NL(1) BSD General Commands Manual NL(1)NAMEnl — line numbering filter
SYNOPSISnl [-p] [-b type] [-d delim] [-f type] [-h type] [-i incr] [-l num]
[-n format] [-s sep] [-v startnum] [-w width] [file]
DESCRIPTION
The nl utility reads lines from the named file or the standard input if
the file argument is omitted, applies a configurable line numbering fil‐
ter operation and writes the result to the standard output.
The nl utility treats the text it reads in terms of logical pages.
Unless specified otherwise, line numbering is reset at the start of each
logical page. A logical page consists of a header, a body and a footer
section; empty sections are valid. Different line numbering options are
independently available for header, body and footer sections.
The starts of logical page sections are signaled by input lines contain‐
ing nothing but one of the following sequences of delimiter characters:
Line "Start of"
\:\:\: header
\:\: body
\: footer
If the input does not contain any logical page section signaling direc‐
tives, the text being read is assumed to consist of a single logical page
body.
The following options are available:
-b type
Specify the logical page body lines to be numbered. Recognized
type arguments are:
a Number all lines.
t Number only non-empty lines.
n No line numbering.
pexpr Number only those lines that contain the basic regular
expression specified by expr.
The default type for logical page body lines is t.
-d delim
Specify the delimiter characters used to indicate the start of a
logical page section in the input file. At most two characters
may be specified; if only one character is specified, the first
character is replaced and the second character remains unchanged.
The default delim characters are ``\:''.
-f type
Specify the same as -b type except for logical page footer lines.
The default type for logical page footer lines is n.
-h type
Specify the same as -b type except for logical page header lines.
The default type for logical page header lines is n.
-i incr
Specify the increment value used to number logical page lines.
The default incr value is 1.
-l num If numbering of all lines is specified for the current logical
section using the corresponding -b a, -f a or -h a option, spec‐
ify the number of adjacent blank lines to be considered as one.
For example, -l 2 results in only the second adjacent blank line
being numbered. The default num value is 1.
-n format
Specify the line numbering output format. Recognized format
arguments are:
ln Left justified.
rn Right justified, leading zeros suppressed.
rz Right justified, leading zeros kept.
The default format is rn.
-p Specify that line numbering should not be restarted at logical
page delimiters.
-s sep Specify the characters used in separating the line number and the
corresponding text line. The default sep setting is a single tab
character.
-v startnum
Specify the initial value used to number logical page lines; see
also the description of the -p option. The default startnum
value is 1.
-w width
Specify the number of characters to be occupied by the line num‐
ber; in case the width is insufficient to hold the line number,
it will be truncated to its width least significant digits. The
default width is 6.
EXIT STATUS
The nl utility exits 0 on success, and >0 if an error occurs.
SEE ALSOpr(1)STANDARDS
The nl utility conforms to X/Open Portability Guide Issue 4, Version 2
(“XPG4.2”) with the exception of not supporting the intermingling of the
file operand with the options, which the standard considers an obsoles‐
cent feature to be removed from a further issue.
HISTORY
The nl utility first appeared in AT&T System V Release 2 UNIX.
BSD February 15, 1999 BSD
