Martin Geisler Online

I’m back from LinuxForum — and to put it short: it wasn’t as good as last year. When Cookie and I arrived at Copenhagen Friday afternoon we started by going to our hostel (I didn’t know that there existed such a word, but a “hostel” is a cheap hotel — you get a bed and that’s about it). After we had checked in, we headed for down-town Copenhagen. It was surprisingly easy to find the right busses and trains, everything went according to the plan Cookie had made from .

We then went to the Tycho Brahe Planetarium where we saw an Omnimaxfilm called Shackleton’s Voyage of Endurance. It was a really good film about how Shackleton managed to save all his men, after his ship was crushed by the ice in Antarctica.

LinuxForum was held the next day. It started out great with Eric S. Raymond who told about the hacker culture. Then there was a speech about Linux mainframe which was OK. But the other speeches were quite boring: they used 45 minutes to talk about something which you could read up on in 10 minutes. So we didn’t learn anything new, they just repeated what we already knew.

It could be, that Cookie and I simply went to the wrong speeches. After the first two speeches, the rest were given in parallel, so you had to choose between them. And it was difficult to judge the speeches beforehand. But we’ll be looking more carefully at the program next year, before we decide if we want to go again.

Cookie, Tais, and I drove to LinuxForum last year, and it was a great trip. This year Cookie and I will be returning by train. The conference begins this Saturday at 10 O’clock in the morning. But because Copenhagen is such a long way from both Aalborg and Århus, we leave tomorrow and spends the whole weekend there.

It looks like we’re going to hear some really interesting speeches this year: Eric S. Raymond will start out by giving a speech about The Zen of Unix: Unix’s design as philosophy, and vice versa. Apart from the speeches, there will be a lot of companies who wants to show us what they can do with Linux and BSD in all it’s flavors.

I told you about TMDA the other day — my new spam rejecting assistant. TMDA has caught 3 junk-mails so far, 2 mails await confirmation and over 50 mails have been let through.

So if you’re bothered by spam too, then I would suggest that you install TMDA at once. I’m using it together with getmail which is a Fetchmail replacement. The good thing about getmail is, that it can deliver the mails directly to TMDA whereas Fetchmail has to deliver them to Exim or whatever you’re running as your MTA. This saves you from the trouble of configuring your MTA (which failed for me) and is a more reasonable way of doing things in my eyes.

The only thing there’s left for me, is to figure out why I get some sporadic messages like this one in the debug-output from TMDA:

Uncaught Python 2.1.2 exception (Mon Feb 25 16:08:01 2002 UTC):
---------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/bin/tmda-filter", line 31, in ?
    execfile(os.path.join(execdir, 'tmda-rfilter'))
  File "/usr/bin/tmda-rfilter", line 153, in ?
    raise Errors.MissingEnvironmentVariable('SENDER')
MissingEnvironmentVariable

I’ve been watching the log while retrieving messages, and nothing has happened. But when I look again a little later, I suddenly see the message. I hope to figure this out — I’ve been checking my messages via a webmail-system, and the ones retrieved correspond to the ones I can see on the server. But if everything fails and you can’t get mail through to me, then drop me a note in the guestbook.

I’ve fed up with spam. Each day I receive one or two mails from strange people who try and sell me strange things… So I’ve now installed TMDA which looks like the ultimate SPAM-buster. TMDA is very efficient because it uses a Whitelist-centric strategy: everything that is not explicitly allowed is denied.

This may sound a little harsh, but you can still get mail through to me, even if I’ve never met you. The first time I receive a mail from you, you’ll get a message back that looks like this one:

From: [email protected] Subject: Please confirm your message by replying to this e-mail Reply-To: [email protected]

Hi, I'm Martin's E-mail Assistant.
Your message has not been lost, it is just waiting for your
confirmation. This is because Martin is receiving so much SPAM, that
he has asked me to hold back e-mails to him from people that he
doesn't recognize.
Unfortunately I didn't recognize your address, so I would like you to
reply to this e-mail. When I receive your reply, I will forward your
original e-mail with the subject of "Hi Martin" to
Martin and add your address to the list of known addresses so that
you wont be bothered again.
You should be able to press 'Reply' in your mail-reader, or you can
send a new empty message to this address:
   [email protected]
I'm sorry for the inconvenience and I hope you understand why it's
necessary.
[ This notice was generated by TMDA v0.47 (http://tmda.sf.net/),
  an automated junk-mail reduction system. ]
— Enclosed is a copy of your message.
From: You
Subject: Hi Martin
Hello Martin - how are you?

When you reply, the mail is sent to a strange-looking address. When I get the reply back, TMDA recognizes the address forward your original mail to me. You’ll only have to go though this confirmation-process once.

I’ve played a lot with MetaPost today — I’ve been making fractals. It’s a lot of fun to make graphics with MetaPost, and making the fractals was no exception.

I’ve made three kinds of fractals: Koch Curves, Hilbert Curves and finally the one shown at the right, Sierpinski’s Sieve. The last one is also know as Sierpinski’s Triangle, for obvious reasons.

You can download the sourcecode and a document here: /downloads/metafractals/. If you’re trying to remake the document, then please note that the images are called filenameN.mps instead of just filename.N. This is because PDFLaTeX works best with those filenames. So you’ll have to rename the files generated by MetaPost before running LaTeX/PDFLaTeX. If you’re running Zsh, then you could use this very little shell-script:

#!/bin/zsh
for basename in $*; do
    mpost $basename
    for file in ${basename%.mp}.<0->; do
        mv $file ${file/./}.mps
    done
done