July 11, 2018

Installing MacOS on Older Macs

I happen to have an older MacBook Air from 2011. Recently I installed Ubuntu on the device to test how well or not this works. (It does work well enough!) However, I decided to go back to MacOS. As I wiped the entire hard drive of my Mac I used the network installer to get back a working system. However, I found that this installer installed a version of MacOS from the times when they still named their OS versions after large felines. Read more

June 21, 2017

Dockerizing Stuff for Fun and Profit

When I want to play with $things, I mostly use virtual machines as throw-away systems that I can mess up with odd software I don't want to install on my Mac or that simply does not run on it. A good while ago I looked into docker as a more lightweight and flexible alternative to a VM. However, I put docker aside as it wasn't usable on a Mac at all. Read more

June 10, 2017

FFMPEG vs My 'Go Low' Action Cam

I got myself a really cheap action cam. Think “China copy” and “Go Pro” and you know what I bought. However, for its 35 EUR price tag that thing is pretty cool. One problem with that cam is that it comes without any software. So you need to dig around a bit if you want to get creative with recorded movies and pictures. So far, I tried two things: time lapse videos from a sequence of photos and stabilized videos. Read more

June 1, 2017

Inline Enumerations in LaTeX

Normally you use the \enumerate command in LaTeX to create enumerated lists like this: I use lots of space! If you prefer your enumeration “inline”, you could do that: ... \newcommand{\inlineEnum}[1]{ \ifcsname c@#1\endcsname \addtocounter{#1}{1} \textbf{\arabic{#1})~} \else \newcounter{#1} \setcounter{#1}{1} \textbf{\arabic{#1})~} \fi } ... \begin{document} \inlineEnum{counter} Here is some text. \inlineEnum{counter} Here is some more text. \inlineEnum{counter} And another sentence! ... \end{document} Much better: … Here is some text. Read more

May 31, 2017

Testing Guetzli - Google's Perceptual Image Encoder

… a quick test of the Guetzli JPEG encoder published some weeks ago by Google. To my big surprise, you cannot encode TIFF or another lossless image format into JPEG. You need to export your RAW camera file first to JPEG @ 100% quality. Then you encode that file with Guetzli. Seems a tad odd to me, as you have a lossless compression two times. The speed of Guetzli is furthermore quite disappointing. Read more

May 31, 2017

Using Two Different GitHub Accounts on the same Computer

Some days ago I created next to my private GitHub account another one for work. At first I was a bit confused how to authenticate to two different GitHub accounts. The solution is rather simple as my former colleague R. H. told me. At first, you need to create two different SSH keys id_rsa_work and id_rsa_priv. Of cause you can use your already existing SSH key for one of the GitHub accounts. Read more

January 20, 2017

Automatically Split and Crop a Multi Page PDF File

My workflow for LaTeX documents with figures is that I typically first draw the figures in MS Visio, then export the drawing to PDF and finally crop the PDF file so that there is no white margin anymore. This is a little tedious when you have lots of figures and lots of updates on these figures… I changed my workflow a bit. Meanwhile I draw all figures in the same Visio file. Read more

December 21, 2015

SVN Externals

I know that subversion is somehow out of fashion. However, svn has some benefits, as you can control access to individual directories quite easily. Today I asked myself if it is possible to combine contents of one svn with contents of the other. Or, to put it differently, to kind of “mount” one SVN into the other. The answer are svn externals. As the documentation is a little crappy, I want to write down what I found out. Read more

September 8, 2015

Some Shell Scripts for Duplicity

Some days ago I accidentally noticed that my ISP upped the meager free online storage capacity included in my contract to a whopping 1TB. This is finally a size where one can think about backing up data to ‘the cloud’. I updated my old duplicity scripts that I did not use for some time and thought I can put them to this place; maybe they are useful to somebody. The files are also available in my github. Read more

May 27, 2015


A while ago I wrote about the combination of encfs, GnuPG and a file synchronization software like OwnCloud. I used this for almost 3 monts and was really happy with it. But suddenly I experienced strange problems: it seemed that encfs was unable to decrypt files. When accessing a file I got something like an input/output error. Interestingly, the affected files were all different ones on my three computers that I synced via this solution. Read more

January 21, 2015

Markdown Magic

I spend a lot of my time at work with typing. Mostly these texts have the nature of simple notes that help me to keep track of my different projects, coordinate my students, etc. So things like Latex or Word, OpenOffice or Pages are overkill. For notes I have been using DokuWiki on a private server for some time. But I am not (never was) really happy with this because a browser is not the best editor in my opinion. Read more

December 15, 2014

Aspell on a Mac

Aspell is a handy-dandy tool for the command line for spell checking text documents. When you're editing Tex documents, Aspell is something you really want to have. However, as a German, installing Aspell on a Mac has one big pitfall: it won't install German per default. What I (foolishly) did up to now is brew install aspell --all which installs all languages Aspell knows. This is quite a lot. So installation takes days. Read more

August 14, 2014


Synthing is a file syncing application that might replace Dropbox and other public Cloud services. In contrast to OwnCloud or Seafile there is no central server. The synchronization is done between equal peers. Well, at least each peer runs the same software. I fiddled around with Syncthing and tried to sync stuff between my two MacBooks. Here the problem is that both computers are rarely running at the same time. So I put a Syncthing instance on my always-on home server and built some kind of a “synchronization star-topology” with a central sync point. Read more

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