phpMan

/* Void Main's man pages */

{ phpMan } else { main(); }

MAN(1P) POSIX Programmer's Manual MAN(1P)

PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (con-
sult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on
Linux.

NAME
man - display system documentation

SYNOPSIS
man [-k] name...

DESCRIPTION
The man utility shall write information about each of the name operands. If name is the name of a standard utility, man
at a minimum shall write a message describing the syntax used by the standard utility, its options, and operands. If more
information is available, the man utility shall provide it in an implementation-defined manner.

An implementation may provide information for values of name other than the standard utilities. Standard utilities that
are listed as optional and that are not supported by the implementation either shall cause a brief message indicating
that fact to be displayed or shall cause a full display of information as described previously.

OPTIONS
The man utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guide-
lines.

The following option shall be supported:

-k Interpret name operands as keywords to be used in searching a utilities summary database that contains a brief
purpose entry for each standard utility and write lines from the summary database that match any of the keywords.
The keyword search shall produce results that are the equivalent of the output of the following command:

grep -Ei '
name
name...

This assumes that the summary-database is a text file with a single entry per line; this organization is not required and
the example using grep -Ei is merely illustrative of the type of search intended. The purpose entry to be included in the
database shall consist of a terse description of the purpose of the utility.

OPERANDS
The following operand shall be supported:

name A keyword or the name of a standard utility. When -k is not specified and name does not represent one of the stan-
dard utilities, the results are unspecified.

STDIN
Not used.

INPUT FILES
None.

ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of man:

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 international-
ization 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_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 in the summary database). The value of LC_CTYPE need
not affect the format of the information written about the name operands.

LC_MESSAGES
Determine the locale that should be used to affect the format and contents of diagnostic messages written to stan-
dard error and informative messages written to standard output.

NLSPATH
Determine the location of message catalogs for the processing of LC_MESSAGES .

PAGER Determine an output filtering command for writing the output to a terminal. Any string acceptable as a com-
mand_string operand to the sh -c command shall be valid. When standard output is a terminal device, the reference
page output shall be piped through the command. If the PAGER variable is null or not set, the command shall be
either more or another paginator utility documented in the system documentation.

ASYNCHRONOUS EVENTS
Default.

STDOUT
The man utility shall write text describing the syntax of the utility name, its options and its operands, or, when -k is
specified, lines from the summary database. The format of this text is implementation-defined.

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
None.

EXAMPLES
None.

RATIONALE
It is recognized that the man utility is only of minimal usefulness as specified. The opinion of the standard developers
was strongly divided as to how much or how little information man should be required to provide. They considered, how-
ever, that the provision of some portable way of accessing documentation would aid user portability. The arguments
against a fuller specification were:

* Large quantities of documentation should not be required on a system that does not have excess disk space.

* The current manual system does not present information in a manner that greatly aids user portability.

* A "better help system" is currently an area in which vendors feel that they can add value to their POSIX implementa-
tions.

The -f option was considered, but due to implementation differences, it was not included in this volume of
IEEE Std 1003.1-2001.

The description was changed to be more specific about what has to be displayed for a utility. The standard developers
considered it insufficient to allow a display of only the synopsis without giving a short description of what each option
and operand does.

The "purpose" entry to be included in the database can be similar to the section title (less the numeric prefix) from
this volume of IEEE Std 1003.1-2001 for each utility. These titles are similar to those used in historical systems for
this purpose.

See mailx for rationale concerning the default paginator.

The caveat in the LC_CTYPE description was added because it is not a requirement that an implementation provide reference
pages for all of its supported locales on each system; changing LC_CTYPE does not necessarily translate the reference
page into another language. This is equivalent to the current state of LC_MESSAGES in IEEE Std 1003.1-2001-locale-spe-
cific messages are not yet a requirement.

The historical MANPATH variable is not included in POSIX because no attempt is made to specify naming conventions for
reference page files, nor even to mandate that they are files at all. On some implementations they could be a true data-
base, a hypertext file, or even fixed strings within the man executable. The standard developers considered the porta-
bility of reference pages to be outside their scope of work. However, users should be aware that MANPATH is implemented
on a number of historical systems and that it can be used to tailor the search pattern for reference pages from the vari-
ous categories (utilities, functions, file formats, and so on) when the system administrator reveals the location and
conventions for reference pages on the system.

The keyword search can rely on at least the text of the section titles from these utility descriptions, and the implemen-
tation may add more keywords. The term "section titles" refers to the strings such as:

man - Display system documentation
ps - Report process status

FUTURE DIRECTIONS
None.