How to write Arabic in Linux Ubuntu? First, you should enable Arabic keyboard layout. The Arabic keyboard layout will look like this picture (click to enlarge):
# Then, open your favorite text editor. I prefer gedit (Applications*Accessories*gedit Text Editor)
# Click Keyboard Preferences (usually it is placed in top-right of desktop panel) and it will be switched from USA to Ara
# Type your word one by one based on Arabic keyboard layout. It will be connected automatically.
# Type Space key to separate one word to another.
It is easy, isn't it? Enjoy!