Linux nl command

Updated: 05/04/2019 by Computer Hope
nl command

On Unix-like operating systems, the nl command numbers the lines in a file.

This document describes the GNU/Linux version of nl.


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


-b, --body-numbering=STYLE use STYLE for numbering body lines
-d, --section-delimiter=CC use CC for separating logical pages
-f, --footer-numbering=STYLE use STYLE for numbering footer lines
-h, --header-numbering=STYLE use STYLE for numbering header lines
-i, --line-increment=NUMBER line number increment at each line
-l, --join-blank-lines=NUMBER group of NUMBER empty lines counted as one
-n, --number-format=FORMAT insert line numbers according to FORMAT
-p, --no-renumber do not reset line numbers at logical pages
-s, --number-separator=STRING add STRING after (possible) line number
-v, --starting-line-number=NUMBER first line number on each logical page
-w, --number-width=NUMBER use NUMBER columns for line numbers
--help display help and exit
--version display version information and exit

By default, nl selects -v1 -i1 -l1 -sTAB -w6 -nrn -hn -bt -fn. CC are two delimiter characters for separating logical pages. A missing second character implies a colon (:).

For a backslash (\), two backslashes (\\).

STYLE is one of:

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 is one of:

ln left justified, no leading zeros
rn right justified, no leading zeros
rz right justified, leading zeros


cat list.txt
nl list.txt
     1	apples
     2	oranges
     3	potatoes
     4	lemons
     5	garlic

In the above example, we use the cat command to display the contents of list.txt. Then we use nl to number each line and display the result to standard output.

nl list.txt > nlist.txt
cat nlist.txt
     1	apples
     2	oranges
     3	potatoes
     4	lemons
     5	garlic

In the above example, we run the same nl command, but redirect the output to a new file, nlist.txt. Then we use cat to display the results.

wc — Display a count of lines, words, and characters in a file.