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Sheogorath's Blog


Depending on the time of the day a friend, a colleague, a wise guy. The beauty of the world is its sense of humor to show humans their way by letting them search their own.


  1. Calculate MXID colours

    Today I learned that the colour for names in the Matrix client “Element” is calculated using an array of 8 pre-defined colour codes and a simple hash algorithm that distributes the colours a bit, based on the MXID. …


  2. Reasons behind double forking

    Today I learned that the reason for double forking of a process, when trying to create a deamonized process is due to the fact that creating processes of the processes that starts a new session can re-attach a terminal to that process. This is unwanted behaviour for a daemon, which being useful for things like a login-daemon. To prevent this from happening the first forked process creates a new session and then forks again, before killing itself and leaving its orphaned child process to the init-process. Now in its own session its no longer possible for the processes of the old session to attach to this process. …


  3. To the court by video

    Today I learned that it’s legal in Germany to attend court by video conferencing software since 2002, given that the judge invited the participants to do so. This is legitimised by the §128a “Zivilprozessordnung” (short ZPO, English: code of civil procedure) and allows lawyers as well as their principal to attend the trial by video conferencing software if there isn’t a strict requirement for them to be in court. This is especially useful for a lot of cases where it’s more important to find a way for both parties to get along with each other than finding “the bad person”. And provides the legal basis for the current usage in the corona pandemic. …


  4. Alarms don't reach me

    Today I learned that alarms for a catastrophic event wouldn’t reach me. Today was a test day for the alarm system for catastrophic alarms. Other than intended, the system didn’t work for me. I was aware that the test alarm would take place at 11 AM today. But I noticed that I wasn’t notified roughly two hours later. I’m not alone with this but it’s definitely something to watch out for. I should re-evaluate the ways one could contact me about this. …


  5. How the altitude influences the taste of coffee

    Today I learned that the taste of coffee is influenced by heigh elevation it was grown at. The higher coffee beans are grown, the slower they grow. This causes them to produce more lactate and the coffee beans to become denser. Which is said to improve the taste of a coffee. …


  6. JAB code

    Today I learned about JAB code, a two-dimensional multi-colour bar code. JAB code works similar to a QR code but due to the use of different colours it achieves a higher data density. It aims to be used on analogue document to sign those digitally and provide a small JAB code for everyone to verify. It’s certified by the German Federal Office for Information Security (better known as BSI) and an implementation is available under LGPL. …


  7. Why light switches click

    Today I learned that light switches click because they are usually spring loaded to keep the switch time as minimal as possible. As switches are made of 2 conductors set up in a way to connect or not connect, the time between being connected and getting enough air between the two conductors is intended to be as minimal as possible. This is done by a spring, that pushes the conductors either together or away from each other, as soon as a critical point is hit, resulting in the clicking sound. All this is done to minimize arking. Arks anywhere in your daily electron’s life are something to avoid, because they are hot and usually not healthy for your equipment. In best case they corrode your contacts in worst case they cause a fire. All in all, something to avoid, therefore switches are spring loaded and clicky. …


  8. OLED is subject to screen burn-in

    Today I learned that OLED displays are subject to burn-ins. Not as in catching fire, but in burning the picture it displays into the monitor. This is nothing new, it was already a thing with cathode-ray tube (CRT) monitors and the sole reason that screensavers exist in first place. Burn-in is a phenomenon where a monitor shows the same picture for an extended amount of time, resulting in pixels becoming “burned” and keep displaying the previous image even when the overall image has changed. Monitor manufacturers try to mitigate this by shifting the image a few pixels automatically or dimming the screen. …


  9. UNIX and the names

    Today I learned that the Debian project has a quite extensive list about binary names and their origin. For example the name bc, while being nowadays being completely rewritten by the GNU project, still stands for basic calculator, Perl standing for Practical Extraction and Report Language, which, if you ever worked with it, makes a lot of sense, or gross, a mail server taking care of greylisting, standing for “graylisting of suspicious sources”1.2 There are a ton of fun examples on this list, which often end up being programs I’ve never seen or used by seem rather interesting on closer inspection. Might be a typo in the Debian page ↩ This sentence had 9 commas and 4 side sentences, I’m sorry for the knot in your brain. ↩ …


  10. Water hammer

    Today I learned about “water hammers” also known as hydraulic shocks. This is a phenomenon one can witness every day when opening and closing a tab in any water pipe system. It’s a shock wave that travels through a liquid backwards, when the liquid’s flow was stopped. Most liquids, like water, are incompressible, which means they are unable to adjust their density to absorb a shock wave. Instead the shock wave travels through the liquid with the entire momentum of the mass of the liquid was moving before. Pipe systems have to account for those shock waves by being able to adjust the system pressure to those shock waves which increase the system pressure by magnitudes for a very short period of time only to drop it below the regular pressure directly afterwards. The Joukowsky equation is used to calculate the shock wave of a hydraulic shock and mainly provides 3 parameters to adjust, which are the speed of the shock wave, the speed of the liquid and the time that is taken to stop the flow. The easiest to adjust for you as a person and therefore reducing the amount of “water hammers” in the pipes you handle every day, is the time that you take to stop the liquid, i.e. closing the tab. Do it slow and the waves will be small, even when the design of your pipe system should already have taken care of them. …