REGEX raplacement in a list of files

sed-recursive.sh

#!/usr/bin/env bash
pattern=$1
replace=$2
list=$3
if ! [ $replace ]; then 
    echo USAGE: $0 PATTERN REPLACEMENT LIST 
    echo EXAMPLE: $0 \""R-\\([a-z]\\+\\)"\" \"\\\$R\\\$-"\1"\" \"\*.tex\"
fi
for i in $list; do  
    sed 's/'"$pattern"'/'"$replace"'/g' $i > /tmp/tmpfile 
    if [ $(diff $i /tmp/tmpfile| wc -l) -gt 0 ]; then 
  mv /tmp/tmpfile $i
    fi
done