Identity

Property	Value
Binary	`lsblk`
Config	No persistent config — invoked directly
Logs	No persistent logs — output to terminal
Type	CLI tool (part of util-linux)
Install	`apt install util-linux` / `dnf install util-linux` (pre-installed on all Linux systems)

Key Operations

Task	Command
Default tree view (names, sizes, types, mountpoints)	`lsblk`
Include all empty and RAM block devices	`lsblk -a`
Show filesystem info (UUID, FSTYPE, LABEL, MOUNTPOINT)	`lsblk -f`
JSON output for scripting	`lsblk -J`
Key=value pairs output	`lsblk -P`
Query a specific device only	`lsblk /dev/sda`
Show sizes in raw bytes	`lsblk -b`
Custom columns: name, size, UUID, label, mountpoint	`lsblk -o NAME,SIZE,UUID,LABEL,MOUNTPOINT`
Custom columns with filesystem type	`lsblk -o NAME,SIZE,FSTYPE,UUID,LABEL,MOUNTPOINT,TYPE`
Show topology information (queues, alignment)	`lsblk -t`
Show disk serial numbers and model	`lsblk -o NAME,SIZE,SERIAL,MODEL,TYPE`
Exclude loop devices (snap/flatpak noise)	`lsblk -e 7`

Pattern	Meaning
`sda`, `sdb`	SATA/SAS/USB disks (first, second)
`sda1`, `sda2`	Partitions on `sda`
`nvme0n1`	First NVMe drive, namespace 1
`nvme0n1p1`	First partition on NVMe drive
`vda`, `vdb`	Virtio block devices (KVM/QEMU VMs)
`mmcblk0`	eMMC / SD card
`mmcblk0p1`	Partition on eMMC
`md0`	Software RAID device (mdadm)
`dm-0`, `dm-1`	Device mapper device (LVM LV or LUKS)
`loop0`..`loop7`	Loop devices (snap packages, mounted images)

Symptom	Cause	Fix
`MOUNTPOINT` column blank for a mounted device	Device is bind-mounted or mounted in a namespace	`findmnt` gives a more complete picture of all mounts
Many `loop` devices cluttering output	snap or flatpak packages each create a loop device	`lsblk -e 7` to exclude loop devices (`7` is the loop device major number)
`dm-*` devices shown without context	LVM logical volumes or LUKS containers — names are not descriptive	`lvdisplay` for LVM details; `dmsetup ls` to see dm device purpose
NVMe drive not shown	Kernel NVMe module not loaded	`modprobe nvme`; check `dmesg
Partition not shown as child of disk	Disk uses a partition table type kernel did not recognize	`gdisk -l /dev/sdX` to inspect; `partprobe /dev/sdX` to re-read table
`lsblk -f` shows no UUID for a partition	Partition exists but has no filesystem	Format with `mkfs.ext4 /dev/sdX1` or appropriate filesystem tool

Reads from sysfs, not root required: lsblk does not require root and reads from /sys/block. This also means it can only report what the kernel knows — if a partition table change was made without partprobe, lsblk will show stale data.
MOUNTPOINT shows only the first mount: if a device is mounted in multiple places (bind mounts, bind namespaces), lsblk shows only one mountpoint. Use findmnt --source /dev/sdX1 to see all mount points for a device.
dm- naming is opaque*: Device mapper devices (dm-0, dm-1) are LVM logical volumes or LUKS containers. The name carries no semantic meaning. Cross-reference with lvdisplay (LVM), cryptsetup status /dev/mapper/name (LUKS), or dmsetup ls --tree (full dependency tree).
loop devices from snap/flatpak: Each snapped application mounts a squashfs image via a loop device. These are legitimate but inflate lsblk output on desktop systems. Use -e 7 to exclude them entirely when looking at real storage devices.
-f flag does not show size: lsblk -f switches the column set to filesystem-centric columns and drops SIZE. Combine explicitly: lsblk -o NAME,SIZE,FSTYPE,UUID,LABEL,MOUNTPOINT to get both.

See references/ for: