#!/bin/bash

if [ $# -eq 0 ]; then
  echo "Please specify a starting extension and ending extension"
fi
if [ $# -eq 1 ]; then
  echo "Please specify an ending extension"
fi
if [ $# -eq 2 ]; then
  for f in *.$1; do
  let "COUNT++"
  mv -- "$f" "${f%.$1}.$2"
  done
  echo "Renamed $COUNT files from .$1 to .$2"
fi
if [ $# -gt 2 ]; then
  echo "Too many args to parse"
fi