#!/bin/sh

if [ $# -eq 0 ]; then
    echo "usage: modrename directory" >&2
    exit 1
fi

IFS="
"
for f in $(find "$1" -type f); do
    case "$f" in
    *.669 | *.[Ff][Aa][Rr] | *.[Ii][Tt] | *.[Mm][Oo][Dd] | *.[Mm][Tt][Mm] | \
    *.[Ss]3[Mm] | *.[Ss][Tt][Mm] | *.[Uu][Ll][Tt] | *.[Xx][Mm])
	:;;
    *)
	dir=$(dirname "$f") tail=$(basename "$f")
	mv -f "$f" "$dir/${tail#[Mm][Oo][Dd].}.mod"
	;;
    esac
done
.