thanks rkmoar
the interaction could be useful in case one would save annotations and highlights that sometimes became complex
i use this this script named clean.app at the moment to delete empty dir
i cd to the directory because with busybox once i deleted anything!
#!/bin/sh
cd /mnt/ext1/system/state
path to find/find -depth -type d -epty - exec rmdir {} \;
cd /mnt/ext1/system/config/Active\ Contents
path to find/find -depth -type d -epty - exec rmdir {} \;
i've to study more to compare paths as you suggested