nl(1p) — Linux manual page


NL(1P)                  POSIX Programmer's Manual                 NL(1P)

PROLOG         top

       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.

NAME         top

       nl — line numbering filter

SYNOPSIS         top

       nl [-p] [-b type] [-d delim] [-f type] [-h type] [-i incr] [-l num]
           [-n format] [-s sep] [-v startnum] [-w width] [file]

DESCRIPTION         top

       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.

OPTIONS         top

       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

       -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.

OPERANDS         top

       The following operand shall be supported:

       file      A pathname of a text file to be line-numbered.

STDIN         top

       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.

INPUT FILES         top

       The input file shall be a text file.


       The following environment variables shall affect the execution of

       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.

                 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).

                 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.



STDOUT         top

       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.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top




EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.



       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.

EXAMPLES         top

       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.

RATIONALE         top




SEE ALSO         top


       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT         top

       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 .

       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 .

IEEE/The Open Group               2017                            NL(1P)