Couple versions ago, Ubuntu has stopped to automatically remove old kernels. It just ignores the setting for this functionality. As a result, after several years od usage, the system gets seriously cluttered. In some cases, it can even run out of space. In order to prevent this, I made a simple bash script to get rid of old kernels. You can run it manually, but I prefer having it on a monthly cron job and forgetting about it. By default, it leaves the two most recent kernels intact. This serves as a safety catch in case kernel upgrade doesn’t go well. However, you can adjust this to your needs. If you have any questions about usage, just leave me a comment.