How does cat -n handle empty files?

When you use cat -n on a completely empty file, it produces no output at all.

Here is how it behaves in different "empty" scenarios:

1. A Truly Empty File (0 bytes)

If the file contains absolutely no data, cat -n will simply return you to the command prompt without printing anything. Since there is no content, there are no lines to number.

2. A File with Only Empty Lines

If a file has content but some lines are blank (e.g., you pressed "Enter" a few times), cat -n will assign numbers to those blank lines.

Example:
If /tmp/blank_test contains:
Line 1: Hello
Line 2: (Empty)
Line 3: World

The command cat -n /tmp/blank_test will show:

     1	Hello
     2	
     3	World

Pro Tip: cat -b

If you only want to number lines that actually have text and skip numbering blank lines, you can use the -b option instead:

cat -b /tmp/blank_test

This would number "Hello" as 1 and "World" as 2, leaving the blank line unnumbered.