Reverting VirtualBox Guest Additions 5.0.22 on Ubuntu 16.04

Earlier today I upgraded my installation of Virtualbox on Windows 10 from 5.0.20 to 5.0.22. This also came up with an update to the guest additions which I installed into my Ubuntu 16.04 guest machine.

After a reboot Ubuntu would no longer boot and instead would flicker as it tried to change the screen resolution inside the virtual machine. This is a known problem in VirtualBox (see: https://www.virtualbox.org/ticket/15526).

I’ve managed to revert VirtualBox and the guest additions back to 5.0.20 using the following steps:

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Central Europe Adventures 2016 – Part Twenty One: Speyer

Until the previous evening I hadn’t even heard of Speyer and discovering it turned out to be one of the highlights of my trip. After spending the morning exploring Worms I jumped on a train for the 35 minute journey to Speyer.

Arriving at Speyer I walked from the Hauptbahnhof along to the Altpörtel and Maximilianstraße, Speyer’s main street. Here the pastel coloured buildings of Speyer felt a lot more like “stereotypical” Germany than Worms or Mainz did. This may be due to it receiving much less damage during WWII than the other two cities.

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Central Europe Adventures 2016 – Part Twenty: Worms

Finding my way from Worms station to my hotel for the night should have been pretty simple. All I had to do was walk down one road and then turn once and walk down a second but somehow I still managed to get lost. It turned out that my hotel was above a restaurant that was closed over the winter. Once I had figured out how to get into the hotel I put my bags into my room and headed out again to find food for dinner.

Worms was a lot smaller than what I was expecting. Trying to find dinner turned out to be quite a challenge as many of the restaurants and pubs contained people openly smoking inside. In the end I just settled for a hot chocolate at a cafe, planned ideas for things to see the following day and then had an early night.

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Central Europe Adventures 2016 – Part Nineteen: The Rhine Valley and Mainz

My next destination after Aachen was Worms around three hours away. Getting to Worms required me to catch three different trains. So rather that trying to get there as fast as possible I gave myself the whole day to do some sightseeing along the way.

It was fortunate that I wasn’t in a hurry as my first train of the day from Aachen to Cologne was delayed by 25 minutes. Once I got to Cologne I changed trains for a slower IC train but one that would wind itself down the side of the Rhine Valley.

I have previously been down the Rhine Valley on my first visit to Germany but it is so spectacular that it is worth doing multiple times – next time I do it I hope to be on a boat, photos taken through a train window just don’t do it justice. For tourism reasons it is called the “Romantic Rhine” and with huge cliffs, many castles and beautiful villages it more than lives up to its name.

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Git logs and commits across multiple branches

Like any good computer scientist I use git for many research and personal projects. My primary use of git is for code backups rather than collaborating with others. However, in some of my recent work I’ve been sharing repositories with colleagues and students which has caused me to improve my git skills.

The following is some of the functionality I’ve only recently discovered that has been extremely helpful:

git cherry-pick commit-id-number
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Central Europe Adventures 2016 – Part Eighteen: Aachen and Liege

Departing Osnabrück in the rain I had to catch two trains to get to Aachen. I had hoped to stop for a few hours in Dusseldorf but given the wet weather I stayed on the train to Cologne and then switched for the local train to Aachen. The second train I caught was completely full of football fans and I had to stand for close to half the journey.

Once I arrived in Aachen I walked down the road to my hotel, the Ibis Hauptbahnhof, which ironically is further from the main station than the Ibis Marschiertor. After I had checked in I met up with a friend who was so excited to see me she literally knock me to the ground when running up to give me a hug. We then joined a larger group of students and had Flammkuchen for dinner (it’s rather similar to Pizza) and rounded off the night drinking a bottle of wine in the student dorms at the university.

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