nl

nl linux command cheatsheet by Thamizhiniyan C S

Introduction

The nl command is used to number lines of files.

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Syntax

nl [OPTION]... [FILE]...

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Important Flags

Flags	Description
-b STYLE	Used for numbering body lines
-i NUMBER	Line number increment at each line
-n FORMAT	Insert line numbers according to FORMAT
-v NUMBER	Change first line number of the given input
-l NUMBER	Group of NUMBER empty lines are counted as one
-s STRING	Add any STRING after every logical line number
-w NUMBER	Use different NUMBER columns for line numbers

Default Options

-b t -d ':' -f n -h n -i 1 -l 1 -n 'rn' -s -v 1 -w 6

STYLE to be used with Options

Values	Description
a	Number all lines
t	Number only nonempty lines
n	Number no lines
pBRE	Number only lines that contain a match for the basic regular expression, BRE

FORMAT to be used with Options

Flags	Description
ln	Left justified, no leading zeros
rn	Right justified, no leading zeros
rz	Right justified, leading zeros

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Examples

Command	Description
nl readme.md	To display a file with line numbers (Numbers all non-empty lines)
nl -b a readme.md	To number all lines (including empty lines also)
nl -b a -l 3 readme.md	Count multiple, consecutive, non-empty lines as one
nl -i 3 readme.md	Override default increment
nl -v 4 readme.md	To make the starting line number different
nl -s "..." readme.md	Add a string literal after line numbers
nl -w 6 readme.md	Change column for line numbers
nl -b pF readme.md	To number all logical lines that match the specified REGEX (number those lines that begin with F)
nl -n ln readme.md	To print the lines using left-justified, no leading zeros number format
nl -n rn readme.md	To print the lines using right-justified, no leading zeros number format
nl -n rz readme.md	To print the lines using right-justified with leading zeros format