The Linux keyboard and console HOWTO: Some properties of the VT100 - application key mode

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## 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'

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.

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