Every time I install a new Linux kernel, it gets left in the grub_config, making the boot menu longer each time.

I know I can manually search through the installed packages and remove them.

Does Ubuntu provide any easier way to clean them up or keep them from showing in the boot list?

  • As well as removing the old kernels, uncomment this line in /etc/default/grub if you want to get rid of the 'recovery' items in the menu: #GRUB_DISABLE_LINUX_RECOVERY="true" – poolie Nov 29 '10 at 6:04
  • In recent releases Ubuntu hides kernels in Grub's sub menu, so it is not that obtrusive. However, it may be good idea to remove extra kernels to save space, especially, if you have a separate small /boot partition. – jarno Apr 17 '15 at 21:44
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    There is an ubuntu command called purge-old-kernels to do the job. See my answer for more information. – jarno May 7 '15 at 11:43
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    sudo apt-get autoremove should do the trick on Ubuntu 14.04+ – hobs Dec 1 '15 at 17:17
  • 1
    The accumulation of old kernels is a bug, with fix in progress: bugs.launchpad.net/bugs/1357093 . When the fix is released, older kernels will autoremove by default. – user535733 Dec 31 '15 at 17:52

37 Answers 37

up vote 572 down vote accepted
+200

16.04 and newer versions of Ubuntu

sudo apt autoremove

This command removes packages that were automatically installed to resolve a dependency, but are now no longer depended on. This includes old versions of linux-headers-* and linux-image-*. (It’s also smart about this process, leaving one spare version of the kernel around as a fallback!)

11.10 and newer versions of Ubuntu

GRUB2 and its display of all kernels

The latest versions of Grub2 installed in Ubuntu automatically display the latest kernel and hides the older kernels that you may have installed.

GNU GRUB

If you do not see your grub - then remember to press Shift whilst booting.

As you can see, only the latest kernel is displayed.

If you select the option shown (press Enter) then all the old kernels become visible and available to boot from.

GNU GRUB Previous versions

How to permanently delete older kernels

First boot with the latest available kernel.

There are a number of ways to delete old kernels. Personally, I wouldn't touch Computer Janitor since this is acknowledged to break your computer with its suggestions.

synaptic

An alternative is Synaptic (sudo apt install synaptic)

search for linux-image, right-click a kernel and choose complete removal and finally click the Apply button to delete the kernel.

Synaptic Package Manager

Repeat the search but this time for linux-header - you can delete the associated headers for the kernel image chosen previously.

Synaptic though will not attempt to verify what you are trying to remove... you could inadvertently delete your newest kernel - or even delete all of your kernels via this tool leaving you with an unbootable Ubuntu!.

Remember to check which kernel you are using type:

uname -r

The result would be similar to:

Terminal <uname -r>

Remember the result and the number - make sure you don't delete the corresponding image or header.

Recommendation

My recommendation is to keep at least two or preferably three kernels including the latest. The reason for the recommendation is that you will have at least one/two other kernels to boot with, if for what-ever reason the latest kernel you are unable to boot with or introducing a regressed capability such as broken wireless.

  • 3
    Removing old "linux-image*" packages using synaptic, worked well with 10.04 too. (I mention it because the title suggests it may only be for 11.10 and up) – mivk May 17 '12 at 16:35
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    the -y switch at the end of the apt-get line is necessary, otherwise apt-get just asks for confirmation and since the input is a pipe, it just aborts. So it should end in: | xargs sudo apt-get purge -y – Josh Aug 26 '13 at 16:30
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    Removing about 20 versions of old linux-image and linux-headers freed 4.5GB of space on my machine. – Andrew Mao Jan 7 '14 at 19:30
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    This method works well, but deletion of every kernel excessively regenerates grub.cfg, which takes time. Is there any way of disabling this for batch deletion, then regenerating it once? – spacediver Mar 25 '14 at 23:47
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    I second the question from @spacediver - this is a crazy-slow process when you have 38 unneeded kernels, since as each one is uninstalled it goes thru all the remaining ones while generating a new grub.cfg. That is what we call an N^2 operation - it processes a kernel about (38^2 / 2) = 722 times, and is very slow. Surely Ubuntu can come up with something better.... – nealmcb Nov 2 '14 at 3:12

First, reboot your System to be sure it is using the latest kernel. Then open terminal and check your current kernel:

uname -r 

DO NOT REMOVE THIS KERNEL!

Next, type the command below to view/list all installed kernels on your system.

dpkg --list | grep linux-image 

Find all the kernels that lower than your current kernel. When you know which kernel to remove, continue below to remove it. Run the commands below to remove the kernel you selected.

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

Finally, run the commands below to update grub2

sudo update-grub2 

Reboot your system.

  • 33
    When doing this in 10.04 and 12.04, I found update-grub was automatically run during the purge process. – aidan Jan 2 '13 at 0:45
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    bash's brace expansion can be used, e.g. sudo apt-get purge linux-image-3.2.0-3{0..5}-generic (removes 30,31,..,35) – ajo Mar 19 '13 at 9:04
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    No need to reboot the system afterward. In fact, you should reboot the system before performing these steps, to ensure you are using the latest kernel version that you probably just downloaded & installed (you did an apt-get update && apt-get upgrade before this, right??) – Ricket Feb 28 '14 at 2:27
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    You may also want to uninstall the linux-signed-image packages that may be installed in UEFI systems: sudo apt-get purge linux-signed-image-3.11.0-{12,14,24}-generic which would remove 12, 14 and 24 – devius Jul 1 '14 at 10:53
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    @jarno I don't know if I'm using a signed kernel or not, but uname -r doesn't have any signed string on my system. I do seem to have a signed image installed and the output of that ls command is: /boot/vmlinuz-3.19.0-16-generic.efi.signed. – devius May 13 '15 at 14:38

My one-liner to remove old kernels (this also frees up disk space)

dpkg --list | grep linux-image | awk '{ print $2 }' | sort -V | sed -n '/'`uname -r`'/q;p' | xargs sudo apt-get -y purge

Explanation (remember, | uses the output of the previous command as the input to the next)

  • dpkg --list lists all installed packages
  • grep linux-image looks for the installed linux images
  • awk '{ print $2 }' just outputs the 2nd column (which is the package name)
  • sort -V puts the items in order by version number
  • sed -n '/'`uname -r`'/q;p' prints the lines before the current kernel
  • xargs sudo apt-get -y purge purges the found kernels

Unwinding the sed invocation:

  • -n tells sed to be quiet
  • `uname -r` outputs the current installed kernel release - we include it in backticks so that the output is includes as part of the command (you might also see this as $(uname -r)
  • /something/q says stop when you match 'something' (in this case, something is output of uname -r) - the / surround a regular expression
  • p is print
  • the ; is the command separtor, so /something/q;p says quit when you match something, else print

altogether, sed -n '/'`uname -r`'/q;p' is print the lines until it matches with the current kernel name.

If you're paranoid (like me), you can make the last part xargs echo sudo apt-get -y purge so that the command to purge the old kernels is printed, then you can check that nothing unexpected is included before you run it.


Modified version to remove headers:

dpkg --list | grep 'linux-image' | awk '{ print $2 }' | sort -V | sed -n '/'"$(uname -r | sed "s/\([0-9.-]*\)-\([^0-9]\+\)/\1/")"'/q;p' | xargs sudo apt-get -y purge
dpkg --list | grep 'linux-headers' | awk '{ print $2 }' | sort -V | sed -n '/'"$(uname -r | sed "s/\([0-9.-]*\)-\([^0-9]\+\)/\1/")"'/q;p' | xargs sudo apt-get -y purge

Note: the sed invocation is modified. "$(uname -r | sed "s/\([0-9.-]*\)-\([^0-9]\+\)/\1/")" extracts only the version (e.g. "3.2.0-44") , without "-generic" or similar from uname -r


All-in-one version to remove images and headers (combines the two versions above):

echo $(dpkg --list | grep linux-image | awk '{ print $2 }' | sort -V | sed -n '/'`uname -r`'/q;p') $(dpkg --list | grep linux-headers | awk '{ print $2 }' | sort -V | sed -n '/'"$(uname -r | sed "s/\([0-9.-]*\)-\([^0-9]\+\)/\1/")"'/q;p') | xargs sudo apt-get -y purge
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    Note that it is little bit dangerous to match current kernel version as regular expression like that: Dots match any character and 3.1.2-23 matches 3.1.2-2 (or is it other way around). See also my answer. – jarno May 16 '15 at 1:22
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    Here's a tuned all-in-one version: sudo apt-get purge $(for tag in "linux-image" "linux-headers"; do dpkg-query -W -f'${Package}\n' "$tag-[0-9]*.[0-9]*.[0-9]*" | sort -V | awk 'index($0,c){exit} //' c=$(uname -r | cut -d- -f1,2); done) See also my answer. – jarno May 18 '15 at 12:38
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    Due to unmet dependencies, I needed to use it with dkpg -Pinstead. Here is the full version: dpkg --list | grep 'linux-headers' | awk '{ print $2 }' | sort -V | sed -n '/'"$(uname -r | sed "s/\([0-9.-]*\)-\([^0-9]\+\)/\1/")"'/q;p' | xargs sudo dpkg -P – Sebastian Sastre Jun 22 '16 at 21:55
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    NO DON'T DO THIS! "That oneliner looks a little dangerous, but surely 220 upvoters can't be wrong!" I thought to myself and blindly copy-pasted. Rebooted, straight to GRUB. That command wiped all my kernels, including the one I was using. Maybe I was running a realtime kernel, can't even remember. Currently looking around my house for a USB stick to install Ubuntu Live CD on :( – Andreas Jansson Aug 26 '17 at 21:04
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    Worked fine for me on old Ubuntu 12.04 and 14.04 today. – tomfanning Aug 30 '17 at 16:21

Ubuntu 16.04+:

$ sudo apt autoremove
...
The following packages will be REMOVED:
  linux-headers-4.4.0-57 linux-headers-4.4.0-57-generic linux-image-4.4.0-57-generic linux-image-extra-4.4.0-57-generic linux-tools-4.4.0-57 linux-tools-4.4.0-57-generic

Ubuntu 15.10 and below:

I find this to be the easiest and quickest way. It keeps the latest kernel as well as two more:

sudo apt-get install bikeshed
sudo purge-old-kernels

To change the number of additional kernels that are kept:

sudo purge-old-kernels --keep 3
  • 1
    That command is a shell script, location of which you can find by which purge-old-kernels. – jarno May 16 '15 at 13:46
  • Glad they made this a lot easier in 16.04! Hope this answer keeps making its way up... – Toby J Mar 30 '17 at 13:53
  • On Ubuntu 16.04 I have purge-old-kernels without bikeshed (random useful tools that do not yet have a permanent home) package or any particular one.Avoid using apt-get -y option, is like closing eyes and hoping everything's going to be alright. Also here it is how autoremove decides how many old kernels to keep. – Pablo Bianchi May 21 '17 at 15:06
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    In 16.04 purge-old-kernels is provided by the byobu package (hint: apt-file search purge-old-kernels). Agreed on apt-get -y, I'll remove it. – bmaupin May 21 '17 at 18:34
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    @Dan since I don't use non-LTS versions I wasn't sure exactly when it started. But I can say for sure that sudo apt-get autoremove doesn't remove kernels in 14.04. Feel free to update the answer with the specific version if you know what it is! – bmaupin Sep 12 '17 at 13:41

Removing Entries from Grub 2 Entries should be removed by editing or removing files in the /etc/grub.d folder. The /boot/grub/grub.cfg file is read-only and should not normally require editing.

Too Many Kernels?

  • If you are not sure of the kernel you are currently using, in a terminal type uname -r.

  • Kernels removed via APT (Synaptic, "apt-get remove", etc.) will automatically update grub.cfg and no user action is required.

  • A great tool for removing kernels (and menu entries) is Ubuntu-Tweak, a safe and easy-to-use GUI app.

  • Install ubuntu tweak

  • Ubuntu-Tweak will be available under Applications > System Tools.

Remove Older Kernel Entries

  • Select "Package Cleaner" on the left and "Clean Kernel" from the right panel.

  • Press the "Unlock" button at the lower right, enter your password.

  • Select from the displayed list the kernel images and headers you wish to remove. The kernel in use is not listed.

  • Press the "Cleanup" button at the lower right to remove the selected kernel images and headers.

Remove Operating Systems from the Grub menu

  • Other Operating Systems which have been removed from the computer will also be removed from the menu once "update-grub" is run as root.

  • Menu items are placed on the Grub2 menu by scripts. If you don't want other Operating Systems to be entered in the menu, disable /etc/grub.d/30_osprober

  • Run this command to stop the script from running
    sudo chmod -x /etc/grub.d/30_os-prober

  • DISABLE_30_OS-PROBER='true' in /etc/default/grub

Remove Memtest86+ from the Grub Menu
sudo chmod -x /etc/grub.d/20_memtest86+

  • Run the update-grub command to allow the changes to be incorporated in grub.cfg

Source

Note: After kernel updates a new entry is added to the GRUB menu.You can remove the older one if you want.However, most experienced users will advise you to keep at least one spare entry in case something goes wrong with an upgrade and you need to boot an older kernel version for troubleshooting purposes.

Alternate way to remove Kernel entries (prior to 10.04)

for GRUB not GRUB2

startupmanager Install startupmanager

You can find it under System>>Administration>> alt text
alt text
You see in the second screenshot you can select how many kernels to show? I generally just keep it on 1, but when I get a kernel upgrade I always change it to 2 before restarting so I can select the older kernel if the new kernel has problems with my hardware. Once I know the new kernel is working well I change it back to 1.

  • 2
    Actually, startupmanager dint give me a window like this on Ubuntu 10.04, instead it just gave a window with two tabs -> Boot options and Advanced.. and in advanced it dint have the option to limit the number of kernels. So please update the answer for Ubuntu 10.04.(And thats why i down-voted this..) – Sen Dec 13 '10 at 5:12
  • any idea how "number of kernels to keep" can be defined on a machine that has no GUI installed (server)? – sylvainulg Mar 28 '13 at 9:24
  • startupmanager is outdated. See grup-customizer – muhasturk Sep 6 '14 at 2:23

Purely commandline, this will remove all but the current and second most current (via the "-2" in the head command below):

OLD=$(ls -tr /boot/vmlinuz-* | head -n -2 | cut -d- -f2- |
    awk '{print "linux-image-" $0 " linux-headers-" $0}' )
if [ -n "$OLD" ]; then
    apt-get -qy remove --purge $OLD
fi
apt-get -qy autoremove --purge
  • 9
    one-liner from there: dpkg -l linux-* | awk '/^ii/{ print $2}' | grep -v -e `uname -r | cut -f1,2 -d"-"` | grep -e [0-9] | xargs sudo apt-get -y purge – Dmitry Verkhoturov Aug 5 '12 at 19:31
  • @DmitryPaskal, You should add this as a new answer. – saji89 Mar 12 '13 at 10:26
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    @DmitryPaskal As always, don't just copy-paste these without understanding them. On my machine this one-liner also matches linux-libc-dev:amd64 which shouldn't be removed. – jamesadney Mar 12 '13 at 20:19
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    @Kees Cook, shouldn't the awk argument only be surrounded by single-quotes? If your intent is to prepend "linux-image-" to the piped lines, this only seems to work if you use awk '{print "linux-image-" $0}'. – Mark Jun 12 '13 at 17:33
  • this does not work for me, it includes my custom installed kernel (Ubuntu 14.04 with 3.17) – Alex R Feb 5 '15 at 9:39

Update: purge-old-kernels is deprecated nowadays.

I made a script to purge kernels even in tricky conditions. It is called linux-purge and you can find it here.

If you just want to purge the kernels (and the related packages) that are older than the currently used kernel, when system is not broken, you could use this script.

There is also an Ubuntu documentation page that I have contributed to concerning removing old kernels here.

  • Looks like purge-old-kernels isn't in the precise version (1.22) of bikeshed. Is there a reasonable/safe way to get a more recent bikeshed for precise? Or would it be simpler/safer to just install the script? I'd prefer to use a repo though, despite the long list of dependencies.. – drevicko Jun 8 '15 at 2:32
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    @drevicko See here. – jarno Jun 8 '15 at 8:27
  • One more slightly tangential question: short of going to the source, is there a way to determine which commands become available when you install bikeshed? – drevicko Jun 8 '15 at 12:00
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    @drevicko, sure, dlocate -lsbin bikeshed – jarno Jun 9 '15 at 4:57
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    @drevicko, see also another question – jarno Jun 9 '15 at 4:59

You can follow the Using the "unattended-upgrades" package section of Automatic Security Updates article on Ubuntu Wiki to perform this.

You need to change the following line in /etc/apt/apt.conf.d/50unattended-upgrades file;

//Unattended-Upgrade::Remove-Unused-Dependencies "false";

with

Unattended-Upgrade::Remove-Unused-Dependencies "true";

to automatically remove old packages, including kernels.

Also remove or comment the line

"^linux-image.*"; 

in the "NeverAutoRemove" section of the file /etc/apt/apt.conf.d/01autoremove.

  • 2
    I did this but it was still collecting 3+ old kernels consuming 100's of MBs. So I added apt-get autoremove to my daily cron job that actually does the upgrades, since it doesn't always go through built-in update-manager. – Marcos Aug 24 '12 at 12:01
  • I think this works in Trusty only for the kernels that have been installed automatically. – jarno Feb 10 '16 at 10:52
  • This is great to prevent buildup of old kernels when auto-upgrading packages, e.g. with unattended-upgrades. However if you don't reboot, you might find that the package for the currently running kernel has been uninstalled! One issue this can cause: new devices which you plug in might not work, because the module for them cannot be hot-loaded, because it is no longer on your disk. (A quick fix for this is just to install the kernel package again, and then unplug and replug the device.) – joeytwiddle Mar 18 '17 at 17:32
  • I created an automated solution to the aforementioned issue. If you think this is a good approach, then feel free to add it to Qwerty's answer. – joeytwiddle May 21 '17 at 6:04

The fastest/simpler way (Applicable at least since 12.04) possible that already comes with Ubuntu is apt-get. Do the following if you wish to remove all older kernel versions that are not in use (Except the previous one that you are no using. This is to make sure that if the current kernel version fails in some way, you have a way to go back to a previous state). Do the following:

sudo apt-get autoclean

This will eliminate any old files (Including kernel versions) you may have. Note that if you have many old versions, it will take a while since it has to make sure that removing the kernel version has no issues. For me, removing the last 12 kernel versions took about 2 minutes. You can also do the following:

sudo apt-get clean

Which will eliminate everything downloaded and stored in the cache folder of apt. Lastly you have:

sudo apt-get autoremove

which would check for any unused packages and remove them if necessary. This is great for those libraries and dependency packages that are no longer needed byt any app installed.

  • 1
    I suppose this has changed in newer releases as in 14.04 this merely cleans package cache and does not affect to installed packages or grub. – jarno May 16 '15 at 12:35
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    I can confirm that sudo apt-get autoremove does remove old (more than one version ago) kernels in 14.04. You may have to run it before and after upgrading your kernel. When I ran before upgrading, it only removed the old kernel's generic version. Then, after upgrading my kernel, it removed the old kernel's lowlatency version, as well. – tekNorah May 16 '15 at 20:24
  • I meant the sudo apt-get autoclean command. @tekNorah I installed a couple of older kernels and thereafter ran sudo apt-get autoremove in Ubuntu Studio 14.04. It did not remove any kernels. I have only lowlatency kernels installed. Why do you have both -generic and -lowlatency kernels installed? – jarno May 18 '15 at 11:05
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    Yes, this worked beautifully for me, cleaned up all old kernels properly, and does not rely on crazy one-line scripts! Recommended, wish I could upvote this more than once! – Jeff Atwood Aug 8 '15 at 5:59
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    @JeffAtwood well, it might remove more kernels that is safe. See bug report – jarno Jan 30 '16 at 7:11

10.04 GUI Method

Computer Janitor can clean up old kernels and I believe is installed by default in Ubuntu (but not Kubuntu).

GRUB 1, if you're using that, has an option in /boot/grub/menu.lst to specify how many kernels it should show at a maximum. GRUB 2, as far as I can tell, does not.

  • 4
    Computer Janitor should not be used - it is buggy and has now been dropped as a default application in natty/oneiric/precise. – fossfreedom Feb 13 '12 at 16:04
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    Rather, install "Ubuntu Tweak" as described in another answer (its own ppa), which has its own "computer janitor" (not to be confused with the "computer janitor" that temporarily was available in older ubuntu versions) – michael Feb 4 '13 at 2:10

To figure out what kernels and headers are installed use

dpkg -l | grep linux-image

dpkg -l | grep linux-headers

You can then remove them one by one or together, just make sure to keep the most recent.

There are also some handy commands and scripts to automate the removal.

http://ubuntuforums.org/showthread.php?t=1658648

The following claims to remove all unused kernels and headers:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d'|grep -E "(image|headers)" | xargs sudo apt-get purge
  • The script you found in the forum is faulty. It might not remove some desired header package (if you happen to use some old -pae kernel), and on the other hand, it might remove some package(s) you want to keep. – jarno Apr 17 '15 at 23:36
  • Thank you for the comment. The script may be not perfect, however, I've been using it for years, mainly on 12.04 and 14.04, 32 and 64 bits, and have not had any problems. ...and yes, linux-libc-dev is installed. – mikewhatever Apr 18 '15 at 3:59
  • I suppose the version number of linux-libc-devmatches the version number of current ḱernel then. Here dpkg -l linux-libc-dev | sed '/^ii/!d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' prints linux-libc-dev:amd64 – jarno Apr 18 '15 at 9:49
  • I still can't reproduce your findings, however, to be on the safe side, I've modified the command by adding an additional filter - grep -E "(image|headers)". – mikewhatever May 2 '15 at 19:15
  • Then the script may leave extra packages installed. I think you can see different types of possible packages by running apt-cache search --names-only "^linux-.*" | cut -d' ' -f1 | grep -E -e linux-.*-[0-9]+(\.[0-9]+){2}-[^-]+ – jarno May 3 '15 at 17:09

In order to remove older Linux image kernels, first boot in the kernel you want to keep.

You can also check the kernel version using command uname -r so that you don't remove the wrong one by mistake.

Now go to synaptic package manager and search for linux-image and remove the older versions except the one shown by upper command. Generally I prefer to go with the latest one.

Now when you restart you'll see a more clean grub menu.

  • This is probably the most basic method that will for users who have installs w/o Computer Janitor. – Broam Sep 17 '10 at 21:34
  • 1
    From Ubuntu 11.04 the grub menu only shows the current kernel by default, older kernels are hidden in the 'Previous kernels' menu. This method will still work for cleaning out the older ones. – Andy May 16 '11 at 16:03

You could install ubuntu-tweak and then Go to Applications -> System tool -> ubuntu tweak and

enter image description here click package cleaner and clean kernels. it does not show the currently used kernel so you will always be safe.

Personally, I like using Synaptic. It makes me feel more secure about what's going on. The only app I've used that has an option to remove old kernels is Ubuntu Tweak.

How to remove the kernels you are not using:

  • Open UbuntuTweak
  • Click on 'Package Cleaner' under 'Applications' in the left-hand pane
  • On the right side of the 'cleaning view' press 'Clean Kernels'
  • Select all kernels - I think the one in use is not listed but just in case check running uname -a in a terminal
  • In Synaptic you can filter on 'Components' -> 'Kernel and modules', which include all the kernels. And sort by the first column: 'S' (Status), so you get all the installed kernels on-top. Indeed update-grub is advised. – danger89 Apr 24 at 20:48

You can uninstall the old kernels (linux-image-... packages) using Synaptic, and that will remove them from the boot menu. Take care not to remove the running kernel (you can check its version with uname -r).

Bear in mind that having a one or two older versions can help you troubleshoot, should something go wrong.

Alternatively, you can edit/remove the entries manually (gksu gedit /boot/grub/grub.cfg), but they will be re-generated when you update to a newer kernel. If you are thinking about removing recovery mode options - don't. They can come in handy if you break something which prevents you from booting.


Refer to this page.

  • Grub2 now builds it's grub entry everytime a new kernel is installed. with update-grub which will re-write all those kernels. – Marco Ceppi Dec 12 '10 at 18:47

This is a pure command line solution.

First generate a list of all installed kernel versions except the currently running kernel:

dpkg-query -W -f='${Package}\n' |
  grep -f <(ls -1 /boot/vmlinuz* | cut -d- -f2,3 |
    grep -v $(uname -r | cut -d- -f1,2))

Alternatively generate a list of all installed kernel versions except the last two:

dpkg-query -W -f='${Package}\n' |
  grep -f <(ls -1 /boot/vmlinuz* | cut -d- -f2,3 |
    sort -V | head -n -2)

Examine the list. Make sure the the kernel versions you want to keep are not part of the list. Use the command uname -r to see the version of the currently running kernel.

If you are happy with the results you can use apt-get to remove the packages.

First a dry run (using the first generator as example):

sudo apt-get --dry-run purge $(
  dpkg-query -W -f='${Package}\n' |
    grep -f <(ls -1 /boot/vmlinuz* | cut -d- -f2,3 |
      grep -v $(uname -r | cut -d- -f1,2)))

Then a real run:

sudo apt-get purge $(
  dpkg-query -W -f='${Package}\n' |
    grep -f <(ls -1 /boot/vmlinuz* | cut -d- -f2,3 |
      grep -v $(uname -r | cut -d- -f1,2)))

If you want to automate the process then add the --yes parameter:

sudo apt-get --yes purge $(
  ...)
  • @jarno I appreciate your effort to combine and optimize my command line. I removed your command line because I prefer readability and simplicity. I deliberately tailored my command for readability and simplicity. At least readable and simple for my brain. Please post your command line as a comment or in your own answer. – lesmana May 16 '15 at 15:59
  • 1
    This combines two objectives: Keep last two kernels and keep kernels newer than the current one sudo apt-get purge -- $(ls -1U /boot/vmlinuz* | cut -d- -f2,3 | sort -uV | head -n -2 | awk -v c=$(uname -r | cut -d- -f1,2) '($0==c){exit} //' | sed -r -e 's/\./\\./g' -e 's/.*/-&($|-)/'). There is no need for dpkg-query since apt-getcan handle regular expressions. Please note how I escape dots, and add prefix and suffix in the regular expression. Using the script in my own answer you can also keep some kernels that are older than the current one. – jarno May 17 '15 at 10:39

The advantage of this answer is native Ubuntu Bash is used without installing third-party applications. Users of custom kernels who didn't use apt or dpkg can change this bash script to suit their needs. This answer is based on (How to selectively purge old kernels all at once).

Zenity based solution

Zenity provides a nice GUI interface to the terminal to process a list and select items with radio-buttons:

rm-kernels 1

As the title indicates the current kernel you booted with cannot be removed and isn't included in the list. The size reported is how much will be saved in /boot directory. More is saved on your disk because kernel binaries reside in other areas too. July 27, 2017 note: The directories /usr/src/*kernel_version* and /lib/modules/*kernel_version* are now included as well.

The Modified Date is discovered using the stat command. On my system that date is "touched" every time the kernel is booted using this (How do you find out when a specific kernel version was last booted?) cron reboot script. However, on your system the date will be the kernel release date, not the last time you booted it.

apt-get purge gives you chance to abort

You are given a final opportunity to view everything that will be purged and see the total disk space (somewhat misleading) that will be recovered:

The following packages will be REMOVED:
  linux-headers-4.7.1-040701* linux-headers-4.7.1-040701-generic*
  linux-headers-4.7.2-040702* linux-headers-4.7.2-040702-generic*
  linux-headers-4.7.3-040703* linux-headers-4.7.3-040703-generic*
  linux-headers-4.8.1-040801* linux-headers-4.8.1-040801-generic*
  linux-headers-4.8.10-040810* linux-headers-4.8.10-040810-generic*
  linux-headers-4.8.11-040811* linux-headers-4.8.11-040811-generic*
  linux-headers-4.8.4-040804* linux-headers-4.8.4-040804-generic*
  linux-headers-4.8.5-040805* linux-headers-4.8.5-040805-generic*
  linux-image-4.7.1-040701-generic* linux-image-4.7.2-040702-generic*
  linux-image-4.7.3-040703-generic* linux-image-4.8.1-040801-generic*
  linux-image-4.8.10-040810-generic* linux-image-4.8.11-040811-generic*
  linux-image-4.8.4-040804-generic* linux-image-4.8.5-040805-generic*
0 upgraded, 0 newly installed, 24 to remove and 2 not upgraded.
After this operation, 2,330 MB disk space will be freed.
Do you want to continue? [Y/n] 

The Code

Copy this code to an executable file named rm-kernels in /usr/local/bin:

#!/bin/bash

# NAME: rm-kernels
# PATH: /usr/local/bin
# DESC: Provide zenity item list of kernels to remove

# DATE: Mar 10, 2017. Modified Jul 28, 2017.

# NOTE: Will not delete current kernel.

#       With 10 kernels on an SSD, empty cache from sudo prompt (#) using:
#       # free && sync && echo 3 > /proc/sys/vm/drop_caches && free
#       First time for `du` 34 seconds.
#       Second time for `du` 1 second.

# PARM: If any parm 1 passed use REAL kernel size, else use estimated size.
#       By default `du` is not used and estimated size is displayed.

# Must be running as sudo
if [[ $(id -u) != 0 ]]; then
    zenity --error --text "root access required. Use: sudo rm-kernels"
    exit 99
fi

OLDIFS="$IFS"
IFS="|"
choices=()

current_version=$(uname -r)

for f in /boot/vmlinuz*
do
    if [[ $f == *"$current_version"* ]]; then continue; fi # skip current version
    [[ $f =~ vmlinuz-(.*) ]]
    v=${BASH_REMATCH[1]}        # example: 4.9.21-040921-generic
    v_main="${v%-*}"            # example: 4.9.21-040921

    # Kernel size in /boot/*4.9.21-040921-generic*
    s=$(du -ch /boot/*-$v* | awk '/total/{print $1}')

    if [[ $# -ne 0 ]] ; then    # Was a parameter passed?
        if [[ -d "/usr/src/linux-headers-"$v_main ]] ; then
             # Kernel headers size in /usr/src/*4.9.21-040921*
             s2=$(du -ch --max-depth=1 /usr/src/*-$v_main* | awk '/total/{print $1}')
        else
             s2="0M"            # Linux Headers are not installed
        fi
        # Kernel image size in /lib/modules/4.9.21-040921-generic*
        s3=$(du -ch --max-depth=1 /lib/modules/$v* | awk '/total/{print $1}')
    else
        # Estimate sizof of optional headers at 125MB and size of image at 220MB
        if [[ -d "/usr/src/linux-headers-"$v_main ]] ; then
             s2="125M"
        else
             s2="0M"            # Linux Headers are not installed
        fi
        s3="220M"
    fi

    # Strip out "M" provided by human readable option of du and add 3 sizes together
    s=$(( ${s//[^0-9]*} + ${s2//[^0-9]*} + ${s3//[^0-9]*} ))
    t=$(( t + s ))
    s=$s" MB"
    d=$(date --date $(stat -c %y $f) '+%b %d %Y') # Last modified date for display
    choices=("${choices[@]}" false "$v" "$d" "$s")
done

# adjust width & height below for your screen 640x480 default for 1920x1080 HD screen
# also adjust font="14" below if blue text is too small or too large

choices=(`zenity \
        --title "rm-kernels - Total: $t MB excluding: $current_version" \
        --list \
        --separator="$IFS" \
        --checklist --multiple \
        --text '<span foreground="blue" font="14">Check box next to kernel(s) to remove</span>' \
        --width=640 \
        --height=480 \
        --column "Select" \
        --column "Kernel Version Number" \
        --column "Modified Date" \
        --column " Size " \
        "${choices[@]}"`)
IFS="$OLDIFS"

i=0
list=""
for choice in "${choices[@]}" ; do
    if [ "$i" -gt 0 ]; then list="$list- "; fi # append "-" from last loop
    ((i++))

    short_choice=$(echo $choice | cut -f1-2 -d"-")
    header_count=$(find /usr/src/linux-headers-$short_choice* -maxdepth 0 -type d | wc -l)

    # If -lowlatency and -generic are purged at same time the _all header directory
    # remains on disk for specific version with no -generic or -lowlatency below.
    if [[ $header_count -lt 3 ]]; then
        # Remove all w.x.y-zzz headers
        list="$list""linux-image-$choice- linux-headers-$short_choice"
    else
        # Remove w.x.y-zzz-flavour header only, ie -generic or -lowlatency
        list="$list""linux-image-$choice- linux-headers-$choice" 
    fi

done

if [ "$i" -gt 0 ] ; then
     apt-get purge $list
fi

NOTE: You need sudo permission to create the file so use:

gksu gedit /usr/local/bin/rm-kernels

To make file executable use:

sudo chmod +x /usr/local/bin/rm-kernels

Server Version

rm-kernels-server is the server version to selectively delete kernels all at once. Instead of a GUI (graphical) dialog box a text-based dialog box is used to select kernels to purge.

  • Before running the script you need to install the dialog function using:

    sudo apt install dialog

Dialog is in the default Ubuntu Desktop installation but not in Ubuntu Server.

Sample screen

rm-kernels-server 1

rm-kernels-server bash code

#!/bin/bash

# NAME: rm-kernels-server
# PATH: /usr/local/bin
# DESC: Provide dialog checklist of kernels to remove
#       Non-GUI, text based interface for server distro's.

# DATE: Mar 10, 2017. Modified Jul 28, 2017.

# NOTE: Will not delete current kernel.

#       With 10 kernels on an SSD, empty cache from sudo prompt (#) using:
#       # free && sync && echo 3 > /proc/sys/vm/drop_caches && free
#       First time for `du` 34 seconds.
#       Second time for `du` 1 second.

# PARM: If any parm 1 passed use REAL kernel size, else use estimated size.
#       By default `du` is not used and estimated size is displayed.

# Must be running as sudo
if [[ $(id -u) != 0 ]]; then
    echo "root access required. Use: sudo rm-kernels-server"
    exit 99
fi

# Must have the dialog package. On Servers, not installed by default
command -v dialog >/dev/null 2>&1 || { echo >&2 "dialog package required but it is not installed.  Aborting."; exit 99; }

OLDIFS="$IFS"
IFS="|"
item_list=() # Deviate from rm-kernels here.

current_version=$(uname -r)
i=0
for f in /boot/vmlinuz*
do
    if [[ $f == *"$current_version"* ]]; then continue; fi # skip current version
    [[ $f =~ vmlinuz-(.*) ]]
    ((i++)) # Item List
    v=${BASH_REMATCH[1]}        # example: 4.9.21-040921-generic
    v_main="${v%-*}"            # example: 4.9.21-040921

    # Kernel size in /boot/*4.9.21-040921-generic*
    s=$(du -ch /boot/*-$v* | awk '/total/{print $1}')

    if [[ $# -ne 0 ]] ; then    # Was a parameter passed?
        if [[ -d "/usr/src/linux-headers-"$v_main ]] ; then
             # Kernel headers size in /usr/src/*4.9.21-040921*
             s2=$(du -ch --max-depth=1 /usr/src/*-$v_main* | awk '/total/{print $1}')
        else
             s2="0M"            # Linux Headers are not installed
        fi
        # Kernel image size in /lib/modules/4.9.21-040921-generic*
        s3=$(du -ch --max-depth=1 /lib/modules/$v* | awk '/total/{print $1}')
    else
        # Estimate sizof of optional headers at 125MB and size of image at 220MB
        if [[ -d "/usr/src/linux-headers-"$v_main ]] ; then
             s2="125M"
        else
             s2="0M"            # Linux Headers are not installed
        fi
        s3="220M"
    fi

    # Strip out "M" provided by human readable option of du and add 3 sizes together
    s=$(( ${s//[^0-9]*} + ${s2//[^0-9]*} + ${s3//[^0-9]*} ))
    t=$(( t + s ))
    s=$s" MB"
    d=$(date --date $(stat -c %y $f) '+%b %d %Y') # Last modified date for display
    item_list=("${item_list[@]}" "$i" "$v ! $d ! $s" off)
done

cmd=(dialog --backtitle "rm-kernels-server - Total: $t MB excluding: $current_version" \
    --title "Use space bar to toggle kernel(s) to remove" \
    --column-separator "!" \
    --separate-output \
    --ascii-lines \
    --checklist "         Kernel Version --------- Modified Date  Size" 20 60 15)

selections=$("${cmd[@]}" "${item_list[@]}" 2>&1 >/dev/tty)

IFS=$OLDIFS

if [ $? -ne 0 ] ; then
    echo cancel selected
    exit 1
fi

i=0
choices=()

for select in $selections ; do
    ((i++))
    j=$(( 1 + ($select - 1) * 3 ))
    choices[i]=$(echo ${item_list[j]} | cut -f1 -d"!")
done

i=0
list=""
for choice in "${choices[@]}" ; do
    if [ "$i" -gt 0 ]; then list="$list- "; fi # append "-" from last loop
    ((i++))

    short_choice=$(echo $choice | cut -f1-2 -d"-")
    header_count=$(find /usr/src/linux-headers-$short_choice* -maxdepth 0 -type d | wc -l)

    # If -lowlatency and -generic are purged at same time the _all header directory
    # remains on disk for specific version with no -generic or -lowlatency below.
    if [[ $header_count -lt 3 ]]; then
        # Remove all w.x.y-zzz headers
        list="$list""linux-image-$choice- linux-headers-$short_choice"
    else
        # Remove w.x.y-zzz-flavour header only, ie -generic or -lowlatency
        list="$list""linux-image-$choice- linux-headers-$choice" 
    fi

done

if [ "$i" -gt 0 ] ; then
    apt-get purge $list
fi

NOTE: In the call to dialog the directive --ascii-lines is passed to replace line-draw extended character set (which ssh doesn't like) with "+-----+" for drawing boxes. If you do not like this appearance you can use the --no-lines directive for no box at all.


July 28, 2017 Updates

The calculated size of each kernel was taken from /boot/*kernel_version* which were 5 files totaling ~50 MB. The formula has changed to include the files in /usr/src/*kernel_version* and /lib/modules/*kernel_version*. The calculated size for each kernel is now ~400 MB. The above code for rm-kernels and rm-kernels-server has been updated. However, the sample screens above do not reflect these changes yet.

The default is to estimate the size of files for linux-headers at 125 MB and linux-image at 220 MB because du can be painfully slow unless files are in cache. To get the real size using du pass any parameter to the script.

The total of all kernel sizes (excluding the current running version which cannot be removed) is now show in the title bar.

The dialog box used to display each Kernel's Last Access Date. This date can get mass overwritten for all kernels during backup or similar operations. The dialog box now shows the Modified Date instead.

An easy way to get rid of almost all obsolete packages, packages no longer in any package list, along with obsolete kernels is to do one of the following:

dpkg --purge $(aptitude search ?obsolete)

However, this will miss packages that are still recommended by other packages, and the -R/--without-recommends argument does not resolve this problem.

dselect after switching sort mode with 'o' will show all obsolete packages including the ones aptitude misses, but some people don't like using it.

  • The given command does not purge old kernels nor affect grub menu in my experience. – jarno May 16 '15 at 12:39

The accepted answer using sed to remove older kernels permanently has some flaws, if someone has not rebooted the computer after upgrading kernel the command will remove the newer kernel too.

Here is an alternate solution that will consider all situations to remove actual older kernels only:

#!/bin/bash
kernels=( $(grep -Po "^linux-image-[^-]+-[^-]+-generic\b" < <(dpkg --get-selections)) )
cur_rel=$(grep -Po ".*(?=-[a-z]*$)" < <(uname -r))

for kernel in "${kernels[@]}"; do
    ker_rel=$(grep -Po "[0-9].*(?=-[a-z]*)" <<< "$kernel")
    dpkg --compare-versions "$ker_rel" gt "$cur_rel" && echo "Please Restart your computer first" && break
    dpkg --compare-versions "$ker_rel" lt "$cur_rel" && sudo apt-get remove "$kernel"
done

If you have any version that is newer than the current one this will give you a warning to restart you computer first. Also note that the older kernels are preserved due to a good reason which is if you somehow mess up your current kernel making your system unstable then you should be able to boot into any older kernel.

  • This will not remove lowlatency kernels or kernels of any other flavor than generic. – jarno May 10 '15 at 17:11
  • I suppose you refer to this sed solutions. – jarno May 16 '15 at 14:39
  • @jarno : How about replacing grep -Po "^linux-image-[^-]+-[^-]+-generic\b" with grep -Eo "^linux-(image|headers|tools)-[^-]+-[^-]+(|-generic)\s" | sed -e "s/\s//g" and grep -Po ".*(?=-[a-z]*$)" with grep -Eo "^[0-9]+\.[0-9]+\.[0-9]+-[0-9]+" and grep -Po "[0-9].*(?=-[a-z]*)" with grep -Eo "[0-9]+\.[0-9]+\.[0-9]+-[0-9]+"? – Sadi Nov 15 '15 at 21:23
  • @Sadi, wel,l that would not find lowlatency kernels either. – jarno Nov 16 '15 at 13:41
  • 1
    Thanks. Other methods didn't work for me. Yours did the job. – Philippe Delteil Dec 22 '17 at 13:10

ailurus has the feature of removing old kernels as well as unused configurations. I personally remove it manually from synaptic. You can install ailurus from getdeb as well as ppa

  • "Ailurus is a tool for backup a name list of installed software. ... In the past Ailurus has many function. Now it has only one function. Because I think one really useful function is better than dozens of less useful function." – jarno May 18 '15 at 10:38

You can use ukuu - it's all GUI - to update and delete old Kernels. Works for me!

Just remember leave the last 2 installed and obviously the 'running' kernel.

You can also set ukuu to only show mainline releases, even RC kernels, hide point releases.

ukuu

You can find ukuu in Synaptic, or instructions are here:

OMG!Ubuntu ukuu install instructions

here is a rough outline of what I did, careful as I am no expert in linux, be sure you know what you are doing and have backed up any files you are modifying.

gedit /boot/grub/grub.cfg

then find the entries you want to keep, we will highlight and copy them

cd /etc/grub.d
ls

you'll see a list of files like 10_linux and 30_os-prober

sudo chmod -x 10_linux

this will stop form auto adding all the linux entries into the grub boot menu.

gksudo gedit 40_custom

open the custom boot menu file, then go back to grub.cfg (which should still be open in gedit), and copy the entries you want to keep... such as

menuentry "My Default Karmic" {
  set root=(hd0,1)
  search --no-floppy --fs-uuid --set cb201140-52f8-4449-9a95-749b27b58ce8
  linux /boot/vmlinuz-2.6.31-11-generic root=UUID=cb201140-52f8-4449-9a95-749b27b58ce8 ro quiet splash
  initrd /boot/initrd.img-2.6.31-11-generic
}

paste them into 40_custom, and then save it.

sudo chmod 755 40_custom

makes it executable, then finally we update grub which will change the grub.cfg file:

sudo update-grub

Now, BEWARE, if you update your kernel or OS, your boot menu probably will not update... you'll have to do that manually. But doing this procedure will let you customize the boot menu a bit more, such as remove the kernel version and just put the ubuntu name... i.e. Ubuntu Lucid 10.04, etc...

Hope someone finds this helpful, as it took me a while to figure out... didn't see this solution anywhere...

  • 3
    This answer seems like overkill. It's better to just remove old kernels. – Scott Severance Jan 8 '12 at 23:32
  • I had read that extra kernels may be useful in the event of recovery situations. Also, this is a simple way to edit the text of the boot entry. So rather than saying "Ubuntu, Linux kernel x.x.xx-yy --text1 -text2 -t3 -t4 --t5 etc etc etc" (where the --text entries just denote some options/parameters I don't understand) you can change it to "Ubuntu xx.yy" although I had a "{" bracket I couldn't get rid of. – Joe Jan 9 '12 at 22:35
  • 1
    I keep the immediate previous kernel around until I've verified the the most current kernel works properly. If it works, it isn't going to stop working. So, after I've verified the most recent kernel (after a week or so), I have no reason to keep the old kernel around. If it doesn't work, then I have the latest known-good kernel to fall back to. Actually, I'm currently running an old kernel due to a showstopper bug in the current kernels. But that doesn't change my overall policy. You only need one known good kernel. – Scott Severance Jan 10 '12 at 5:14

Install the synaptic package manager and go down to the filters tab (I think filters, if not try all 5) and select "local". This will show you orphaned packages on your system, such as the kernels. After you uninstall them, run update-grub. That command updates the list of boot options for grub.

If this fails, you can always try apt-get remove linux-image-version-generic.

  • In Synaptic you can filter on 'Components' -> 'Kernel and modules', which include all the kernels. And sort by the first column: 'S' (Status), so you get all the installed kernels on-top. Indeed update-grub is advised. – danger89 Apr 24 at 20:48

Based on a previous answer by David Kemp, the following script will purge all headers and images except for the last 2 versions.

#!/bin/sh
# This script assumes that the installed linux-image and linux-headers packages
# share the same versions (i.e. if a linux-image version number is installed,
# the corresponding linux-headers package will also be installed, and vice
# versa.)

SECONDTOLASTVER=$(dpkg --list | grep linux-image | awk '{ print $2 }' | sort -r -n | sed '/^[^0-9]\+$/d' | sed 's/^.*-\([0-9\.]\+-[0-9]\+\).*/\1/' | uniq | sed -n 2p)

# get a list of package names matching the argument passed to the function, and
# return only those package names which should be removed
get_pkgs_to_remove_matching () {
    if [ -n "$SECONDTOLASTVER" ]; then
        echo $(dpkg --list | grep $1 | awk '{ print $2 }' | sort | sed -n '/'"$SECONDTOLASTVER"'/q;p')
    fi
}

echo $(get_pkgs_to_remove_matching linux-image) $(get_pkgs_to_remove_matching linux-headers) | xargs sudo apt-get -y purge
  • Any reason why this was downvoted? Did it not work for someone? When copying/pasting make sure you aren't wrapping long-lines when you paste. I have had no problems with it working. – Mark Jan 24 '14 at 20:56
  • Newest kernel release in my machine is 3.13.0-43-lowlatency. This script would purge linux-headers-3.13.0-43-lowlatency. – jarno Jan 2 '15 at 20:40
  • @jarno how did you determine that? to try it out without actually doing anything, add a "-s" flag to the apt-get command (or just remove the | xargs sudo apt-get -y purge altogether). If it prints out 3.13.0-43-lowlatency, then perhaps you have some later versions than that installed on your system. – Mark Jan 4 '15 at 6:05
  • I tried simulation. No, but I had some earlier kernel version removed, but not purged, and respective header packages purged. – jarno Jan 4 '15 at 20:59
  • Anyway, I have been developing a script based on the idea of Sankalp's answer. – jarno Jan 4 '15 at 21:13

The following string of commands will purge any installed linux kernels except the currently running one (grep -v uname -r) and the lastest available kernel (dpkg -l | .... | tail -1):

dpkg -l | grep -E linux-image-.*-generic | cut -d ' ' -f3 | grep -v `dpkg -l | grep -E linux-image-.*-generic | cut -d ' ' -f3 | tail -1` | grep -v `uname -r` | xargs apt-get -y purge

I use this to keep desktop's boot volumes relatively clean, but in a server situation you'd probably want to expand the logic and write some additional scripting to maintain a list of the last X kernels the server has booted.

Something like a startup script that does:

uname -r >> /root/bootedkernels
cat /root/bootedkernels | sort -u | tail -3 > /root/bootedkernels # Keep the last 3 booted kernels

and then use:

dpkg -l | grep -E linux-image-.*-generic | cut -d ' ' -f3 | grep -vf /root/bootedkernels | grep -v `dpkg -l | grep -E linux-image-.*-generic | cut -d ' ' -f3 | tail -1` | grep -v `uname -r` | xargs apt-get -y purge
  • Simpler form would be sudo apt-get purge $(dpkg-query -W -f'${Package}\n' 'linux-image-[0-9]*' | head -n -1 | grep -v $(uname -r)), but even that raises questions: Can you rely on that dpkg lists newest kernel last? Can you rely on matching the current version as such regular expression? A dot in version string matches any character. What if the package name has one more character in version number than the current version? To be strict, you had better use uname -r | sed -r -e 's/\./\\./g' -e 's/.*/-&($|-)/' as the regular expression to match in the last grep command. – jarno May 16 '15 at 14:15
  • Besides, the script does not purge any linux-header packages or other related packages. – jarno May 16 '15 at 14:25

To have a bit more control over which versions to keep, explicitly select the ones you want to remove. For instance if you want to remove kernel versions 3.2.0.[49-53], use a simple for loop:

for k in 49 51 52 53 ; do aptitude remove --purge linux-image-3.2.0-${k}-generic ; done

Adjust the list of kernel versions to fit.

Try this. Run it as root.

Save this script as, say ./keep-n-kernels.sh

Pass, as a command line argument, the number of most recent kernels you want to preserve.

    
#!/bin/bash

# pass n as a command line argument, and it will find all the installed
# kernels and keep only the n most recent ones => uninstall all older ones

# dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d'
# this command gives the list of all packages EXCEPT for the latest kernel.
# source : https://help.ubuntu.com/community/Lubuntu/Documentation/RemoveOldKernels

n=$1

# find the installed kernel versions :
# dpkg-query -W -f='${Version}\n' 'linux-image-*' | grep . | sort -n
# gives version numbers, one in each line
# dpkg-query -W -f='${Version}\n' 'linux-image-*' | grep . | sed 's/\...$//g' | grep -v '\...$'| sort -u
# gives only the ones that appear in linux-image

# suffix, e.g. -generic-pae
# the kind of kernel you boot into
suffix=$(uname -r | sed 's:^[0-9]\.[0-9]\.[0-9]\-[0-9]\{2\}::g')

command="apt-get purge "

for version in $(dpkg-query -W -f='${Version}\n' 'linux-image-*' | grep . | sed 's/\...$//g' | grep -v '\...$'| sort -u | head -n -${n})
do
    command=${command}"^linux-image-${version}${suffix} "
done

$command

Sample usage :

# ./keep-n-kernels.sh 4 # launch the apt-get command to remove all but the 4 most recent kernels

If you want [AND AT YOUR OWN RISK], you can add a -y (or a force flag) to the apt-get command and make it non-interactive.

  • It removes all kernels, if you run ./keep-n-kernels.sh 0. Detecting suffix string does not work; I think suffix=$(uname -r | sed -r 's/^[0-9.]*(-[0-9.]+)*//') or suffix=$(uname -r | egrep --only-matching -- '-[[:alpha:]-]+$') would do. – jarno Jan 2 '15 at 18:57
  • But I think the idea is nice. I have been working on improving the script and maybe I'll post it here sometime, when I think it is ready enough. – jarno Jan 4 '15 at 21:07
  • Do please share, @jarno . Glad to know the idea seems useful. – Sankalp Jan 6 '15 at 18:41
  • Ok, there it is: link – jarno Jan 8 '15 at 14:38

I'm using a KDE desktop, and the easiest option I found was using the kde-config-grub2 application as suggested here: https://www.kubuntuforums.net/showthread.php?58075-remove-old-linux-versions (which I already had installed for setting background image, default boot option, and the like). Next to the drop-down box where you can choose the default entry, there is a "Remove Old Entries" button. Clicking this button presents you with a list of all installed kernels and you can select which ones to remove. When you apply the changes it will use dpkg to actually remove them from the system as well as the GRUB menu.

Just to chime in, you can also issue

apt-get remove linux-{image,headers}-x.y.z-{1,2,...,n}

as root, and the job will be done.

I have a script for this that does not need very fancy string parsing.

Remove headers and images except the current one to release space

sudo apt-get autoremove --purge 'linux-headers-[0-9].*' linux-headers-$(uname -r)+ linux-headers-$(uname -r | cut -d- -f1,2)+ 'linux-image-[0-9].*' linux-image-$(uname -r)+

protected by Community Aug 2 '15 at 6:05

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