1NL(1P) POSIX Programmer's Manual NL(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 nl — line numbering filter
13
15 nl [-p] [-b type] [-d delim] [-f type] [-h type] [-i incr] [-l num]
16 [-n format] [-s sep] [-v startnum] [-w width] [file]
17
19 The nl utility shall read lines from the named file or the standard
20 input if no file is named and shall reproduce the lines to standard
21 output. Lines shall be numbered on the left. Additional functionality
22 may be provided in accordance with the command options in effect.
23 The nl utility views the text it reads in terms of logical pages. Line
25 numbering shall be reset at the start of each logical page. A logical
26 page consists of a header, a body, and a footer section. Empty sections
27 are valid. Different line numbering options are independently available
28 for header, body, and footer (for example, no numbering of header and
29 footer lines while numbering blank lines only in the body).
30 The starts of logical page sections shall be signaled by input lines
32 containing nothing but the following delimiter characters:
33 ┌───────────┬────────────┐
35 │ Line │ Start of │
36 ├───────────┼────────────┤
37 │\:\:\: │ Header │
38 │\:\: │ Body │
39 │\: │ Footer │
40 └───────────┴────────────┘
41 Unless otherwise specified, nl shall assume the text being read is in a
42 single logical page body.
43
45 The nl utility shall conform to the Base Definitions volume of
46 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines. Only one file
47 can be named.
48 The following options shall be supported:
50 -b type Specify which logical page body lines shall be numbered. Rec‐
52 ognized types and their meaning are:
53 a Number all lines.
55 t Number only non-empty lines.
57 n No line numbering.
59 pstring Number only lines that contain the basic regular
61 expression specified in string.
62 The default type for logical page body shall be t (text lines
64 numbered).
65 -d delim Specify the delimiter characters that indicate the start of a
67 logical page section. These can be changed from the default
68 characters "\:" to two user-specified characters. If only one
69 character is entered, the second character shall remain the
70 default character ':'.
71 -f type Specify the same as b type except for footer. The default for
73 logical page footer shall be n (no lines numbered).
74 -h type Specify the same as b type except for header. The default
76 type for logical page header shall be n (no lines numbered).
77 -i incr Specify the increment value used to number logical page
79 lines. The default shall be 1.
80 -l num Specify the number of blank lines to be considered as one.
82 For example, -l 2 results in only the second adjacent blank
83 line being numbered (if the appropriate -h a, -b a, or -f a
84 option is set). The default shall be 1.
85 -n format Specify the line numbering format. Recognized values are: ln,
87 left justified, leading zeros suppressed; rn, right justi‐
88 fied, leading zeros suppressed; rz, right justified, leading
89 zeros kept. The default format shall be rn (right justified).
90 -p Specify that numbering should not be restarted at logical
92 page delimiters.
93 -s sep Specify the characters used in separating the line number and
95 the corresponding text line. The default sep shall be a
96 <tab>.
97 -v startnum
99 Specify the initial value used to number logical page lines.
100 The default shall be 1.
101 -w width Specify the number of characters to be used for the line num‐
103 ber. The default width shall be 6.
104
106 The following operand shall be supported:
107 file A pathname of a text file to be line-numbered.
109
111 The standard input shall be used if no file operand is specified, and
112 shall be used if the file operand is '-' and the implementation treats
113 the '-' as meaning standard input. Otherwise, the standard input shall
114 not be used. See the INPUT FILES section.
115
117 The input file shall be a text file.
118
120 The following environment variables shall affect the execution of nl:
121 LANG Provide a default value for the internationalization vari‐
123 ables that are unset or null. (See the Base Definitions vol‐
124 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
125 ables for the precedence of internationalization variables
126 used to determine the values of locale categories.)
127 LC_ALL If set to a non-empty string value, override the values of
129 all the other internationalization variables.
130 LC_COLLATE
132 Determine the locale for the behavior of ranges, equivalence
133 classes, and multi-character collating elements within regu‐
134 lar expressions.
135 LC_CTYPE Determine the locale for the interpretation of sequences of
137 bytes of text data as characters (for example, single-byte as
138 opposed to multi-byte characters in arguments and input
139 files), the behavior of character classes within regular
140 expressions, and for deciding which characters are in charac‐
141 ter class graph (for the -b t, -f t, and -h t options).
142 LC_MESSAGES
144 Determine the locale that should be used to affect the format
145 and contents of diagnostic messages written to standard
146 error.
147 NLSPATH Determine the location of message catalogs for the processing
149 of LC_MESSAGES.
150
152 Default.
153
155 The standard output shall be a text file in the following format:
156 "%s%s%s", <line number>, <separator>, <input line>
159 where <line number> is one of the following numeric formats:
161 %6d When the rn format is used (the default; see -n).
163 %06d When the rz format is used.
165 %-6d When the ln format is used.
167 <empty> When line numbers are suppressed for a portion of the page;
169 the <separator> is also suppressed.
170 In the preceding list, the number 6 is the default width; the -w option
172 can change this value.
173
175 The standard error shall be used only for diagnostic messages.
176
178 None.
179
181 None.
182
184 The following exit values shall be returned:
185 0 Successful completion.
187 >0 An error occurred.
189
191 Default.
192 The following sections are informative.
194
196 In using the -d delim option, care should be taken to escape characters
197 that have special meaning to the command interpreter.
198
200 The command:
201 nl -v 10 -i 10 -d \!+ file1
204 numbers file1 starting at line number 10 with an increment of 10. The
206 logical page delimiter is "!+". Note that the '!' has to be escaped
207 when using csh as a command interpreter because of its history substi‐
208 tution syntax. For ksh and sh the escape is not necessary, but does
209 not do any harm.
210
212 None.
213
215 None.
216
218 pr
219 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
221 Variables, Section 12.2, Utility Syntax Guidelines
222
224 Portions of this text are reprinted and reproduced in electronic form
225 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
226 table Operating System Interface (POSIX), The Open Group Base Specifi‐
227 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
228 Electrical and Electronics Engineers, Inc and The Open Group. In the
229 event of any discrepancy between this version and the original IEEE and
230 The Open Group Standard, the original IEEE and The Open Group Standard
231 is the referee document. The original Standard can be obtained online
232 at http://www.opengroup.org/unix/online.html .
233 Any typographical or formatting errors that appear in this page are
235 most likely to have been introduced during the conversion of the source
236 files to man page format. To report such errors, see https://www.ker‐
237 nel.org/doc/man-pages/reporting_bugs.html .
238IEEE/The Open Group 2017 NL(1P)