Gremlins removing kernels: where did they go?

[life0riley]

... What I now do, when a kernel update or new kernel gets installed, is NOT to run the autoremove during that session. I'll reboot first, then update and dist-upgrade again, followed by the autoremove. That has resulted in keeping the two installed kernels (for me).

Good to know. Thanks

[GreyGeek]

I'll have to look for that. Would this apply to updates using apt?

I usually use apt-get in a terminal to get the updates. Usually it tells me when the unused kernels can be removed and recommends autoremove.

[Qqmike]

I've also seen that at the terminal, GreyGeek. But now I'm curious to see what that box says that Muon pops up asking for an OK every time it installs a new kernel. I'll have to wait until the next 14.04 kernel upgrade.

[Qqmike]

As far as I can tell, Muon is not removing the previous kernel, even when I run apt-get autoremove/autoclean/clean -- it is keeping two kernels; but--apparently--Bleachbit is removing the previous kernel when it runs those three "clean categories." googling is not clearing this up for me.

I've disabled those options in Bleachbit. I am not really sure how Bleachbit works. There needs to be better documentation on Bleachbit: users would be quite upset to find their previous kernel (their backup) deleted without their permission. I did not test Bleachbit on this--I'd have to re-install the old kernel if it is deleted, and I'm not real sure which/how many files to re-install (as there appears to be several for each kernel version), and I might be testing this stuff all damned day.

Open Q: So to manually clean apt of such leftover junk, what are the best commands? -->
sudo apt-get autoremove?
and/or
sudo apt-get autoclean? or sudo apt-get clean? (not both)

man apt-get suggests autoremove and autoclean would be safe -- however, it does not mention kernels.

/etc/apt/apt.conf.d/01autoremove-kernels -->
It shows two kernels. Does that suggest it is properly set to keep the two most recent?
Its first line:
APT::NeverAutoRemove
Does that mean never remove the two most recent kernels (which are listed below in that file)?

I want to read this right so I don't leave it to a crap-shoot in the future. I'm relying on both GRUB and rEFInd to detect two kernels for safety.

[GreyGeek]

I just remembered the app KDE-config-GRUB2. After installing it you can find it in System Settings under the "Startup and Shutdown" option as "GRUB2 Boot loader"

It allows for easy setting of a ton of options including choosing and removing kernels, grub wallpaper, etc.

[Qqmike]

apt-get autoremove
It removed all but the two most recent kernels.
BUT ... here's the deal:

Before autoremove, I had kernels -55 and -54 present.
As an experiment, I installed -53.
Now I have -55, -54, -53.
Then apt-get autoremove removed -54 and kept -53 and kept -55.
Bleach bit (run as root) behaved the same way.
Note that -53 is more "recently installed" than is -54; though -53 is an older kernel version than is -64.

If I look in /boot, I actually now have just -55 and -53; -54 is gone.

But /etc/apt/apt.conf.d/01autoremove-kernels shows that it will keep -55 and -54!
(Even though -54 is gone and -53 is present. I re-booted to be sure this is the case.)

The GRUB boot menu now shows choices for -55 and -53. (Before this experiment, it showed choices for -55 and -54.)

So:

autoremove does seem to keep two kernels, but it may not be the two latest-version kernels.

Bleachbit does not seem to be misbehaving (it simply runs autoremove and autoclean and clean if you ask it to do so -- you can see this by running Bleachbit in Preview mode or try an experiment, as I did).

GRUB behaves as it should, following what is left after autoremove.

The file /etc/apt/apt.conf.d/01autoremove-kernels seems to rule the show, but it may contain confusing entries.


Re the OP:
I still do not know how I ended up with just one kernel in /boot (and also offered by GRUB).
How did I end up with just one kernel (the latest-version kernel)?

Removing unwanted kernels:
That's not the issue here (the OP). It is easy: use apt-get or use Muon.

I guess this is not a big deal because if you find yourself with just one kernel, you can simply install the previous kernel, too, so you'd have two installed, as Snowhog indicated.

[Qqmike]

Btw, rEFInd is keeping up with all this.

As explained above, I started with kernels -55 and -54. I installed -53. I experimented and ended up with -55 and -53. rEFInd now gives me the option of stub-booting directly the two kernels -55 and -53.

Nice.

[ronw]

I've seen unkind words about autoremove-kernels being too easily confused. Perhaps justified, as your test indicates.