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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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NL(1P) POSIX Programmer's Manual NL(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
nl — line numbering filter
nl [-p] [-b type] [-d delim] [-f type] [-h type] [-i incr] [-l num]
[-n format] [-s sep] [-v startnum] [-w width] [file]
The nl utility shall read lines from the named file or the
standard input if no file is named and shall reproduce the lines
to standard output. Lines shall be numbered on the left.
Additional functionality may be provided in accordance with the
command options in effect.
The nl utility views the text it reads in terms of logical pages.
Line numbering shall be 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
(for example, no numbering of header and footer lines while
numbering blank lines only in the body).
The starts of logical page sections shall be signaled by input
lines containing nothing but the following delimiter characters:
┌────────────┬────────────┐
│ Line │ Start of │
├────────────┼────────────┤
│ \:\:\: │ Header │
│ \:\: │ Body │
│ \: │ Footer │
└────────────┴────────────┘
Unless otherwise specified, nl shall assume the text being read
is in a single logical page body.
The nl utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines. Only one
file can be named.
The following options shall be supported:
-b type Specify which logical page body lines shall be
numbered. Recognized types and their meaning are:
a Number all lines.
t Number only non-empty lines.
n No line numbering.
pstring Number only lines that contain the basic
regular expression specified in string.
The default type for logical page body shall be t (text
lines numbered).
-d delim Specify the delimiter characters that indicate the
start of a logical page section. These can be changed
from the default characters "\:" to two user-specified
characters. If only one character is entered, the
second character shall remain the default character
':'.
-f type Specify the same as b type except for footer. The
default for logical page footer shall be n (no lines
numbered).
-h type Specify the same as b type except for header. The
default type for logical page header shall be n (no
lines numbered).
-i incr Specify the increment value used to number logical page
lines. The default shall be 1.
-l num Specify the number of blank lines to be considered as
one. For example, -l 2 results in only the second
adjacent blank line being numbered (if the appropriate
-h a, -b a, or -f a option is set). The default shall
be 1.
-n format Specify the line numbering format. Recognized values
are: ln, left justified, leading zeros suppressed; rn,
right justified, leading zeros suppressed; rz, right
justified, leading zeros kept. The default format shall
be rn (right justified).
-p Specify that 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
shall be a <tab>.
-v startnum
Specify the initial value used to number logical page
lines. The default shall be 1.
-w width Specify the number of characters to be used for the
line number. The default width shall be 6.
The following operand shall be supported:
file A pathname of a text file to be line-numbered.
The standard input shall be used if no file operand is specified,
and shall be used if the file operand is '-' and the
implementation treats the '-' as meaning standard input.
Otherwise, the standard input shall not be used. See the INPUT
FILES section.
The input file shall be a text file.
The following environment variables shall affect the execution of
nl:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_COLLATE
Determine the locale for the behavior of ranges,
equivalence classes, and multi-character collating
elements within regular expressions.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments and input files), the behavior
of character classes within regular expressions, and
for deciding which characters are in character class
graph (for the -b t, -f t, and -h t options).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
The standard output shall be a text file in the following format:
"%s%s%s", <line number>, <separator>, <input line>
where <line number> is one of the following numeric formats:
%6d When the rn format is used (the default; see -n).
%06d When the rz format is used.
%-6d When the ln format is used.
<empty> When line numbers are suppressed for a portion of the
page; the <separator> is also suppressed.
In the preceding list, the number 6 is the default width; the -w
option can change this value.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
In using the -d delim option, care should be taken to escape
characters that have special meaning to the command interpreter.
The command:
nl -v 10 -i 10 -d \!+ file1
numbers file1 starting at line number 10 with an increment of 10.
The logical page delimiter is "!+". Note that the '!' has to be
escaped when using csh as a command interpreter because of its
history substitution syntax. For ksh and sh the escape is not
necessary, but does not do any harm.
None.
None.
pr(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 NL(1P)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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