How to use `dialog` command in a shell script.

dlg

#!/usr/bin/bash

dialog \
    --title "Yeah!" \
    --msgbox "Test for dialog.\nPress OK." \
    7 60

dialog \
    --title "Excuse me?" \
    --yesno "Are you still there?" \
    0 0
res=$?

if [ $res -ne 0 ]; then
    clear
    echo "Okay bye."
    exit $res
fi

inputBox() {
    local prompt=${1-"Enter"}
    local box=${2-"inputbox"}
    local inp=
    local warn=
    while [ -z "$inp" ]
    do
        # Swapping stdout and stderr.
        # `dialog` uses stderr for printing the result
        # while we want it in stdout.
        inp=$(dialog \
            --${box} "${prompt}\n${warn}" \
            10 60 3>&1 1>&2 2>&3 3>&-)
        res=$?

        if [ $res -ne 0 ]; then
            return $res
        fi
        if [ -z "$inp" ]; then
            warn="Enter something *NOT* empty."
        fi
    done
    echo $inp
}

name=$(inputBox "Enter your name.")
res=$?
if [ $res -ne 0 ]; then
    clear
    echo "See you later."
    exit $res
fi

pw=$(inputBox "Enter your password." passwordbox)
res=$?
if [ $res -ne 0 ]; then
    clear
    echo "See you later."
    exit $res
fi

choice=$(dialog \
    --no-cancel \
    --menu "What would you like?" \
    10 60 3 1 apple 2 orange 3 banana 3>&1 1>&2 2>&3 3>&-)

dialog \
    --infobox "Okay, now let me think it over..." 5 60

sleep 3
clear
echo "Hello, $name"
echo "You selected #${choice}, right?"