Michael Dales has found a new way to make your grubby old keyboard all clean and shiny. As long as you’re not in a hurry.
The key to cleanliness
January 8th, 2007
GRUB CD image and Error 15
January 7th, 2007
This is a post for anyone who, like me, has been doing web searches to find out what might be the problem if your Linux machine displays GRUB Error 15 on booting. Or who has general GRUB issues to debug.
My problem was Error 15, which indicates that GRUB cannot find one of the files it needs. If you get it while setting up GRUB, it’s often fairly easy to find out what’s wrong. But if GRUB thinks it’s installed OK, and you then reboot, you can still get this message but without any further information to help you debug it.
To cut a long story short, the issue for me was that the BIOS (and GRUB while booting), saw my two hard disks in a different order from the way the kernel saw them after booting. So my assumptions that /dev/sda was the same as (hd0) was invalid.
Finding this out took a very long time, though, because, for reasons too complex to go into here, I was booting this server not from a regular CD but from an emulated CD the other side of the Atlantic.
Things became a lot faster when I found this section in the GRUB documentation which explained how to make a bootable CD ISO image with GRUB on it. To save you the trouble, here’s one:
I could mount this and use the GRUB console command line to find out what was wrong. It’s worth exploring the GRUB console, if you haven’t already. It can do things like filename completion when you press TAB, and can even display the contents of text files using, for example,
cat (hd0,0)/boot/grub/menu.lst
In my case I found that the BIOS of the machine allowed me to choose the boot order of the hard disks, and swapping them there was the easiest solution.
Hope this is useful to somebody!
Expanding your window and broadening your mind?
January 6th, 2007
The YouTube player that appears in a web page has a button in the bottom right hand corner that I hadn’t previously tried:
It switches the little in-window player into something approaching full-screen mode. Now, most videos on YouTube are short enough and of low-enough quality that there’s not much point in doing this. But those who have a ‘director’ account can upload videos of greater length; things for which you may prefer to retire to a comfy chair and watch from a distance.
And so it was that I spent an hour and three quarters this morning watching YouTube because somebody has uploaded the talk that Richard Dawkins gave at Randolph-Macon Woman’s College in Lynchburg, Virginia in October.
There are two parts to the video. The first is Dawkins reading extracts from The God Delusion. The second, longer clip is the Q&A from the audience afterwards, which is, as he predicts, generally more interesting. What adds a certain frisson to some of the discussions is the fact that the other academic institution in Lynchburg is the contraversial Baptist college, Liberty University, founded by Jerry Falwell.
If you’re interested in the subject from either side of the fence, or are sitting on it, this is worth watching.
Follow-up: Dave Hill points out that you can get the whole thing as a Quicktime download here. Similar quality, but you can right-click on the link and save the file to your machine if you want to keep a copy.
Sky dance
January 6th, 2007
My friend Martin pointed me at a rather unusual and rather delightful web page.
Take a look…
Optical illusions
January 5th, 2007
Davina Bristow has a few nice optical illusions in this Telegraph article.
Here’s one.
The faces of this cube are, in fact, the same colour. Davina suggests a way to confirm this by cutting holes in a bit of paper which hides the surroundings – on my Mac I used the Digital Color Meter utility which shows the top actually to be slightly lighter in this rendition. It’s the edges of the faces, and the appearance of a shadow, which causes us to deduce that the top is grey and the bottom white.
Thanks to Claes-Frederik for the link.
By any other name…
January 4th, 2007
It’s uncanny. Just last night over dinner I was commenting to Rose that the flowers on the table were still beautiful even though they were wilting.
And I then went upstairs, looked at John’s blog and saw his lovely photo of the ageing roses on his windowsill.
So here’s my contribution to the genre…
Kristoffer Strom’s whiteboard
January 4th, 2007
Excellent…
MacNovice?
January 4th, 2007
If you, or a friend, are a new Mac user, you’ll appreciate Adam Pash’s Guide for switching to the Mac, which introduces you to things like the most important keyboard shortcuts. Nicely done.
No comment
January 4th, 2007
John quotes from Joel Stein’s lovely rant in the LA Times. Here’s another bit:
Huge portions of my e-mails come from people who haven’t even read my article. They’re just assuming, based on a headline or an excerpt on a blog, that I’m unpatriotic or irreligious or lecherous. Sure, they happen to be right, but it would have been nice if they had clicked on my column and moved me up on that “most-read articles” list.
A lot of e-mail screeds argue that, in return for the privilege of broadcasting my opinion, I have the responsibility to listen to you. I don’t. No more than you have a responsibility to read me. I’m not an elected servant. I’m an arrogant, solipsistic, attention-needy freak who pretends to have an opinion about everything. I don’t have time to listen to you. I barely have time to listen to me.
Part of the problem is that no etiquette has yet been established for the hyper-interactive world. And I, born before MySpace and e-mail, don’t feel comfortable getting a letter and not answering it. And then, if I do, suddenly, we’re pen pals, with all those pen pal responsibilities.
Full piece here. (Free registration needed)
How to find happiness, and achieve justice
January 2nd, 2007
I’ve written before about some of the great talks available online from the TED conference. Here are a couple I’ve just watched, and would definitely recommend:
- Dan Gilbert talks about what really makes us happy, and the research that shows how bad we are at predicting what really makes us happy.
- Oxford Statistician Peter Donnelly explores the common mistakes humans make in interpreting statistics, and the devastating impact these errors can have on the outcome of criminal trials.
Both good stuff. And the wonderful thing about having a Mac Mini sitting under my TV as a PVR is that I can use iTunes to subscribe to the RSS feeds of things like this and watch them from the comfort of my sofa…
Quicksort
January 2nd, 2007
Paul Bissex has a lovely example of the power of Python – a Quicksort implementation in 99 bytes.
>>> q=lambda s:s if len(s)<2 else q([x for x in s[1:]if x<s [0]])+[s[0]]+q([x for x in s[1:]if x>=s[0]]) >>> print q([9,7,5,3,1,8,6,4,2]) [1, 2, 3, 4, 5, 6, 7, 8, 9] >>>
If you unwrap it to make it a bit more readable, it’s doing this:
q=lambda s:
s if len(s)<2
else
q( [ x for x in s[1:] if x<s[0] ] )
+[ s[0] ]
+q( [ x for x in s[1:] if x>=s[0] ] )
Very nice! Needs Python 2.5. If you don’t know the Quicksort algorithm, here’s how it works.
In which we serve…
January 2nd, 2007
2007 is starting in an interesting way for me – with jury service.
I can’t, of course, say anything to anybody about the cases I may be involved with, but I can still communicate with the outside world thanks to the 3G connection on my phone, at least while I’m in the jury lounge waiting to be called.
I wonder if this is the first blog entry to be posted from within Cambridge Crown Court?
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