dd, lzma, whiptail, gauge

    exec 3>&1
    mkfifo "$fifoname"

    realsize=`(while read line
        do
            if [[ "$line" =~ bytes ]]
            then
                echo "$(( ${line%% *}*100/$disksize ))"
                echo "${line%% *}" >&2
            fi
        done< <( dd if="$disk" 2>&1 >"$fifoname" &
            ddpid=$!
            lzma -q -c -z <"$fifoname" >${img}.lzma 2>/dev/null &
            sleep 0.2
            while kill -USR1 $ddpid 2>/dev/null
            do
                sleep 1
            done
            ) \
        | whiptail --title "Image" \
            --gauge "Taking an image of ${disk}..." 8 70 0
    ) 2>&1 1>&3 | tail -n 1`

    rm -f "$fifoname"
    exec 3>&-