Free Up Space in /boot on Ubuntu

If you notice your /boot directory on Ubuntu is getting full, these steps can help relieve some space.

1. Find the current kernel version to avoid accidental deletion

   $ uname -r

2. List all installed kernel versions.

   $ dpkg --list 'linux-image*' | grep ^ii

3. Uninstall all kernels whose versions are two or more before the currently installed version.

   # apt-get remove ...

4. Clean up old headers

   # apt-get autoremove