message: use $() over ``.
diff: @@ -6,7 +6,7 @@ set -ex
  # new volume looks like this
  # $corename/-files-
  -for datadir in `ls -d /var/solr/*` ; do
  +for datadir in $(ls -d /var/solr/*) ; do
  corename=$(basename $datadir)
  if [ -d ${datadir}/data ]; then
  echo "${datadir}/data is in old format, moving to ${datadir}."
  