diff --git a/centos.sh b/centos.sh
index 9310e74..c24e3b5 100644
--- a/centos.sh
+++ b/centos.sh
@@ -1,3 +1,4 @@
+#!/bin/bash
 echo installing Docker
 yum install -y yum-utils
 yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo