Shift camera picture filenames by a certain amount to avoid files with same name

rename.sh

#!/bin/bash

INITIAL_NUM=1012
SEPARATOR='_'

for i in *.JPG
do
  basename=`basename $i .JPG`
  prefix=`echo $basename | cut -d $SEPARATOR -f1`
  current_num=`echo $basename | cut -d $SEPARATOR -f2`
  new_num=`expr $INITIAL_NUM + $current_num`
  mv $i ${prefix}${SEPARATOR}${new_num}.JPG
done