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



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

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 shall read lines from the named file or the standard input if no file is named and shall repro-
       duce the lines to standard output. Lines shall be numbered on the left. Additional functionality  may  be  pro-
       vided 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
       The nl utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility Syn-
       tax 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 for-
              mat 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
       The following operand shall be supported:

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


STDIN
       The standard input is a text file that is used if no file operand is given.

INPUT FILES
       The input file named by the file operand is a text file.

ENVIRONMENT VARIABLES
       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 IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for  the  prece-
              dence 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 ele-
              ments within regular expressions.

       LC_CTYPE
              Determine  the locale for the interpretation of sequences of bytes of text data as characters (for exam-
              ple, 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  writ-
              ten to standard error.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .


ASYNCHRONOUS EVENTS
       Default.

STDOUT
       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
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

        0     Successful completion.

       >0     An error occurred.


CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       In  using  the -d delim option, care should be taken to escape characters that have special meaning to the com-
       mand interpreter.

EXAMPLES
       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 syn-
       tax. For ksh and sh the escape is not necessary, but does not do any harm.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       pr

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard  for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 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 .



IEEE/The Open Group                  2003                               NL(1P)