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+## >= is not a valid operator. Use '! a > b' instead.
+
+### Problematic code:
+
+    [[ a <= b ]]
+
+### Correct code:
+
+    [[ ! a > b ]]
+
+### Rationale:
+
+The typical operators `<=` and `>=` are not supported by Bourne shells. Instead of "less than or equal", rewrite as "not greater than". 
+
+### Contraindications
+
+None
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