Lucid Electric Dreams

Kile is a fantastic editor for creating LaTEX documents. It is part of the KDE suite of applications, but runs perfectly fine under Gnome when the KDE libraries are installed.

Unfortunately, the Kile package in Fedora 16 appears to be broken. When trying to start the application, a dialog box pops up with the message: "No editor component found. Please check your KDE installation". The application still manages to load, but is missing all icons. Attempting to open a file causes Kile to crash.

Through trial-and-error and a nudge in the right direction from the Arch forum (https://bbs.archlinux.org/viewtopic.php?id=124428), I managed to fix Kile by installing two more packages.

sudo yum install kate-libs libkate

Installation of nvidia drivers under Fedora is well documented. (See http://forums.fedoraforum.org/showthread.php?t=204752). In previous versions of Fedora, enabling the plymouth graphical boot was quite easy. All one had to do was to add the following kernel arguments to grub.conf.

rdblacklist=nouveau nomodeset vga=ask

Starting from release 16, Fedora uses Grub2 as the bootloader. The unfortunate side effect of this change is that the vga parameter is now obsolete. I absolutely hate the ugly text based boot screen - but going back to the nouveau driver was not an option. (Simply because I am stubborn like a mule). So after a lot of tinkering, here's how I managed to get back the graphical boot screen.

DISCLAIMER: Modifying Grub configuration files could make your system unbootable. Proceed at your own risk.

1. Find the video modes supported by the vbe driver. To do this, press "c" at the grub menu to launch the grub console and run the following commands:
   

   set pager=1
   insmod vbe
   vbeinfo
   

   
   vbeinfo command will list all the accessible video modes it finds. Choose one that you like. Eg. 1280x800x24. Press ESC to exit the console and hit ENTER to boot the OS.
   
   
2. Create a Grub2 font. I chose the excellent DejaVu font as the example here. Feel free to choose a different font in it's place.
   

   sudo grub2-mkfont --output=/boot/grub2/DejaVuSansMono.pf2 --size=24 /usr/share/fonts/dejavu/DejaVuSansMono.ttf

   
   
3. Edit /etc/default/grub and add the following lines to the end
   

   GRUB_VIDEO_BACKEND="vbe"
   GRUB_TERMINAL_OUTPUT="gfxterm"
   GRUB_FONT_PATH="/boot/grub2/DejaVuSansMono.pf2"
   GRUB_GFXMODE="1280x800x24"
   

   
   replace GRUB_FONT_PATH with the correct filename of the font you generated in the previous step. GRUB_GFXMODE should be the mode you chose from the output of the vbeinfo command.
   
   
4. Backup /boot/grub2/grub.cfg and regenerate it using the new settings.
   

   sudo cp /boot/grub2/grub.cfg /boot/grub2/grub.cfg.bkp
   sudo grub2-mkconfig -o /boot/grub2/grub.cfg

   
   
5. Reboot and enjoy the graphics.

After upgrading to Fedora 16, I noticed that the font rendering looked awful in Firefox. Even an upgrade to Firefox Aurora made no difference. Purely out of desperation, I tried a method I had used previously to fix a similar issue with Chrome, (http://www.lucidelectricdreams.com/2010/09/ugly-font-rendering-in-chrome-linux.html) and hit the jackpot!.

The original post by Zach Beane can be found here and all credit should go to him.

Save the following to ~/.fonts.conf:
<match target="font">
<edit name="autohint" mode="assign">
<bool>true</bool>
</edit>
<edit name="hinting" mode="assign">
<bool>true</bool>
</edit>
<edit mode="assign" name="hintstyle">
<const>hintslight</const>
</edit>
</match>

Regular readers probably know that I am a big fan of the Caffeine project (https://launchpad.net/caffeine). I even contributed the Gnome Shell patches to it (http://www.lucidelectricdreams.com/2011/06/disabling-screensaverlock-screen-on.html). After a fresh install of Fedora 16 "Verne", I attempted to install the latest version of Caffeine from the project page - which at the moment is 2.4.1 - and ran into a few problems. So for anyone interested, here's how to install the latest version from source.

1. Download the tarball from Launchpad and extract it:
   

   wget http://launchpad.net/caffeine/2.4/2.4.1/+download/caffeine_2.4.1%2B419~oneiric1.tar.gz
   mkdir caffeine 
   tar xvf caffeine_2.4.1%2B419~oneiric1.tar.gz --strip-components 1 -C caffeine
   cd caffeine
   

2. Run the setup scripts:
   

   python setup.py build
   sudo python setup.py install
   

3. Update the icon cache and GSetting schemas:
   

   sudo gtk-update-icon-cache /usr/share/icons/hicolor/
   sudo glib-compile-schemas /usr/share/glib-2.0/schemas/
   

4. Correct the permissions:
   

   sudo chmod 744 /usr/share/caffeine/images/*
   sudo chmod 744 /usr/share/caffeine/glade/*
   

5. To add Caffeine to startup items, run the following command and click the "Add" button. The path to the executable is /usr/bin/caffeine
   

   gnome-session-properties
   

Some very handy tips here. I particularly wasn't aware that I could use the scroll wheel to zoom in on windows in the overview mode.

https://live.gnome.org/GnomeShell/CheatSheet

GTINs (Global Trade Item Number) are ubiquitous. We commonly see them as barcodes on products. They come in several different types and names such as EAN, UPC or ISBN etc.

Recently, I needed to validate a set of GTINs stored in a file. To my surprise (unless my Google-fu is getting weak), I could not find any libraries written in Python for doing this. The algorithm (http://www.gs1.org/barcodes/support/check_digit_calculator) is simple enough to knock together in a few minutes, but I think the requirement is common enough to warrant a ready-made library.

My first attempt at this can be found at https://github.com/charithe/gtin-validator. This module can validate GTIN-8, GTIN-12, GTIN-13 and GTIN-14 codes in either numeric or string forms. Dashes in the code (as is common with ISBN numbers) are supported.

I have never worked on a publicly available Python module before. Neither am I a professional Python developer. The chances are that there are certain parts in the code that do not conform to conventions. However, it's fully open source - so anybody can contribute to make it better.

Microsoft has just released the Developer Preview of Windows 8 - which can be grabbed from http://msdn.microsoft.com/en-us/windows/home/.

I had a gander by installing it on a VM. The Metro UI looks quite good and I think it's great that most vendors are moving towards HTML5, CSS and Javascript based apps. (well.. at least they are mostly standardised and for once many giants of the industry are on common grounds). It's a shame that there is no common OS interface standard though. I would quite like to have my Gnome shell extensions work with little or no modifications on Windows 8. One could only dream I suppose.

One thing that drives me up the wall is the trend that OS developers seem to follow; not all users are high school kids who spend their whole time on social networks. Think of the power users dammit! I can't imagine having a very productive work flow on Windows 8. Hopefully I won't ever be forced to use it extensively - I have only just grudgingly gotten used to Gnome shell.

Yes, I am getting old.