Nun also doch: Ich blogge.

Geplant ist, euch an dieser Stelle über meine Aktivitäten zu informieren, von Unternehmungen zu berichten und euch mit weiteren geistigen Ergüssen (auch Brain-Dumps genannt) zu unterhalten.

Im Moment möchte ich nur kurz auf die Blogsoftware eingehen.

Es ist also ein WordPress geworden, mal wieder. Ja, ich habe mir Alternativen angeschaut. Am liebsten wäre mir ja etwas mit Django gewesen, weil ich damit schon für unser Kassensystemprojekt k4ever gearbeitet habe und Python mir als Programmiersprache bisher am angenehmsten ist.

Django-Mingus ist dahingehend ein sehr vielversprechendes Projekt, das mehrere Django-Applikationen integriert. Im Blog des Entwicklers befinden sich einige Artikel, die auf Mingus und weitere Django-/Pythonthemen eingehen. Machte also einen guten Eindruck. Allerdings stolperte ich über so einige Unklarheiten in der Dokumentation, sowie Fehler. Als es dann aufgesetzt war, überzeugte mich das Admininterface, in dem man die Artikel einstellt, leider nicht.
Tja, da siegte die Bequemlichkeit über die Präferenz der Programmiersprache.

Da WordPress mich netterweise Artikel exportieren lässt, bin ich nach wie vor flexibel, wenn mir eine attraktive Alternative begegnet.
Aber mal ehrlich, es hält doch erfahrungsgemäß nichts länger als ein Provisorium, nicht wahr…?

Manche Tools oder Websiten benoetigen einen Text eingegeben per "keypress" von der Tastatur.

Um diesen dennoch einen kopierten Text unterzujubeln, hier ein kleines Script von mir:

#!/usr/bin/python

import os

import virtkey

import time



def presskey(keyName):

        vk.press_unicode(ord(keyName))

        vk.release_unicode(ord(keyName))



vk=virtkey.virtkey()



time.sleep(2)



for c in os.popen('xsel').read():

        presskey(c)

Ihr muesst dafuer die pakete python (evt. python-dev) und xsel installiert haben. Haf Vun!

Until recently, page margins in LaTeX had more control over me than I had over them. I already heard that package geometry could be of use here, but quick hacks seemed more fun than going through the docs of that package.

I had a closer look now and geometry turned out to be much more convenient than I expected in the end.

The code that I experimented with can be reduced to this snippet:

%% Demo by Sebastian Pipping <sebastian@pipping.org>
%% Released to the public domain
\documentclass[a4paper]{article}
\usepackage[hmargin=2cm,vmargin=1cm]{geometry}
\begin{document}
\rule{\textwidth}{\textheight}
\end{document}

So I am abusing \rule here to draw a filled rectangle that spans the whole content area. I am asking for horizontal margins of 2cm width and vertical ones of 1cm height.

Strangely, the output I received did not match my expectations. Look how much bigger the left margin is than the right one.

It turns out that indentation of the first line of a paragraph is at work here. The insertion of \noindent solved that problem.

LWN.net brought my attention to this: Microsoft confirms UEFI fears, locks down ARM devices

Dass man RFID-Chips in Kleidung einbauen kann, war mir klar, aber dass es wirklich gemacht wird, hat mich dann doch ziemlich vom Hocker geworfen:

FoeBuD enttarnt RFID-Chips in Kleidung

Nachdem sich die Festplattenpreise stabilisiert haben auf gut das doppelte, hier ein Ueberblick mit Alternativen:

Das ganze geplotet:

Massenspeicher im Vergleich

Intro

I recently got bitten by the hyphenation of LaTeX and learned a few things in return. I noticed that two other LaTeX users in my environment were running into similar hyphenation trouble or were about to start a bigger text document without sufficient knowledge of hyphenation. So I would like to summarize a few essentials here.

Why care about hyphenation?

By default, LaTeX does hyphenation for you. If it gets things wrong the reader will attribute that error to you, not to LaTeX. Sometimes bad or wrong hyphenation even affects the layout of the page and makes text go into the margin area. Maybe a reader attributes that to LaTeX; however, it still doesn’t look very professional.

Why hyphenation needs to be correct from the very start (and for every word)

Imagine you work on a document 20+ pages long. You pass a snapshot of the document to someone to read, get some corrections back, start integrating corrections. If you modify content on page 10 there is a chance that hyphenations on pages later in the document change: it may happen the the set of hyphenated words before and after do not share a single word. What that means is that as long as you work on the document, places of hyphenation change. That means errors that no reviewer had a chance to see before. Ouch.

Common pitfalls with hyphenation

Words containing hyphens, e.g “well-understood”

If you use words that contain hyphens, e.g “well-understood”, LaTeX breaks these at the very place of the present hyphens only. It may even write the end into the margin area of the page, if it exceeds a certain length. The following example illustrates the issue.

Let’s look at a document made of the text

Hyphenation is well-understood. Maybe not.

six times. Without manual work you get output as shown in the following excerpt. Focus on the right border.

\documentclass{article}
\usepackage{hyphenat}
\begin{document}
Hyphenation is well\hyp{}understood. Maybe not.
[..]
\end{document}

This time the output respects the size of the text area. Again, focus on the right border.

Mixing languages, e.g. English and German

If you mix two or more languages within the same document you have to tell LaTeX which words belong to which language. (Once you get used to it, it’s bearable; there isn’t much of a way around it.) Otherwise you end up with things like German hyphenation applied to English words, i.e. wrong hyphenation.
In a case where the main text is written in language A it makes sense to mark selected words as language B.
To mark English words in an otherwise German document I use a simple self-made command \ENG:

\usepackage{babel}
[..]
\newcommand{\ENG}[1]{\foreignlanguage{english}{#1}}

An example use would be

UnionFS ist ein \ENG{Stackabe file system}.

Mapping that to other combinations is left to the reader

Debugging tool \showhyphens

The command \showhyphens can be used to query all the places where LaTeX dares to hyphenate a word (or compound word). The output however does not go into the actual document but to the shell and the log file. If you feed the following document to LaTeX

\documentclass{article}
\usepackage{hyphenat}
\begin{document}
\showhyphens{well-defined}
\showhyphens{well\hyp{}defined}
Dummy
\end{document}

you can spot this output on the shell:

...
[] \OT1/cmr/m/n/10 well-defined
...
[] \OT1/cmr/m/n/10 well-de-fined
...

In case you have a script extracting all used words from a LaTeX document for another view on spelling mistakes you could combine that with the results of \showhyphens to a make a single list with all words and their hyphenation for review.

Futher reading and sources

• Wikibook LaTeX -> LaTeX/Formatting -> Hyphenation
• Multilingual LaTeX with the Babel Package
• \showhyphens #1
• \showhyphens #2

I recently discovered that the sound of rain makes a great ambient sound for working. Unlike with real music I do not have to switch artists or albums every few hours and there are no foreign words injected into my thinking process so it’s easier for me to focus.

Finding a good recording of rain can be a bit difficult. What I ended up using is these two CC-BY-licensed samples in loop at the same time:

• rain.wav by mystiscool
• rain_on_car_roof.flac by 833-45

The Freesound website makes that kind of playback possible without even involving sound editors. All you need is two tabs (or even one) kept open in a browser.

I ran into error 24 today: “Too many open files”. Ooops.

The solution that I eventually went for is not among the first Google hits for “increase limit open files” so I felt like blogging about it here.

There are two functions getrlimit and setrlimit that allow querying and modifying certain resource limits, e.g. the maximum number of open files for a single process (and they do have a shared, detailed man page). For each of the resource limit types, there is a hard and a soft limit: the soft limit, is the one you run into. In my case the soft is 1024, the hard one is 4096. The cool things is: Any non-root process can increase the soft limit to the hard one. That’s my rescue.

Simplified, this is what I do:

#include <sys/time.h>
#include <sys/resource.h>

...

struct rlimit open_file_limit;

/* Query current soft/hard value */
getrlimit(RLIMIT_NOFILE, &open_file_limit);

/* Set soft limit to hard limit */
open_file_limit.rlim_cur = open_file_limit.rlim_max;
setrlimit(RLIMIT_NOFILE, &open_file_limit);

Works like a charm.

Wer kennt das nicht, da hat man eine USB-Soundkarte gekauft, weil der Eingang des Notebooks zu nah an der Festplatte vorbei geführt wird (sic!) und dann kann man an der Soundkarte kein Linepegen anlegen.

Nun, für diesen Fall möchte man ein Dämpfungsglied bauen. Ohne zu sehr auf die Details einzugehen, was die Anpassung angeht, hier ein einfacher Schaltplan um ein Mikrofoneingang zu einem Line-In zu machen.

Obacht: Dies ist für XLR, also symmetrische Signale, gedacht.

       ___ 7500
 o)---|___|-----o--------(o 
       R1       |                mit 2x7.5 und 1x150
LINE           | | 150     MIC   ergibt sich ein Teiler
 IN            |_| R3      OUT   verhältnis von 
       ___      |                15000:150 = 100:1 = -40dB
 o)---|___|-----o--------(o      Bitte 
       R2  7500                  Metallschichtwiderstände
                                 verwenden, die Rauschen nicht.

Für asymmetrische Signale sollte ein normaler Spannungsteiler funktionieren:

         ___15000
 o)-----|___|----o-----(o
                 |
                | | 150
IN              |_|          OUT
                 |
 o)--------------o-----(o

Samstag nichts zu tun? Perfekt fuer ein update aufs neue Ubuntu! Ist doch sicherlich Idioten sicher... dacht ich mir.

Leider hatte der idiotensichere Aktualisierungsmanager vergessen, dass /boot volllaufen kann und war der Meinung, dass das updaten des initramfs so kritisch waere, dass er irgendwie versucht hat die Installation rueckgaenging sic zu machen bzw. dann einfach wegzusterben. Natuerlich hat er dabei mich mit paar Paketen zu wenig zurueck gelassen und komplett gnome mitgenommen beim sterben.

Also: Neustart.. Hilft doch sonst immer!

Danach befand ich mich in einer schicken schlichten Unity-Oberflaeche, der aber die Symbole und die Windowdecoration (die kommt wohl von Compiz?) fehlten. Diese 'neue' Oberflaeche bedeutet aber mehr Klicken, weniger blinkende Applets und keine/schlechte Konfiguration.. da kann ich mir ja gleich Fluxbox installieren! Also geguckt wie ich das "gute, alte" gnome wiederbekommen:

aptitude install gnome-session-fallback

Danach alle Applets wieder zusammen gesucht, die ganze 3D-Optik reduziert und alle hotkeys wieder eingerichtet. Jetzt laeufts wieder.. aber ob ich das beim naechsten Ubuntu-update immernoch machen kann? Naja.. man wird sehen.

I recently wanted to disable echoing of the terminal in Python. When googling for that you quickly run into recommendations on getpass.getpass. Sadly, in my case of sort-of-non-blocking I/O it didn’t fit. It needed something to fit with this:

def read_line(timeout, timeout_func):
	ready_to_read, _, _ = select.select([sys.stdin], [], [], timeout)
	if ready_to_read:
		return sys.stdin.readline().rstrip()
	else:
		timeout_func()
		return &apos&apos

So I needed a way to just disable terminal echo. This is what I came up with:

import termios

def enable_echo(fd, enabled):
       (iflag, oflag, cflag, lflag, ispeed, ospeed, cc) \
                     = termios.tcgetattr(fd)
       if enabled:
               lflag |= termios.ECHO
       else:
               lflag &= ~termios.ECHO
       new_attr = [iflag, oflag, cflag, lflag, ispeed, ospeed, cc]
       termios.tcsetattr(fd, termios.TCSANOW, new_attr)

Also, I added this code to restore the terminal on progam exit:

import atexit
atexit.register(enable_echo, sys.stdin.fileno(), True)

It was the newsletter of Trinity Concerts that brought my attention to BOY a few days ago: a female-female duo making good mood music — quite fun to listen to. Sadly it seems the local concerts are sold out already. YouTube has quite a few videos on/of them though, both live and studio. Check them out. Among my favourites are the two below: “Little numbers” (studio) on top and “Boris” (live) at the bottom. Enjoy.

The atoi function has a serious flaw: it “does not detect errors”, see man 3 atoi. Same with its siblings atol, atoll, atoq.

Recently I played with different replacements for atol, the long-producing version of atoi: one based on strtol, the other on sscanf. The following is what I came up with.

Replacement using strtol:

#include <stdlib.h>
int str_to_long__strtol(const char * text, long * output) {
	if (! text) return 0;
	char * end;
	long number = strtol(text, &end, 10);
	if (end != text) {
		*output = number;
		return 1;
	}
	return 0;
}

Replacement using sscanf:

#include <stdio.h>
int str_to_long__sscanf(const char * text, long * output) {
	if (! text) return 0;
	long number;
	int count = sscanf(text, "%ld", &number);
	if (count == 1) {
		*output = number;
		return 1;
	}
	return 0;
}

Both of these two functions deliver behavior equivalent to atol on these inputs:

• “0002″
• “2″
• “2Hallo”
• “+2″
• “  2″

However, they differ to atol in two aspects:

• No crash on input NULL
• No success on input “”

Please note that all of these functions happily turn “2Hallo” into integer 2 with no complaints.

The code above is public domain.

When you accompany beamer slides with notes (using the \note{...} command) and you make them shown (using \setbeameroption{show notes}) you gain extra note pages like this:

When printing note pages alone, the header and preview makes sense. In my case with both slides and notes, it doesn’t. What I want is note pages that…

• contain no header, no preview, no date (which also increases space for note content)
• do not increment page numbers
• have proper spacing between paragraphs

To put that into an image, I want this:

To get there I came up with the following. First, to get rid of the header and preview I re-write the note page beamer template:

\setbeamertemplate{note page}{%
  \insertnote%
}

If you want to stay closer to the original, you can copy from the default code of that template, located at /usr/share/texmf-site/tex/latex/beamer/base/themes/outer/beamerouterthemedefault.sty in Gentoo Linux:

\defbeamertemplate*{note page}{default}
{%
  [..]
  \vskip.25em
  \nointerlineskip
  \insertnote
}

Second, to fix page numbers and spacing I wrote a wrapper around the \note{...} command using \renewcommand{\note}[1]{...}:

\newlength{\parskipbackup}
\setlength{\parskipbackup}{\parskip}
\newlength{\parindentbackup}
\setlength{\parindentbackup}{\parindent}

\let\notebackup\note
\renewcommand{\note}[1]{\notebackup{%
	\mode<handout>{\addtocounter{page}{-1}}%
	\setlength{\parindent}{0ex}%
	\setlength{\parskip}{10pt}%
	\noindent%
	{\normalsize{}#1}%
	\setlength{\parskip}{\parskipbackup}%
	\setlength{\parindent}{\parindentbackup}%
}%
}

If you have used \renewcommand before, this code should explain itself. If not, please drop me a mail. If you have ideas on improving above-mentioned approach, I’d be interested to hear from you, too.

The sources of the presentation are available here:

• .tar.gz download
• Gitweb

Die Razzia bei Pfarrer Lothar König

Nachdem ich schon die Hoffnung auf einen File-Commander fuer Linux, der so ist wie der TotalCommander unter Windows/Android *hint*, abgeschrieben hatte, habe ich mich letzte Woche irgendwann doch nochmal dazu verleiten lassen genauer zu suchen und auszuprobieren.

Liste der getesteten Programme:

1. Total Commander (mit wine)
2. Gnome Commander
3. mc (MidnightCommander)
4. bsc (BSCommander)
5. gentoo
6. Krusader

I remember when I first came across that list: “Shit, it’s that bad? Ouch”. It certainly changed my view. I just stumbled over the list again and remembered I wanted to blog about it.

I bet as a male you’ll probably find some points you didn’t think of:
The Male Privilege Checklist

Comments closed on purpose.

Sarah Kaminsky: My father the forger

“[I]t will help the Git community a lot to understand your needs, what you like about Git, and of course what you don’t like about it.” (quoted from here)

Git User’s Survey 2011