Table of Contents

Ubuntu - Boot - Free up space in /boot

/boot partition is nearly full; or a warning is received every time the system is rebooted.

Confirm this is the case: 

df
ls /boot/

Purge unused kernels

sudo apt-get purge linux-image-x.x.x-x

NOTE: Removing the linux-image-x.x.x-x package will also remove linux-image-x.x.x-x-generic.

Delete source headers

The headers are installed into /usr/src and are used when building out-tree kernel modules. 

ls /usr/src

Returns 

linux-headers-4.4.0-21          linux-headers-4.4.0-34-generic  linux-headers-4.4.0-42          linux-headers-4.4.0-45-generic
linux-headers-4.4.0-21-generic  linux-headers-4.4.0-36          linux-headers-4.4.0-42-generic  linux-headers-4.4.0-47
linux-headers-4.4.0-31          linux-headers-4.4.0-36-generic  linux-headers-4.4.0-43          linux-headers-4.4.0-47-generic
linux-headers-4.4.0-31-generic  linux-headers-4.4.0-38          linux-headers-4.4.0-43-generic
linux-headers-4.4.0-34          linux-headers-4.4.0-38-generic  linux-headers-4.4.0-45

Delete unused source headers 

rm -Rf /usr/src/linux-headers-4.4.0-21*

ALERT: Take special care that you have entered the rm command correctly to prevent deleting unintended files.