How to number all lines?

To number all lines of a file using the nl command, you can use the following syntax:

nl filename.txt

This command will output the contents of filename.txt with all lines numbered.

If you want to customize the output further, you can use options like -b to specify which lines to number. For example, to number all lines, you can use:

nl -b a filename.txt

Here, -b a indicates that all lines should be numbered.

Feel free to ask if you have more questions!