#!/bin/bash
function help() {
    echo "Flatten the directory structure from the current folder downwards"
    echo "Files in subfolders will be renamed / -> _"
    echo "Empty folders are removed"
    echo "   -f  to force action "
}

function helpexit() {
    help
    exit
}
[[ -z "$1" ]] && {
    help
    echo "Are you sure? Break with ctrl-c"
    read i   
}
[[ "$1" = "-h" ]] && helpexit

IFS=$'\n'

for f in $( find . -mindepth 2 -type f -path '*.*' -printf %P'\n' );
do mv -iv "$f" "$( echo $f | sed s,[/],_,g )"
done
find . -depth -type d -empty -delete