1MAN(P) POSIX Programmer's Manual MAN(P)
2
6 man - display system documentation
7
9 man [-k] name...
10
12 The man utility shall write information about each of the name oper‐
13 ands. If name is the name of a standard utility, man at a minimum shall
14 write a message describing the syntax used by the standard utility, its
15 options, and operands. If more information is available, the man util‐
16 ity shall provide it in an implementation-defined manner.
17 An implementation may provide information for values of name other than
19 the standard utilities. Standard utilities that are listed as optional
20 and that are not supported by the implementation either shall cause a
21 brief message indicating that fact to be displayed or shall cause a
22 full display of information as described previously.
23
25 The man utility shall conform to the Base Definitions volume of
26 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
27 The following option shall be supported:
29 -k Interpret name operands as keywords to be used in searching a
31 utilities summary database that contains a brief purpose entry
32 for each standard utility and write lines from the summary data‐
33 base that match any of the keywords. The keyword search shall
34 produce results that are the equivalent of the output of the
35 following command:
36 grep -Ei '
39 name
40 name...
41 This assumes that the summary-database is a text file with a single
43 entry per line; this organization is not required and the example using
44 grep -Ei is merely illustrative of the type of search intended. The
45 purpose entry to be included in the database shall consist of a terse
46 description of the purpose of the utility.
47
50 The following operand shall be supported:
51 name A keyword or the name of a standard utility. When -k is not
53 specified and name does not represent one of the standard utili‐
54 ties, the results are unspecified.
55
58 Not used.
59
61 None.
62
64 The following environment variables shall affect the execution of man:
65 LANG Provide a default value for the internationalization variables
67 that are unset or null. (See the Base Definitions volume of
68 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
69 ables for the precedence of internationalization variables used
70 to determine the values of locale categories.)
71 LC_ALL If set to a non-empty string value, override the values of all
73 the other internationalization variables.
74 LC_CTYPE
76 Determine the locale for the interpretation of sequences of
77 bytes of text data as characters (for example, single-byte as
78 opposed to multi-byte characters in arguments and in the summary
79 database). The value of LC_CTYPE need not affect the format of
80 the information written about the name operands.
81 LC_MESSAGES
83 Determine the locale that should be used to affect the format
84 and contents of diagnostic messages written to standard error
85 and informative messages written to standard output.
86 NLSPATH
88 Determine the location of message catalogs for the processing of
89 LC_MESSAGES .
90 PAGER Determine an output filtering command for writing the output to
92 a terminal. Any string acceptable as a command_string operand to
93 the sh -c command shall be valid. When standard output is a ter‐
94 minal device, the reference page output shall be piped through
95 the command. If the PAGER variable is null or not set, the com‐
96 mand shall be either more or another paginator utility docu‐
97 mented in the system documentation.
98
101 Default.
102
104 The man utility shall write text describing the syntax of the utility
105 name, its options and its operands, or, when -k is specified, lines
106 from the summary database. The format of this text is implementation-
107 defined.
108
110 The standard error shall be used only for diagnostic messages.
111
113 None.
114
116 None.
117
119 The following exit values shall be returned:
120 0 Successful completion.
122 >0 An error occurred.
124
127 Default.
128 The following sections are informative.
130
132 None.
133
135 None.
136
138 It is recognized that the man utility is only of minimal usefulness as
139 specified. The opinion of the standard developers was strongly divided
140 as to how much or how little information man should be required to pro‐
141 vide. They considered, however, that the provision of some portable way
142 of accessing documentation would aid user portability. The arguments
143 against a fuller specification were:
144 * Large quantities of documentation should not be required on a system
146 that does not have excess disk space.
147 * The current manual system does not present information in a manner
149 that greatly aids user portability.
150 * A "better help system" is currently an area in which vendors feel
152 that they can add value to their POSIX implementations.
153 The -f option was considered, but due to implementation differences, it
155 was not included in this volume of IEEE Std 1003.1-2001.
156 The description was changed to be more specific about what has to be
158 displayed for a utility. The standard developers considered it insuffi‐
159 cient to allow a display of only the synopsis without giving a short
160 description of what each option and operand does.
161 The "purpose" entry to be included in the database can be similar to
163 the section title (less the numeric prefix) from this volume of
164 IEEE Std 1003.1-2001 for each utility. These titles are similar to
165 those used in historical systems for this purpose.
166 See mailx for rationale concerning the default paginator.
168 The caveat in the LC_CTYPE description was added because it is not a
170 requirement that an implementation provide reference pages for all of
171 its supported locales on each system; changing LC_CTYPE does not neces‐
172 sarily translate the reference page into another language. This is
173 equivalent to the current state of LC_MESSAGES in
174 IEEE Std 1003.1-2001-locale-specific messages are not yet a require‐
175 ment.
176 The historical MANPATH variable is not included in POSIX because no
178 attempt is made to specify naming conventions for reference page files,
179 nor even to mandate that they are files at all. On some implementa‐
180 tions they could be a true database, a hypertext file, or even fixed
181 strings within the man executable. The standard developers considered
182 the portability of reference pages to be outside their scope of work.
183 However, users should be aware that MANPATH is implemented on a number
184 of historical systems and that it can be used to tailor the search pat‐
185 tern for reference pages from the various categories (utilities, func‐
186 tions, file formats, and so on) when the system administrator reveals
187 the location and conventions for reference pages on the system.
188 The keyword search can rely on at least the text of the section titles
190 from these utility descriptions, and the implementation may add more
191 keywords. The term "section titles" refers to the strings such as:
192 man - Display system documentation
195 ps - Report process status
196
198 None.
199
201 more
202
204 Portions of this text are reprinted and reproduced in electronic form
205 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
206 -- Portable Operating System Interface (POSIX), The Open Group Base
207 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
208 Electrical and Electronics Engineers, Inc and The Open Group. In the
209 event of any discrepancy between this version and the original IEEE and
210 The Open Group Standard, the original IEEE and The Open Group Standard
211 is the referee document. The original Standard can be obtained online
212 at http://www.opengroup.org/unix/online.html .
213IEEE/The Open Group 2003 MAN(P)