use  #!/usr/bin/env bash
for portability
diff --git a/releng.control/killall.sh b/releng.control/killall.sh
index 7f4c4de..8f82ef8 100644
--- a/releng.control/killall.sh
+++ b/releng.control/killall.sh
@@ -1,3 +1,3 @@
-#!/bin/sh
+ #!/usr/bin/env bash
 
 pkill -f webtools