According to Wikipedia,
Avestan (pronounced /əˈvɛstən/ ) is an Iranian language known only from its use as the language of Zoroastrian scripture, i.e. the Avesta, from which it derives its name. The language must also at some time have been a spoken language, but how long ago that was is unknown. Its status as a sacred language ensured its continuing use for new compositions long after the language had ceased to be a living language.
Only recently was the Avestan script added to the Unicode standard (Unicode 5.2). For more, see page 17 at the Archaic scripts section of Unicode 5.2 (PDF) and the Unicode block details for U+10B00. See also the proposal to add Avestan to Unicode as an archaic script.
A user from UbuntuForums.org asked for help to create a keyboard layout for the Avestan script.
So, how can you use the new keyboard layout?
1. Add avestan.txt at the end of /usr/share/X11/xkb/symbols/ir
sudo gedit /usr/share/X11/xkb/symbols/ir
in order to open (as administrator) the 'ir' layout, and paste the contents of avestan.txt at the end of the 'ir' file. Click Save and exit.
2. Register the new 'avestan' layout in evdev.xml and base.xml files.
Both files have a section that looks like the following. Do a simple search for 'ku_ara' or some other string in order to find the segment.
Open base.xml with
sudo gedit /usr/share/X11/xkb/rules/base.xml
Then open evdev.xml with
sudo gedit /usr/share/X11/xkb/rules/evdev.xml
Replace the '-----------HERE------------' with the following lines:
What we do here is we insert a variant description for the 'avestan' keyboard layout.
Click Save and exit the text editor.
3. Install a suitable font. Follow the steps from http://www.bomahy.nl/hylke/blog/adding-fonts-in-gnome/
which says to install the font in your home directory, in a '.fonts' subdirectory. Normally, Ubuntu will pick up the font as soon as you copy it in there. Any newly started application should be able to use the new font.
4. Finally, add the new Avestan keyboard layout. Go to System → Preferences → Keyboard → Layouts, click on the [Add...] button and select from the list 'Iran' and layout 'Avestan'. Click OK. Notice the new keyboard layout indicator on the panel that allows you to switch between English and Avestan.
Increasingly more scripts and symbols are added to the Unicode standard. These scripts are not useful unless there is a comfortable way to type in them. Find a script you like and help create a keyboard layout.