROUP,MODE.

-N, --nvme

Output info about NVMe devices only.

-v, --virtio

Output info about virtio devices only.

-n, --noheadings

Do not print a header line.

-o, --output list

Specify which output columns to print. Use --list-columns to get a list of all supported columns. The columns may affect tree-like output. The default is to use tree for the column 'NAME' (see also --tree).

The default list of columns may be extended if list is specified in the format +list (e.g., lsblk -o +UUID).

-O, --output-all

Output all available columns.

-P, --pairs

Produce output in the form of key="value" pairs. The output lines are still ordered by dependencies. All potentially unsafe value characters are hex-escaped (\x<code>). See also option --shell.

-p, --paths

Print full device paths.

-Q, --filter expr

Print only the devices that meet the conditions specified by the expr. The filter is assessed prior to lsblk collecting data for all output columns. Only the necessary data for the lazy evaluation of the expression is retrieved from the system. This approach can enhance performance when compared to post-filtering, as commonly done by tools such as grep(1).

This feature is EXPERIMENTAL. See also scols-filter(5). For example exclude sda and sdb, but print everything else ('!~' is a negative regular expression matching operator):

lsblk --filter 'NAME !~ "sd[ab]"'

--highlight expr

Colorize lines matching the expression. This feature is EXPERIMENTAL. See also scols-filter(5).

--ct name [: param [: function ]]

Define a custom counter. The counters are printed after the standard output. The name is the custom name of the counter, the optional param is the name of the column to be used for the counter, and the optional function specifies the aggregation function, supported functions are: count, min, max, or sum. The default is count.

If the param is not specified, then the counter counts the number of lines. This feature is EXPERIMENTAL. See also --ct-filter.

For example, --ct MyCounter:SIZE:sum will count the summary for SIZE from all lines; and to count the number of SATA disks, it is possible to use:

lsblk --ct-filter 'TYPE=="disk" && TRAN=="sata"' --ct "Number of SATA devices"

--ct-filter expr

Define a restriction for the next counter. This feature is EXPERIMENTAL. See also --ct and scols-filter(5). For example, aggregate sizes by device type:

lsblk --ct-filter 'TYPE=="part"' --ct Partitions:SIZE:sum \


      --ct-filter 'TYPE=="disk"' --ct WholeDisks:SIZE:sum

-r, --raw

Produce output in raw format. The output lines are still ordered by dependencies. All potentially unsafe characters are hex-escaped (\x<code>) in the NAME, KNAME, LABEL, PARTLABEL and MOUNTPOINT columns.

-S, --scsi

Output info about SCSI devices only. All partitions, slaves and holder devices are ignored.

-s, --inverse

Print dependencies in inverse order. If the --list output is requested then the lines are still ordered by dependencies.

-T, --tree[=column]

Force tree-like output format. If column is specified, then a tree is printed in the column. The default is NAME column.

-t, --topology

Output info about block-device topology. This option is equivalent to

-o NAME,ALIGNMENT,MIN-IO,OPT-IO,PHY-SEC,LOG-SEC,ROTA,SCHED,RQ-SIZE,RA,WSAME.

-h, --help

Display help text and exit.

-V, --version

Print version and exit.

-w, --width number

Specifies output width as a number of characters. The default is the number of the terminal columns, and if not executed on a terminal, then output width is not restricted at all by default. This option also forces lsblk to assume that terminal control characters and unsafe characters are not allowed. The expected use-case is for example when lsblk is used by the watch(1) command.

-x, --sort column

Sort output lines by column. This option enables --list output format by default. It is possible to use the option --tree to force tree-like output and than the tree branches are sorted by the column.

-y, --shell

The column name will be modified to contain only characters allowed for shell variable identifiers, for example, MIN_IO and FSUSE_PCT instead of MIN-IO and FSUSE%. This is usable, for example, with --pairs. Note that this feature has been automatically enabled for --pairs in version 2.37, but due to compatibility issues, now it’s necessary to request this behavior by --shell.

-z, --zoned

Print the zone related information for each device.

--sysroot directory

Gather data for a Linux instance other than the instance from which the lsblk command is issued. The specified directory is the system root of the Linux instance to be inspected. The real device nodes in the target directory can be replaced by text files with udev attributes.

EXIT STATUS

0

success

1

failure

32

none of specified devices found

64

some specified devices found, some not found

ENVIRONMENT

LSBLK_DEBUG=all

enables lsblk debug output.

LIBBLKID_DEBUG=all

enables libblkid debug output.

LIBMOUNT_DEBUG=all

enables libmount debug output.

LIBSMARTCOLS_DEBUG=all

enables libsmartcols debug output.

LIBSMARTCOLS_DEBUG_PADDING=on

use visible padding characters.

NOTES

For partitions, some information (e.g., queue attributes) is inherited from the parent device.

The lsblk command needs to be able to look up each block device by major:minor numbers, which is done by using /sys/dev/block. This sysfs block directory appeared in kernel 2.6.27 (October 2008). In case of problems with a new enough kernel, check that CONFIG_SYSFS was enabled at the time of the kernel build.

AUTHORS

Milan Broz <gmazyland@gmail.com>, Karel Zak <kzak@redhat.com>

SEE ALSO

blkid(8), findmnt(8) ls(1), scols-filter(5)

REPORTING BUGS

For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY

The lsblk 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/>.

2024-07-04 util-linux 2.40.2