Arnt Gulbrandsen
About meAbout this blog

Linux tarsnap wrapper

Here is the shell script I use to back up my linux laptop. The odd word you'll see in the source is the laptop's name.

Key points: Full backup of the entire file system (tarsnap itself skips /proc and /sys), automatic gradual deletion of old backups, simplicity.

I so want tarsnap for Android.


Literate Programming: the book

Donald Knuth's book Literate Programming is a collection of articles about what he did in the the TexBook and in various other programs. I read it around 1995, while working on qdoc, and thought it was terribly naïve. I reread it in portions this year (the same copy, which found its way to me from Trolltech's once-extensive library — better to me than wherever Nokia is going) and this time I wanted to write down my thoughts. I wish I'd had a blog in 1995.

The book is all about writing two things at the same time, in two separate languages, not connected, merely adjacent in a single file. The main point is that WEB is inherently bilingual, and that such a combination of languages proves to be much more powerful than either single language by itself. WEB does not make other languages obsolete; on the contrary, it enhances them. (p101) Yes, no, no. WEB does not enhance either of the two languages (relevantly, at least). The Τεχ source is just that, it doesn't receive anything from WEB. You cannot access the list of Pascal variables in the Τεχ part, (more…)


Google DNS maltreats Spamhaus

I couldn't understand why so much spam got through the filters.

Yesterday and today I checked 667 addresses that have tried to send me spam in the past days. 661 of the 667 are listed by the Spamhaus Zen list right now, but Google's public DNS resolvers report that only 33-74 are listed, so Spamhaus is effectively neutered.

Google offers two IPv4 and two IPv6 addresses. All four report similar numbers, and the results have been largely stable over the past 24 hours.

A smaller RBL operator does not suffer, so I expect it's some sort of rate limiting by Google. DoS mitigation gone wrong.