You must set the terminal into raw mode to get the scan codes and handle them (that is: disable ICANON, you want the non-canonical mode). You probably also want to disable ECHO (so that it doesn't print your input on the terminal).
That is what readline or linenoise are doing. See here for some code. Esp. see the function linenoiseEnableRawMode
. Some other simple sample Python code is here where I have written a simple console media player which checks for the keypresses left ("\x1b[D") and right ("\x1b[C").
The relevant calls are to tcgetattr
(to get the current terminal state and modify that state struct to get into raw mode and enable some other useful behavior stuff) and tcsetattr
(to set the state).
readline, libedit or linenoise are some libraries which do all that work for you and provide you with history, autocompletion, etc.
At the end, you must restore back the old state, otherwise you get the behavior you are describing in your shell.