lsblk

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 |

Device Naming Reference

| 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) |

Common Failures

| 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 | grep nvme | | 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 |

Pain Points

• 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.

References

See references/ for:

• cheatsheet.md — 10 task-organized patterns for common lsblk workflows
• docs.md — man pages and upstream documentation links