nl

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. Unless otherwise specified, nl shall assume the text being read is in a single logical page body. The nl utility shall conform to XBD Utility Syntax Guidelines . Only one file can be named. Specify which logical page body lines shall be numbered. Recognized types and their meaning are: 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). 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 ':'. Specify the same as b type except for footer. The default for logical page footer shall be n (no lines numbered). Specify the same as b type except for header. The default type for logical page header shall be n (no lines numbered). Specify the increment value used to number logical page lines. The default shall be 1. 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). Specify the characters used in separating the line number and the corresponding text line. The default sep shall be a . Specify the initial value used to number logical page lines. The default shall be 1. The standard input shall be used if no file operand is specified, and shall be used if the file operand is '-' and the implementation treats the '-' as meaning standard input. Otherwise, the standard input shall not be used. See the INPUT FILES section. Provide a default value for the internationalization variables that are unset or null. (See XBD Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.) If set to a non-empty string value, override the values of all the other internationalization variables. Determine the locale for the behavior of ranges, equivalence classes, and multi-character collating elements within regular expressions. Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error. Determine the location of message catalogs for the processing of LC MESSAGES. When line numbers are suppressed for a portion of the page; the is also suppressed. In the preceding list, the number 6 is the default width; the -w option can change this value. In using the -d delim option, care should be taken to escape characters that have special meaning to the command interpreter. The obsolescent behavior allowing the options to be intermingled with the optional file operand is removed.