lsblk Command in Linux: List Block Devices

When you plug in a new drive, set up a fresh partition, or try to remember which disk is mounted where, you need a quick way to see every block device attached to the system. The lsblk command reads information from sysfs and the udev database and prints a tidy tree of disks, partitions, loop devices, and LVM volumes, together with their sizes and mount points.

This guide explains how to use lsblk to inspect block devices, pick the columns you need, and format the output for scripts.

lsblk Syntax #

The general form of the command is:

lsblk [OPTIONS] [DEVICE...]

With no arguments, lsblk lists every block device except RAM disks and empty devices. You can pass one or more device paths to limit the output, for example lsblk /dev/sda.

Unlike fdisk , lsblk does not need root privileges for most queries, which makes it safer for quick checks.

Basic Usage #

Run lsblk with no options to see a tree of all devices on the system:

lsblk

NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda           8:0    0 465.8G  0 disk
├─sda1        8:1    0   512M  0 part /boot/efi
├─sda2        8:2    0    16G  0 part [SWAP]
└─sda3        8:3    0 449.3G  0 part /
sdb           8:16   1  14.3G  0 disk
└─sdb1        8:17   1  14.3G  0 part /media/john/usb
sr0          11:0    1  1024M  0 rom

Each row describes one device. The tree characters on the left show which partitions belong to which disk. The TYPE column tells you whether the entry is a whole disk, a partition, an optical rom, an LVM lvm volume, a crypt container, and so on. The MOUNTPOINTS column is empty when the partition is not mounted.

The RM column is 1 when the kernel marks a device as removable, and RO is 1 for read-only devices. Some USB drives report RM as 0, so use the TRAN column when you specifically need to identify USB storage.

Hide Partitions and Child Devices #

When you only care about top-level devices, pass the -d (or --nodeps) flag to hide their partitions, holders, and slaves:

lsblk -d

NAME MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda    8:0    0 465.8G  0 disk
sdb    8:16   1  14.3G  0 disk
sr0   11:0    1  1024M  0 rom

This is handy when you do not want partition noise. It does not filter by device type, so entries such as the sr0 optical drive can still appear.

Snap packages mount as loop devices, so on an Ubuntu desktop the list can fill with loop0 through loop20 before you reach the real disks. Exclude them by major number with -e (or --exclude):

lsblk -e 7

Major number 7 is the loop driver. You can pass several numbers as a comma-separated list, for example lsblk -e 7,11 to drop optical drives as well.

Show Filesystem Information #

Passing -f (or --fs) replaces the default columns with filesystem details such as the type, label, UUID, and how full each mounted filesystem is:

lsblk -f

NAME   FSTYPE FSVER LABEL UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda
├─sda1 vfat   FAT32       4F3A-91BC                             470.1M     8% /boot/efi
├─sda2 swap   1           9f4b5a44-6d1e-44a8-a0ae-2c3d3e4f1234                 [SWAP]
└─sda3 ext4   1.0   root  be2e1f8e-7a0b-4ab1-9f1d-5c6d7e8f9012  312.5G    25% /
sdb
└─sdb1 vfat   FAT32 USB   1A2B-3C4D                              12.8G    10% /media/john/usb

This is usually the fastest way to find a UUID for /etc/fstab or to confirm which filesystem type sits on a given partition.

Pick Specific Columns #

The default columns cover the common cases, but you can choose exactly what to show with the -o (or --output) option. Pass a comma-separated list of column names:

lsblk -o NAME,SIZE,TYPE,MOUNTPOINTS

NAME     SIZE TYPE MOUNTPOINTS
sda    465.8G disk
├─sda1   512M part /boot/efi
├─sda2    16G part [SWAP]
└─sda3 449.3G part /
sdb     14.3G disk
└─sdb1  14.3G part /media/john/usb
sr0     1024M rom

To see the full list of columns lsblk understands, run:

lsblk --list-columns

On util-linux versions older than 2.41, that option does not exist yet, and lsblk --help prints the column list instead.

Useful columns include UUID, LABEL, MODEL, SERIAL, VENDOR, FSTYPE, PARTTYPE, HOTPLUG, and TRAN (transport, for example sata, nvme, or usb).

To add columns to the default set rather than replace it, prefix the list with +. For example, this command adds the model and serial number:

lsblk -o +MODEL,SERIAL

The -O (or --output-all) flag has a different purpose: it displays every available column.

Show Device Paths #

By default, lsblk prints short names such as sda1. If you want the full /dev path in the NAME column, add -p (or --paths):

lsblk -p

NAME           MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
/dev/sda         8:0    0 465.8G  0 disk
├─/dev/sda1      8:1    0   512M  0 part /boot/efi
├─/dev/sda2      8:2    0    16G  0 part [SWAP]
└─/dev/sda3      8:3    0 449.3G  0 part /

Full paths are easier to copy into a script or a mount command.

List a Single Device #

You can pass a device path to inspect only that device and its partitions:

lsblk /dev/sda

This narrows the output to one disk, which is useful on servers with many drives.

Flat and ASCII Output #

The tree layout is readable in a terminal but awkward to parse in scripts. Use -l (or --list) to print one device per line with no tree characters:

lsblk -l

NAME MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sda    8:0    0 465.8G  0 disk
sda1   8:1    0   512M  0 part /boot/efi
sda2   8:2    0    16G  0 part [SWAP]
sda3   8:3    0 449.3G  0 part /

If your terminal does not render Unicode box-drawing characters correctly, swap them for plain ASCII with -i (or --ascii).

Machine-Readable Output #

For scripts, the -J (or --json) flag prints the same information as structured JSON that is easy to parse with tools such as jq:

lsblk -J -o NAME,SIZE,FSTYPE /dev/sda

{
   "blockdevices": [
      {
         "name": "sda",
         "size": "465.8G",
         "fstype": null,
         "children": [
            {
               "name": "sda1",
               "size": "512M",
               "fstype": "vfat"
            },
            {
               "name": "sda2",
               "size": "16G",
               "fstype": "swap"
            },
            {
               "name": "sda3",
               "size": "449.3G",
               "fstype": "ext4"
            }
         ]
      }
   ]
}

Each disk becomes an object, and its partitions appear in the children array, so the tree relationship survives the conversion. Fields that do not apply are null rather than empty strings, which keeps the types stable for jq.

You can also use -P (pairs) for line-oriented KEY="value" output, or -r (raw) for space-separated fields with no padding.

The default columns can change between util-linux releases. In scripts, always select the columns you expect with -o, then choose a predictable format such as -J, -P, or -l.

For example, to list only mounted ext4 partitions in a script:

lsblk -lnp -o NAME,FSTYPE,MOUNTPOINTS | awk '$2 == "ext4" && $3 != "" {print $1, $3}'

The -n (or --noheadings) flag drops the header row so that the output is pure data.

Show Sizes in Bytes #

Sizes are printed in human-readable units by default, for example 465.8G. For exact values, use -b (or --bytes):

lsblk -b -o NAME,SIZE

This is the form you want when comparing sizes in a script, since 465.8G is not directly comparable with 449.3G as a string.

Quick Reference #

Common lsblk flags and what they do:

• -a - Include empty devices and RAM disks that are normally hidden.
• -b - Print sizes in bytes instead of human-readable units.
• -d - Hide partitions, holders, and slaves.
• -e LIST - Exclude devices by major number (7 is loop).
• -f - Show filesystem information (type, label, UUID, usage).
• -i - Use plain ASCII characters for the tree instead of Unicode.
• -J - Output as JSON.
• -l - Use a flat list instead of the tree layout.
• -n - Omit the header row.
• -o LIST - Choose which columns to display.
• -o +LIST - Add columns to the default output.
• -O - Display every available column.
• -p - Print full device paths such as /dev/sda1.
• -P - Output as KEY="value" pairs for shell scripts.
• -r - Raw output with no padding.
• -S - Show information about SCSI devices only.
• -t - Print topology information (alignment, I/O sizes).

FAQ #

How is lsblk different from fdisk -l?
lsblk reads from sysfs and udev and shows a tree of devices with mount points and filesystem details, all without root privileges for the common cases. fdisk -l reads the partition table directly from the device and focuses on partition layout, sector offsets, and disk identifiers. Use lsblk for a quick overview and fdisk when you care about the raw partition table.

Why is a device missing from lsblk output?
Run lsblk -a to include empty devices and RAM disks that are normally hidden. If you just connected or changed a device, run udevadm settle before trying lsblk again so udev can finish processing the event. A drive that the kernel never detected cannot appear in the list; check the cable or port and inspect recent messages with sudo dmesg | tail -n 30.

How can I get only the UUID of a partition?
Combine -n to drop the header, -o UUID to pick the column, and the device path:
lsblk -no UUID /dev/sda3.

Does lsblk show LVM and encrypted volumes?
Yes. LVM logical volumes appear as children of their physical volume with type lvm, and LUKS-encrypted containers show as crypt. The tree layout makes the stacking relationship easy to follow.

Can lsblk show disk model or serial number?
Yes. Add them to the output list: lsblk -o NAME,MODEL,SERIAL,SIZE. Some virtual devices do not expose these fields, so they may be empty.

Conclusion #

lsblk is the fastest way to answer the “what disks and partitions does this machine have?” question, and its JSON and column-selection options make it equally useful inside scripts. Pair it with df for usage stats and with mount when you are ready to attach a new device.

About the authors

Dejan Panovski

Dejan Panovski is the founder of Linuxize, an RHCSA-certified Linux system administrator and DevOps engineer based in Skopje, Macedonia. Author of 800+ Linux tutorials with 20+ years of experience turning complex Linux tasks into clear, reliable guides.

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