Welcome

This is my home in the virtual world, where I write about things that I want to share. The freely available software that I've written as well as some of the photographs I've taken over the years can also be found here. Please use the navigation links on the right if you are looking for something.

Recent articles

1. Making my first EPUB

   Now that I got an EPUB reader, I started looking for a way to make EPUB documents.

   In principle, an EPUB file is a zipfile with a certain layout, as can be seen on the wikipedia page linked above.

   The actual contents are just XHTML, while the metadata files are ...

2. Sony Reader review

   A lot of classic books that are in the public domain because their copyrights have expired (as they are supposed to) are available from Project Gutenberg. Long before e-readers were available I downloaded these books in text or HTML format and read them on my PC. This unfortunately was less ...

3. Filtering a sound recording

   Recently I was listening to an MP3 file of a talk about no-till gardening when I noticed that there was a noticable buzz in the sound. I figured I would try my hand at sound filtering with Python as a learning experience.

   The Python standard library doesn't have a ...

4. Automated local backups

   These days it is commonplace to have hardware or software RAID1, even in common PCs. In previous machines I've used ataraid to implement RAID1.

   The advantage is that every write is recorded on two disks at once, minimizing the chance of data loss. The flip side of the coin ...

5. Updating multiple systems using a pre-built FreeBSD

   Recently I updated my workstation to FreeBSD 9.1-RELEASE-p1. Since my laptop runs the same OS, I wanted to update it without rebuilding the world and kernel locally. I used the folowing steps to accomplish that.

   • Using netcat in combination with tar, the directories /usr/src and /usr/obj were ...

6. Should system backups be compressed?

   Every now and then I make backups of my FreeBSD system's filesystems with the venerable dump program. This is the only program that can capture all features of the UFS filesystem. The filesystems to be backed up are:

   • The root filesystem.
   • The /usr filesystem.
   • The /var filesystem.

   Note

   My ...

7. Fixing squeaky bicycle disk brakes

   The Shimano Deore XT disk brakes on my HP Velotechnik Scorpion trike have always been very noisy when dry. Oddly enough they were much quieter when wet. Over the years I've tried sanding the pads and different detergents and cleaners including strong industrial solvents.

   But only recently I solved ...

8. Updating to FreeBSD 9.1-RELEASE-p1

   There have been some changes in the FreeBSD update process. The csup program has been retired, source code updating is now done with subversion. Since I haven't used that before, I'm documenting the steps that I took here.

   I'm using source updates instead of freebsd-update because I ...

9. Making a composite plug or mould

   For the bus rear floor we initially made a prototype mould. This was done because of time constraints and because we weren't sure that there wouldn't be changes to the design.

   Now that the design is frozen it is time to make a fiberglass mould. This is done ...

10. Cycling in the snow

    On the 15th of January we had a couple of centimeters of snow. It wasn't that much (even for us), but it did look beautiful.

    I took a small detour over the unpaved path through the Triangular Wood to take the picture below.

    

    It is not often that I ...