move cursor on terminal (up: k, down: j, left: h, right: l, quit: q)

move_cursor.sh

#! /bin/sh

function show_coordinate() {
    tput civis
    tput sc
    tput cup 0 0 ; printf "[%3d,%3d] up:k, down:j, left:h, right:l, quit:q" ${1} ${2}
    tput rc
    tput cnorm
}

###  keyboard assignment  ###
assign_key_up=k
assign_key_down=j
assign_key_left=h
assign_key_right=l

###  set maximum size of the window  ###
declare -i x_position_max=`tput lines`
declare -i y_position_max=`tput  cols`

###  initial cursor position  ###
declare -i x_position=5
declare -i y_position=10

###  clear terminal  ###
clear

###  move cursor and show the coordinate  ###
tput cup ${x_position} ${y_position}
show_coordinate ${x_position} ${y_position}

###  set terminal in raw mode  ###
stty raw -echo

while : ; do

    ###  real time input => ${char}  ###
    char=`dd bs=1 count=1 2>/dev/null`

    ###  set position of the cursor with checking if the cursor is at the edge of the window  ###
    if   [ "${char}" == ${assign_key_up}    ] ; then
        if [ ${x_position} -eq 0 ] ; then
            x_position=${x_position_max}
        else
            x_position=`expr ${x_position} - 1`
         fi
    elif [ "${char}" == ${assign_key_down}  ] ; then
        if [ ${x_position} -eq ${x_position_max} ] ; then
            x_position=0
        else
            x_position=`expr ${x_position} + 1`
        fi
    elif [ "${char}" == ${assign_key_left}  ] ; then
        if [ ${y_position} -eq 0 ] ; then
            y_position=${y_position_max}
        else
            y_position=`expr ${y_position} - 1`
        fi
    elif [ "${char}" == ${assign_key_right} ] ; then
        if [ ${y_position} -eq ${y_position_max} ] ; then
            y_position=0
        else
            y_position=`expr ${y_position} + 1`
        fi
    fi

    ###  move cursor  ###
    tput cup ${x_position} ${y_position}

    ###  update cursor coordinate  ###
    show_coordinate ${x_position} ${y_position}

    ###  "q" is defined as an escape key  ###
    if [ "${char}" == "q" ] ; then
        clear
        stty -raw echo
        exit
    fi

done

###  unset terminal in raw mode  ###
stty -raw echo

###  clear terminal  ###
clear