[Feature]Change env.sh

Change-Id: Ic30d837676f2998383e3b9a81b09888b2c25fca6
diff --git a/env.sh b/env.sh
index 421cc59..b219fe9 100755
--- a/env.sh
+++ b/env.sh
@@ -1,3 +1,5 @@
+#!/bin/bash
+
 chmod 664 meta/poky/scripts/postinst-intercepts/*
 chmod 775 meta/poky/scripts/postinst-intercepts/postinst_intercept
 export TEMPLATECONF=${PWD}/meta/meta-mediatek-mt2731/conf/base/auto2731evb-ivt-main