Delete Google Cloud Storage date named items on Mac & CentOS

#!/bin/bash

# assumes file or directory name looks like: "file_starts_with_2017-03-23"

BUCKET_NAME="my_bucket_name"
FILE_PREPEND_NAME="file_starts_with"

for i in `seq 30 90`;
do
    NEW_DATE=`date --date "-${i} days" +%Y-%m-%d`
    NAME="${FILE_PREPEND_NAME}_${NEW_DATE}"
    gsutil -m rm -r gs://$BUCKET_NAME/$NAME
done

#!/bin/bash

# assumes file or directory name looks like: "file_starts_with_2017-03-23"

BUCKET_NAME="my_bucket_name"
FILE_PREPEND_NAME="file_starts_with"

for i in `seq 30 90`;
do
    NEW_DATE=`date -j -v"-${i}d" +%Y-%m-%d`
    NAME="${FILE_PREPEND_NAME}_${NEW_DATE}"
    gsutil -m rm -r gs://$BUCKET_NAME/$NAME
done