1MAN(1P) POSIX Programmer's Manual MAN(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 man - display system documentation
13
15 man [-k] name...
16
18 The man utility shall write information about each of the name oper‐
19 ands. If name is the name of a standard utility, man at a minimum shall
20 write a message describing the syntax used by the standard utility, its
21 options, and operands. If more information is available, the man util‐
22 ity shall provide it in an implementation-defined manner.
23 An implementation may provide information for values of name other than
25 the standard utilities. Standard utilities that are listed as optional
26 and that are not supported by the implementation either shall cause a
27 brief message indicating that fact to be displayed or shall cause a
28 full display of information as described previously.
29
31 The man utility shall conform to the Base Definitions volume of
32 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
33 The following option shall be supported:
35 -k Interpret name operands as keywords to be used in searching a
37 utilities summary database that contains a brief purpose entry
38 for each standard utility and write lines from the summary data‐
39 base that match any of the keywords. The keyword search shall
40 produce results that are the equivalent of the output of the
41 following command:
42 grep -Ei 'name name...' summary-database
45 This assumes that the summary-database is a text file with a single
47 entry per line; this organization is not required and the example using
48 grep -Ei is merely illustrative of the type of search intended. The
49 purpose entry to be included in the database shall consist of a terse
50 description of the purpose of the utility.
51
54 The following operand shall be supported:
55 name A keyword or the name of a standard utility. When -k is not
57 specified and name does not represent one of the standard utili‐
58 ties, the results are unspecified.
59
62 Not used.
63
65 None.
66
68 The following environment variables shall affect the execution of man:
69 LANG Provide a default value for the internationalization variables
71 that are unset or null. (See the Base Definitions volume of
72 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
73 ables for the precedence of internationalization variables used
74 to determine the values of locale categories.)
75 LC_ALL If set to a non-empty string value, override the values of all
77 the other internationalization variables.
78 LC_CTYPE
80 Determine the locale for the interpretation of sequences of
81 bytes of text data as characters (for example, single-byte as
82 opposed to multi-byte characters in arguments and in the summary
83 database). The value of LC_CTYPE need not affect the format of
84 the information written about the name operands.
85 LC_MESSAGES
87 Determine the locale that should be used to affect the format
88 and contents of diagnostic messages written to standard error
89 and informative messages written to standard output.
90 NLSPATH
92 Determine the location of message catalogs for the processing of
93 LC_MESSAGES .
94 PAGER Determine an output filtering command for writing the output to
96 a terminal. Any string acceptable as a command_string operand to
97 the sh -c command shall be valid. When standard output is a ter‐
98 minal device, the reference page output shall be piped through
99 the command. If the PAGER variable is null or not set, the com‐
100 mand shall be either more or another paginator utility docu‐
101 mented in the system documentation.
102
105 Default.
106
108 The man utility shall write text describing the syntax of the utility
109 name, its options and its operands, or, when -k is specified, lines
110 from the summary database. The format of this text is implementation-
111 defined.
112
114 The standard error shall be used only for diagnostic messages.
115
117 None.
118
120 None.
121
123 The following exit values shall be returned:
124 0 Successful completion.
126 >0 An error occurred.
128
131 Default.
132 The following sections are informative.
134
136 None.
137
139 None.
140
142 It is recognized that the man utility is only of minimal usefulness as
143 specified. The opinion of the standard developers was strongly divided
144 as to how much or how little information man should be required to pro‐
145 vide. They considered, however, that the provision of some portable way
146 of accessing documentation would aid user portability. The arguments
147 against a fuller specification were:
148 * Large quantities of documentation should not be required on a system
150 that does not have excess disk space.
151 * The current manual system does not present information in a manner
153 that greatly aids user portability.
154 * A "better help system" is currently an area in which vendors feel
156 that they can add value to their POSIX implementations.
157 The -f option was considered, but due to implementation differences, it
159 was not included in this volume of IEEE Std 1003.1-2001.
160 The description was changed to be more specific about what has to be
162 displayed for a utility. The standard developers considered it insuffi‐
163 cient to allow a display of only the synopsis without giving a short
164 description of what each option and operand does.
165 The "purpose" entry to be included in the database can be similar to
167 the section title (less the numeric prefix) from this volume of
168 IEEE Std 1003.1-2001 for each utility. These titles are similar to
169 those used in historical systems for this purpose.
170 See mailx for rationale concerning the default paginator.
172 The caveat in the LC_CTYPE description was added because it is not a
174 requirement that an implementation provide reference pages for all of
175 its supported locales on each system; changing LC_CTYPE does not neces‐
176 sarily translate the reference page into another language. This is
177 equivalent to the current state of LC_MESSAGES in
178 IEEE Std 1003.1-2001-locale-specific messages are not yet a require‐
179 ment.
180 The historical MANPATH variable is not included in POSIX because no
182 attempt is made to specify naming conventions for reference page files,
183 nor even to mandate that they are files at all. On some implementa‐
184 tions they could be a true database, a hypertext file, or even fixed
185 strings within the man executable. The standard developers considered
186 the portability of reference pages to be outside their scope of work.
187 However, users should be aware that MANPATH is implemented on a number
188 of historical systems and that it can be used to tailor the search pat‐
189 tern for reference pages from the various categories (utilities, func‐
190 tions, file formats, and so on) when the system administrator reveals
191 the location and conventions for reference pages on the system.
192 The keyword search can rely on at least the text of the section titles
194 from these utility descriptions, and the implementation may add more
195 keywords. The term "section titles" refers to the strings such as:
196 man - Display system documentation
199 ps - Report process status
200
202 None.
203
205 more
206
208 Portions of this text are reprinted and reproduced in electronic form
209 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
210 -- Portable Operating System Interface (POSIX), The Open Group Base
211 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
212 Electrical and Electronics Engineers, Inc and The Open Group. In the
213 event of any discrepancy between this version and the original IEEE and
214 The Open Group Standard, the original IEEE and The Open Group Standard
215 is the referee document. The original Standard can be obtained online
216 at http://www.opengroup.org/unix/online.html .
217IEEE/The Open Group 2003 MAN(1P)