revert an upgrade?

[Karl Auer]

An almost-worst-case-scenario happened this morning - a power failure
while upgrading Ubuntu on my laptop. The battery is failing (new one
ordered), and when the power cable was inadvertently pulled - well, you
get the picture.

When I powered my laptop back up, I was faced with a grub prompt:

   grub>

A bit of googling, a bootable USB stick and a nifty program called
boot-repair later, and I had a bootable system again. But not the latest
version - I have to boot the *previous* kernel. If I try to boot the
latest kernel, the splash screen is lo-res, I get a lo-res (but
functional) greeter, and after I log in I just get a black screen with a
visible (large) mouse cursor. Text consoles are still accessible via
Alt-Ctl-F1 etc and they still work (but are also lo-res).

I guess not everything got installed, or the install did not complete
properly, or... something.

So my question is, how can I "redo" the last set of updates?
Specifically from kernel 3.11.0.19 to 3.11.0.20? Or back out the upgrade
completely?

/var/log/apt/history.log shows the list of packages being installed or
updated; the line after the list consists rather ominously of about
sixty NUL characters, but the list of packages seems complete. The line
of NULs appears where I'd have expected the "End-Date:" line, and the
last packages mentioned are similar to the last entries in a previous
kernel upgrade. There's an "Install:" line and an "Upgrade:" line. Can I
just "apt-get remove" the packages mentioned in the "Install:" line?

They are:
  linux-image-extra-3.11.0-20-generic:amd64 (3.11.0-20.34),
  linux-image-3.11.0-20-generic:amd64 (3.11.0-20.34),
  linux-headers-3.11.0-20:amd64 (3.11.0-20.34),
  linux-headers-3.11.0-20-generic:amd64 (3.11.0-20.34)

The packages mentioned in the "Upgrade:" line are related; can I just
"apt-get remove" the later versions? They are (some might wrap in your
mailer):

linux-headers-generic:amd64 (3.11.0.19.20, 3.11.0.20.21)
cups-server-common:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
pepflashplugin-installer:amd64 (13.0.0.182~cr34.0.1847.116-1-0skunk0, 13.0.0.206~cr34.0.1847.132-1-0skunk0)
libcups2:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
libcups2:i386 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
cups-daemon:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
libcupsmime1:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
cups-client:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
ubuntu-release-upgrader-gtk:amd64 (0.205.5, 0.205.6)
libcupsimage2:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
chromium-codecs-ffmpeg-extra:amd64 (33.0.1750.152-0ubuntu0.13.10.1~pkg984.1, 34.0.1847.116-0ubuntu~1.13.10.0~pkg991)
cups:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
chromium-browser-l10n:amd64 (33.0.1750.152-0ubuntu0.13.10.1~pkg984.1, 34.0.1847.116-0ubuntu~1.13.10.0~pkg991)
cups-bsd:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
libcupscgi1:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
python3-distupgrade:amd64 (0.205.5, 0.205.6)
libcupsppdc1:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
cups-common:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
ubuntu-release-upgrader-core:amd64 (0.205.5, 0.205.6)
cups-ppdc:amd64 (1.7.0~rc1-0ubuntu5.2, 1.7.0~rc1-0ubuntu5.3)
linux-libc-dev:amd64 (3.11.0-19.33, 3.11.0-20.34)
chromium-browser:amd64 (33.0.1750.152-0ubuntu0.13.10.1~pkg984.1, 34.0.1847.116-0ubuntu~1.13.10.0~pkg991)
linux-image-generic:amd64 (3.11.0.19.20, 3.11.0.20.21)
linux-generic:amd64 (3.11.0.19.20, 3.11.0.20.21)

I'm hoping that the answer to the above two questions is "yes" and that
I can then do an "apt-get autoremove ; apt-get upgrade" to redo the
upgrades.

Yours hopefully, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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