Dear mac users, I want to change permission on a file using this command below, but it doesn't work. it seems there is a permission problem or the file is locked in some way. what i get as a result is: Code: sudo chmod g+rwx "Copy of index.php" chmod: Unable to change file mode on Copy of index.php: Operation not permitted the error happens when i try to change file owner ship. There are other files in the folder, and my above command works except this one file. Please help.