NL(1)                        General Commands Manual                       NL(1)

     nl – line numbering filter

     nl [-p] [-b type] [-d delim] [-f type] [-h type] [-i incr] [-l num]
        [-n format] [-s sep] [-v startnum] [-w width] [file]

     The nl utility reads lines from the named file or the standard input if the
     file argument is omitted, applies a configurable line numbering filter
     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 containing
     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
     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, 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
                        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.

     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)

     The nl utility conforms to IEEE Std 1003.1-2001 (“POSIX.1”).

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

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

macOS 12.1                      January 26, 2005                      macOS 12.1