CORD-2027 fix vtr tcpdump

Change-Id: I29aff1571c878b156bd7043c5571c1a3a813259f
(cherry picked from commit b7faa07d8c2766449856216c1825bb32e6f12774)
diff --git a/xos/synchronizer/files/run_tcpdump.sh b/xos/synchronizer/files/run_tcpdump.sh
index a39bf56..6eb6a98 100644
--- a/xos/synchronizer/files/run_tcpdump.sh
+++ b/xos/synchronizer/files/run_tcpdump.sh
@@ -1,3 +1,4 @@
+#! /bin/bash   
 
 # Copyright 2017-present Open Networking Foundation
 #
@@ -13,9 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
-#! /bin/bash
 INTERFACE=$1
 tcpdump -n -e -i $INTERFACE -c 10 &
-curl http://xosproject.org/ &> /dev/null &
+curl http://xosproject.org/ -o /dev/null &
 sleep 10s