We all know, that <a href="http://en.wikipedia.org/wiki/MD5#Security" title="Wikipedia: MD5 / Security" target="_blank" rel="noopener">md5 has its weaknesses</a>. But, as always, exploiting such weaknesses in practice is not a piece of cake.
<a href="https://blag.nullteilerfrei.de/2013/09/04/reverse-md5-hash/#more-2126" class="more-link">Do you want to know more?</a>
The new version of TaskWarrior (2.2.0) supports the new field `scheduled` which is/maybe pretty handy. The short version of how to install it on a linux machine (without asking root): Follow the instructions in the file `INSTALL` from the source tarball and set the flag `DCMAKE_INSTALL_PREFIX` of `cmake` to your home directory. <a href="https://blag.nullteilerfrei.de/2013/08/27/howto-build-taskwarrior-from-source-without-root-privileges/#more-2115" class="more-link">Do you want to know more?</a>
If you happen to be in Berlin, you can get <a href="https://www.hotspot.kabeldeutschland.de/" target="_blank">30 minutes of free WiFi</a> in quite a lot of places from a KabelDeutschland™ HotSpot. Unfortunately, each connecting device gets only 30 minutes of free internet per day. On a completely unrelated note, I will talk about changing the MAC address of your WiFi card in Windows 7. I must, again, emphasize the fact that these two topics are in no way related. <a href="https://blag.nullteilerfrei.de/2013/08/25/kabel-deutschland-hotspots-and-wifi-macs/#more-2086" class="more-link">Do you want to know more?</a>
Mein Eindruck ist, dass viele vernünftige Leute das Problem haben, unter Windows texen zu wollen und bei schrecklichen Programmen wie <a href="http://www.latexeditor.org" title="Latex Editor" target="_blank" rel="noopener">LaTeX Editor</a> oder <a href="http://www.texniccenter.org" title="TeXnicCenter" target="_blank" rel="noopener">TeXnicCenter</a> hängen bleiben. Prinzipiell funktionieren die ja auch. Vielleicht nicht perfekt und manchmal sind sie hier oder da etwas unpraktisch, oder stürzen ab (beim Editiern von <em>Text</em>) - aber sie tun ihre Arbeit und, hey, es gibt ja auch nichts besseres.
<a href="https://blag.nullteilerfrei.de/2013/07/12/latex-unter-windows-mit-vorschau-und-deinem-lieblingseditor/#more-1969" class="more-link">Do you want to know more?</a>
This guide is for the people who only want to get this thing done where you only type
```bash
ssh remotehost
```
to ssh to your server at `crazylongdomainname.com` with the user `u3321445longandunhandy` on a windows pc with cygwin. <a href="https://blag.nullteilerfrei.de/2013/07/01/ssh-cygwin-windows-quick-dirty/#more-1974" class="more-link">Do you want to know more?</a>
You might have come across the same problem I have faced pretty often: You want to write a small snippet of code for a friend who's not into programming to solve some task. You want to use the scripting language of your choice (yeah, [Perl](http://www.perl.org/)). But for many people, especially Windows users, explaining them how to [install perl](http://www.perl.org/get.html), install some modules from [CPAN](http://cpan.org), and finally how to use the script from the command line is tedious and often takes more time than writing it in the first place. And sometimes it even takes more time than solving the task by hand which is quite frustrating.
So I always wanted to build stand-alone applications with a GUI for those cases. But building GUIs is usually a huge pain in the ass, so I always avoided it; until I got the idea to build web applications with [Mojolicious](http://mojolicio.us/) as GUI. Building stand alone executables without the need of installing perl, modules, or libraries can be solved with [PAR-Packer](http://search.cpan.org/dist/PAR-Packer/). So far, that was just a thought.
A few days ago I got a small task: My brother wanted an application to automatically correct one kind of systemic error in large data sets. So I wanted to put that idea to the test. It worked out quite well!
<a href="https://blag.nullteilerfrei.de/2013/05/17/building-perl-stand-alone-applications-with-a-gui-using-mojolicious-and-par-packer/#more-1907" class="more-link">Do you want to know more?</a>
This glab post is essentially about running a certain shell command remotely on multiple systems within a network that has been set up for public-key authentication. It's a standard task for experienced system administrators I am sure, but for me it was a little adventure in bash scripting — and I wanted to share it with you.
<a href="https://blag.nullteilerfrei.de/2013/05/11/my-quest-for-cpu-power/#more-1806" class="more-link">Do you want to know more?</a>
I'm using <a href="http://truecrypt.org/">TrueCrypt</a> system encryption for my Windows Partition and use its chain loader to boot Linux via <a href="http://www.gnu.org/software/grub/">GRUB</a>, which is installed on my /boot partition. However, at some point I also had GRUB installed on my root partition. Because of that the TrueCrypt boot loader — after pressing ESC when I didn't want to boot Windows — showed a list of partitions to boot from instead of directly starting the only other boot loader. That's less convenient and a little bit annoying, so I wanted to get rid of the entry.
As the TrueCrypt boot loader seems to detect boot loaders on partitions automatically, I wanted to try deleting the redundant one. However, I didn't find anything on how to delete a boot loader from a partition; that's probably because it usually isn't necessary. A quick search on <a href="http://en.wikipedia.org/wiki/Volume_boot_record">Wikipedia</a> revealed that the boot loader on a partition is stored in the volume boot record (VBR) of the partition, which is just the first sector, similar to the MBR. So I first made a backup in case I got anything wrong ((make sure to backup to a different partition than the one you're going to write on :) )):
```bash
$ dd if=/dev/sda5 of=sda5.vbr bs=512 count=1
```
and then wrote zeros to the VBR:
```bash
$ dd if=/dev/zero of=/dev/sda5 bs=512 count=1
```
which did exactly what I wanted.
Be aware, however, that when you want to delete the boot loader from an extended partition, this would overwrite the partition table in the extended boot record (EBR), so you may only overwrite the first 446 bytes of the sector instead of all 512.
One last thing that cannot be stressed enough: <strong>Have a current and complete backup handy, and be prepared you might have to use it.</strong> I'm no expert on the subject. If the VBR is used for more purposes than just containing a boot loader as I expect, zeroing the whole sector may really go wrong.
I was riding the backseat of a car, a pal of mine with a large Sudoku book on the seat beside me. I glared over at him and remarked that I find Sudokus utterly boring and would feel that my time is wasted on any of them. He looked up at me, clearly demanding an explanation for that statement. I continued to explain that a computer program could solve a Sudoku with such ease that there is no need for humans to do it. He replied that something similar could be said about chess, but still it's an interesting game. And it was <b>then</b>, that I realized <b>why</b> Sudoku is so horribly boring, and chess is not.
It was the fact that I could code a Sudoku solver and solve the Sudoku he was puzzling about, and I would be able to do it faster than it would take him to solve the entire thing by hand. This does not apply to chess, evidently. Of course, I confidently explained this to him. <i>»Prove it.«</i>, he said. So I did.
<a href="https://blag.nullteilerfrei.de/2013/04/17/why-sudoku-is-boring/#more-1744" class="more-link">Do you want to know more?</a>
I have a folder `data` with stuff in it. I am not using an Administrator account on my Windows machine, and that folder is supposed to be owned by my user. When you search for how to take ownership of all files and folders in a certain directory recursively, you get told to use `TAKEOWN`, a lot. Well, it has a little catch: You can only really use it to <i>take</i> ownership. Not to <i>give</i> it. A much more giving command is
```bash
ICACLS C:\data /setowner rattle /T
```
Oh yea, it's the `/T` switch that makes it recursive.
Harm Derksen <a href="http://www.math.lsa.umich.edu/~hderksen/preprint.html">brachte uns</a> schon im Jahre 1998 die weltschnellste Methode zur Berechnung irreduzibler Charaktere der symmetrischen Gruppe. Aber in seinem preprint, <i>Computing with Characters of the Symmetric Group</i>, bleiben einige Fragen offen, die ich hiermit zu klären versuche.
<div style="font-size:160%;font-weight:bold;margin-left:10%;text-align:right"><i>» The code to end all codes «</i></div>
<p style="margin-left:25%;text-align:right"><i>Die Welt ist einen halben Herzschlag alt. Der unsterbliche Prophet meditiert seit Anbeginn der Laufzeit auf dem <span style="line-height:80%" title="Taj Mahal">তাজমহল</span> und studiert die heiligen 12 Zeilen C-Code, die jede <b>SAT</b> Instanz in $\mathcal{O}(n^{9699690})$ lösen. Wenn der Puls eine Ganzzahl wird, so wird er erwachen und die Wahrheit verkünden, und Lob wird gepriesen, und Licht wird ewig scheinen auf die Kinder des Schaltkreises. Denn er ist der Taktgeber, und an der Spitze des Signals wird es sein, wenn er uns erscheint.</i> <span style="margin-left:auto;text-align:right;display:block">Buch Arithmæl Circulæ, Vers 21:7</span>
<a href="https://blag.nullteilerfrei.de/2013/03/27/characters-of-the-symmetric-group/#more-2570" class="more-link">Wollen Sie mehr wissen?</a></p>
Suppose you have a Laptop, which therefore must be a [ThinkPad](http://www.lenovo.com/products/us/laptop/thinkpad/). Let's also assume that you [use Windows 2008 as a workstation](http://www.win2008workstation.com/), just like [I do](/2012/03/22/turning-windows-2008-r2-into-a-workstation/). Then, you might run into some issues with [Lenovo System Update](http://support.lenovo.com/de_DE/detail.page?LegacyDocID=TVSU-UPDATE). To be precise, it tells you:
> An error occurred while gathering user information.
Then it stops. I will provide a solution to this problem which is not specific to Windows 2008 R2, and therefore, I hope that my solution will also work for future versions of Windows that are not out-of-the-box supported by SystemUpdate.
<a href="https://blag.nullteilerfrei.de/2013/03/09/lenovo-system-update-somewhat-demystified/#more-1587" class="more-link">Do you want to know more?</a>
Trust me, I am not one to enjoy deeply nested case distinctions in a mathematical proof. In fact, I'd rather there were no case distinctions necessary at all. However, to quote the famous mathematician Nikolai Nowaczyk:
> Some theorems have beautiful proof - and some theorems are worth fighting for.
Anyway. If you have to do it, you should do it in beautiful $\KaTeX$. <a href="https://blag.nullteilerfrei.de/2013/03/07/nested-case-distinctions-in-latex/#more-1565" class="more-link">Do you want to know more?</a>