The Linux keyboard and console HOWTO

21. Some properties of the VT100 - application key mode

: 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'  

        % echo -e '\033[?1h' 

        % echo -e '\033[?1l' 

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=' 

        % echo -e '\033>'