FIND_DIR=/tmp
FIND_STRING='DEST=/etc/skel'
REPLACE_STRING='DEST=${1:-/etc/skel}'

printf $0
printf "\nBefore: \n"; grep DEST= 020*

sed -i "s|${FIND_STRING}|${REPLACE_STRING}|g" $(find ${FIND_DIR} -type f  -name "0*0_*" ! -path "$0" | xargs grep ${FIND_STRING} | awk -F: '{print $1}')

printf "\nAfter: \n"; grep DEST= 020*