Usage of hg commit –date (mercurial)

Recently, I was trying to move some stuff from RCS to mercurial. There does not seem to exist a converter and since it was only a few revisions, I decided to do it by hand. The problem arose how to set the commit date manually and google yielded a nice blog post that answered my question (refering to the formidable but less searchable hgbook).

Makefiles for LaTeX

Makefiles for LaTeX

This entry was originally submitted to Debian Package of the day, but rejected because make is well known. Figure 1:The file In is used to produce InterM that is itself used to produce Out. Therefore Out depends directly on InterM and indirectly on In. I agree that most programmers and administrators know GNU make. Sadly, it is ignored by most others. GNU make solves a very common problem that everyone faces when processing more than one file with more than one programm. It keeps track which file has been changed and which files have to be regenerated.

Constantize in Python

Rails offers a nice function called constantize. It is easy to rebuild this (to some extend) in python. But the price is too high.

Constantize with Care

The String#constantize method is a feature that makes rails fun to code with. This method converts a string to the constant that the string contains (or throws a NameError if there is no such constant). It makes it easy to store class-types in databases as strings and to code controllers that work with classes of the same duck type. Most people know that eval on user data is dangerous, but noboddy seems to care about constantize. Beware, it is also dangerous and you should constantize with care!

Avoiding Shell Injection in Ruby, Python and PHP.

I recently found a shell injection bug in some Ruby-gem I use. Shell injections have scared me for a long time and I usually prefer to whitelist certain characters/patterns rather than to blacklist. This means that the system fails to the save side. Unfortunally it usually does fail – my whitelisting is to rigorous and data that would not cause any problems gets rejected. So I decided to take the opportunity to investigate how to prevent shell injection in my favorite scripting language (Python), the language I found the problem in and finally the language that I can not avoid (PHP).

NoArchive-Tag for Robots-Meta

I tweaked the robots-meta plugin by Joost de Valk for WordPress to support the noarchive tag. This prevents google and from providing cached versions of your blog. I've put up a mercurial repo with my version at