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nl - line numbering filter

 

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 or the standard input if
      the file argument is omitted, applies a configurable line numbering fil‐
      ter operation and writes the result to the standard output.
 
      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 contain‐
      ing nothing but one of the following sequences of delimiter characters:
 
            Line      Start of
            \:\:\:    header
            \:\:      body
            \:        footer
 
      If the input does not contain any logical page section signalling direc‐
      tives, 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.  Recog‐
                   nized 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 regu‐
                           lar 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 speci‐
                   fied, the first character is replaced and the second charac‐
                   ter 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 logi‐
                   cal section using the corresponding -b a, -f a or -h a
                   option, specify 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 logi‐
                   cal 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).
      The nl utility exits 0 on success, and >0 if an error occurs.
      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.2 UNIX.
 

BUGS

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

Sections

Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.