diff --git a/readme.md b/readme.md
index 970da07..aeeb5dc 100644
--- a/readme.md
+++ b/readme.md
@@ -130,7 +130,8 @@ stat -x readme.md
 **STOP DOUBLE CLICKING A FILE**
 
 ```
-open file
+open file       # on macOS
+xdg-open file   # on Linux
 ```
 
 ## <a id="zipfolder"></a>zip a folder