Planet Open Ghana

vm.overcommit_memory = 2, vm.overcommit_ratio = 0

2008-09-05T17:06:44+00:00

Do you know this experience: A program, in my case subversion, has a bug and starts to eat memory. You can not interact with your system any more, only watch the memory and swap run full (if you have a display for that). Then it takes a while, while the kernel kills the (hopefully right) program. Things start to move again, until they are fully recovered from the swap and you can continue your work. Or the kernel does somehow not kill the right program, and you are screwed.

During regular work, though, your swap is hardy ever needed. Only after a while, a few megabytes of never-used RAM is swapped out, to make space for using the RAM as a file cache.

I’d like to see the kernel not give out more memory to processes than there is physical memory, because that’s plenty for normal work, and if there is more requested, then that’s most likely wrong. But I still want the kernel to use the rest of the memory for caching files, and also move some unused RAM pages to the swap file.

Unfortunately, there does not seem to be a settings that achieves this directly. But if you happen to have the swap about the same size as your RAM, then these settings, when written to /etc/sysctl.d/vm.conf, will do the job:

vm.overcommit_memory = 2
vm.overcommit_ratio = 0

The first one is to make sure the kernel does not hand out more memory than you tell it to, and the second is to make sure that it only hands out (swap size + 0 * RAM size) to processes.

Beware that things go wrong if you happen to have no swap any more for some reason, beause then the kernel will hand out zero memory! Therefore, you need to make sure that these settings are applied after swap was enabled. On a Debian machine, rename /etc/rcS.d/S30procps to /etc/rcS.d/S37procps. This would not be possible if you could also specify the ration of swap memory to be used. Then I could set that to zero and the RAM ratio to 100.

If anyone knows better ways to achieve this, I’m interested to hear them.

No it’s not an abandon blog!

2008-09-03T13:50:36+00:00

Yes, I know, I’ve not made any posts in about a month but I certainly have not abandoned this blog. There simply hasn’t been enough time for me to get away and do some blogging. Perhaps more hours should be found for the day

S Leone president declares assets

2008-09-02T05:11:28+00:00

President Ernest Bai Koroma has become the first head of state in Sierra Leone to declare his assets to the country’s Anti-Corruption Commission.

As i read this news item, i was wondering when all other African leaders will do follow this. Expecially in Ghana were there is been much talk about such a thing. We always here leaders saying i already had my money or wealth before i came to power.

Koroma, i hope this will not be a nine day wonder, but to go beyond that let things work in S-Leone.

Google launches internet browser

2008-09-02T05:00:29+00:00

Google is launching an open source web browser to compete with Internet Explorer and Firefox.

The browser is designed to be lightweight and fast, and to cope with the next generation of web applications that rely on graphics and multimedia.

Called Chrome, it will launch as a beta for Windows machines in 100 countries, with Mac and Linux versions to come.

“We realised… we needed to completely rethink the browser,” said Google’s Sundar Pichai in a blog post.

The new browser will help Google take advantage of developments it is pushing online in rich web applications that are challenging traditional desktop programs.

Just waiting to try it out.

Debian on the FreeRunner

2008-08-15T18:01:51+00:00

I’ve been at DebConf for almost two week, but haven’t blogged a lot about it. It’s mostly because we’ve been working on getting Debian to run on the OpenMoko FreeRunner. Today we finally sent out the official annoucement for this, because it seems that the installer script and packages seem to work so far.

Great thing about this is the sheer amount of software that’s now available on my phone. I already blogged about running Xmonad on it, and I have also ran my screen-message program, on it, as can be seen here. I only did minimal testing of the phone features, because it would be relatively expensive here in Argentinia with my German SIM card, but it seems to work as well.

Not dead, missing or abandoned

2008-08-14T17:46:13+00:00

Just working on getting this thesis done as well as I possibly can for my Masters. After its done expect a bunch of rants about the evils of Visual Studio, my love of Python, Numpy, iPython, Matplotlib, Mayavi2 and .

Oh, and musings about my slow but steady infatuation with judo.

In the meantime Wish me luck, weeks until I’m done.

Xmonad on my mobile phone

2008-08-09T14:46:00+00:00

Here at DebConf 8 in Argentinia, I’m working on getting Debian to work on the OpenMoko Freerunner Smartphone. We are progressing quite nicely, soon having the same features as the official freesmartphone.org image. See the pkg-fso wiki page for more on that.

And why do we want to do that? Because we can use everything in the Debian archive on our phones!

This is the xmonad window manager, programmed in Haskell and usually running on my Desktop, now on my mobile phone! And it’s almost usable. Only problem is that the screen keyboard, metacity-keyboard, gets the focus by xmonad, so I can’t actually type into other windows. This could be fixed by configuring xmonad, but for that, I need to install ghc and I do not have these 280MB left on my SD card...

Update: I even made it on the front page of the xmonad home page with this image:

pam-dbus: authentication by bubbles

2008-08-08T05:19:00+00:00

Imagine you have a device, such as a linux phone, that allows login via ssh, e.g. when on a wireless network. You don’t want to set a password with the (limited) phone UI. On the other hand, you don’t want to allow passwordless root logins into your phone. But you do want the ability to login via ssh, after all that’s why you have bought a linux smartphone. This led me to the idea of a pam module and corresponding UI piece that asks the currently logged in user: „Hey, someone tries to login. Is that ok or not?“ This might also be useful for guest accounts on regular laptops. For more on that, see my last blog post.

So I hacked it together (actually twice, due to some unfortunate use of rm at some point), invested most of the time in learning more about the python garbage collector vs. callbacks, explicitly marked global variables and proper automake stuff. In the end I got, well, just what I wanted. A simple pam module, dubbed pam-dbus that sends a request via the dbus system bus and an autostart program (written in python for now, but I might re-implement it in C) that uses notification-daemon to get confirmation from the user.

You are welcome to try the sources and binary debian packages or have a look at the darcs repository for pam-dbus (with debian/ directory, repository browser). This will end up in Debian later, I guess.

Update: Erik Johansson pointed out that if you want to use this with ssh, you need to set UsePAM yes in /etc/ssh/ssd_config.

Flow control with pam configuration

2008-08-08T04:20:22+00:00

Usually, files in /etc/pam.d/ are simple, linear descriptions of how a user should be authenticated, e.g. „Try to authenticate him against ldap, and then against the local data base“. But sometimes, you want something more advanced, for example „If the user is called guest, please authenticate him with pam_dbus, otherwise use regular pam_unix.“ This is possible, and here I’ll note down how to do that.

There are actually two problems to solve: How to detect the username, and then how to do the flow control.

For the first problem, I recently discovered the pam_succeed_if module, that allows for relatively advanced logic for checking uids, usernames, hostnames and group membership. For our case, the line would read

auth ? pam_succeed_if.so quiet user = guest

Now what next? If we just wanted to allow unrestricted access to guest, we could put „sufficient“ for the questionmark. But we need something like if..then..else. Unfortunately (and I hope this will be fixed eventually), the only flow control available is „skip the next n lines“. So we can skip to pam_unix when this module fails (i.e. the user was someone else but guest), and if we did not skip, we can run the guest-specific module and then skip over pam_unix. So here is the complete snippet:

auth [default=2 success=ignore] pam_succeed_if.so quiet user = guest
auth [success=ok new_authtok_reqd=done ignore=ignore default=die] pam_dbus.so
auth [default=1] pam_permit.so
auth required pam_unix.so

You can read more about this advanced configuration in the PAM Administration guide. And here is the corresponding configuration for gdm, where guest can always login:

auth [default=2 success=ignore] pam_succeed_if.so quiet user = guest
auth required pam_permit.so
auth [default=1] pam_permit.so
auth required pam_unix.so

So I have a guest account with a locked password and I can allow ssh logins with a mouse click and use it directly with gdm. I probably should put the gdm configuration also in xscreensaver to not lock me out.

Changing Server Timezone On Ubuntu

2008-07-31T06:51:44+00:00

Is amazing how sometimes such small issues on linux can frustrate a linux user.

I’m currently reconfiguring a machine on the other side of the globe, so I want to get it to work to IST instead of EST.

A quick google brought up a rather complex way of doing it which sounded really complex to me, so I refined my query and found the same solution in the Ubuntu documentation.

Simply run the following command as root (or using “su”):
sudo dpkg-reconfigure tzdata

And just follow the instructions.

No silly reboots or other craziness required.

To keep your server’s time in sync with the rest of civilisation setup a cronjob to poll an ntp server once every 24 hours:
/usr/sbin/ntpdate yourfavouritentpserveraddress

Problem solved

One Week with an OpenMoko Freerunner

2008-07-21T09:18:00+00:00

About one week ago, I received my OpenMoko Freerunner. This is an openly developed mobile phone that runs purely on Free Software. So this is what I have to tell about it.

The hardware

It was smaller than I thought, and is quite light. My girlfriend says it’s ugly, but I’m fine with the look of it. Besides being a GSM-phone, it comes with some nice gimmics: GPS, accelerometer, WLAN. The touchscreen works fine, although I don’t have anything to compare it with.

The software

The system it comes with, even after upgrading, is still very rough. It mostly works for doing phone calls and SMSs, but there are a number of unsolved quirks that prevent me from using the Freerunner as my sole phone for now. The suspend mode is left too often, resulting in a battery life of about eight hours, and there are issues with the audio for the conversation partners, who will hear static and echoes. But, as this is free software, there is hope that this will be fixed eventually.

Development

The OpenMoko distribution is based on Openembedded, which uses bitbake for building software. So if I got it right, and this is not sure, because documentation is rare and spread, there is the git repository at git.openmoko.org, which is a copy of the openembedded git repository. This contains bitbake recipies for all the packages, which includes where they can be downloaded, the package metadata (such as dependencies and version numbers) and sometimes patches. These recipies reference upstream tarballs or subversion URLs. For the “native” OpenMoko applications, the source is in the OpenMoko subversion repository.

One of the suggested ways of compiling software for the FreeRunner is by using a “toolchain” tarball, that can easily be extracted somewhere and used to build the software from the subversion repository, or other (hopefully autoconf’ed) software. This builds the binaries, but does not produce “proper” .ipk files, so no version number or dependencies.

The other way is the full openembedded setup, made easy using the MokoMakefile. This, automatically, fetches and builds everything needed for the cross compiliation and all available packages, producing the same output as can be found on the openmoko servers. Setting this up requires about 6 gigabytes of storage and takes over a day the first time, but then hacking the phone is relatively painless, as it resolves dependencies and is self-contained.

The community

For a free software project, the state of the community is very important. The OpenMoko seems to suffer from a rush of interested people on the mailing lists, so it’s hard to follow real development in a mass of frequently asked questions and nice ideas from people who have neither an OpenMoko phone nor wil do any coding.

On the other hand, it’s not easy for new contributers. I have written some code that make sure the phone can handle numbers such as 0172/123 456 instead of the “official” +49172123456 in the phonebook and the SMS app, something that other users have complained about as well. But no one could tell me where and how I should submit my patches, and the mail to the mailing list with the patches and the bug report is unanswered. It is not clear, at least to me, who is responsible for what part of the project – quite different to what I’m used to from Debian, where there is a clear list of maintainers for each package, and a well known way of submitting patches (by going through bugs.debian.org).

For interested users, I have published my branch of the git repository at git.nomeata.de, and I will hopefully add more features and bugfixes later – at least when I find out how to properly contribute to OpenMoko.

Adeona, free Laptop-Tracking System

2008-07-15T11:30:39+00:00

Adeona is the first Open Source system for tracking the location of your lost or stolen laptop that does not rely on a proprietary, central service. This means that you can install Adeona on your laptop and go — there’s no need to rely on a single third party. What’s more, Adeona addresses a critical privacy goal different from existing commercial offerings. It is privacy-preserving. This means that no one besides the owner (or an agent of the owner’s choosing) can use Adeona to track a laptop. Unlike other systems, users of Adeona can rest assured that no one can abuse the system in order to track where they use their laptop.

Adeona

The server encountered an internal error or misconfiguration

2008-07-14T10:54:20+00:00

I encountered the following error when I uploaded an existing site to a new server.

The server encountered an internal error or misconfiguration and was unable to complete your request.

The problem was the .htaccess file. I deleted the .htaccess and the web server worked again.

Subsequently, I recreated the file directly on the server using vim and the server still worked, I think therefore the problem was likely to be an issue with DOS carriage returns / line feeds versus what the Linux server expected.

Several tools exist on the web to help create .htaccess files online, but generally any text editor will work. Do be sure to test your site thoroughly after making an adjustments to the .htaccess file.

The Hunt Continues…

2008-07-01T10:38:54+00:00

Since yesterday, I’ve been looking for a collection manager for my videos. I want something similar to Amarok’s functionality… for video. I’ve tried a few so-called ‘collection managers’ but they simply did not fit my designs. Tellico. GcStar, Elisa… nope. All of these require you to manually enter entries for each video file and only GcStar came close to allowing you to play the video from within the manager (technically, it called up mplayer but that’s okay). I have tons of music videos, tv shows, movies… and I want to just tell the app “this is the folder in which all my videos live” and let it handle the rest. Yeah I know, I’m, lazy.

I especially want playlists for my music videos and I also want a ratings system… sigh. I guess I’ll just have to keep looking. I’d really appreciate a few hints though.

Frustrations…

2008-06-30T07:56:46+00:00

First, I am annoyed… very annoyed. Now on to why I am annoyed. I tried out the piece of crap encryption software called Conceal or something like that. It was supposed to provide one-click encryption. When I tried to encrypt something on Friday, it just showed me a progress bar for four hours and deleted almost all the files in my home folder. Luckily, I’d done a backup the night before so no real damage was done. But enough damage was done to annoy me. I’d mirrored about 8gb of the hardy repositories… I lost that. So now I’m gonna have to stay here in Winneba for another two weeks to re-download all those packages.

Synaptic proxy configuration problems

2008-06-25T18:25:12+00:00

Synaptic gave me at least 15 minutes of pure unmitigated frustration this afternoon when it started choking with this piece of gibberish:

407 Proxy Authentication Required

I’d already configured my proxy settings in apt.conf and my bashrc file, and had assigned the right values to the http_proxy and ftp_proxy variables, not to mention the fact that synaptic had been working okay earlier in the day with no problems so this came as a surprise. Just to make pin-point the problem, I dropped into the terminal and did a sudo apt-get update… worked fine. Tried installing something with apt-get… worked. Tried downloading something with wget… worked fine. Yet synaptic would still not work.

In the end, I tracked down the problem to gksu. When I launched synaptic like so

gksudo synaptic

The problem just disappears and synaptic works… weird. So I used the Alacarte menu editor (right-click on the menu icon and select ‘Edit Menus’) to change the entry for synaptic package manager from

gksu /usr/sbin/synaptic

gksudo /usr/sbin/synaptic

I don’t know what caused this problem and I probably should file a bug report somewhere…

What to do when you lose your password

2008-06-07T17:41:08+00:00

Disclaimer: This how-to details procedures for gaining root access to linux boxes. If the linux box is not yours, get the (written) permission of the owner… it’ll save you a lot of trouble. I will not be responsible for anything illegal you do with the stuff you learn on this page.

Okay, so you lost your password? It’s not the end of the world. But first you need physical access to the box.

1. Boot the machine (and press escape at the GRUB menu loading stage if the menu is hidden).

2. Select the correct entry for booting into your linux system - it usually is the first item and is probably already selected - and press “e” on your keyboard.

3. Select the line that begins with root and press “e”on your keyboard to edit it.

4. Now navigate to the end of this line, leave a space and type:

rw single init=/bin/bash.

5. Press “enter” then “b” on your keyboard and wait for the system to boot and give you a command prompt.

6. Now you need to use the passwd command to change your password. Do:

passwd $user

Replace $user with your username

7. Enter and confirm a new password when prompted, and reboot the machine with the reboot command. I sometimes get an error message when I try to reboot; if you run into the same problem, just turn the pc off and back on.

8. That’s it, you’re good.

Re-building My Local Ubuntu Repository

2008-06-02T13:43:31+00:00

Hardy Heron was released about a month ago and I’m still going through the painful process of mirroring the ubuntu servers. It’s been slow going here and it might take me another month to get the major stuff on my hard disk. Then I’ll make to full transitition to Ubuntu 8.04.

Drupal Links

2008-06-02T10:05:14+00:00

Drupal is a very powerful content management system (CMS). But it can be very confusing and fustrating to start with and get documentations.
I have been working on some drupal projects for the past 2 weeks. And i have really come a long way getting some documentation links on Drupal. So i have decided not to allow people also go through by parcelling all the documentation links i came across on the web and also got through the IRC.

And i will be updating each time somthing new comes up

For Drupal Clean URLS
http://drupal.org/node/15365

Flash Video in Drupal 5: A complete multimedia tutorial
http://www.travistidwell.com/flashvideo

How to zip files on linux

2008-06-02T09:55:40+00:00

Ziping files on linux using shell is one of the most easy things to do
but today i got a bit confused when a friend asked me how to zip a file with
a different name.
example : normally i zip with the source and target name all been same.

zip -r foobar foobar

which will result in

foobar.zip

but what my friend wanted was having a different name for the result.

So i had to jump straight to the linux channel on IRC. below is what i learnt from there.

zip -r foo.zip bar

which results in foo.zip

what abt unziping too

unzip foo.zip

but what about unziping to have different name .

unzip foo.zip && mv foo bar

Howto enable wireless on ACER 4520 on Ubuntu Hardy

2008-06-02T07:13:59+00:00

Just today i had all my configurations for my wifi card which is
Atheros Communications Inc. AR242x 802.11abg Wireless PCI Express Adapter (rev 01) wiped of after a Hardy upgrade. So below i fixed it. But i used it also for the first time when installing Hardy fresh.

1. Open you terminal

2. Get this version of madwifi:

wget -c http://snapshots.madwifi.org/special/madwifi-ng-r2756+ar5007.tar.gz

3. Untar the downloaded package:

tar xvf madwifi-ng-r2756+ar5007.tar.gz

4. Get inside the unpacked directory:

cd madwifi-ng-r2756+ar5007

5. If you haven’t compiled anything from source before on your linux then you propably need the build essential package:

sudo apt-get update && sudo aptitude install build-essential

6. Now you can build your madwifi and install the modules:
make

sudo make install
sudo modprobe ath_pci
sudo modprobe wlan_scan_sta

The last 2 commands can cause some complications on some systems. If they do check your System >> Administration >> Restricted Drivers Manager and disable atheros here. Then try again.

7. Now restart your computer and you should be able to see any aviable networks in your Network Manager.

My first OpenStreetMap Contribution

2008-05-27T15:51:29+00:00

Yesterday I was visiting the Open Source Expo Karlsruhe, a new, quite small conference, at which the guys from OpenStreetMap hat a booth. I was amazed by the progress of OpenStreetMap while I wasn’t looking (which is just a few months, I guess); their level of detail in some places like Karlsruhe is astonishing.

Anyways, I got hooked and started to try out some of the tools and websites and finally, by tracing the Yahoo satellite image, added my first way to the map: A small footpath in Herrenberg that I know quite well:

The live data can also be seen on the OpenStreetMap map, of course.

Unfortunately, there is not much to map around where I live in Karlsruhe, even the driveway to my dorm is included, but maybe I can do some proper mapping (with a GPS device) in Herrenberg someday.

Installing Ubuntu7.10 on Acer4520

2008-05-27T07:35:00+00:00

System Specs
………….
Acer Aspire 4520
AMD64 Athlon X2
Nvidia GeForce 7000M
160 Gig
802.11b/g WLAN
1Gig DDR2

I have been trying for the past weeks since i had this laptop with
the above specs to run ubuntu7.10 but all failed. So i finally got myself
into runing 7.04 rather. But have finally gotten a way to run 7.10 on it and
this is how i did it.

I realised that anytime i installed the 7.10 and i reboot, it hangs at the splashcreen and so for some reason i felt it might be the menu.lst file so edited couple of times but nothing happened. so WHat i finally did was to get the 7.04 ubuntu cds and install and upgrade that to 7.10. And that worked. But when i upgraded the kernel to the original one used by 7.10, i got the same splashscreen hanging again. So i kept the upgrade on but now uses the 7.04 kernel rather instead of the 7.10 kernel which still works fine for me.

But after that, it wasnt all dont since it could not detect some of my hardware devices like the wireless and vga card.

1. to fix the X.
………………

I used the ubuntu livecd and mounted the installed my root(/) partition to get aaccess to xorg.conf file. commands below.

> mkdir /media/system
> mount /dev/sda1 /media/system

The above could be different for you. i mean the mount points

> cd /media/system
> vim etc/X11/xorg.conf

Once you are in this file, look for this lines

Section “Device”
Identifier “nVidia Corporation NVIDIA Default Card”
Driver “nvidia”
BusID “PCI:0:18:0″
EndSection

change the “Driver nvidia” part to “Driver vesa” instead and save and
reboot without the livecd.

2. how to fix sound too
………………………
simple first download the packages from the below site and copy them into one folder

http://www.alsa-project.org/main/index.php/Download

you need one of the c libraries and curses libraries for this i guess you are done with adding extra repositories if not message me i will explain

open the terminal and fire the following
sudo synaptic

and next search for g++ library

after that search for curses library for c

after this automatically done by the synaptic

go the folder where you have downloaded the packages and extract each and everything like below

> tar xjf alsa-(name of the package)

after extarcting just type this

> cd alsa-(extracted package)

> ./configure

> make

> sudo make install

do the above for all packages u just downloaded from the above link.
and afterward just reboot ur machine. u should hear sound now

3. howto fix wireless
………………….

Before we start, we have to make sure that MadWifi drivers don’t get loaded at boot, since we could have a conflict between the two. You can do this typing this:

blacklist ath_pci

in /etc/modprobe.d/blacklist file or by using the restricted driver manager:

> vim /etc/modprobe.d/blacklist

Install ndiswrapper
> sudo apt-get install ndiswrapper
> sudo apt-get install ndisgtk

you can also install ndisgtk or use synaptic instead of the console

after, download the Atheros driver
form this link http://www.atheros.cz/download.php?atheros=AR5006EG&system=1
anyway that is the link i used in getting mine to work.

afterwards you need to unzip the file just downloaded from the link

Install the .inf file in ndiswrapper, using ndisgtk or the command
> sudo ndiswrapper -i net5416.inf
from the unzipped file

Save ndiswrapper module configuration files by issuing the command:
> sudo ndiswrapper -ma && sudo ndiswrapper -mi

You can now reboot and bravo. u can check to see u should be done now.

Web users ‘getting more selfish’

2008-05-27T07:06:42+00:00

Web users are getting more ruthless and selfish when they go online, reveals research. This was made known by usability guru Jakob Nielsen in an annual report into web habits.
I think now people have fair idea as to what really they want or looking for on the web. Is not like sometimes back where people dont really know what exactly they want and so spend so much time on the web.
And in so doing, web users have become very impatient.

FrakView: An Haskell Renderer for Iterated Function Systems

2008-05-17T12:31:10+00:00

For a recent university seminar, I wrote a haskell program to render and edit iterated function systems (IFS), which generates a certain class of fractals, namely self-similar sets. I think the result is quite nice, so I’m sharing the code.

With FrakView you can view a rendering of the attraktor of the IFS, whith a choice of two algorithms (a straight forward, and a probabilistic), configurable depth and anti-aliasing. You can also modify the IFS by dragging the colored boxes with arrows you see on the screenshot. For the academically inclined, there is also support to visualize cylinder sets and otherwise explore the coding space of the IFS a bit.

The program is written in haskell and uses gtk2hs, the gtk bindings for haskell. It might be interesting for other gtk2hs programmers to see how FrakView solves some issues: For example, it uses the CoroutineT monad transformer I recently blogged about – check out the pausingForM_ function in GUI.hs. Also, the current state of the screen is in one algebraic data type (ScreenConfig) that supports equality checks, so when the user interacts, the code recomputes the new ScreenConfig (using getRenderer), but only redraws the screen if it differs from the previous. This is much easier and more robust than having to decide for each possible user interaction whether it changes what’s on the screen.

You can get the source from the FrakView darcs repository.

Finally compiled it

2008-05-13T17:04:44+00:00

I finally got some free time over on Sunday to compile the 2.6.25.3 kernel and I was very surprised at how easy it was. I’ve read some ghastly stories about custom kernel compiles going horribly wrong and most of the initial tutorials I read were unnecessarily long but I found an excellent tutorial on the ubuntu forums that makes things simple. The only tedious part was choosing what should be compiled… that was essentially the whole point of compiling the custom kernel but that doesn’t mean I have to like it. It took just about an hour and a half to finish compiling and then I found out I had not enabled CONFIG_TIMER_STATS (powertop needed it to estimate power usage) and I had to do it all over again.

Now that I know how to compile the kernel however, my natural urge to speed things up has taken over and I spent the best part of the night disabling kernel modules and options I did not need. This might occupy my time for the best part of the week.

Linux vrs Windows –My Thoughts

2008-05-03T16:21:56+00:00

Change is good but change is very difficult for the majority of people.
I believe that people who say that linux is not ready or is not as user friendly as Windows are making a mistake.This is simply because Linux is not Windows and may never be Windows.It seems that because these people started their computing life with Windows they seem to think that using Linux should be the same as Windows.Impossible.If possible then I guess there will be no need to have Linux.We will just have Windows and Windows 2 ; the same everywhere.
This “thingy” also seems to be something that affects Linux users also since Linux advocates also tend to badmouth Windows users sometimes very unpleasantly.Please its got to stop!!.
Its quite bad and a sign of intolerance to “diss” someone because they have decided on something or made a choice that you disagree with.Come on !!.VARIETY IS THE SPICE OF LIFE.Imagine how boring it will be if everyone wore the same dress or did the same things.sheesh.
These are two different operating systems with different GUIs or desktops.
Also dont forget despite all supposed bad stuff Microsoft like Linux does employ people who though they may not agree with their employers objectives or mission statement or philosophy,have to earn a living and as such have no alternatives.Also in areas like Africa since most organisations use Windows,it does serve as a means of livelihood for computer technicians with many charging for burning an XP or Vista cd and doing installations of Windows(more on copyright issues and licensing in Ghana,my motherland).

I think the best way to check all this “My own is better” competition will be to get two people with no computing knowledge who will be then introduced to Linux and Windows separately and following each other that is one would start his or her computing life or experience with Windows and another will start with Linux.They will then switch over after some time and share their experiences on each as compared to the operating system they started on.I believe this will then serve as a better means of really evaluating which of the two operating systems is better in terms of user experience or functionality.
Of course the top bleeding edge sample or product of each operating system will have to be used.
Also one must not forget that Linux distros are constantly being tweaked and improved.Its like having a product/research that you cant really finally bring out and say “Aahh!!Finally I’m done.Igor its alive!!!”. Its never ending unlike Windows or Apple where a product is released and left on the market until a new version comes along.
Unfortunately this could also throw a kinda bad light on Linux constantly since improving your stuff means you may decide not make your product better at once and roll out but instead roll it out by degrees and slowly add improvements making the product interesting as you go along.Kinda like a software engineering problem.All of this is IMHO of course with no insult intended to any Linux distro developers.

Funny enough I dont seem to recall a time when people ever argued about or had a war on the merits of Windows vrs Apple or Apple vrs Linux.Why not????

For those who claim that they cant get the look,feel and operation of Windows applications on Linux applications I just want to ask them “have they tried investing a little bit of time and effort into learning and using Linux applications effectively?” Its not as if there was no learning curve associated with learning how to use Windows applications.They definitely had to take some time to learn how to use these software.Reading manuals and so on.So why cant they do the same with Linux software??Especially with the tons of available manuals and tutorials on how to use Linux applications.
For those who also tend put forward the claim that Windows has a larger software base than Linux as their main reason for not fully using Linux I believe that this is no longer so especially with the huge amounts of software found in repositories and being constantly produced.Of course big game companies like EA and so on could also help by writing or porting by cool and fine games over to Linux.
I have an idea that we could something like the DirectX api for Linux.I mean OpenGL and Mesa are there but we need something that is failsafe and guaranteed to make gaming more d**n fine than it is now on Linux.
Of course I have to say that Linux games rock.There are many games for everyone.I’m currently convincing the kids and my parents that Linux rocks for kids due to the number of advanced educational stuff available such as gcompris.

From the above therefore I think that if we want Linux world domination then we have to think about Linux in a different way altogether.
Unforunately I’m still trying to think of how this can be achieved.
Any ideas?????

ABOUT ME:I’m currently a university student studying Accounting and living in Ghana,aka the GH, in West Africa.My main passion has always been computers and science.I’m also crazy about Linux and free and open source software.

Still Here, People!

2008-05-02T16:48:36+00:00

Yeah, my internet access problems have almost melted away so it’s back to business as usual. Which reminds me, I should rant about slow internet here in Ghana one of these days…

I’m baaaaaaaaaaccck

2008-05-01T14:40:32+00:00

Wow! Like the genie stuck in a bottle i’m free at last.
Actually i wasnt stuck anywhere.I just had a long vacation to clear my head and get ready for the new stuff that will hopefully come up this year.
I’m now the proud owner of a MEDION TCM Edition Notebook.YEEEEESSS! Tis like a dream come true.GHz range processor,Lots of harddisk space,cute ,portable and best of all inbuilt wifi.Now i can try some wardriving and get access to free internet in hotspots.With free and hopefully reliable net access(both wifi and wired network) the power of synaptic to me as a user in Ghana becomes realistic and just breathtaking.I mean u can get all of these gazillions of programs free of charge and which are easily installable?? Now thats what i’m talking! On another note i hope someone or an organization in Ghana will offer to do local hosting or mirroring of the ubuntu repositories cuz it really takes some time to download stuff from the rpositories.Anyone???
Since getting this lap i’ve really come to love being able to use my computer anywhere,anytime.Self-Immersive Computing???
Hopefully with the acquisition of this notebook i will be able to resurrect my programming activities.Started sometime ago learning how to code but got bored cuz the machine i had at home just wasnt situated at the right place and was way too uncomfortable to use.Aah !!
Below are some pics of my notebook.Aint she a beaut????All virgin white.!

Pausable IO actions for better GUI responsiveness

2008-04-24T22:50:00+00:00

For a university seminar I’m currently writing a GUI program to view fractals based on simple iterated function systems (only similaritudes allowed). It supports three different drawing algorithms and you can edit the IFS by dragging squares around on the screen. But this post is not about this program (I might present it later), but how Haskell allowed me to solve a problem very nicely:

The first instances of the code had a problem that a lot of GUI programmers know: The drawing of the fractal took quite some time, and during that time the gtk main loop is blocked and the program becomes unresponsive. At first I avoided this problem by manually splitting the drawing function (e.g. by repeatedly increasing the resolution) and kept re-drawing it at higher resolutions in an idle handler, so at least I could interact whenever one resolution has finished drawing. It worked somewhat but it was not easily done for the other, not pixel based, algorithms and it was ugly.

So I wanted a way to (a) pause the drawing at any convenient point, to resume it later, and (b) safely abort the drawing if what I’m drawing has changed and I need to restart.

A common solution to this would be to do the drawing in a separate thread, so (a) is actually not needed, but I did not know if I can safely do (b), and I have heard that threads cause problems with gtk.

So I tried to dig deeper for the hidden treasures of advanced haskell programming: I need a monad transformer! I expected the infamous ContT monad transformer to help, but I couldn’t figure out how, and I started to create my own monad transformer, called CoroutineT.

I tried to figure out what an action of type (CoroutineT IO a) should do, and I came up with this type signature:

pausingAction :: IO (Either (CoroutineT IO a) a)

which means that after the pausingAction is done, it is Either paused (and I get back another pausingAction to run when I want it), or it is done (and I get the result). Note that I’m writing IO here, but it can be any monad.

The definition of the datatype and the monad instance came mostly from trying to make this type work (yay to haskell’s type system, less thinking required), and looks like this:

data CoroutineT m a = CoroutineT {unCoroutineT :: (m (Either (CoroutineT m a) a)) }

instance (Monad m) => Monad (CoroutineT m) where
    return v = CoroutineT (return (Right v))
    a >>= b = CoroutineT $ do
          r <- unCoroutineT a
          case r of
            Left  paused   -> return $ Left (paused >>= b)
            Right unpaused -> unCoroutineT (b unpaused)

This translates to english like this: A call to return is not paused. When an action is already paused, further actions should be run after the paused action is resumed. When an action is not paused, further actions can happen now.

Like every well behaving monad transfomer, I also need a "runCoroutineT" function to start the coroutine. I probably could have used unCoroutineT directly, but for my use case (GUI drawing) I did not need a return value, so this function is more handy:

runCoroutineT :: Monad m => CoroutineT m () -> m (Maybe (CoroutineT m ()))
runCoroutineT a = either (Just) (const Nothing) `liftM` unCoroutineT a

Nothing surprising here, basically just turning the Either into a Maybe. So it becomes clear how to do (b): We can just throw away the resume action returned by runCoroutineT (if any). The more interesting thing is how we do (a): We need a pause action of type (Coroutine m ()). But how should it work? I did not really try to understand why it works, but by looking at the types, I came up with this:

pause :: Monad m => CoroutineT m ()
pause = CoroutineT (return (Left (CoroutineT (return (Right ())))))

Yes, it sounds like some dance step instructions (read the second line out aloud!), but it works somehow.

So here is some example code: I have a pausable IO action that counts from one to ten, pausing after each number. I also have function that resumes an pausable action up to n times:

example n = keepGoingFor n $ do
        liftIO $ putStrLn "This is the coroutine"
        forM_ [1..10] $ \i -> do
            liftIO $ putStrLn $ "Counting to "++ show i ++" while you keep calling it"
            pause

  where --keepGoing :: Monad m => CoroutineT m () -> m ()
      keepGoingFor 0 _   = putStrLn "Here I just abort the run"
      keepGoingFor n cor = do
        resume <- runCoroutineT cor
        case resume of
            Just runAgain -> keepGoingFor (n-1) runAgain
            Nothing       -> putStrLn "Finally stopped"

And here is the output of two different runs:

*CouroutineT> example 5
This is the coroutine
Counting to 1 while you keep calling it
Counting to 2 while you keep calling it
Counting to 3 while you keep calling it
Counting to 4 while you keep calling it
Counting to 5 while you keep calling it
Here I just abort the run
*CouroutineT> example 14
This is the coroutine
Counting to 1 while you keep calling it
Counting to 2 while you keep calling it
Counting to 3 while you keep calling it
Counting to 4 while you keep calling it
Counting to 5 while you keep calling it
Counting to 6 while you keep calling it
Counting to 7 while you keep calling it
Counting to 8 while you keep calling it
Counting to 9 while you keep calling it
Counting to 10 while you keep calling it
Finally stopped

So it does really works fine, and it proved very useful in my GUI drawing problem. For that, I created this nice control structure which works like mapM_, but calls pause every n iterations, and therefore hides the pausing stuff almost completely:

pausingForM_ :: Monad m => Int -> [a] -> (a -> CoroutineT m ()) -> CoroutineT m ()
pausingForM_ period list action = pausing' 0 list
  where pausing' _ []     = return ()
        pausing' n (x:xs) = do action x
                       if n==period then pause >> pausing' 0     xs
                                    else          pausing' (n+1) xs

I have put the complete module (including instances omitted here) in the darcs repository that might later also contain the fractal drawing program.

Announcing DarcsWatch

2008-04-17T17:25:15+00:00

A lot of haskell-related projects use the darcs version control system. Darcs has the nice feature that you can easily submit a patch by e-mail, usually sent to the project maintainer or a mailing list. What has bothered me in the past was that I had to manually check whether my patch was applied yet.

So this week, I wrote DarcsWatch. DarcsWatch receives submitted patches and compares them to the repositories it knows about, whether the patch is missing there or not. You either send your patches to DarcsWeb directly when submitting them, using CC, or DarcsWatch is subscribed to the project mailing list itself, which is the case for the darcs-devel and xmonad lists. Other than that, not much is to do, and you’ll find a nice overview of your patches, like this overview of my patches, with diffs and download links.

If you want to use DarcsWatch for your contributions to other projects, or for your own projects, have a look the documentation. There are probably still bugs around, and the problem of marking patches as obsolete is not really solved yet, so if you have ideas about it, mail me, comment here, or come to #darcs on freenode. Patches are always welcome, you can get the source from DarcsWatch’s repository.

Aah, beaten to it(another Wire post)

2008-04-07T11:40:20+00:00

There was meant to be a follow up to my post on The Wire where I would discuss what a version of that show looking at Africa would look like. However I’ve been slow about writing these things and so fellow African geek aflakete pointed me to this post on Brown Man’s Burden that beat me to the punch. Hence I’ll just quote him

I think an interesting show, similar to the Wire, could be made about economic development and foreign aid. It would document NGOs, the World Bank, bureaucrats, politicians, big foundations and academics in their efforts to distribute aid and stimulate economic growth.

The key would be to show how the self-interest of each of these groups both helps and hinders the process of growth, and to convey how complicated stimulating growth and poverty alleviation is.

Obviously the man is a genius since we both had the exact same idea. Except he’s faster at writing these things out than I have been recently. Its still a great idea though, and it’ll provide a convenient launching pad for my next post on this topic. Sooner rather than later people, don’t worry.