Root is Nearly Full - in LiveUSB Mode to Delete old Kernels

[Mark_in_Hollywood]

I don't have the GRUB Recovery Screen due to a video card exchange. I asked for help about fixing that over a year ago, but have never had a response.

This 12.04 LTS hangs at boot time. I've spent the last 3 days on LiveUSB mode trying to fix it. It's come down to this:

I saw the number of old kernels a few days ago and started deleting about half of them. I was very very careful to not delete my

3.2.0.36-generic-pae ( or very close to those numbers I cannot recall the numbers, exactly).

or any with matching those numbers.

After those 20 or so old kernels were manually deleted, the OS would no longer boot. So here I am in LiveUSB and need help in deleting the out-of-date kernels. I could not perform that in boot-repair-disk session; even though it said I should. Maybe I'm not familiar with how it operates. It's my first use of it. Meanwhile in Boot-Repair-Disk the number of old kernels looked to be around 50, even though I though I manually deleted about half of them. And in another section of the Boot-Repair-Disk, under the heading GRUB, the old kernels were still there, too. I cannot post the RESULTS.txt as this forum says 49Kb is too large.

Can you explain how I can mount the hard-drive and somehow delete the old kernels and then start working on repairing GRUB2?

Also, please tell me the name of the folder (directory) where all the kernles are kept. For example: is that / OR /Boot or Bin -- with / being root, obviously?

I found a command line tutorial about removing old kernels with one line here:

http://tuxtweaks.com/2010/10/remove-...h-one-command/

[prodigy_]

I'd suggest reinstalling on a bigger partition. Removing old kernels can yield some space but almost certainly not enough in the long run.

But if you really need to fix this installation, try to reinstall Grub (via chroot): https://help.ubuntu.com/community/Gr...ing#via_ChRoot This should help unless you've deleted ALL kernels.

[Mark_in_Hollywood]

I'd suggest reinstalling on a bigger partition. Removing old kernels can yield some space but almost certainly not enough in the long run.

But if you really need to fix this installation, try to reinstall Grub (via chroot): https://help.ubuntu.com/community/Gr...ing#via_ChRoot This should help unless you've deleted ALL kernels.

My / (root partition) is about 16 gig. It's 14.5 gig full. Boot-Repair-Disk says delete them, as that fullness is preventing a boot. My /home is on a separate partiton. /sda3 and sda5 respectively.

I don't understand what you mean by: "But if you really need to fix this installation" - Please explain, briefly if possible, how a GRUB reinstall will fix the problem, but removing the old kernels won't? My theory here is: less is more.

[Mark_in_Hollywood]

If no error reported then /boot/grub is NOT mounted?

ubuntu@ubuntu:~$ sudo grub-install --boot-directory=/mnt/boot /dev/sda
Installation finished. No error reported.

ubuntu@ubuntu:~$ sudo chroot /mnt

root@ubuntu:/# grub-install --recheck /dev/sda

/usr/sbin/grub-probe: error: cannot find a device for /boot/grub (is /dev mounted?).

[frank604]

Just some precursory investigations here, please copy paste the output for

dpkg -l | grep linux-image

uname -a

[Mark_in_Hollywood]

I'm not adept at this, but I believe this information is the LiveUSB filesystem and NOT my hard-disk (real) kernel. I'm more likely to be wrong than right, here, but I'm just double-checking.

ubuntu@ubuntu:~$ dpkg -l | grep linux-image
ii linux-image-3.2.0-23-generic-pae 3.2.0-23.36 Linux kernel image for version 3.2.0 on 64 bit x86 SMP
ii linux-image-generic-pae 3.2.0.23.25 Generic Linux kernel image
ubuntu@ubuntu:~$ uname -r
3.2.0-23-generic-pae
ubuntu@ubuntu:~$

[prodigy_]

Please explain, briefly if possible, how a GRUB reinstall will fix the problem, but removing the old kernels won't? My theory here is: less is more.

Hm. If I understand correctly, the problem is that your Ubuntu no longer boots after some kernel cleanup. That's what you can fix with with the update-grub command (while chrooted into your installation as described in the HOWTO I linked).

And if you actually can boot into your installation, just use the one-liner from your OP. It'll do the job (remove old kernels) for you.

[Mark_in_Hollywood]

I want to do a little more than merely remove the old kernels. Some 18 months ago, my video card (EVGA 9500GT) was RMA'd to EVGA for a defect. During that time, I used the on-board video. That caused a GRUB resolution problem, with, if I'm recalling correctly, the GRUB boot time lines either scrolling off screen (right side) or some other problem. I got some help to reset the GRUB resolution or boot-time screen resolution. After re-installing the new vid card, GRUB had no video at any other screen that the selectable options, to wit: Ubuntu, Memory Test, and Windows 7. Trying Recover (or Rescue) or whatever it is called blanks the screen. I posted to IRC#GRUB (or some such) and posted about that problem, this Forum at that time, but never received an answer.

So what I want to accomplish in LiveUSB is to purge and re-install GRUB and all it's associated files, in hopes of restoring proper working order GRUB boot-time and then I'll remove the old kernels.

[frank604]

http://askubuntu.com/questions/28099...ng-all-kernels

Perhaps the top comment in the link + the grub-install you wish to do. But the mounting in this post makes sense prior to chrooting in.

[Mark_in_Hollywood]

Per the post at AskUbuntu.com I did in a terminal via cut and paste, only:

Boot into a live CD (or live USB), mount some systems, chroot into it and install the kernel. After a successful installation of the kernel, unmount the filesystems.

Open Terminal
Mount the Ubuntu partition: sudo mount /dev/sdXY /mnt

Mount some special partitions:

sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys

Chroot into the /mnt: sudo chroot /mnt
Install the Linux kernel: apt-get install linux-image-generic (no sudo required as you are root after a chroot)

After a successful installation of the kernel, get out the chroot and unmount some filesystems:

exit
sudo umount /mnt/sys
sudo umount /mnt/proc
sudo umount /mnt/dev
sudo umount /mnt

Reboot and remove CD or USB: sudo reboot

apt-get reported that current (or latest) kernel is installed.

on reboot it hangs after about 10 to 15 seconds. It seems like the same place every time, but I can't be certain of that.

=========

I next again tried:

ubuntu@ubuntu:~$ sudo mount /dev/sda3 /mnt/boot

ubuntu@ubuntu:~$ sudo chroot /mnt
chroot: failed to run command `/bin/bash': No such file or directory

=========

and I tried:


ubuntu@ubuntu:~$ sudo chroot /mnt/boot
root@ubuntu:/# update-grub
/usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?).