lsblk: Inspect Block Devices Efficiently

lsblk: Inspect Block Devices Efficiently

A lightweight tool to list information about block devices in a tree-like view. It works well for quick audits of disks, partitions, and filesystems without needing to parse /proc or /sys manually.

Quick start

  • Basic usage (tree view of all devices):
lsblk
  • Include empty devices (no partitions) in the output:
lsblk -a
  • Show data in bytes instead of human-friendly units:
lsblk -b
  • Show filesystem information alongside devices:
lsblk -f
  • Use ASCII characters for the tree (no unicode):
lsblk -i
  • Display a topology view (how devices connect to each other):
lsblk -t

Tip: Combine options to tailor output for scripts or reports. For example, a clean, ASCII tree with filesystem info:

lsblk -aif

Common options you’ll love

  • -a, —all: Include empty devices in the listing.
  • -b, —bytes: Display SIZE in bytes rather than human-readable units.
  • -f, —fs: Print filesystem information (FSTYPE, LABEL, UUID, MOUNTPOINT).
  • -i, —ascii: Use ASCII characters for the tree format.
  • -t, —topology: Show device topology information (RING, SLOTS, etc.).
  • -e, —exclude: Exclude specified major device numbers (comma-separated).
  • -o, —output: Choose exactly which columns to print.

Example: show a custom set of columns

lsblk -o NAME,SERIAL,MODEL,TRAN,TYPE,SIZE,FSTYPE,MOUNTPOINT

Practical examples

  • List all devices with a focus on the mount points and filesystem type:
lsblk -o NAME,SIZE,FSTYPE,MOUNTPOINT
  • Exclude common non-storage devices (e.g., RAM disks) by major number:
lsblk -e 1,7
  • Print SIZE in bytes for scripting precision:
lsblk -b
  • Display a filesystem-aware view including mount points:
lsblk -f
# Note: when running with sudo vs. non-sudo
# lsblk generally works without root, but some values may be limited by permissions.

Common pitfalls

  • Misreading the SIZE column after switching between -h (human-readable) and -b (bytes). If your script expects fixed bytes, always use -b.
  • Relying on the default order. lsblk prints in a structured tree, but the ordering may not match your expectations for large arrays; specify -o to fix the columns you care about.
  • Forgetting that -a includes empty devices. This can dramatically increase output on systems with many virtual devices.

When to prefer lsblk over other tools

  • For a clean, script-friendly snapshot of disks and partitions without parsing /proc/partitions.
  • When you need a quick topology view to understand how devices are connected (SATA, NVMe, loop devices).
  • When you want to tailor the output to a report by selecting exact columns with -o.

Quick tips for scripting

  • Always pin the columns you need with -o to ensure consistent output parsing.
  • Combine -f with -o to quickly capture filesystem details in logs.
  • Use -a cautiously in automation to avoid flood of unnecessary entries.

TL;DR

  • lsblk lists block devices in a readable, tree-like format.
  • Use -a to include empty devices, -f for filesystem info, -t for topology, -b for bytes, -i for ASCII, and -o to tailor columns.
  • Example: lsblk -o NAME,SERIAL,MODEL,TRAN,TYPE,SIZE,FSTYPE,MOUNTPOINT

See Also