Hi, I'm Volker Diels-Grabsch. I'm not just hacking around, but strive to create things with sustainable value.
Contact: v@njh.eu with PGP key 0xA29FBD515F8990AF
Find me at: Codeberg, GitLab, GitHub, Bitbucket, SourceForge, PyPI, StackOverflow
2,555 bytes Linux intro in pure ANSI text mode. Released at Deadline (Berlin) 2024.
Convert text to PNM.
Secure and efficient copying of block devices.
Material zu meiner Vortragsreihe „Mathematische Spielereien“.
My contribution to the OpenSSH project.
We describe a methodology that can be used to construct new distances which produce many famous means. Its main application is to construct a distance for the logarithmic mean, settling an old open problem. We also use it to construct alternative distances for already known means, such as the arithmetic and all quasi-arithmetic means. Moreover, we show how to construct distances for almost all means that can be obtained from Cauchy's Mean Value Theorem, and apply this to construct distances for all Stolarsky means. Finally, we show how to construct a distance for a mean Mq(a,b)=q-1(M(q(a), q(b))), where M is another mean for which a distance is already known, and q is a monotone bijection to a subinterval.
Vortrag im Datengarten 106 zur Vorstellung des International Obfuscated C Code Contest und Sezierung eines meiner Gewinner-Programme: Ankündigung, Folien (Folien-Quelltext), Video-Aufzeichnung.
Rearrange dominoes on different platforms to start a chain reaction.
Foxda is a very old program that I created in 2001. Despite its age, it is still actively used and has been receiving a steady stream of small improvements over the years and decades.
Automate the installation of LineageOS as much as possible.
My two winning entries at the 26th International Obfuscated C Code Contest (IOCCC) 2019 in the categories "Best small program" and "Most self-aware". Announcements on twitter: Best small program, Most self-aware, Summary.
Artikel für die Wurzel-Zeitschrift zur Klärung einiger Fragen, die Armin Singer in seinem Wurzel-Artikel „Höherdimensionale Krähenfüße“ aufwarf.
How to install LineageOS on a Samsung Galaxy S II (GT-I9100, i9100).
How to compile your own GPG locally.
Texcaller is a convenient interface to the TeX command line tools that handles all kinds of errors without much fuzz. It is written in plain C, is fairly portable, and has no external dependencies besides TeX.
What happened to the “Surgical Team” pattern from “The Mythical Man-Month”?
How to setup a private PGP/GPG keyserver on Debian.
Print your GPG key fingerprint with LaTeX, and be better prepared for the next key signing party!
How to create a self-signed server certificate for SSL/TLS with OpenSSL.
How to configure Nginx to use a different upstream depending on whether the request method is GET or POST.
Protect against Joomla security flaws by not running Joomla in public.
Diploma thesis in mathematics at the Humboldt University of Berlin:
Parallel reversal schedules using more checkpoints than processors
SHA-1 implementation in C++ that is 100% Public Domain.
Solving connection issues with Intel Wireless-N 7265 under GNU/Linux.
German translation of Neil W. Rickert's "The Parable of the Two Programmers" from 1985
Diplomarbeit im Fachbereich Informatik der Humboldt-Universität zu Berlin:
Erarbeitung und Evaluierung von möglichen Lösungsarchitekturen für das System „Besondere Nutzung Luftraum“
Drivers for CUPS to get some printers working under GNU/Linux. These are PPD files as well as direct contributions to foomatic-db.
Sehr einfache IPv6-fähige Netzwerkkonfiguration für virtuelle Maschinen (via KVM) in einem Linux-Host.
Mcpdf fixes PDFtk's unicode issues, so you can write Łódź into your forms. It implements a small subset of PDFtk for which it implements compatible command line interface, so it can be used as a drop-in replacement for this subset of commands.
Live view of a drone camera in ASCII.
This was our competition entry at the NodeCopter birthday bash 2013.
New sequence discovered:
Number of bangbangs (!!) in shell substitution when starting with
: '!!'
and
: "!!" '!!'.
This beautiful integer sequence was discovered by Shadab Ahmed and analyzed by Robin Houston. I registered it as A228162 in the OEIS.
wwan-helper is a script that establishes a UMTS connection using a Ericsson F3507g Mobile Broadband Module. It was designed to be used with a ThinkPad T420s. It takes care of resetting and reinitializing the modem if the hardware fails to get a WWAN connection, and retries as often as necessary until the UMTS connection is really established. It is meant to run as a hook script for the ifup / ifdown mechanism, but should also work on other networking systems.
Script to manage KVM-based hosting, powered entirely by XSLT
Bitcoinproof creates a forgery-proof timestamp for your data, secured by the Bitcoin network. It allows you to prove that a certain event happened before a certain point in time. Maybe you want to prove that the damage in your flat already existed when you moved in, or that you were in possession of a great artwork before it was published, proving you are the author.
Efficient backups by SHA-based data splitting: Shasplit takes a large data block, splits it into smaller parts, and puts those into an SHA-based content-addressed store. Reassembling those parts is a trivial "cat" invocation. Repeating parts (e.g. from previous split operations) are stored only once, which allows for efficient incremental backups of whole LVM snapshots via Rsync. Shasplit shows its strengths on encrypted block devices, but might be useful for non-encrypted data, too.
Simple content-addressed store. This project is outdated, please have a look at Shasplit.
How to contribute to OpenPrinting.
How to redirect the website of a Savannah project.
Draft of a parser for ASTERIX binary data such as CAT062, written in Python
MXE (M cross environment) is a Makefile that compiles a cross compiler and cross compiles many free libraries such as SDL and Qt. Thus, it provides a nice cross compiling environment for various target platforms.
Python interface to Linux-VServer for managing hosting systems.
Nachtrag: Juniper-VPN mit IcedTea-Web + OpenJDK unter Debian.
Storing k-Subsets Efficiently.
This bookmarklet reloads a website over and over again. It is written in the style of self-contained literate programming.
This is the summary of a short, unprepared talk I gave on 2012-01-17 at the Berlin PHP UserGroup. In that meeting, everyone was invited to present their favourite editor or IDE. So I demonstrated my current way of doing things.
Convert LaTeX or TeX source to PDF or DVI, and escape strings for LaTeX.
Juniper-VPN mit IcedTea-Web + OpenJDK unter Debian.
Ich habe gerade sehr viel Zeit mit dem Einrichten von Java in meinem Browser verschwendet. Ich hoffe, mit diesem Posting andere davon abzuhalten, die gleichen Irrwege zu gehen.
Beautify the Git commit hash! This is a little useless toy inspired by BitCoin's "proof of work" concept. It enables you to modify your Git commit to enforce a certain prefix on the Git commit hash.
A bilingual short story, licensed under CC BY-SA 3.0.
Eine zweisprachige Kurzgeschichte, lizensiert unter CC BY-SA 3.0.
Sammlung von Standard-Floskel-Sammlungen, inspiriert durch Dieter Brügmann.
Technischer Import von medizinischen Bilddaten
Der Verein zur aktiven Bekämpfung von Anglizismen – Lokalzirkel Berlin (VzaBvA-LB) fordert die Abschaffung von Anglizismen im Berliner öffentlichen Personennahverkehr.
Small Qt program to upload images directly from the clipboard to a website. Its main purpose is uploading (possibly edited) screenshots to a documentation wiki.
Getting started with SDL and Objective Caml
German translation of Paul Graham's "Writing, Briefly"
Folien zum Vortrag „Freie Software veröffentlichen“.
The Exim Ldap Mail Administrator provides a comprehensive frontend to manage single server up to multiple server email sites.
Anleitung zum Erstellen eines einfachen Firewall-Scripts "für den Hausgebrauch" mit iptables
Simple 64b intro that displays a TV screen. (tvscreen.zip)
Demonstration of the technique of self-contained literate programming.
Animated ASCII art
Collection of shell scripts to create simple Debian packages.
Repository of Debian cross compiling packages based on GnuWin32. This repository has been superseded by the MXE project.
Answer to the StackOverflow question: "How to write a self reproducing code?"
This module contains various functions and classes which are very useful for my daily work with Python.
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Seminarvortrag an der Humboldt-Universität zu Berlin im Informatik-Seminar „Projektmanagement“.
Seminarvortrag an der Humboldt-Universität zu Berlin im Informatik-Seminar „Dimensionen der Softwareentwicklung“.
Seminarvortrag an der Humboldt-Universität zu Berlin im Informatik-Seminar „Parallelisierung“.
Dieser Artikel ist eine Einführung in IPv6, das Internet Protokoll der nächsten Generation.
Seminarvortrag an der Humboldt-Universität zu Berlin im Informatik-Seminar „Matroidtheorie“.
Manage different cronjobs with only one system user.
Projektarbeit im Rahmen der Informatik-Vorlesung „Grundlagen der Rechnerkommunikation“ an der Humboldt-Universität zu Berlin.
Vortragsfolien im Rahmen der Informatik-Vorlesung „XML, XPath, XQuery“ an der Humboldt-Universität zu Berlin.
Lösung eines interessanten Problems, das an der Freien Universität Berlin gestellt wurde.
How to create a small, primive HTTP Proxy using just INETD and Netcat
Debian provides the qmail-1.03 source with some patches already applied. Thus, some other patches won't work. This site provides slightly modified versions of some popular patches that work with Debian's qmail sources.
Projektarbeit im Rahmen der Informatik-Vorlesung „Künstliche Intelligenz“ an der Humboldt-Universität zu Berlin.
Einführungs-Kurs in das Thema „Freie Software“ auf der CdE Sommerakademie 2006 in Kirchheim.
Projektarbeit im Rahmen der Informatik-Vorlesung „Technische Informatik 2“ an der Humboldt-Universität zu Berlin.
3D-Simulation von Satelliten-Netzen im Rahmen des informatiCup 2005.
Praktikums-Semesterarbeit zur Mathematik-Vorlesung „Numerik“ an der Humboldt-Universität zu Berlin.
This is a simple scoresheet for the game Kniffel which is also known as Yahtzee. The scoresheet has been created with LaTeX.
Simulator & Programm-Generator für den „MC4“ Microcomputer.
Jugend forscht-Projekt über das Raucherverhalten von 16- bis 21jährigen.
Would you like to have some facilities for database applications? Or are you looking for a stable log system? I want to offer you many features you probably miss in Sun's Java API.
DAVIS is an easy and useful language for IRC bots. It contains our own bots, some bots for demonstration, a parser that creates Java, C, Perl and IRC-Script code out of a DAVIS file, and an interpreter for DAVIS files.
In 2003 we entered the "Jugend forscht" (youth does research) contest with DAVIS as our project.
Hosh is a shell for fun. There are commands like "make world" as well as "configure" which checks the whole machine – even the power status and the coffee temperature.
It is possible to hang up a picture on two nails such that it falls down if only one of the two nails breaks. Since this is some kind of optimization of Murphy's law, I call such an arrangement "murphystic". This can be generalized to any number of nails and is a popular funny exercise on the theory of fundamental groups.
Murpi is a program that generates such arrangements and visializes them as PostScript files.
VoLT is a nice tool for those who want to create MUDs with LPC. It makes it easy to create and edit rooms and worlds.