b=$(date +%Y%m%d%H%M%S)
mkdir -p /mnt/save/$b
(
   set -e
   pg_dump $DATABASE_URL --clean > /mnt/save/$b/.pg.dump
   mv /mnt/save/$b/{.,""}pg.dump
) \
   || (
      rm -rf /mnt/save/$b
      echo "backup failed; deleting $b"
      exit 1
   )
if du -sh /mnt/save/$b | grep -Ei "^[ ]*(4|2.).0K"; then
   rm -rf /mnt/save/$b
   echo rm empty backup $b
fi