NL(1)							    BSD General Commands Manual 						     NL(1)

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 signalled by input lines containing nothing but one of the following sequences of delimiter charac-
     ters:

	   Line      Start of
	   :::    header
	   ::      body
	   :	     footer

     If the input does not contain any logical page section signalling 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, spec-
		  ify 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; in case the width is insufficient to hold the line number,
		  it will be truncated to its width least significant digits.  The default width is 6.

ENVIRONMENT

     The LANG, LC_ALL, LC_CTYPE and LC_COLLATE environment variables affect the execution of nl as described in environ(7).

EXIT STATUS

     The nl utility exits 0 on success, and >0 if an error occurs.

SEE ALSO

     jot(1), pr(1)

STANDARDS

     The nl utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY

     The nl utility first appeared in AT&T System V Release 2 UNIX.

BUGS

     Input lines are limited to LINE_MAX (2048) bytes in length.

BSD
								    May 4, 2014 							       BSD