Ubuntu Manpage: 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 shall read lines from the named file or the standard input if no file is named and shall
       reproduce the lines to standard output. Lines shall be numbered on the left. Additional functionality may
       be provided 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 Syntax 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 format 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  precedence  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 elements within regular expressions.

       LC_CTYPE
              Determine  the locale for the interpretation of sequences of bytes of text data as characters (for
              example, 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
              written 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
       command 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 syntax. For ksh and sh the escape is not necessary, but does not do any harm.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  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 .