//po4a: entry man manual
= lsblk(8)
:doctype: manpage
:man manual: System Administration
:man source: util-linux {release-version}
:page-layout: base
:command: lsblk
:smartcols-json:

== 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*::
include::man-common/in-bytes.adoc[]

*-H*, *--list-columns*::
List the columns that can be specified with the *--output* option.
Can be used with *--json* or *--raw* to get the list in a 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.

include::man-common/hyperlink.adoc[]

*-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* _expression_::
Print only the devices that meet the conditions specified by _expression_. 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, to exclude sda and sdb, but print everything else
('!~' is a negative regular-expression matching operator):
____
 lsblk --filter 'NAME !~ "sd[ab]"'
____

*--highlight* _expression_::
Colorize lines matching _expression_.
+
This feature is EXPERIMENTAL. See also *scols-filter*(5).

*--ct* _name_[**:**_parameter_[**:**_function_]]::
Define a custom counter. Custom counters are printed after the standard output.
The _name_ is the custom name of the counter, the optional _parameter_ 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*, *sum*.
The default function is *count*. If _parameter_ 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* reports the total of the SIZE values.
To report the number of SATA disks, one can use:
____

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


*--ct-filter* _expression_::
Define a restriction for the next counter.
+
This feature is EXPERIMENTAL. See also *--ct* and *scols-filter*(5).
+
For example, to 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*.

*-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.

*--properties-by* _list_::
This option specifies the methods used by *lsblk* to gather information about
filesystems and partition tables. The list is a comma-separated list of method
names. The default setting is "file,udev,blkid". The supported methods are:
+
*udev*;;
Reads data from udev DB. If unsuccessful, it continues to the next probing method.
*blkid*;;
Reads data directly from the device using libblkid. If unsuccessful, it continues to the next probing method.
*file*;;
Reads data from a file. This method is only used if the --sysroot option is specified. This method always stops probing if used.
*none*;;
Does not probe. This method always stops probing.

include::man-common/help-version.adoc[]

== EXIT STATUS

0::
success

1::
failure

32::
none of specified devices found

64::
some specified devices found, some not found

include::man-common/colors.adoc[]

== ENVIRONMENT

*LSBLK_DEBUG*=all::
enables *lsblk* debug output.

*LIBBLKID_DEBUG*=all::
enables *libblkid* debug output.

*LIBMOUNT_DEBUG*=all::
enables *libmount* debug output.

include::man-common/env-smartcols.adoc[]

*LSBLK_COLUMNS*=::
specifies a comma-separated list of output columns to print. All columns listed by *--list-columns* can be used.

== 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

mailto:gmazyland@gmail.com[Milan Broz],
mailto:kzak@redhat.com[Karel Zak]

== SEE ALSO

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

include::man-common/bugreports.adoc[]

include::man-common/footer.adoc[]

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