diff --git a/2.md b/2.md
index 42c933e..beb2b4f 100644
--- a/2.md
+++ b/2.md
@@ -4,4 +4,12 @@
 
     Alice -> Bob: Another authentication Request
     Alice <-- Bob: Another authentication Response
+
+```
+
+
+```bash
+if [ -z $AA ]; then
+ echo "XX"
+fi
 ```
\ No newline at end of file