Thinkhole Labs

I did a talk on Dropbox and Ubuntu One at the CPLUG meeting on Tuesday night. The slides are online:

I was surprised that no one had heard of Ubuntu One even though quite a few people in the room were running Ubuntu 9.10.

Ran through the Gosu Ruby Tutorial tonight…

I’m having a lot of fun with this. :)

I recorded some video of the intermittent display issues I’ve been having with the new 27″ iMac. You can see examples of both the horizontal white static/noise (need to watch carefully to see it in the video) and the complete screen blanking:

There’s a second video showing similar problems as well.

Looks like this is not uncommon, and the procedure is to take it back to the Apple store and they’ll replace it. That’s cool, but still kind of a pain.

One of the Project Euler problems deals with the Collatz conjecture, which can basically be summed up like this:

We take any whole number n greater than 0. If n is even, we halve it (n/2), else we do “triple plus one” and get 3n+1. The conjecture is that for all numbers this process converges to 1.

So you start with some seed number (n) and keep moving to the next number in the sequence by either dividing by two or multiplying by three and adding one. If you start with 1, you’d get 1, 4, 2, 1. If you start with 5, you’d get 5, 16, 8, 4, 2, 1. The reason these are also known as “hailstone sequences” is because the numbers rise and sink like ice in an thunderstorm cloud. Every number ever tested has always ended up falling to 1, but it’s never been mathematically proven that every number does the same.

Anyway, here’s some Ruby that, given a seed (n), will yield each number in the sequence and return the total length:

I added a few lines to write the output to a .csv file and then plotted it (n=27) using R:

That’s 112 data points going as high as 9232 before eventually dropping down to 1.

I recently switched my home file server from Gentoo to Ubuntu and noticed that, by default, Ubuntu uses UUIDs to identify hard drives in /etc/fstab.

That’s cool, because I’ve had some issues in the past with USB drives grabbing different device names than I expected. Using a truly unique identifier (or at least one that’s unlikely to be duplicated) such as a UUID helps out with that.

So how do you find the UUID of a device? Easy! You can either use:

root@europa:/root# blkid
/dev/sda1: UUID="3f467d1c-12bd-459e-be63-20e313faad88" TYPE="ext3"
/dev/sda5: TYPE="swap" UUID="cfe7d582-aa62-469b-8f4f-40927d013748"
/dev/sdb1: UUID="da488135-3744-487e-89e2-4898653db209" SEC_TYPE="ext2" TYPE="ext3"
/dev/sdc1: UUID="d438941d-e928-4ec1-9b96-eead147cd23e" TYPE="ext3"

Or if you need to find the UUID of a specific device, you can use this:

root@europa:/root# vol_id -u /dev/sdc1
d438941d-e928-4ec1-9b96-eead147cd23e

Copy and paste the UUID into /etc/fstab, add your mounting options, and you’re done.