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 or the standard input if
     the file argument is ommitted, 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).

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                            January 26, 2005                            BSD