diff --git a/doc/bash_tips.md b/doc/bash_tips.md
index 485eb10..2abfed0 100644
--- a/doc/bash_tips.md
+++ b/doc/bash_tips.md
@@ -63,3 +63,8 @@ count=$((count+1))
 ```
 
 ## sudo -E or better source if already root
+
+From within a miaou-bash script and in case sudo is required
+
+1. prefer using source if already root
+2. or force preserving the MIAOU_BASH_DIR environment variable with `sudo -E