NAME
nl —
line numbering filter
SYNOPSIS
nl |
[-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, applies a configurable line numbering filter
operation, and writes the result to the standard output. If
file is a single dash (‘-’) or absent,
nl reads from the standard input.
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 containing
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 directives, 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, specify 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
number; if 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 ALSO
pr(1)
STANDARDS
The
nl utility is compliant with the
X/Open
Portability Guide Issue 4, Version 2 (“XPG4.2”)
specification.
HISTORY
The
nl utility first appeared in
AT&T
System V Release 2 UNIX.