In the context of the nl command, the r in the -n rz option stands for "right-aligned." This means that the line numbers will be aligned to the right side of the output.
So, when you use nl -n rz, it formats the line numbers to be right-aligned, which is useful for maintaining a neat appearance, especially when dealing with varying lengths of text. The z option adds leading zeros to the line numbers, ensuring they have a consistent width.
