How to remove old kernel versions?

Question

How can I remove old kernels after upgrading to a new version?

It is annoying me to have these kernel entries in the Grub boot menu.

Answer 1

It is always recommended to leave the 2 latest versions of the kernel, but to remove other kernel versions I used the following commands:

dpkg -l | fgrep linux-image-

Never remove the kernel shown in uname -r or linux-image-generic-lts-utopic.

Finally sudo apt-get purge <package names> for the kernels you want to remove (see screenshot for reference).

Then sudo update-grub to update the Bootloader.

Answer 2

You can use this one-liner to automatically clean up all old kernels (make sure to restart the computer before doing this if you have just updated the kernel):

sudo apt purge $( dpkg --list | grep -P -o "linux-(headers|image)-\d\S+" | grep -v $(uname -r | grep -P -o ".+\d") )

What it does is uninstall (apt purge) the installed packages (dpkg --list) whose names match "linux-headers-[number]" or "linux-image-[number]" (grep -P -o "linux-(headers|image)-\d\S+"), except (grep -v) those corresponding to the current kernel version (uname -r | grep -P -o ".+\d").

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Sources:

• CommandLineFu.com - the original inspiration
• Ask Ubuntu - using apt’s "purge" rather than "remove")
• Ask Ubuntu - ensuring the entries returned could be safely removed
• Stack Overflow - using PCRE in grep (\d, \S, etc) and using the -P option
• Super User - using -o to make grep return only the matched content

Answer 3

You can simply run

sudo apt-get autoremove

to "remove all unused packages" which includes older kernels.

You should test a reboot before to be shure the new kernel works!

It is more secure to leave the 2 latest versions as John pointed out in his answer.

Answer 4

To remove old kernels you can also use synaptic:

To install synaptic:

sudo apt-get install synaptic

Now open synaptic and search for linux-image under installed tab as shown and then

Right click on selected old kernel and select mark for complete removal

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Note: Screenshots are only examples from my system.I already deleted old kernels.Please select old kernels as per your system.

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Answer 5

Removing old kernels:

(I suggest boot to latest kernel)

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Remove Manually:

First list current kernel:

uname -r

Example output:3.19.0-28-generic

To list all kernels :

dpkg --list | grep linux-image

Now purge old kernels manually,(be sure don't purge current kernel)

For example:

sudo apt-get purge linux-image-3.16.0-34 linux-image-3.16.0-46 linux-image-3.16.0-48 linux-image-3.16.0-49 

Note: In general to remove old kernels use linux-image-x.x.x-x where replace x with numbers.

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Automatic:

sudo apt-get purge $(dpkg -l linux-{image,headers}-"[0-9]*" | awk '/ii/{print $2}' | grep -ve "$(uname -r | sed -r 's/-[a-z]+//')")

Note: you can verify deleting kernels with following command-here the output excludes current loaded/running kernel .So please boot to latest kernel.

kernelver=$(uname -r | sed -r 's/-[a-z]+//')
dpkg -l linux-{image,headers}-"[0-9]*" | awk '/ii/{print $2}' | grep -ve $kernelver

Reference here

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Answer 6

UKUU is a good GUI based tool for managing kernels

 sudo apt-add-repository -y ppa:teejee2008/ppa
 sudo apt update
 sudo apt install ukuu

Answer 7

there is a simpler way:

sudo apt install byobu
sudo purge-old-kernels

that's all, it will leave 2 kernel versions and remove all others