Argument special characters

sep21-conditionals.md

@@ -14,3 +14,21 @@ Wrong: `ls /tmp/foo bar`
 Correct: `ls /tmp/foo\ bar`
 
 Also Correct: `ls "/tmp/foo bar"`
+
+## Argument special characters
+
+```
+$ test -z "hello"
+
+$# = 2
+
+$@ = "-z" "hello"
+
+$* = "-z hello"
+
+$0 = test
+
+$1 = -z
+
+$2 = "hello"
+```