I've installed Xubuntu 12.10 and I've occours that Fn key (I used that for type / ) doesn't work inside standard shell (but it works in the rest of programs).
How can I fix it?
The purpose of Fn (short for function) key is quite different: for example to change display or audio settings quickly, such as brightness, contrast, or volume, and is held down in conjunction with the appropriate key to change the settings. When you press only the the Fn key, this doesn't send any data to the computer.
According with this post, in general there is no way to know that Fn was pressed and the keycode of key-combinations including Fn depends on the individual keyboard design.
So unfortunately, you can't bind it to another key.
More about: http://en.wikipedia.org/wiki/Fn_key.