Remove Old Kernels In Ubuntu With One Command
A while back I wrote a post on how to remove old kernels from your Ubuntu system. While that process works just fine, it is a four step process. One person who read that post left a comment with a nice command line one-liner that removes all but the currently running kernel. And while that one-liner works quite well, I must admit that I don't understand all the regular expressions used in it, so I decided to try and come up with my own one-liner to remove the old kernels from my system.
I'm going to take you through this step by step so you can see how the individual commands in this one-liner tie together. If you're impatient, you can skip to the end to see the final command.
Step 1) List all packages that start with "linux-"
We'll use the dpkg command with the -l switch to list the packages, whether installed or not, that start with the string linux-.
Step 2) Filter that list to show only installed packages
To filter the list, I'm going to pipeline the output of the first command into the awk command. I'm also going to use awk to filter out everything but the package names.
Step 3) Filter out packages for the currently running kernel
OK, so now I'm down to a pretty limited number of packages, but I don't want to remove the packages for my currently running kernel. I'm going to use a few commands to do that. First off, I can determine my currently running kernel with the uname -r command. Currently on my system that command outputs: 2.6.32-25-generic.
To do my package filtering, I only want the numeric portion of that output. I'll pipeline the output of uname -r and use the cut command with a hyphen as the field delimiter. I'll cut fields 1 & 2.
Now I'm going to use this result as the filter for a grep command. In Linux, to use the result of one command as an argument in another command, you enclose the command in single back-quotes ( ` that's the key to the left of the 1 on a standard US keyboard). So here's my one-liner so far.
This is the output so far on my system:
linux-generic
linux-headers-2.6.32-24
linux-headers-2.6.32-24-generic
linux-headers-generic
linux-image-2.6.32-24-generic
linux-image-generic
linux-libc-dev
linux-sound-base
Step 4) Filter the list for only the kernel packages
So now I have a package list that excludes the packages for my current kernel. The only packages from the list above that I want to remove are: linux-headers-2.6.32-24, linux-headers-2.6.32-24-generic, linux-image-2.6.32-24-generic.
What makes these packages unique from the others in the list is that they all contain numbers. So I can use grep again to filter the list down to only packages with numbers in their names. I'll pipeline the output of the previous command into grep -e [0-9].
So now the output on my system is only the following:
linux-headers-2.6.32-24-generic
linux-image-2.6.32-24-generic
Step 5) Putting it all together: Removing the packages
So now that I have a good list of packages I can use another pipe and the xargs command to invoke apt-get to remove the packages. First I'm going to show it using the --dry-run switch with apt-get. That way you can give it a try without actually changing your system.
If everything looks good after the dry run, you can go ahead and remove the old kernels with:
So there you have it. One command, albeit a long one, to remove the old kernels from your Ubuntu system. I imagine the same command should work on other Debian based systems as well, but I've only tested this on my 32 bit system. I'd be interested to know if it works just as well on a 64 bit system.
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Hey, it works. Had to run update-grub, then because I'm using BURG, had to run update-burg. There oughta be a button somewhere for this command, eh?
[...] Remove Old Kernels In Ubuntu With One Command [...]
"I'd be interested to know if it works just as well on a 64 bit system"
Testing on Ubuntu Lucid amd64 system, and it works.
Also someone posted this at Ubuntu forums a while back as a function script that works well:
rmkernel () { local cur_kernel=$(uname -r|sed 's/-*[a-z]//g'|sed 's/-386//g') local kernel_pkg="linux-(image|headers|ubuntu-modules|restricted-modules)" local meta_pkg="${kernel_pkg}-(generic|i386|server|common|rt|xen|ec2)" sudo aptitude purge $(dpkg -l | egrep $kernel_pkg | egrep -v "${cur_kernel}|${meta_pkg}" | awk '{print $2}') } rmkernel exit 0Thanks for the 64 bit verification and for the nice tip about the script.
Thanks for posting my rmkernel script (fun to see where it ends up!)
I made a new version, which can also be used for Debian, as the previous version did not work for that OS.
http://blog.opperschaap.net/2011/02/04/removing-old-kernels-in-debian-or-ubuntu/
It's always a good idea to keep the previous kernel installed, in case you need to roll back. So, I'd add another line for previous kernel:
local pre_kernel=$(echo ${cur_kernel} | tr '' \\\n | awk 'BEGIN{FS="-";OFS="-"} {print $1,$2-1}')
and then modify the 'aptitude' to add 'pre_kernel' to the exclude list:
sudo aptitude purge $(dpkg -l | egrep $kernel_pkg | egrep -v "${cur_kernel}|${pre_kerne}|${meta_pkg}" | awk '{print $2}')
Cheers!!
it works with 64-bit. thanks
Thanks it worked great.
To take it one step further, you can purge all the old configuration files with the following (after completing the Big One Liner (above):
dpkg -l 'linux-*' | awk '/^rc/{ print $2}' | sudo xargs apt-get -y purge
Thanks for this nice little ditty!
Does anyone know how (or whether it makes sense) to delay the execution of the postrm.d scripts until after all the pieces are removed? It gets a little tiresome watching all those initramfs and zz-update-grub calls...
Thanks for the tip. I didn't know those rc status config files were still hanging around. However, when I try your command I get this type of error:
When I modify your command to:
it works.
After doing some research, it looks like if I change my one-liner to purge instead of remove, then it should get rid of the config files as well and make this all moot, so I'm updating my post. I'll install an older kernel and re-run the command to see if it works.
OK, I verified that changing my one-liner to purge instead of remove resolves the config file issue.
Thanks for the handy script.
I had to add -y argument to apt-get to make it work. Ubuntu 10.10.
It's always a good idea to keep the last kernel installed. So, I'd modify the rmkernel script to add this line for the previous version of kernel:
[code]local pre_kernel=$(echo ${cur_kernel} | tr '' \\\n | awk 'BEGIN{FS="-";OFS="-"} {print $1,$2-1}')[/code]
and then add pre_kerne to the exclude list:
[code]sudo aptitude purge $(dpkg -l | egrep $kernel_pkg | egrep -v "${cur_kernel}|${pre_kernel}|${meta_pkg}" | awk '{print $2}'[/code]
For the one-liner:
[code]dpkg -l linux-* | awk '/^ii/{ print $2}' | grep -v -e `uname -r | cut -f1,2 -d"-"` -e `uname -r | gawk 'BEGIN{FS="-";OFS="-"} {print $1,$2-1}'` | grep -e [0-9][/code]
Cheers!!
Very nice, but this article seems to assume that you're already running the OS with the latest kernel, so as this article goes, it will delete all kernels except the one currently running, which may be an old one.
What would be a better command is if it deleted all kernels except the latest one (and perhaps also the one currently running).
Speaking of which, why doesn't ubuntu default to running the latest one? Despite installing kernel updates, mine's still defaulting to an old one...
That's a configuration option. You can adjust the booted kernel in /etc/default/grub
That's rather more than one command. LOL
Yes, I suppose that's true, but it is all on one line!
Thank you!!! It worked like a charm.
I modified it a little bit to keep both the running and the newest kernel.
Thanks for the script!
[code]
rmkernel () {
local cur_kernel=$(uname -r|sed 's/-*[a-z]//g'|sed 's/-386//g')
local kernel_pkg="linux-(image|headers|ubuntu-modules|restricted-modules)"
local meta_pkg="${kernel_pkg}-(generic|i386|server|common|rt|xen|ec2|amd64)"
local pre_kernel=$(echo ${cur_kernel} | tr '' \\\n | awk 'BEGIN{FS="-";OFS="-"} {print $1,$2-1}')
local latest_kernel=$(dpkg -l linux-* | awk '/^ii/{ print $2}' | grep -v -e `uname -r | cut -f1,2 -d"-"` | grep -e [0-9] | tail -1 | cut -f3,4 -d"-")
aptitude purge -y $(dpkg -l | egrep $kernel_pkg | egrep -v "${cur_kernel}|${meta_pkg}|${latest_kernel}" | awk '{print $2}')
}
rmkernel
exit 0
[/code]
Little correction:
#!/bin/bash
rmkernel () {
local cur_kernel=$(uname -r|sed 's/-*[a-z]//g'|sed 's/-386//g')
local kernel_pkg="linux-(image|headers|ubuntu-modules|restricted-modules)"
local meta_pkg="${kernel_pkg}-(generic|i386|virtual|server|common|rt|xen|ec2|amd64)"
local latest_kernel=$(dpkg -l linux-* | awk '/^ii/{ print $2}' | grep -e [0-9] | tail -1 | cut -f3,4 -d"-")
aptitude purge -y $(dpkg -l | egrep $kernel_pkg | egrep -v "${cur_kernel}|${meta_pkg}|${latest_kernel}" | awk '{print $2}')
}
rmkernel
exit 0
Worked perfectly for me.
After I finished, I ran /usr/sbin/update-grub just to be safe.
Matt Locke - Nashville, TN
i'v been updating for almost 2 years now.. this freed 2.7 GB of storage.. THANKS
Hi all ... thank you for the nice command ... I have just run it on my Ubuntu Lucid 64 bit and it worked perfectly ...
Thanks worked a treat!
Thanks, this made my life alot easier!
superboer12 - great command, worked fine on my 64 bit Lucid. How would I modify this script to keep the last two kernels? I had .39, .40 and .41. After running this I had only .41. Booted OK but I always worry.
Thanks!
I use this script to clear my kernels
#/bin/bash
ls /boot/ | grep vmlinuz | sed 's@vmlinuz-@linux-image-@g' | grep -v `uname -r` > /tmp/kernelList
for I in `cat /tmp/kernelList`
do
aptitude remove $I
done
rm -f /tmp/kernelList
update-grub
Why not just
$sudo apt-get autoremove
?
Does
remove old kernels for you? It doesn't on any of my systems.