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    G-AVLN in front of her home

    G-AVLN in front of her home

    Mostly Unix and Linux topics. But flying might get a mention too.

    Thursday, July 17, 2008

    HP drivers in Ubuntu

    Some off-the-shelf HP printers won't work in Ubuntu, until proprietary drivers are installed.

    The quickest way I found is to use the existing hp-setup tool, provided in Ubuntu distributions. Just plug your printer in, and run:

    $ sudo hp-setup

    Couple of answers later (d for download and y for yes, I agree to the license terms), your printer is ready. Painless and quick.

    As always, remember that if you are behind a proxy, you need to sort it out first (see several entries below regarding this).

    Wobble your screen in Ubuntu 8.04

    I'm moving onto the new Ubuntu version, and many people around me are twisting my arm to start using the 3D effects brought to Ubuntu by the Compiz set of packages.

    I can't imagine needing these effects long term (call me conservative and stingy), but having managed to get it work well (with some hints from our current resident whiz-kid, Lubo), I thought I'd document the process.

    You need the graphics card capable of 3D acceleration, of course, but most contemporary cards will do. Beware, some machines require proprietary drivers, so you may need to do more prep work.

    Ubuntu 8.04 comes with the main Compiz package already present and installed. You can recognize its presence by the slightly different feel to windows manipulation actions: different transparency, transitions, etc. But to get the full benefit of Compiz, so that you get to convert your screen into various shapes and bounce them on your terminal whilst the applications they display continue running, you need to install and enable a bit more.

    Step 1 - only required if you are sitting behind a proxy (if not, move to step 2). If you use proxy, the likelyhood is that all you have configured so far is your browser. I.e. firefox can access the world through the proxy, but no other application. There are several ways (as always) of allowing other applications to get to the proxy, but for the purpose of this exercise, we will only instruct package management tools (apt) ...

    First of all, identify what proxy address is being used on your site, and which port. Edit the apt configuration file: /etc/apt/apt.conf by running the following command (substitute proxy-address shown below for the proxy address and XX for the port number, often 8080) :

    $ sudo echo 'Acquire::http::Proxy "http://proxy-address:XXXX";' >> /etc/apt/apt.conf

    You may need to extend the stanza, if you use proxy user name and password. The entry would then look similar to this:
    Proxy "http://proxy-address:XXXX/";
    "USER @";
    "PASS ";

    Step 2 - assuming you repository file (/etc/apt/sources.list) has been set up, which in 8.04 is done during installation, you should be able to continue with the Compiz install.

    Rebuild the database of available packages, the check for compiz packages, and install the front-end tool for it:

    $ sudo apt-get update
    $ sudo apt-cache search compiz


    compizconfig-settings-manager - Compiz configuration settings manager


    $ sudo apt-get install compizconfig-settings-manager

    Once done, follow the path:

    System --> Preferences --> Advanced Desktop Effects Settings

    for all your 3D setting delights!

    Happy playing... (I'm moving to other things) ;-)

    Tuesday, July 15, 2008

    Atomic file system

    I had a discussion with a delegate about pros and cons of a journalling file systems. What is special about them, and what are their main characteristics - in other words, is it worth to upgrade to a journalling file system from a traditional predecessor.

    First of all, why would anybody be still working with a filesystem that is *not* journalling. Long gone the days where administrator would be prepared to do a full system fsck, just in case there is a filesystem inconsistency.

    The main characteristic of a journalling filesystem is the fact that it can maintain a log of all transactions. However, unlike "standard" system logs, which record transactions after the event, filesystem logging records intentions, before the operation is even attempted (although there are various methods of achieving this, and some - such as metadata-only journalling - are more efficient than others). Of course, there is penalty in logging: in both performance and disk space, so for that reason, some administrators switch the logging off. How crazy! This is the very feature that journalling filesystems excel at, yet for many admins the term journal, or log seems to be sufficiently off-putting to turn it off!

    Therefore, when describing a journalling filesystem for the first time to, I tend to use another term as the main characteristic: I introduce these filesystems as "atomic filesystems", rather than journalling. Atomic transaction means it either happens fully, completely and successfully, or it doesn't happen at all. One can provide numerous illustrations why data transfers, file and directory manipulation or database transactions should have the atomic nature.

    But the moral of the story is: once you turn the attention to the advantages of transaction atomicity, then the term journal is not that scary anymore...

    Thursday, July 03, 2008

    Stallman on Microsoft on BBC site

    Our NLUG (Northants Linux User Group) have been discussing the article, by Richard Stallman, published on the bbc site:

    Richard Stallman is writing about. Having read it, I agree with most facts pointed out by Richard Stallman.

    However, I felt a bit uneasy reading it. I'm quite conversant with the terminology he is using, I'm familiar with technologies and legal events he is referring to. Would a typical reader be though? One of our group members said: "
    I think he is really preaching to the converted. We Open Source fanatics will agree; but the general public / PC users will probably not have a clue what he is talking about, they see the universality of Microsoft as an advantage."

    I wholeheartedly agree! Most PC users genuinely don't care about any of this.

    And I can't escape a thought that Stallman's powerful, albeit very eloquent, attack might end up being counter-productive as most people will not really understand what he is saying, instead, will interpret the article as a dogmatic expression of hate towards Microsoft.

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