nl

nl

Purpose

Add line numbers to nonblank lines of text in a file and write to standard output.

Syntax

nl [options] []

Options

-ba numbers all lines.

-bt numbers text lines only (the default).

-sc separates text from line numbers with the character c (the default is tab).

-wn uses n columns to show the line numbers.

Description

The nl command adds a line number to each nonblank line of text from a file and writes the lines to standard output. Suppose the file sample.txt has the following lines:

A line followed by a blank line and then another non-blank line.

The nl command applied to this file produces the following result: 

nl sample.txt
      1  A line followed by a blank line and
      2  then another non-blank line.