Fixed Python string formatting

websocketd_server.py

@@ -5,7 +5,7 @@ import sys
 
 def main():
 	output_file = sys.argv[1]
-	print("Saving output to %" % output_file)
+	print("Saving output to %s" % output_file)
 	for line in sys.stdin:
 		entry = line.strip() + ',' + datetime.datetime.now().isoformat()
 		with open(output_file, 'a') as f: