Configure Ubuntu Package Repository Location

Simplest method is using Ubuntu Software Center. You can go to Edit menu, choose Software Sources, then make some changes that you want. 

If you want to use command line tools like apt-get you can configure repository location in /etc/apt/source.list.
$ nano /etc/apt/source.list
Then change some deb and deb-src location that you need.

Install and Unisntall Program Package in Ubuntu

There are some methods to install program in Ubuntu. The easiest way is using Ubuntu Software Center or Synaptic. Another way is using terminal. You can use dpkg, apt-get, or aptitude.

dpkg is used if you have .deb file. To install package use this command.
$ sudo dpkg -i package_name.deb
To uninstall package use this command.
$ sudo dpkg -r package_name
Another simpler method then dpkg is using apt-get or aptitude. You just need to connect with package repository server through internet or LAN. Then you can install package use this command.
$ sudo apt-get install package_name
To uninstall or remove a package use this command.
$ sudo apt-get remove package_name
But above command will leave data and configuration file of the package. To remove data and configuration file use this command.
$ sudo apt-get purge package_name
By using above command will remove data and configuration file but not for dependencies which was installed when main package was being installed. To remove unnecessary dependencies you can use this command.
$ sudo apt-get autoremove
Before you can install a package using apt-get you should configure package repository location. See this post to know how to configure package repository location.

Setup Mail Server in Windows using hMailServer

Sometimes network/web application developer need a local mail server to test their application. There are some mail server applications that can be used in Windows. One of simple mail server for Windows is hMailServer. You can download hMailServer here. It can work in Windows 8. Another preparation before you run this mail server you should install database server. It can be a Microsoft SQL, MySql, or PostgreSql server.

These are some steps to setup hMailServer for local mail server.

How to Build Chat Server Using Openfire

Openfire is one of server application which implement XMPP (Jabber) protocol to serve chatting for client. This application is built in Java so you must install JRE on your server. Configuration of this server is so easy. You will have a web-based control panel for server configuration. This application is developed by Jive Software. It's support Windows, Linux, and Mac. You can download the installation file from HERE. Beside that there are many plugin such as for archiving or monitoring.

I want to show you how to install and make configuration of it on Linux.

Selection Sort

This method is a sorting method that will look for smallest or biggest value depend on ascending or descending order then being placed at the forefront place. After that, it will look for the next smallest or biggest value along all elements of array reduced by 1, and so on. For example, there is an array that contains these number :
If the data above is sorted in ascending by selection method, the result is:

Insertion Sort

Straight insertion is a sorting method which takes a parenthesis data on ordered data and shoves data which is bigger than parenthesis data so parenthesis data can be placed on right place. For example, there is an array that contains these number :
If the data above is sorted in ascending by straight insertion, the result is:

Introduction to Parallel Programming Using CUDA

CUDA (Compute Unified Device Architecture) is a scheme which is made by NVIDIA that make NVIDIA as a GPU (Graphic Processing Unit) is able to create computations not only for graphic-rendering but also for general-purpose. So, with CUDA, we can utilize quite a lot of processors that is own by NVIDIA for various computations. Now day, GPU likes ATI, also has had many processors on it. Scheme that ATI build is called ATI Stream. Parallel programming becomes so important because need of computer computation ability continues to increase for multitasking and powerful graphic processing. Current methods for performance enhancement are different with earlier methods where enhancement of processor clock is preferred. Clock speed enhancement is restricted by physical capabilities such as power and heat problem. In 2005, various computer industries started to offer computer with some cores on it starting from 2, 3, 4, 6, and so on. At the beginning of development of GPU with many cores, GPU utilization were only done by interface like OpenGL and DirectX which these interfaces are specialized only for graphical processing.
Latest series of NVIDIA have supported CUDA, exactly after 2006. For the list of series that support CUDA can be seen at As the beginning in study of parallel programming using CUDA, it’s better to use C or C++ as programming language. CUDA C has been first special programming language that is developed by a GPU company to facilitate general-purpose computing on GPU. Some matters that should be prepared when using CUDA C to make an application are these below.

Update GRUB List Order

After you installed Ubuntu alongside Windows in your computer, now you should change the highlighted text when you want boot into Windows because after Ubuntu installation the default operating system will be Ubuntu, like the picture below.

There are two ways for updating GRUB list order in Ubuntu. I try it in Ubuntu 12.04 and I think it also can be done in nearest older version before it. First is by changing the name of the file in “/etc/grub.d/” and second is by changing the default value in “etc/default/grub”. First way is to change the first text in the list become Windows. Second way is to change default highlighted text into Windows (the last text). You should choose one of the ways, the first or the second way.

Installing Ubuntu alongside Windows

In this case, you have a computer that has been installed by Windows first and you want add Ubuntu on it. You can use CD from Ubuntu site or the easier way is use bootable USB that can be made by some applications. You can see explanation to make bootable USB flash drive from this postAfter you have bootable USB flash drive you can run these steps.

1.       Restart your computer, get into boot menu, and change the first boot location to USB. Some computers can get into boot menu directly by press ‘F12’ or other keys like a picture below.

Create Bootable USB Flash Drive

There are some applications to do it in Windows or other operating systems. If we refer  from offical website of Ubuntu (, they give us information to use Universal USB Installer from  Another application that we can use is UnetBootin. There are Linux and Windows version for both applications.

First way, how to use Universal USB Installer from
1.       Download this application from
2.       After download was complete. Open the application by double- click it.