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I was reading this. It's about detecting installed kernels. KERNELS???!! Is it possible that I have more than a kernel?? How is that??!!!!!

...so I followed the command in the instructions and this is my output:

username@hostname:~$ dpkg --list | grep linux-image
rc  linux-image-3.11.0-12-generic             3.11.0-12.19                                 i386         Linux kernel image for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-3.11.0-13-generic             3.11.0-13.20                                 i386         Linux kernel image for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-3.11.0-14-generic             3.11.0-14.21                                 i386         Linux kernel image for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-3.11.0-15-generic             3.11.0-15.25                                 i386         Linux kernel image for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-3.11.0-17-generic             3.11.0-17.31                                 i386         Linux kernel image for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-3.11.0-18-generic             3.11.0-18.32                                 i386         Linux kernel image for version 3.11.0 on 32 bit x86 SMP
rc  linux-image-3.8.0-19-generic              3.8.0-19.30                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-3.8.0-25-generic              3.8.0-25.37                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-3.8.0-26-generic              3.8.0-26.38                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-3.8.0-27-generic              3.8.0-27.40                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-3.8.0-30-generic              3.8.0-30.44                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
ii  linux-image-3.8.0-31-generic              3.8.0-31.46                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-extra-3.11.0-12-generic       3.11.0-12.19                                 i386         Linux kernel extra modules for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-extra-3.11.0-13-generic       3.11.0-13.20                                 i386         Linux kernel extra modules for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-extra-3.11.0-14-generic       3.11.0-14.21                                 i386         Linux kernel extra modules for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-extra-3.11.0-15-generic       3.11.0-15.25                                 i386         Linux kernel extra modules for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-extra-3.11.0-17-generic       3.11.0-17.31                                 i386         Linux kernel extra modules for version 3.11.0 on 32 bit x86 SMP
ii  linux-image-extra-3.11.0-18-generic       3.11.0-18.32                                 i386         Linux kernel extra modules for version 3.11.0 on 32 bit x86 SMP
rc  linux-image-extra-3.8.0-19-generic        3.8.0-19.30                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-extra-3.8.0-25-generic        3.8.0-25.37                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-extra-3.8.0-26-generic        3.8.0-26.38                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-extra-3.8.0-27-generic        3.8.0-27.40                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
rc  linux-image-extra-3.8.0-30-generic        3.8.0-30.44                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
ii  linux-image-extra-3.8.0-31-generic        3.8.0-31.46                                  i386         Linux kernel image for version 3.8.0 on 32 bit x86 SMP
ii  linux-image-generic                       3.11.0.18.19                                 i386         Generic Linux kernel image
username@hostname:~$

Woah! Hold on a second!! So those things are kernels???!! And I had all that in my system and I didn't know??! I didn't install anything!! Or maybe it's the update manager that did this? ... ... ...If it's true then do I need all this?? If no then it should be taking up lots of space of my drive!! And then how do I clean up??

Please explain as much details as possible! It seems that there's a lot that I don't understand!

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  • 1
    What makes you think having multiple kernels kernels installed is a problem in any way ? – Panther Mar 21 '14 at 22:03
  • @bodhi.zazen firstly I didn't know it was possible to have more than a kernel on a system! But now that it's true well I don't think it's a problem. Only except if it's bugging me on disk space :) – Mina Michael Mar 21 '14 at 23:14
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The kernel can be updated during a normal update. All the kernels remain on the hard disk and should be able to be booted from the grub menu presented at boot time. I keep the old kernels, there is no harm in doing so.

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  • Okay now that you've mentioned it, I went to grub, selected "advanced options..." (where I should find the kernels) and I found 2 versions only. Well what's up with this big list up there? Can you explain? – Mina Michael Mar 21 '14 at 23:30
  • Where the versions in your advance menu 3.8.0 and 3.11.0 ? It will probably be listing the latest version of each. As Ross says, you can delete them if you want. They don't take up all that much space and so I would always keep the last 3 or 4 kernels as a fallback. – hatterman Mar 22 '14 at 7:08
  • actually both were 3.8 XD both were totally identical but the lower one had " (recovery...) " in the end. I'm guessing that 3.11 is the normal "Ubuntu" option in the main grub menu so it didn't list it under "advanced options".(correct me if I'm wrong) ... ... ...okay thank you so much! both of you deserve the accepted answer. :D But sadly there's only one I can give. – Mina Michael Mar 23 '14 at 11:56
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To preface, more information about kernels. At a very high level, the kernel is the actual operating system itself (talks to the hardware, runs applications, etc). You need to have one kernel installed to run Linux.

The kernels that you see listed are installed, but they are not being used (except for the one running). There is no harm in keeping multiple versions, and it's usually a good idea to do so in case you hit any issue with the newer version.

If you don't like them being on your system, they can be removed with:

sudo apt-get autoremove

Which should clear out the unused kernels (along with other unused packages). There's no harm in keeping them, though.

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  • hmmm they're not in use! alright that explains!! thanks :) – Mina Michael Mar 21 '14 at 23:29

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