#!/bin/bash
cd test
valid="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890-_."
find . | while read f; do
j=1
        d=$(echo ${#f})
        while [ $j -lt $d ]; do
               c=$(echo ${f:j:1})
                k=`echo $valid | grep -i $c`
                if [ "$k" = "" ]; then
                        c="_"
                fi
                r=$r$c
                let j=j+1
      done
  r=$(echo ${r:1:d-2})
#if ["$f" -ne "$r"]; then
 mv "$f" "$r" 
#fi
r=""
done