I have used the INTSIO (interrupt driven UART) example to implement my getkey and putchar functions. Seems like the Backspace or the del key is not handled by the same. How can I handle the backspace and del keys?
Perhaps, you'll have to implement a (simple) text editor. It will likely require a more elaborate API than a single getchar() function.
It is not really the place of these low-level character IO functions to interpret such things - you will need to implement line editing at a higher level, if you require it...
As soon as you go the line-input mode, you must decide what command-line length you should support, potentially wasting a lot of RAM if the user never uses so long text lines.