diff --git a/tools/test/topos/att-onos b/tools/test/topos/att-onos
index e473359..9ad918a 100755
--- a/tools/test/topos/att-onos
+++ b/tools/test/topos/att-onos
@@ -1,3 +1,7 @@
+#!/bin/bash
+# -----------------------------------------------------------------------------
+# Starts ATT ONOS topology in mininet.
+# -----------------------------------------------------------------------------
 cd $(dirname $0)
 if [ -n "$1" ]; then
     sudo python att-onos.py "$@"