aws s3 ls s3://bucket/folder --recursive | awk 'BEGIN {total=0}{total+=$3}END{print total/1024/1024" MB"}'
aws s3 ls s3://<bucketname> --recursive | grep -v -E "(Bucket: |Prefix: |LastWriteTime|^$|--)" | awk 'BEGIN {total=0}{total+=$3}END{print total/1024/1024" MB"}'