: Sometimes my cursor keys or keypad keys produce strange codes?
When the terminal is in application cursor key mode the cursor keys produce Esc O x and otherwise Esc [ x where x is one of A,B,C,D. Certain programs put the terminal in application cursor key mode; if you kill them with kill -9, or if they crash, then the mode will not be reset.
% echo -e '\033c'
resets all properties of the current VC. Just changing the cursor application key mode is done by
% echo -e '\033[?1h'
(set) and
% echo -e '\033[?1l'
(clear).
When the terminal is in application keypad key mode the keypad keys produce Esc O y and otherwise Esc [ z ~ for certain y and z. Setting application keypad key mode is done by
% echo -e '\033='
and
% echo -e '\033>'
clears it again.