Cleaning Linux: Jed’s Nappy /boot

My home NAS machine is an Ubuntu 14.04 machine with a ZFS volume. I need the linux-headers packages in order to compile my ZFS dkms modules. Those take more space than the kernels tend to, so I try and stay on top of removing them. Wonder how many I have?

> dpkg-query -l linux-header* | grep 'ii ' | wc -l
45

Oh. Guess I got a bit lazy there. Notice how I combine dpkg-query and grep ‘ii ‘ (with a space after ‘ii’). This filters out what’s installed. However, I have kernels to boot into that I have booted yet and I need to filter out which of those actual packages are behind my present kernel and not un-install anything newer.

dpkg-query -l linux-header* | grep 'ii ' | while read k ; do v=`echo "$k"| cut -d- -f4|cut -d' ' -f1` ; [ ! -z "$v" ] && [ "$v" -lt 65 ] && echo $k|cut -d' ' -f2 ; done

Now, I had to work on that one for a bit. I really did it as a one-liner but I would up-arrow and edit up-arrow and edit until I got it printing what I wanted. Let’s look at it a bit more like a shell script:

dpkg-query -l linux-header* \
| grep 'ii ' \
| while read k ; do \
v=`echo "$k" \
| cut -d- -f4 \
| cut -d' ' -f1`;
[ ! -z "$v" ] \
&& [ "$v" -lt 65 ] \
&& echo $k \
|cut -d' ' -f2
done

And that gives me output like:

linux-headers-3.13.0-59
linux-headers-3.13.0-59-generic
linux-headers-3.13.0-61
linux-headers-3.13.0-61-generic
linux-headers-3.13.0-62
linux-headers-3.13.0-62-generic
linux-headers-3.13.0-63
linux-headers-3.13.0-63-generic

…but much more. I’m going to uninstall these immediately by piping this to xargs dpkg -r:

And what else do I need to remove? Well, a whole lot of installed kernels, too:

 > dpkg-query -l linux-image* | grep 'ii ' \
| fgrep '3.5' | awk '{print $2}'

linux-image-3.5.0-25-generic
linux-image-3.5.0-27-generic
linux-image-3.5.0-38-generic
linux-image-extra-3.5.0-25-generic
linux-image-extra-3.5.0-27-generic
linux-image-extra-3.5.0-38-generic

And of course, we remove those by piping to xargs dpkg -r again. I will not bother you with the output of that because it’s pages of post-install grub output.

But that just leaves me with two kernels installed and I’ve cleaned up a lot of space.

Jed Reynolds

Jed Reynolds has been known to void warranties and super glue his fingers together. When he is not doing photography or fixing his bike, he can be found being a grey beard programmer analyst for Candela Technologies. Start stalking him at https://about.me/jed_reynolds.