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Read-only first

Boot partition full on Linux

Check /boot usage, installed kernels, and the running kernel before cleanup.

Safest first command

df -h /boot

Before you run this

Expected output: Filesystem usage for /boot, including Use% and available space.

When not to use it: Do not delete kernel files directly from /boot and never remove the running kernel.

Expected output example

Filesystem Size Used Avail Use% Mounted on
/dev/sda1 470M 450M 20M 96% /boot

How to read the result

A high Use% on /boot can block kernel updates. Cleanup must preserve the running kernel and at least one known-good fallback.

What to check next

/boot is nearly full

Means: Kernel packages or initramfs files may block updates.

Next step: List installed kernels for the distro.

Check /boot Disk Usage

Many old kernels installed

Means: Package-managed cleanup may reclaim space.

Next step: Compare installed kernels with the running kernel.

List Installed Debian Kernels

Current kernel matches removal candidate

Means: That package is not safe to remove now.

Next step: Record running kernel first.

Show Running Kernel Version

Boot partition decision tree

Measure /boot, list installed kernels, and record the running kernel before package cleanup. Use package tools, not manual deletion, whenever possible.

  1. df -h /boot
  2. dpkg -l 'linux-image*' | awk '/^ii/{print $2,$3}'
  3. rpm -q kernel
  4. uname -r

Bad fixes to avoid

Do not delete files directly from /boot. Do not remove the running kernel. Do not purge all old kernels without keeping a fallback.

Common causes

  • Many old kernel packages
  • Small /boot partition
  • Failed prior cleanup
  • Initramfs files accumulating
  • Package manager interrupted

What not to change yet

  • Do not delete the running kernel.
  • Do not remove kernel files manually.
  • Do not reboot until boot files are known-good.

Stop and escalate if

  • The next step could interrupt users, remove data, or lock out access.
  • The output includes secrets, customer data, or private infrastructure details.
  • You cannot explain the blast radius of the repair command.

supporting commands

Command path

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