Using pv as progress value with yad [.targz current directo]

#!/bin/bash
if [[ $UID -eq 0 ]]; then
(tar cf - . \
| pv -n -s $(du -sb . | awk '{print $1}') \
| gzip -9 > out.tgz) 2>&1 \
| yad --width 300 --height 100 --title "Progress .tgz Current Directory" --progress 'Progress' 7 70
else
yad --title "Sorry" --text-info --entry "This script must be ran as root"