Kasun's Tech Blog

Let Xorg to listen on TCP

2011-08-04T08:55:00.000-07:00

Typically in this method, no configurations are required to be done to the XOrg. The tool "socat" can be used to forward the incoming traffic to UNIX domain socket which the Xorg is listening to.

# socat -d -d TCP-LISTEN:6000,fork,reuseaddr,range=172.25.70.192/32 UNIX-CONNECT:/tmp/.X11-unix/X0

See the socat man page for more information.

Apache log4cxx installing error on Linux with automake

2010-11-08T20:47:00.000-08:00

I after looking at many loggers for C++, I decided to use Apache log4cxx in one of my projects. Because it is easy to configure and its configurations can be changed at the run-time. But I want to mention that this is not the best logger for C++.

I got the latest version of log4cxx from their svn repository.

The compilation went fine. But the installation failed with the following error

make[5]: Entering directory `/home/lab409/log4cxx/src/main/include/log4cxx/private'
make[6]: Entering directory `/home/lab409/log4cxx/src/main/include/log4cxx/private'
make[6]: Nothing to be done for `install-exec-am'.
test -z "/usr/local/include/log4cxx/private" || /bin/mkdir -p "/usr/local/include/log4cxx/private"
/bin/install -c -m 644 ../../../../../src/main/include/log4cxx/private/log4cxx_private.h log4cxx_private.h '/usr/local/include/log4cxx/private'
/bin/install: will not overwrite just-created `/usr/local/include/log4cxx/private/log4cxx_private.h' with `log4cxx_private.h'
make[6]: *** [install-privateincHEADERS] Error 1
make[6]: Leaving directory `/home/lab409/log4cxx/src/main/include/log4cxx/private'
make[5]: *** [install-am] Error 2
make[5]: Leaving directory `/home/lab409/log4cxx/src/main/include/log4cxx/private'
make[4]: *** [install-recursive] Error 1
make[4]: Leaving directory `/home/lab409/log4cxx/src/main/include/log4cxx'
make[3]: *** [install-recursive] Error 1
make[3]: Leaving directory `/home/lab409/log4cxx/src/main/include'
make[2]: *** [install-recursive] Error 1
make[2]: Leaving directory `/home/lab409/log4cxx/src/main'
make[1]: *** [install-recursive] Error 1
make[1]: Leaving directory `/home/lab409/log4cxx/src'
make: *** [install-recursive] Error 1

The error happened when trying to overwrite the same file which is just created at the destination directory.
To fixed the error, follow these

Get a fresh copy of log4cxx from the svn repository.
Change the followings:

In src/main/include/log4cxx/private/Makefile.am,

"privateinc_HEADERS= $(top_builddir)/src/main/include/log4cxx/private/*.h log4cxx_private.h" to "privateinc_HEADERS= $(top_builddir)/src/main/include/log4cxx/private/*.h"

In src/main/include/log4cxx/Makefile.am

"log4cxxinc_HEADERS= $(top_srcdir)/src/main/include/log4cxx/*.h log4cxx.h" to "log4cxxinc_HEADERS= $(top_srcdir)/src/main/include/log4cxx/*.h"

3. Now rebuild the source as mention here.

Have fun

Pidgin - Ping timeouts

2010-03-27T07:43:00.000-07:00

I'm using Pidgin as my universal chat client. But recently, Pidgin had a problem which was it continued to disconnect periodically when I was using it with gtalk. One of my best friends has asked me once "Hey, What are you doing. Have you started to play a game by going online and offline" :)

First, I thought it was a problem with the Internet connection. But later, I realized that there is something to do with Pidgin instead of the Internet connection. So I opened the debug window of Pidgin and looked at carefully to know what is going on. I saw the following error.

Since the error is with jabber.org, I set the file transfer proxies to a blank in the Modify Account window as follows.

Now it seems the problem has gone. Try this out if you have the same problem.

Power off problem of Old Computers with Debian

2009-12-20T00:25:00.000-08:00

I still remember the day that I have got my first PC which is an used Pentium II 450MHz computer. Though now I'm having a far superior PC than my old one I still love it.

Recently, I installed Debian lenny on it to use it as a downloading server. But I had a problem with it's power off. Though I have issued the command "poweroff", it didn't completely power off itself and continued to display a message saying "System has halted." on the screen.

I found the solution to my problem from here after spending days until I have a working one.

There are two main standards for power management schemes: APM and the newer ACPI, both off which support powering down the computer completely.

Advanced Power Management (APM) allows computer's BIOS to control system's power management without the knowledge of the operating system.

Advanced Configuration and Power Interface (ACPI) is the successor to APM, which places the responsibility of power management away from the BIOS and into the hands of the operating system.

Today most of the operating systems use ACPI by allowing more intelligent management than it is possible with BIOS controlled APM. As a result most of the Linux kernels including debian's one now shipped with ACPI support compiled in, so should be able to shut down most modern computers itself. But, new operating systems may not completely power off the older computers that are having BIOS controlled APM. If you are interested on more details about the power management, you may refer this article.

Shortly, the solution is the enabling APM and disabling ACPI. This can be done by passing following kernel parameters from the boot loader.

acpi=off apm=power_off

Moreover, the APM module has to be loaded by adding the following to /etc/modules

apm power_off=1

Though this works on debian, I found that there a small difference in the way that is given the kernel parameters on some Linux es like KNOPPIX. In KNOPPIX 5.1(Kernel 2.6.19) it is given as apm=power-off. You may try out either of the ways if other one is not working.

Listning to SHOUTcast with Amarok

2009-04-27T12:40:00.001-07:00

SHOUTcast is an audio streaming sever developed by Nullsoft who owns the most famous media player Winamp . SHOUTcast makes it possible to inexpensively set up an Internet broadcasting station, so hobbyists and large radio network owners alike can use it to set up their own broadcasting network for a fraction of the cost of a traditional AM broadcasting or FM radio station.

Here, I’m not going to talk about its technical stuff, instead, I'm going to talk about how we can listen SHOUTcast radio stations and I’m using Amarok music player as a client which has built in support for the SHOUTcast. Amarok is one of the most popular music players for Linux boxes. But you can use even Winamp(has built in support) or Windows Media Player(does not have built in support).

First open Amarok, then select “Playlists” from the left side bar as shown in following figure. Then click on the plus sign of “Shoutcast Streams” which is seen under the “Radio Streams”. It is important to mention that you have to have good internet connection since you are going to listen online radio streams :-)

After that you will see a list of stations which are categorized using their genre(See the following figure).

Click on the plus sign of one genre. Then you will see a list of online stations under that genre. The available stations for one of my favorite genres can be seen as follows.

Double click on one station. You will see one or more items in the current play list as below. Sometimes, you will see only one item for one station. These items represent streaming servers which you can connect and listen. Some stations use multiple streaming servers to reduce the load to one streaming server. You are free to connect any server. If you do not hear the station in a smooth way you can try another server.

I use my 512kbps ADSL line to listen online radio stations. As you can see in the following figure, the data-rate of the stream is 160kbps which is beyond the quality of an average MP3(128kbps). Moreover, I can still surf internet while downloading torrents on 30KB/s rate without interfering the radio stream. As I think, the main reason to be so is that the low latency in ADSL lines which may not quite cheep to obtain in other lines(i.e: Wi-Max, HSDPA).

If you right click on one stream you will see a dialog box as follows. You can use the url seen to use Windows Media player as a client.

(In Windows Media player, File->Open Url)

For the people who use windows, here is the way you can listen SHOUTcast radio stations using Winamp. Go to “MEDIA LIBRARY” and select “SHOUTcast radio” under the “Online Services”. Then select your favorite station and click “TUNE IN!”

Maxthon Web browser

2009-04-06T09:29:00.001-07:00

Some time ago, I found a web browser which is faster than both IE and Firefox. It is called as Maxthon which is one of the most popular web browsers in China. I accidently came to know about it while I was searching for information about xAurora. xAurora is a hacked version of Maxthon Classic. It is a really shaming thing to mention the name of the guy who did the hacking. If you want more information how he did it, please go here. Lets forget about xAurora and think about its original.

There are two versions of Maxthon. Maxthon2 uses the Trident layout engine, like Microsoft's Internet Explorer, while Classic Maxthon (Maxthon 1.x) continues to support both Trident and the Gecko engine used in Mozilla Firefox .

Here is a screenshot I have taken. I applied the Chrome theme to it. Maxthon is a really nice web browser. Try it out.

Official Web link : http://www.maxthon.com/

How to have a nice graphical animated GRUB

2008-11-13T10:05:00.000-08:00

Soon On.........

Column Edit Mode in VI

2008-10-23T23:29:00.000-07:00

Here is an easy way to comment out a paragraph in VI editor

* Ctrl + V to go into column mode
* Select the columns and rows where you want to enter your text
* Shift + i to go into insert mode in column mode
* Type in the text you want to enter. (Dont be discouraged by the fact that only the first row is changed.)
* Esc to apply your change (or alternately Ctrl+c)

Contiki AJAX-style web server for the Tmote Sky / TelosB

2008-07-13T21:28:00.000-07:00

Just a quick video this time. This video shows the newly committed AJAX-style web server for the Tmote Sky / TelosB boards that shows a continuously updated web page with the sensor data from the on-board sensors as well as the power profile of the current application.

Singularity: Rethinking Dependable System Design

2008-07-13T10:35:00.000-07:00

Some times ago, I came to know about an Operating System named “Singularity” which is written almost entirely in an extension of C#, a modern, high-level programming language. I surprised by hearing that because at that time I thought, an operating system can be written only by using low-level programming languages like C, C++.

At that time, there was no way for other Operating Systems enthusiasts to run and evaluate Singularity in their boxes since there was no a distributable image or source code available. But now I am happy to say that the “Singularity Research Development Kit” (RDK) 1.1 is available for academic non-commercial use since 04, March at the “CodePlex”, Microsoft's open source project hosting website.

I have successfully built and ran the Singularity on Virtual PC 2007. I have put some screenshots taken in middle of the process. You can download, build and run it easily. There is a nice documentation available with the RDK explaining how to build and run it.

Hunt, a principal researcher and manager of Microsoft Research Redmond’s Operating Systems Group, and Larus, a research-area manager in the Software Improvement Group, aimed to rethink system design in light of many research advances and a changed computing environment. And now that Singularity has reached a useful level of stability and functionality, they think it’s time that other researchers in academia and industry have an opportunity to build on their research.

While Booting Singularity

Singularity Shell

While Playing an audio

Kernel Mode Debugger

Installing VMWare Server on Ubuntu 8.04

2008-05-03T03:13:00.000-07:00

I tried to install VMWare Server on Ubuntu 8.04 today. But I got some problems while compiling modules. I googled for a help and I found an article. The witter of that article had the same problem. Thanks to him, I could install the VMWare Server on Ubuntu 8.04. Here is the way he did it.

Download and use VMWare-Any-Any-Update116 instead
When finished, before running VMWare do the following in a terminal:

sudo cp /lib/libgcc_s.so.1 /usr/lib/vmware/lib/libgcc_s.so.1/

sudo cp /usr/lib/libpng12.so.0 /usr/lib/vmware/lib/libpng12.so.0/

If you have errors like this when running, do the above thing again. It worked for me.

:/usr/lib/vmware$ vmware
/usr/lib/vmware/bin/vmware: /usr/lib/vmware/lib/libgcc_s.so.1/libgcc_s.so.1: version `GCC_3.4' not found (required by /usr/lib/libcairo.so.2)

Ubuntu 8.04 LTS Desktop Edition Released

2008-04-21T21:43:00.000-07:00

LONDON, April 21, 2008 – Canonical Ltd. announced the upcoming availability of Ubuntu 8.04 LTS Desktop Edition for free download on Thursday 24 April. In related news, Canonical also announced the simultaneous release of Ubuntu 8.04 LTS Server Edition.

Ubuntu 8.04 Long Term Support (LTS) provides a stable platform for software and hardware vendors, developers and users. With three years of support and maintenance on the desktop, 8.04 LTS is a great choice for large-scale deployment. A substantial and growing ecosystem of free and commercial software built for Ubuntu provides a rich set of choices for desktop users. This is the eighth desktop release of Ubuntu. Ubuntu's track record in delivering - on a precise schedule every six months - a commercial operating system that is free, stable, secure and fully supported, remains unique.

Try out Ubuntu 8.04 LTS and enjoy the freedom of Linux

Ubuntu Studio

2008-03-14T21:24:00.000-07:00

They are saying "Let Your Creativity Fly... "
Yeah! actually it seems your creativity is going to fly with ubuntu studio. Ubuntu studio is amazing .

Ubuntu Studio. A multimedia creation flavor of Ubuntu.

Ubuntu Studio is aimed at the GNU/Linux audio, video and graphic enthusiast as well as professional.

We provide a suite of the best open-source applications available for multimedia creation. Completely free to use, modify and redistribute. Your only limitation is your imagination.

You can get more information from their place http://ubuntustudio.org/

Here are some screen shots of ubuntu studio

GDM Login

Desktop

Icons

Theme

Ardour 2

Image Editing

Let the creativity fly...

IR – Decoder for Sony Remotes

2008-01-27T06:30:00.001-08:00

Infrared remote control has been around for a very long time now, and we tend to take it for granted. Yet, it is a marvel of modern technology, which allows a whole variety of devices to be activated with the touch of a button. Remote control handsets are so abundant that they may be purchased new for a few pounds, which makes them viable items for experimentation. There are dedicated chips available that will decode the signals from a particular handset, however, with the flexibility and cost effectiveness of the PIC range of microcontrollers we can develop a decoding subroutine that may be placed into your own programs, or used as a standalone infrared to RS232 converter.

It is not my intention to teach you how to program a PICmicro, therefore, throughout this article; it is assumed that you already have some knowledge of either assembler or PicBASIC Pro. And that you have a means of programming the PIC16F84. For more information concerning the PicBASIC range of compilers, as well as an assortment of programmers, visit Crownhill Associate’s dedicated web site at www.picbasic.co.uk. For information concerning assembler programming, visit Microchip’s web site at www.microchip.com.

Here is the circuit diagram. I successfully built this.

The out put of RS232 is like this

IR_BUT<Button Code>\rIR_DEV<Device Code>\r

Button Code is the value assigned to the button i.e E00(in hex) is the value for for Number 1 button
Device code is the value assigned to the device.

Source Code written is PICBasic

'****************************************************************
'* Name : Sony_ir.BAS
'* Author : K.C. Hewage
'* Date : 2/1/2007
'* Version : 1.0
'* Notes :
'****************************************************************

Include "modedefs.bas"

DEFINE OSC 4

'*******Alias************

Red_Led var PORTA.0
Green_Led var PORTA.1
IR_Sense var PORTA.2
Serial_out var PORTA.3

'*******Variables************

IR_Dev var byte
IR_But var byte
ST var word
IR_Word var st
BitCnt var byte
ID var byte
IR_Valid var bit

Serout Serial_out,N9600,["My IR Device",13]
Serout Serial_out,N9600,["Hello",13]

Main:

low red_led
low green_led

gosub irin

If IR_Valid = 1 then

high red_led
pause 200
low red_led

Serout PortA.3,N9600,["IR_BUT", ir_but, 13, "IR_DEV", IR_dev, 13]

endif

goto main

IRIN:

IR_Valid = 1

pulsin IR_Sense, 0, st

If st < ir_valid =" 0"> 270 then IR_Valid = 0 : Return' If not valid then exit

ir_word = 0
ID = 0
ir_but = 0
ir_dev = 0

For Bitcnt=0 to 11 ' Create a loop of 12
Pulsin ir_sense,0,Id ' Receive the IR bit pulse

If id >= 90 then ' If it's >= 90 then we've received a 1
ir_word.0[bitcnt] = 1
else
ir_word.0[bitcnt] = 0
endif

Next ' Close the loop

ir_but = ir_word & %01111111
ir_dev = 011111 & (ir_word >> 7)

return

Repositioning the navbar to the bottom of the page

2008-01-27T06:02:00.000-08:00

It seems that removing navbar leads to logging problems(You have to go a round to login the blog.). So instead of removing navbar completely, we can reposition it to the bottom of the page. Here is the way you should do.

On your Dashboard, select Layout. This will take you to the Template tab. Click Edit HTML. Under the Edit Template section you will see you blog's HTML.
paste the following CSS definition in the top of the template code:

body { position: relative; }
#navbar-iframe {

position: absolute;
top: inherit;
bottom: 0px;
margin-bottom: 0;
}

Go to my other blog http://kasunch.blogspot.com . You can see it

How to remove NavBar From blogger

2008-01-25T23:32:00.001-08:00

Hiding NavBar is a simple task. Here is the way

Log in to blogger
On your Dashboard, select Layout. This will take you to the Template tab. Click Edit HTML. Under the Edit Template section you will see you blog's HTML.
paste the following CSS definition in the top of the template code:

#navbar-iframe {
display: none !important;
}

That's it.