I'm back from a short holiday (therefore of course sick, but it was relaxing up to that point!). I found out last week-end that the paper I wrote with my FYP supervisor, based on my final year project and dissertation in UL, has been published! The article abstract is available on the Inderscience website: "Seeing is believing: using Data Visualisation for formative feedback in computer supported online learning collaboration". I'm quite proud! The article talks about using data visualisation to help provide useful formative feedback in the context of the DVReport Moodle plug-in I wrote (and that I should really resume refactoring, some time...)

Another lovely look into Feynman's life, this book is a collection of letters Feynman sent during his lifetime. Witty replies to friends and laypeople, humble (and sometimes annoyed!) comments about the Nobel Prize, encouraging answers to students and many different types of letter make for a very interesting and entertaining read. The letters are arranged according to different time periods, with major events explained at the beginning of some chapters and other contextual information lightly interspersed.

I'd still recommend first giving a shot to "Surely You're Joking Mr Feynman" as an initial glimpse into Feynman's life, but this is a very nice addition, and if you've enjoyed the other one you'll like this one too.

Since attending GUADEC I've been meaning to build Gnome-Shell from source and give it a serious try. Unfortunately, the few times I had the time to work on it my trusty laptop couldn't handle it, in that even left alone for 3 or 4 hours it couldn't manage to finish building the first project... out of 23.

Enters last Friday whereby after 3 weeks of little to no communication I finally received my new laptop, a fantastically beautiful and shiny ThinkPad X201 *_* Oh joy. There's another post coming with getting various Linux distros to work on it, but for now:

Building Gnome-Shell on Debian (Squeeze/unstable)

Let's begin from the wonderful documentation: http://live.gnome.org/GnomeShell#building.

I'm starting from a basically brand new Linux install, so there were many dependencies to install, which thankfully Jhbuild kindly specified in one go at the beginning.

The first script creates a ~/bin folder and stores the jhbuild command in there, so this should be added to your $PATH (and in .bashrc for the future). I decided to follow the doc recommendation and created a gsbuild alias to avoid conflict with any other Gnome work I may end up doing, especially as Sugar also uses a custom version of jhbuild -- the more conflicts I can avoid, the better.

After about 2 hours, the 23 projects were checked out and built. At that very same time, any guilt I may have been feeling at acquiring a brand new laptop disappeared in a puff of spoke. In 2 hours that little guy empowered me to do and try more things I couldn't do before -- awesome!

Of course it would be a bit too simple to leave it at that, so one of the 23 projects did not built successfully, I name gjs. 

configure: error: mozilla-js >= 1.9.2 is required

I'll spare my trials with various libraries... Here's what I should have looked up first:

$ dpkg-query -S mozilla-js
libmozjs-dev: /usr/lib/pkgconfig/mozilla-js.pc

Unfortunately, aptitude show libmozjs-dev reveals that only 1.9.1 is available in unstable. Time to go experimenting with, heh, experimental.

[/etc/apt/sources.list]
# Experimental
deb http://ftp.ie.debian.org/debian experimental main

And to "override" a package already installed with one from another repo branch:

aptitude install -t experimental libmozjs-dev

This changes the error message into: "Could not figure out where Firefox JavaScript library lives", solved with:

aptitude install -t experimental xulrunner-dev

And tadam! gsbuild build gjs completes! Time for a full rebuild (...and to comment out the experimental source, in my case.)

collect2: ld returned 1 exit status

Moving on: project 22 out of 23, gnome-shell, now fails with a collect2 error. Googling around I stumble upon this incredibly helpful blog post that mentions, in passing, that you may come up against this error and how to solve it. Here's the 32-bit solution.

rm <GNOME_SHELL>/install/lib/*.la

A bit mysterious for a newbie Gnome hacker like me, but yay! Victory!

Browsing away from the Shell...

...then switching context

I'm really impressed and happy with how seamlessly it all works and comfortably fits my workflow. Many distros package it, give it a shot!

Now, I better go and find a gnome-love bug related to Gnome-Shell to sink my teeth into...

If your hard drives are currently doing fine and you're ready to skip this article, please just do this for me: run fdisk -l as root, maybe fdisk -u -l as well and store the output in a file on a usb stick or another machine. Thanks. That's the kind of thing you chuckle at until a twitch or update destroys your partition table and you're staring at a black screen with a blinking grey underscore instead of a boot screen, knowing that your data is there somewhere but the computer doesn't know where to find it. Neither do you. With that info you'll be able to recreate the partition table using fdisk or parted, following tutorials online.

Now let's assume you're like me and you don't have that data. Here are a few links and ideas that you can try out, most of which didn't work for me but all taken together ended up giving me a working system back. Arm yourself with a LiveUSB stick running Linux, and let's begin.

Try #1: gpart

Not to confuse with gparted, which by the way is the tool I messed up my laptop with. I was reading the menus wondering why the resize option was greyed out, when I had one of those finger twitches (too much caffeine?) and bam! An 'error' alert popped up and the layout of my hard drive changed to "Unallocated" -- and that was it. One twitch! I should try to reproduce the bug now that I have my fdisk output, but I'm not brave enough yet... (Working machines are so handy!)

...Anyhow. Gpart came with the recommendation that "it worked for me X years ago, and here's the actual web page I used to fix things", so I tried it. Gpart works non-destructively and tries to guess where your lost partitions start and end.

I'm afraid to say gpart failed miserably for me, only listing a 3Mb partition that I don't think actually exist, after a 2h run. It's still worth a shot, and won't do any harm if it doesn't work.

Resources:

• Recovering a lost partition table, including what to do after gpart gives you back accurate looking information
• Partition-Rescue HOWTO -- I was reading this while waiting for gpart to finish, it gives other tips on how to find/guess your partition table, including a command (cat /proc/partitions) that should work beautifully if you haven't rebooted the machine yet after erasing/losing the partition table
• gpart -- A bit more information, example output, manpage, changelog

Try #2: Testdisk

Running testdisk (quick search)

Googling more I came across Testdisk, a very cool utility that do the same thing as gpart and then more, and is also available in the Fedora repositories. The most important thing I can say is to read the site carefully. I found the step by step guide especially useful. The commands are not always straightforward (p to list files?) but it's incredibly powerful and the second the "Quick search" started running it was already listing a fairly good idea of my 6 main partitions and their types.

Running testdisk (deep search)

I thought deep search wasn't working for me but reading the step by step guide, I realised it gives back potentially overlapping partitions and it's up to you to examine them to find the most likely one. Considering I could list the files off all my partitions after the quick search, I decided to give up on the deep search output and start again, using what quick search gave me as my best bet for writing a new partition table.

Writing the partition table

Select the Write option when you feel ready. This is not a destructive option either, in that if you get it wrong you can try running gpart or testdisk again, and write another table based on a different guess.

Win #1: Data backup

The new partition table didn't actually quite work for me. Windows wouldn't boot, and Grub was gone so I had no access to my Linux partitions. I booted off the LiveUSB stick again, and mounted the newly remade partitions from the 'Places' menu to back up the files I sort of cared about (this is a 1-week old laptop! Not much data).

chroot magic + grub

Making sure I only had one partition mounted (Ubuntu in this case), I chrooted into it from its mount point in /media.

chroot /media/1234-5678-90ab-cdef 

From there the idea was to use grub-install to reinstall grub. The hard drive I was trying to rehabilitate was /dev/sda, replace with the drive you want to fix.

grub-install /dev/sda

Now that didn't quite work for me. I forgot to write down the exact error messages, but it was complaining about not being able to write to /dev/null. This Ubuntu Forum post helped me solve that one, and by the way also contains more ideas to try out if you end up still grub-less.

Now, for the proper /dev directory to be picked up in your chroot environment:

mount -o bind /dev /media/1234-5678-90ab-cdef/dev

grub-install /dev/sda should now works handsomely :) Rebooting the machine, only Ubuntu was visible in the Grub boot menu. Running update-grub within Ubuntu resulted in an accurate list of every OS during the following boot, yay.

Note that I actually sort of lost a partition in the process, the OEM "Rescue partition" that Lenovo set up at the end of the drive. TestDisk picked it up properly, but this partition is supposed to run when pressing the blue ThinkVantage button, and wouldn't start anymore. I didn't feel too sorry and deleted it (one more primary partition slot for me!). I also had to recreate the swap partition, which is pretty minor.

Thanks TestDisk for saving the day! :)

Resources:

• TestDisk
• Ubuntu forums: How to restore grub from a LiveCD