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.1‐2008, 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

       −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

       −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

       −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 nl:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1‐2008, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale

       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

                 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.1‐2008, 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, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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                 2013                              NL(1P)