download&remove firestore

#!/bin/bash
now="$(date +'%d%m%Y')"
echo "Starting backup..."
#/snap/bin/gsutil cp -r gs://backup-newlikewallet/"$now" ./backup

DATE="$(date --date="-15 day" "+%s")"
echo $DATE
echo "successfully backup !"
list=`cd backup && ls`
echo "$list"

for f in $list
do
        y=${f:4:4}
        echo $y
        m=${f:2:2}
        echo $m
        d=${f:0:2}
        createDate="$(date -d "$y-$m-$d" "+%s")"
        echo $createDate
        if [[ "$createDate" < "$DATE" ]]; then
                echo "yes, starting remove $f"
                remove=`rm -r ./backup/$f`
                echo "remove $f succesfully"
        fi
done

echo "Successfully backup !"