make sure it runs using bash
diff --git a/xos/scripts/docker_start_xos b/xos/scripts/docker_start_xos
index e5d6558..9e1ce6c 100755
--- a/xos/scripts/docker_start_xos
+++ b/xos/scripts/docker_start_xos
@@ -1,3 +1,5 @@
+#! /bin/bash
+
 function wait_postgres {
     sudo -u postgres psql -c '\q'
     while [[ "$?" != "0" ]]; do