Remove quotes from subshell call in bash script

Always no quotes for $() statement.

We don't need quotes to hold blanks in result:
 # i=$(echo 1 2 3)
 # echo $i
 1 2 3
 #

These quotes can make something wrong in some case:
 # i=$(echo '!')
 #
 # i="$(echo '!')"
 -bash: !: event not found
 #

No real problem for current code, only to use a better code style.

Change-Id: I06520f4b11ea6b56c4e73049b6f38bfc62fe1392
Closes-Bug: #1499716
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>

docker/ceph/ceph-mon/start.sh

@@ -21,7 +21,7 @@ set_configs
 # of the KOLLA_BOOTSTRAP variable being set, including empty.
 if [[ "${!KOLLA_BOOTSTRAP[@]}" ]]; then
     # Lookup our fsid from the ceph.conf
-    FSID="$(awk '/^fsid/ {print $3; exit}' /etc/ceph/ceph.conf)"
+    FSID=$(awk '/^fsid/ {print $3; exit}' /etc/ceph/ceph.conf)
 
     # Generating initial keyrings and monmap
     ceph-authtool --create-keyring "${KEYRING_MON}" --gen-key -n mon. --cap mon 'allow *'

docker/ceph/ceph-osd/start.sh

@@ -21,10 +21,10 @@ if [[ "${!KOLLA_BOOTSTRAP[@]}" ]]; then
     partprobe || true
 
     # We look up the appropriate device path with partition.
-    OSD_PARTITION="$(ls ${OSD_DEV}* | egrep ${OSD_DEV}p?1)"
+    OSD_PARTITION=$(ls "${OSD_DEV}"* | egrep "${OSD_DEV}p?1")
     JOURNAL_PARTITION="${OSD_PARTITION%?}2"
 
-    OSD_ID="$(ceph osd create)"
+    OSD_ID=$(ceph osd create)
     OSD_DIR="/var/lib/ceph/osd/ceph-${OSD_ID}"
     mkdir -p "${OSD_DIR}"
     mkfs.xfs -f "${OSD_PARTITION}"
@@ -47,7 +47,7 @@ if [[ "${!KOLLA_BOOTSTRAP[@]}" ]]; then
 fi
 
 # We look up the appropriate journal since we cannot rely on symlinks
-JOURNAL_PARTITION="$(ls ${OSD_DEV}* | egrep ${OSD_DEV}p?2)"
+JOURNAL_PARTITION=$(ls "${OSD_DEV}"* | egrep "${OSD_DEV}p?2")
 OSD_DIR="/var/lib/ceph/osd/ceph-${OSD_ID}"
 CMD="/usr/bin/ceph-osd"
 ARGS="-f -d -i ${OSD_ID} --osd-journal ${JOURNAL_PARTITION} -k ${OSD_DIR}/keyring"