#!/bin/bash

NEWSIZE=$(( 1024* $(kdialog --inputbox "Please enter new size in gigabytes (GB)")));

while [ $# -gt 0 ]; do
    VBOXMACHINE=$1
    VBoxManage modifyhd "$VBOXMACHINE" --resize $NEWSIZE
    shift
done

if [[ "$NEWSIZE" == ?(-)+([0-9]) ]]; then
    kdialog --msgbox "Done. Use a live-cd to extend the partition." --title "Resize VirtualBox Machine"
fi