diff --git a/rsa.py b/rsa.py
old mode 100644
new mode 100755
index 8cc7895..d82341e
--- a/rsa.py
+++ b/rsa.py
@@ -31,6 +31,11 @@ ID = 6
 
 def main():
     print("hesham-rsa version ", VERSION)
+
+    if len(sys.argv) == 1:
+        printHelp()
+        sys.exit(127)
+
     if sys.argv[1] == "gen" and len(sys.argv) == 4:  ##rsa gen <keysize> <keyname>
         keyFileName = sys.argv[3]
         if keyExist(keyFileName):