Schlomo Schapiro

Software rules the world, and everybody is its subject. But you can be a ruler, too - if you like  I keep telling my family. Here is a little example where I try to rule my secondary printer by automating the tedious task of rotating and scaling content to print. My Little Zebra Printer My secondary printer (shown here on the shelf in my home office) is a little miracle device: It is a thermal transfer receipt printer , that prints on a roll of continuous paper that is 10cm (4in) wide. Specifically a Zebra GX420d . You can get such a used printers relatively cheap. This is exactly a printer like you know from your local supermarket. And it is a super useful tool to have at home, as many print jobs don't require a full A4 page and don't need to be printed on fancy bright white paper with ever-lasting toner. Most common print jobs are shipping labels (no need to cut them to size), small shopping lists (fits in a pocket), little notes to stick into a book (e.g. reading order for ...

I'm a big fan of test driven development  (TDD) for infrastructure components. I'm currently working on a hardware-related topic where we also use the system serial number as identifier. To create a proper integration test, we need to be able to start a system and set the serial number to a known value. This can easily be done with the help of virtual machines like in VMware or VirtualBox , but I couldn't find a way for changing the system serial number on hardware boxes, cloud VMs (e.g. on Alibaba Cloud) or other Linux system. Problem Analysis I was thinking: Linux is the operating system where I can potentially do everything . So how hard can this be? After some digging around I found out that there are those main sources for the serial number on Linux: /sys/firmware/dmi/tables/DMI contains a binary blob of Desktop Management Interface data provided by the kernel and the dmidecode utility is commonly used to decode...

I was really excited, when Firefox OS became commercially available as KaiOS for "smart" feature phones. Unfortunately the high hopes I had put into this platform have been utterly shattered. I was recently looking for a button phone that had only three requirements : very good battery run time, at least several days or a week of standby without charging easy backup or even synchronization of the contacts VoLTE support to benefit from LTE coverage  In Theory... On paper, KaiOS phones look like the perfect match for those requirements. PhoneCopy for KaiOS is a cloud synchronization service that comes with an app for KaiOS (and many other platforms) to synchronize contacts and other phone content to the cloud (and back). With batteries of 1500 mAh and more , KaiOS phones have the potential to deliver outstanding battery performance. The Alcatel 3088X , for example, boasts "up to 300h standby and more than 7h talk time" with a 1530 mAh battery: Battery specification...

Our door bell is not very loud and we don't hear it in the kitchen when the internal doors are closed. We already missed people calling at our apartment door because of this. To solve this problem I found a 10€ remote bell that sits in the kitchen and rings whenever somebody rings our door bell. Initially I wanted a fancy WIFI based solution based on an ESP32 that would call me via SIP... But in the end this simple solution is "good enough" and has the benefit of zero maintenance. My solution is based on a kinetic wireless doorbell  (batterielose Funktürklingel) that has two components: A ringer that sits in a power socket and a transmitter without batteries. The "without batteries" part is really important as it allows a direct connection and integration of the transceiver into the door phone. As it happens, what I needed was available for 10€ at a local supermarket, but you can easily find this type of doorbell in online stores as well. The ringer contains a l...

After more than half a year of home office I decided to improve my setup by adding proper lights to my work space. Following a recommendation I bought 2 video lights off Amazon, and then at the recent Black Friday week I bought the same video lights in a set of 2 with tripods (because the set cost less than I paid previously for the 2 single units). To my dismay I discovered that the 4 video lights, same brand and same model, actually looked different and performed different! The question is, which video light is more "correct" and therefore better to keep? I wanted to keep two and return two because I don't need four lights. Two is more than enough. The lights can be adjusted for brightness and for color temperature, but all the four lights would look different at the same setting. So which light was correct? Which to keep? After breaking my head for a bit I suddenly remembered the old colorimeter I have in my cabinet. It actually does ...