mirror of https://github.com/mkerrisk/man-pages
1147 lines
34 KiB
Groff
1147 lines
34 KiB
Groff
.\" (C) Copyright 1992-1999 Rickard E. Faith and David A. Wheeler
|
|
.\" (faith@cs.unc.edu and dwheeler@ida.org)
|
|
.\" and (C) Copyright 2007 Michael Kerrisk <mtk.manpages@gmail.com>
|
|
.\"
|
|
.\" %%%LICENSE_START(VERBATIM)
|
|
.\" Permission is granted to make and distribute verbatim copies of this
|
|
.\" manual provided the copyright notice and this permission notice are
|
|
.\" preserved on all copies.
|
|
.\"
|
|
.\" Permission is granted to copy and distribute modified versions of this
|
|
.\" manual under the conditions for verbatim copying, provided that the
|
|
.\" entire resulting derived work is distributed under the terms of a
|
|
.\" permission notice identical to this one.
|
|
.\"
|
|
.\" Since the Linux kernel and libraries are constantly changing, this
|
|
.\" manual page may be incorrect or out-of-date. The author(s) assume no
|
|
.\" responsibility for errors or omissions, or for damages resulting from
|
|
.\" the use of the information contained herein. The author(s) may not
|
|
.\" have taken the same level of care in the production of this manual,
|
|
.\" which is licensed free of charge, as they might when working
|
|
.\" professionally.
|
|
.\"
|
|
.\" Formatted or processed versions of this manual, if unaccompanied by
|
|
.\" the source, must acknowledge the copyright and authors of this work.
|
|
.\" %%%LICENSE_END
|
|
.\"
|
|
.\" 2007-05-30 created by mtk, using text from old man.7 plus
|
|
.\" rewrites and additional text.
|
|
.\"
|
|
.TH MAN-PAGES 7 2021-03-22 "Linux" "Linux Programmer's Manual"
|
|
.SH NAME
|
|
man-pages \- conventions for writing Linux man pages
|
|
.SH SYNOPSIS
|
|
.B man
|
|
.RI [ section ]
|
|
.I title
|
|
.SH DESCRIPTION
|
|
This page describes the conventions that should be employed
|
|
when writing man pages for the Linux \fIman-pages\fP project,
|
|
which documents the user-space API provided by the Linux kernel
|
|
and the GNU C library.
|
|
The project thus provides most of the pages in Section 2,
|
|
many of the pages that appear in Sections 3, 4, and 7,
|
|
and a few of the pages that appear in Sections 1, 5, and 8
|
|
of the man pages on a Linux system.
|
|
The conventions described on this page may also be useful
|
|
for authors writing man pages for other projects.
|
|
.SS Sections of the manual pages
|
|
The manual Sections are traditionally defined as follows:
|
|
.TP
|
|
.B 1 User commands (Programs)
|
|
Commands that can be executed by the user from within
|
|
a shell.
|
|
.TP
|
|
.B 2 System calls
|
|
Functions which wrap operations performed by the kernel.
|
|
.TP
|
|
.B 3 Library calls
|
|
All library functions excluding the system call wrappers
|
|
(Most of the
|
|
.I libc
|
|
functions).
|
|
.TP
|
|
.B 4 Special files (devices)
|
|
Files found in
|
|
.I /dev
|
|
which allow to access to devices through the kernel.
|
|
.TP
|
|
.B 5 File formats and configuration files
|
|
Describes various human-readable file formats and configuration files.
|
|
.TP
|
|
.B 6 Games
|
|
Games and funny little programs available on the system.
|
|
.TP
|
|
.B 7 Overview, conventions, and miscellaneous
|
|
Overviews or descriptions of various topics, conventions, and protocols,
|
|
character set standards, the standard filesystem layout, and miscellaneous
|
|
other things.
|
|
.TP
|
|
.B 8 System management commands
|
|
Commands like
|
|
.BR mount (8),
|
|
many of which only root can execute.
|
|
.\" .TP
|
|
.\" .B 9 Kernel routines
|
|
.\" This is an obsolete manual section.
|
|
.\" Once it was thought a good idea to document the Linux kernel here,
|
|
.\" but in fact very little has been documented, and the documentation
|
|
.\" that exists is outdated already.
|
|
.\" There are better sources of
|
|
.\" information for kernel developers.
|
|
.SS Macro package
|
|
New manual pages should be marked up using the
|
|
.B groff an.tmac
|
|
package described in
|
|
.BR man (7).
|
|
This choice is mainly for consistency: the vast majority of
|
|
existing Linux manual pages are marked up using these macros.
|
|
.SS Conventions for source file layout
|
|
Please limit source code line length to no more than about 75 characters
|
|
wherever possible.
|
|
This helps avoid line-wrapping in some mail clients when patches are
|
|
submitted inline.
|
|
.SS Title line
|
|
The first command in a man page should be a
|
|
.B TH
|
|
command:
|
|
.PP
|
|
.RS
|
|
.B \&.TH
|
|
.I "title section date source manual"
|
|
.RE
|
|
.PP
|
|
The arguments of the command are as follows:
|
|
.TP
|
|
.I title
|
|
The title of the man page, written in all caps (e.g.,
|
|
.IR MAN-PAGES ).
|
|
.TP
|
|
.I section
|
|
The section number in which the man page should be placed (e.g.,
|
|
.IR 7 ).
|
|
.TP
|
|
.I date
|
|
The date of the last nontrivial change that was made to the man page.
|
|
(Within the
|
|
.I man-pages
|
|
project, the necessary updates to these timestamps are handled
|
|
automatically by scripts, so there is no need to manually update
|
|
them as part of a patch.)
|
|
Dates should be written in the form YYYY-MM-DD.
|
|
.TP
|
|
.I source
|
|
The source of the command, function, or system call.
|
|
.IP
|
|
For those few \fIman-pages\fP pages in Sections 1 and 8,
|
|
probably you just want to write
|
|
.IR GNU .
|
|
.IP
|
|
For system calls, just write
|
|
.IR "Linux" .
|
|
(An earlier practice was to write the version number
|
|
of the kernel from which the manual page was being written/checked.
|
|
However, this was never done consistently, and so was
|
|
probably worse than including no version number.
|
|
Henceforth, avoid including a version number.)
|
|
.IP
|
|
For library calls that are part of glibc or one of the
|
|
other common GNU libraries, just use
|
|
.IR "GNU C Library" ", " GNU ,
|
|
or an empty string.
|
|
.IP
|
|
For Section 4 pages, use
|
|
.IR "Linux" .
|
|
.IP
|
|
In cases of doubt, just write
|
|
.IR Linux ", or " GNU .
|
|
.TP
|
|
.I manual
|
|
The title of the manual (e.g., for Section 2 and 3 pages in
|
|
the \fIman-pages\fP package, use
|
|
.IR "Linux Programmer's Manual" ).
|
|
.\"
|
|
.SS Sections within a manual page
|
|
The list below shows conventional or suggested sections.
|
|
Most manual pages should include at least the
|
|
.B highlighted
|
|
sections.
|
|
Arrange a new manual page so that sections
|
|
are placed in the order shown in the list.
|
|
.PP
|
|
.RS
|
|
.TS
|
|
l l.
|
|
\fBNAME\fP
|
|
\fBSYNOPSIS\fP
|
|
CONFIGURATION [Normally only in Section 4]
|
|
\fBDESCRIPTION\fP
|
|
OPTIONS [Normally only in Sections 1, 8]
|
|
EXIT STATUS [Normally only in Sections 1, 8]
|
|
RETURN VALUE [Normally only in Sections 2, 3]
|
|
.\" May 07: Few current man pages have an ERROR HANDLING section,,,
|
|
.\" ERROR HANDLING,
|
|
ERRORS [Typically only in Sections 2, 3]
|
|
.\" May 07: Almost no current man pages have a USAGE section,,,
|
|
.\" USAGE,
|
|
.\" DIAGNOSTICS,
|
|
.\" May 07: Almost no current man pages have a SECURITY section,,,
|
|
.\" SECURITY,
|
|
ENVIRONMENT
|
|
FILES
|
|
VERSIONS [Normally only in Sections 2, 3]
|
|
ATTRIBUTES [Normally only in Sections 2, 3]
|
|
CONFORMING TO
|
|
NOTES
|
|
BUGS
|
|
EXAMPLES
|
|
.\" AUTHORS sections are discouraged
|
|
AUTHORS [Discouraged]
|
|
REPORTING BUGS [Not used in man-pages]
|
|
COPYRIGHT [Not used in man-pages]
|
|
\fBSEE ALSO\fP
|
|
.TE
|
|
.RE
|
|
.PP
|
|
.IR "Where a traditional heading would apply" ", " "please use it" ;
|
|
this kind of consistency can make the information easier to understand.
|
|
If you must, you can create your own
|
|
headings if they make things easier to understand (this can
|
|
be especially useful for pages in Sections 4 and 5).
|
|
However, before doing this, consider whether you could use the
|
|
traditional headings, with some subsections (\fI.SS\fP) within
|
|
those sections.
|
|
.PP
|
|
The following list elaborates on the contents of each of
|
|
the above sections.
|
|
.TP
|
|
.B NAME
|
|
The name of this manual page.
|
|
.IP
|
|
See
|
|
.BR man (7)
|
|
for important details of the line(s) that should follow the
|
|
\fB.SH NAME\fP command.
|
|
All words in this line (including the word immediately
|
|
following the "\e\-") should be in lowercase,
|
|
except where English or technical terminological convention
|
|
dictates otherwise.
|
|
.TP
|
|
.B SYNOPSIS
|
|
A brief summary of the command or function's interface.
|
|
.IP
|
|
For commands, this shows the syntax of the command and its arguments
|
|
(including options);
|
|
boldface is used for as-is text and italics are used to
|
|
indicate replaceable arguments.
|
|
Brackets ([]) surround optional arguments, vertical bars (|)
|
|
separate choices, and ellipses (\&...) can be repeated.
|
|
For functions, it shows any required data declarations or
|
|
.B #include
|
|
directives, followed by the function declaration.
|
|
.IP
|
|
Where a feature test macro must be defined in order to obtain
|
|
the declaration of a function (or a variable) from a header file,
|
|
then the SYNOPSIS should indicate this, as described in
|
|
.BR feature_test_macros (7).
|
|
.\" FIXME . Say something here about compiler options
|
|
.TP
|
|
.B CONFIGURATION
|
|
Configuration details for a device.
|
|
.IP
|
|
This section normally appears only in Section 4 pages.
|
|
.TP
|
|
.B DESCRIPTION
|
|
An explanation of what the program, function, or format does.
|
|
.IP
|
|
Discuss how it interacts with files and standard input, and what it
|
|
produces on standard output or standard error.
|
|
Omit internals and implementation details unless they're critical for
|
|
understanding the interface.
|
|
Describe the usual case;
|
|
for information on command-line options of a program use the
|
|
.B OPTIONS
|
|
section.
|
|
.\" If there is some kind of input grammar or complex set of subcommands,
|
|
.\" consider describing them in a separate
|
|
.\" .B USAGE
|
|
.\" section (and just place an overview in the
|
|
.\" .B DESCRIPTION
|
|
.\" section).
|
|
.IP
|
|
When describing new behavior or new flags for
|
|
a system call or library function,
|
|
be careful to note the kernel or C library version
|
|
that introduced the change.
|
|
The preferred method of noting this information for flags is as part of a
|
|
.B .TP
|
|
list, in the following form (here, for a new system call flag):
|
|
.RS 16
|
|
.TP
|
|
.BR XYZ_FLAG " (since Linux 3.7)"
|
|
Description of flag...
|
|
.RE
|
|
.IP
|
|
Including version information is especially useful to users
|
|
who are constrained to using older kernel or C library versions
|
|
(which is typical in embedded systems, for example).
|
|
.TP
|
|
.B OPTIONS
|
|
A description of the command-line options accepted by a
|
|
program and how they change its behavior.
|
|
.IP
|
|
This section should appear only for Section 1 and 8 manual pages.
|
|
.\" .TP
|
|
.\" .B USAGE
|
|
.\" describes the grammar of any sublanguage this implements.
|
|
.TP
|
|
.B EXIT STATUS
|
|
A list of the possible exit status values of a program and
|
|
the conditions that cause these values to be returned.
|
|
.IP
|
|
This section should appear only for Section 1 and 8 manual pages.
|
|
.TP
|
|
.B RETURN VALUE
|
|
For Section 2 and 3 pages, this section gives a
|
|
list of the values the library routine will return to the caller
|
|
and the conditions that cause these values to be returned.
|
|
.TP
|
|
.B ERRORS
|
|
For Section 2 and 3 manual pages, this is a list of the
|
|
values that may be placed in
|
|
.I errno
|
|
in the event of an error, along with information about the cause
|
|
of the errors.
|
|
.IP
|
|
Where several different conditions produce the same error,
|
|
the preferred approach is to create separate list entries
|
|
(with duplicate error names) for each of the conditions.
|
|
This makes the separate conditions clear, may make the list easier to read,
|
|
and allows metainformation
|
|
(e.g., kernel version number where the condition first became applicable)
|
|
to be more easily marked for each condition.
|
|
.IP
|
|
.IR "The error list should be in alphabetical order" .
|
|
.TP
|
|
.B ENVIRONMENT
|
|
A list of all environment variables that affect the program or function
|
|
and how they affect it.
|
|
.TP
|
|
.B FILES
|
|
A list of the files the program or function uses, such as
|
|
configuration files, startup files,
|
|
and files the program directly operates on.
|
|
.IP
|
|
Give the full pathname of these files, and use the installation
|
|
process to modify the directory part to match user preferences.
|
|
For many programs, the default installation location is in
|
|
.IR /usr/local ,
|
|
so your base manual page should use
|
|
.I /usr/local
|
|
as the base.
|
|
.\" May 07: Almost no current man pages have a DIAGNOSTICS section;
|
|
.\" "RETURN VALUE" or "EXIT STATUS" is preferred.
|
|
.\" .TP
|
|
.\" .B DIAGNOSTICS
|
|
.\" gives an overview of the most common error messages and how to
|
|
.\" cope with them.
|
|
.\" You don't need to explain system error messages
|
|
.\" or fatal signals that can appear during execution of any program
|
|
.\" unless they're special in some way to the program.
|
|
.\"
|
|
.\" May 07: Almost no current man pages have a SECURITY section.
|
|
.\".TP
|
|
.\".B SECURITY
|
|
.\"discusses security issues and implications.
|
|
.\"Warn about configurations or environments that should be avoided,
|
|
.\"commands that may have security implications, and so on, especially
|
|
.\"if they aren't obvious.
|
|
.\"Discussing security in a separate section isn't necessary;
|
|
.\"if it's easier to understand, place security information in the
|
|
.\"other sections (such as the
|
|
.\" .B DESCRIPTION
|
|
.\" or
|
|
.\" .B USAGE
|
|
.\" section).
|
|
.\" However, please include security information somewhere!
|
|
.TP
|
|
.B ATTRIBUTES
|
|
A summary of various attributes of the function(s) documented on this page.
|
|
See
|
|
.BR attributes (7)
|
|
for further details.
|
|
.TP
|
|
.B VERSIONS
|
|
A brief summary of the Linux kernel or glibc versions where a
|
|
system call or library function appeared,
|
|
or changed significantly in its operation.
|
|
.IP
|
|
As a general rule, every new interface should
|
|
include a VERSIONS section in its manual page.
|
|
Unfortunately,
|
|
many existing manual pages don't include this information
|
|
(since there was no policy to do so when they were written).
|
|
Patches to remedy this are welcome,
|
|
but, from the perspective of programmers writing new code,
|
|
this information probably matters only in the case of kernel
|
|
interfaces that have been added in Linux 2.4 or later
|
|
(i.e., changes since kernel 2.2),
|
|
and library functions that have been added to glibc since version 2.1
|
|
(i.e., changes since glibc 2.0).
|
|
.IP
|
|
The
|
|
.BR syscalls (2)
|
|
manual page also provides information about kernel versions
|
|
in which various system calls first appeared.
|
|
.TP
|
|
.B CONFORMING TO
|
|
A description of any standards or conventions that relate to the function
|
|
or command described by the manual page.
|
|
.IP
|
|
The preferred terms to use for the various standards are listed as
|
|
headings in
|
|
.BR standards (7).
|
|
.IP
|
|
For a page in Section 2 or 3,
|
|
this section should note the POSIX.1
|
|
version(s) that the call conforms to,
|
|
and also whether the call is specified in C99.
|
|
(Don't worry too much about other standards like SUS, SUSv2, and XPG,
|
|
or the SVr4 and 4.xBSD implementation standards,
|
|
unless the call was specified in those standards,
|
|
but isn't in the current version of POSIX.1.)
|
|
.IP
|
|
If the call is not governed by any standards but commonly
|
|
exists on other systems, note them.
|
|
If the call is Linux-specific, note this.
|
|
.IP
|
|
If this section consists of just a list of standards
|
|
(which it commonly does),
|
|
terminate the list with a period (\(aq.\(aq).
|
|
.TP
|
|
.B NOTES
|
|
Miscellaneous notes.
|
|
.IP
|
|
For Section 2 and 3 man pages you may find it useful to include
|
|
subsections (\fBSS\fP) named \fILinux Notes\fP and \fIGlibc Notes\fP.
|
|
.IP
|
|
In Section 2, use the heading
|
|
.I "C library/kernel differences"
|
|
to mark off notes that describe the differences (if any) between
|
|
the C library wrapper function for a system call and
|
|
the raw system call interface provided by the kernel.
|
|
.TP
|
|
.B BUGS
|
|
A list of limitations, known defects or inconveniences,
|
|
and other questionable activities.
|
|
.TP
|
|
.B EXAMPLES
|
|
One or more examples demonstrating how this function, file, or
|
|
command is used.
|
|
.IP
|
|
For details on writing example programs,
|
|
see \fIExample programs\fP below.
|
|
.TP
|
|
.B AUTHORS
|
|
A list of authors of the documentation or program.
|
|
.IP
|
|
\fBUse of an AUTHORS section is strongly discouraged\fP.
|
|
Generally, it is better not to clutter every page with a list
|
|
of (over time potentially numerous) authors;
|
|
if you write or significantly amend a page,
|
|
add a copyright notice as a comment in the source file.
|
|
If you are the author of a device driver and want to include
|
|
an address for reporting bugs, place this under the BUGS section.
|
|
.TP
|
|
.B REPORTING BUGS
|
|
The
|
|
.IR man-pages
|
|
project doesn't use a REPORTING BUGS section in manual pages.
|
|
Information on reporting bugs is instead supplied in the
|
|
script-generated COLOPHON section.
|
|
However, various projects do use a REPORTING BUGS section.
|
|
It is recommended to place it near the foot of the page.
|
|
.TP
|
|
.B COPYRIGHT
|
|
The
|
|
.IR man-pages
|
|
project doesn't use a COPYRIGHT section in manual pages.
|
|
Copyright information is instead maintained in the page source.
|
|
In pages where this section is present,
|
|
it is recommended to place it near the foot of the page, just above SEE ALSO.
|
|
.TP
|
|
.B SEE ALSO
|
|
A comma-separated list of related man pages, possibly followed by
|
|
other related pages or documents.
|
|
.IP
|
|
The list should be ordered by section number and
|
|
then alphabetically by name.
|
|
Do not terminate this list with a period.
|
|
.IP
|
|
Where the SEE ALSO list contains many long manual page names,
|
|
to improve the visual result of the output, it may be useful to employ the
|
|
.I .ad l
|
|
(don't right justify)
|
|
and
|
|
.I .nh
|
|
(don't hyphenate)
|
|
directives.
|
|
Hyphenation of individual page names can be prevented
|
|
by preceding words with the string "\e%".
|
|
.IP
|
|
Given the distributed, autonomous nature of FOSS projects
|
|
and their documentation, it is sometimes necessary\(emand in many cases
|
|
desirable\(emthat the SEE ALSO section includes references to
|
|
manual pages provided by other projects.
|
|
.SH FORMATTING AND WORDING CONVENTIONS
|
|
The following subsections note some details for preferred formatting and
|
|
wording conventions in various sections of the pages in the
|
|
.IR man-pages
|
|
project.
|
|
.SS SYNOPSIS
|
|
Wrap the function prototype(s) in a
|
|
.IR .nf / .fi
|
|
pair to prevent filling.
|
|
.PP
|
|
In general, where more than one function prototype is shown in the SYNOPSIS,
|
|
the prototypes should
|
|
.I not
|
|
be separated by blank lines.
|
|
However, blank lines (achieved using
|
|
.IR .PP )
|
|
may be added in the following cases:
|
|
.IP * 3
|
|
to separate long lists of function prototypes into related groups
|
|
(see for example
|
|
.BR list (3));
|
|
.IP *
|
|
in other cases that may improve readability.
|
|
.PP
|
|
In the SYNOPSIS, a long function prototype may need to be
|
|
continued over to the next line.
|
|
The continuation line is indented according to the following rules:
|
|
.IP 1. 3
|
|
If there is a single such prototype that needs to be continued,
|
|
then align the continuation line so that when the page is
|
|
rendered on a fixed-width font device (e.g., on an xterm) the
|
|
continuation line starts just below the start of the argument
|
|
list in the line above.
|
|
(Exception: the indentation may be
|
|
adjusted if necessary to prevent a very long continuation line
|
|
or a further continuation line where the function prototype is
|
|
very long.)
|
|
As an example:
|
|
.PP
|
|
.RS
|
|
.nf
|
|
.BI "int tcsetattr(int " fd ", int " optional_actions ,
|
|
.BI " const struct termios *" termios_p );
|
|
.fi
|
|
.RE
|
|
.IP 2. 3
|
|
But, where multiple functions in the SYNOPSIS require
|
|
continuation lines, and the function names have different
|
|
lengths, then align all continuation lines to start in the
|
|
same column.
|
|
This provides a nicer rendering in PDF output
|
|
(because the SYNOPSIS uses a variable width font where
|
|
spaces render narrower than most characters).
|
|
As an example:
|
|
.PP
|
|
.RS
|
|
.nf
|
|
.BI "int getopt(int " argc ", char * const " argv[] ,
|
|
.BI " const char *" optstring );
|
|
.BI "int getopt_long(int " argc ", char * const " argv[] ,
|
|
.BI " const char *" optstring ,
|
|
.BI " const struct option *" longopts ", int *" longindex );
|
|
.fi
|
|
.RE
|
|
.SS RETURN VALUE
|
|
The preferred wording to describe how
|
|
.I errno
|
|
is set is
|
|
.RI \(dq errno
|
|
is set to indicate the error"
|
|
or similar.
|
|
.\" Before man-pages 5.11, many different wordings were used, which
|
|
.\" was confusing, and potentially made scripted edits more difficult.
|
|
This wording is consistent with the wording used in both POSIX.1 and FreeBSD.
|
|
.SS ATTRIBUTES
|
|
.\" See man-pages commit c466875ecd64ed3d3cd3e578406851b7dfb397bf
|
|
Note the following:
|
|
.IP * 3
|
|
Wrap the table in this section in a
|
|
.IR ".ad\ l" / .ad
|
|
pair to disable text filling and a
|
|
.IR .nh / .hy
|
|
pair to disable hyphenation.
|
|
.IP *
|
|
Ensure that the table occupies the full page width through the use of an
|
|
.I lbx
|
|
description for one of the columns
|
|
(usually the first column,
|
|
though in some cases the last column if it contains a lot of text).
|
|
.IP *
|
|
Make free use of
|
|
.IR T{ / T}
|
|
macro pairs to allow table cells to be broken over multiple lines
|
|
(also bearing in mind that pages may sometimes be rendered to a
|
|
width of less than 80 columns).
|
|
.PP
|
|
For examples of all of the above, see the source code of various pages.
|
|
.SH STYLE GUIDE
|
|
The following subsections describe the preferred style for the
|
|
.IR man-pages
|
|
project.
|
|
For details not covered below, the Chicago Manual of Style
|
|
is usually a good source;
|
|
try also grepping for preexisting usage in the project source tree.
|
|
.SS Use of gender-neutral language
|
|
As far as possible, use gender-neutral language in the text of man
|
|
pages.
|
|
Use of "they" ("them", "themself", "their") as a gender-neutral singular
|
|
pronoun is acceptable.
|
|
.\"
|
|
.SS Formatting conventions for manual pages describing commands
|
|
For manual pages that describe a command (typically in Sections 1 and 8),
|
|
the arguments are always specified using italics,
|
|
.IR "even in the SYNOPSIS section" .
|
|
.PP
|
|
The name of the command, and its options, should
|
|
always be formatted in bold.
|
|
.\"
|
|
.SS Formatting conventions for manual pages describing functions
|
|
For manual pages that describe functions (typically in Sections 2 and 3),
|
|
the arguments are always specified using italics,
|
|
.IR "even in the SYNOPSIS section" ,
|
|
where the rest of the function is specified in bold:
|
|
.PP
|
|
.BI " int myfunction(int " argc ", char **" argv );
|
|
.PP
|
|
Variable names should, like argument names, be specified in italics.
|
|
.PP
|
|
Any reference to the subject of the current manual page
|
|
should be written with the name in bold followed by
|
|
a pair of parentheses in Roman (normal) font.
|
|
For example, in the
|
|
.BR fcntl (2)
|
|
man page, references to the subject of the page would be written as:
|
|
.BR fcntl ().
|
|
The preferred way to write this in the source file is:
|
|
.PP
|
|
.EX
|
|
.BR fcntl ()
|
|
.EE
|
|
.PP
|
|
(Using this format, rather than the use of "\efB...\efP()"
|
|
makes it easier to write tools that parse man page source files.)
|
|
.\"
|
|
.SS Use semantic newlines
|
|
In the source of a manual page,
|
|
new sentences should be started on new lines,
|
|
and long sentences should be split into lines at clause breaks
|
|
(commas, semicolons, colons, and so on).
|
|
This convention, sometimes known as "semantic newlines",
|
|
makes it easier to see the effect of patches,
|
|
which often operate at the level of individual sentences or sentence clauses.
|
|
.\"
|
|
.SS Formatting conventions (general)
|
|
Paragraphs should be separated by suitable markers (usually either
|
|
.I .PP
|
|
or
|
|
.IR .IP ).
|
|
Do
|
|
.I not
|
|
separate paragraphs using blank lines, as this results in poor rendering
|
|
in some output formats (such as PostScript and PDF).
|
|
.PP
|
|
Filenames (whether pathnames, or references to header files)
|
|
are always in italics (e.g.,
|
|
.IR <stdio.h> ),
|
|
except in the SYNOPSIS section, where included files are in bold (e.g.,
|
|
.BR "#include <stdio.h>" ).
|
|
When referring to a standard header file include,
|
|
specify the header file surrounded by angle brackets,
|
|
in the usual C way (e.g.,
|
|
.IR <stdio.h> ).
|
|
.PP
|
|
Special macros, which are usually in uppercase, are in bold (e.g.,
|
|
.BR MAXINT ).
|
|
Exception: don't boldface NULL.
|
|
.PP
|
|
When enumerating a list of error codes, the codes are in bold (this list
|
|
usually uses the
|
|
.B \&.TP
|
|
macro).
|
|
.PP
|
|
Complete commands should, if long,
|
|
be written as an indented line on their own,
|
|
with a blank line before and after the command, for example
|
|
.PP
|
|
.in +4n
|
|
.EX
|
|
man 7 man\-pages
|
|
.EE
|
|
.in
|
|
.PP
|
|
If the command is short, then it can be included inline in the text,
|
|
in italic format, for example,
|
|
.IR "man 7 man-pages" .
|
|
In this case, it may be worth using nonbreaking spaces
|
|
("\e\ ") at suitable places in the command.
|
|
Command options should be written in italics (e.g.,
|
|
.IR \-l ).
|
|
.PP
|
|
Expressions, if not written on a separate indented line, should
|
|
be specified in italics.
|
|
Again, the use of nonbreaking spaces may be appropriate
|
|
if the expression is inlined with normal text.
|
|
.PP
|
|
When showing example shell sessions, user input should be formatted in bold, for example
|
|
.PP
|
|
.in +4n
|
|
.EX
|
|
$ \fBdate\fP
|
|
Thu Jul 7 13:01:27 CEST 2016
|
|
.EE
|
|
.in
|
|
.PP
|
|
Any reference to another man page
|
|
should be written with the name in bold,
|
|
.I always
|
|
followed by the section number,
|
|
formatted in Roman (normal) font, without any
|
|
separating spaces (e.g.,
|
|
.BR intro (2)).
|
|
The preferred way to write this in the source file is:
|
|
.PP
|
|
.EX
|
|
.BR intro (2)
|
|
.EE
|
|
.PP
|
|
(Including the section number in cross references lets tools like
|
|
.BR man2html (1)
|
|
create properly hyperlinked pages.)
|
|
.PP
|
|
Control characters should be written in bold face,
|
|
with no quotes; for example,
|
|
.BR \(haX .
|
|
.SS Spelling
|
|
Starting with release 2.59,
|
|
.I man-pages
|
|
follows American spelling conventions
|
|
(previously, there was a random mix of British and American spellings);
|
|
please write all new pages and patches according to these conventions.
|
|
.PP
|
|
Aside from the well-known spelling differences,
|
|
there are a few other subtleties to watch for:
|
|
.IP * 3
|
|
American English tends to use the forms "backward", "upward", "toward",
|
|
and so on
|
|
rather than the British forms "backwards", "upwards", "towards", and so on.
|
|
.IP *
|
|
Opinions are divided on "acknowledgement" vs "acknowledgment".
|
|
The latter is predominant, but not universal usage in American English.
|
|
POSIX and the BSD license use the former spelling.
|
|
In the Linux man-pages project, we use "acknowledgement".
|
|
.SS BSD version numbers
|
|
The classical scheme for writing BSD version numbers is
|
|
.IR x.yBSD ,
|
|
where
|
|
.I x.y
|
|
is the version number (e.g., 4.2BSD).
|
|
Avoid forms such as
|
|
.IR "BSD 4.3" .
|
|
.SS Capitalization
|
|
In subsection ("SS") headings,
|
|
capitalize the first word in the heading, but otherwise use lowercase,
|
|
except where English usage (e.g., proper nouns) or programming
|
|
language requirements (e.g., identifier names) dictate otherwise.
|
|
For example:
|
|
.PP
|
|
.EX
|
|
.SS Unicode under Linux
|
|
.EE
|
|
.\"
|
|
.SS Indentation of structure definitions, shell session logs, and so on
|
|
When structure definitions, shell session logs, and so on are included
|
|
in running text, indent them by 4 spaces (i.e., a block enclosed by
|
|
.I ".in\ +4n"
|
|
and
|
|
.IR ".in" ),
|
|
format them using the
|
|
.I .EX
|
|
and
|
|
.I EE
|
|
macros, and surround them with suitable paragraph markers (either
|
|
.I .PP
|
|
or
|
|
.IR .IP ).
|
|
For example:
|
|
.PP
|
|
.in +4n
|
|
.EX
|
|
.PP
|
|
.in +4n
|
|
.EX
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
return 0;
|
|
}
|
|
.EE
|
|
.in
|
|
.PP
|
|
.EE
|
|
.in
|
|
.SS Preferred terms
|
|
The following table lists some preferred terms to use in man pages,
|
|
mainly to ensure consistency across pages.
|
|
.ad l
|
|
.TS
|
|
l l l
|
|
---
|
|
l l ll.
|
|
Term Avoid using Notes
|
|
|
|
bit mask bitmask
|
|
built-in builtin
|
|
Epoch epoch T{
|
|
For the UNIX Epoch (00:00:00, 1 Jan 1970 UTC)
|
|
T}
|
|
filename file name
|
|
filesystem file system
|
|
hostname host name
|
|
inode i-node
|
|
lowercase lower case, lower-case
|
|
nonzero non-zero
|
|
pathname path name
|
|
pseudoterminal pseudo-terminal
|
|
privileged port T{
|
|
reserved port,
|
|
system port
|
|
T}
|
|
real-time T{
|
|
realtime,
|
|
real time
|
|
T}
|
|
run time runtime
|
|
saved set-group-ID T{
|
|
saved group ID,
|
|
saved set-GID
|
|
T}
|
|
saved set-user-ID T{
|
|
saved user ID,
|
|
saved set-UID
|
|
T}
|
|
set-group-ID set-GID, setgid
|
|
set-user-ID set-UID, setuid
|
|
superuser T{
|
|
super user,
|
|
super-user
|
|
T}
|
|
superblock T{
|
|
super block,
|
|
super-block
|
|
T}
|
|
timestamp time stamp
|
|
timezone time zone
|
|
uppercase upper case, upper-case
|
|
usable useable
|
|
user space userspace
|
|
username user name
|
|
x86-64 x86_64 T{
|
|
Except if referring to result of "uname\ \-m" or similar
|
|
T}
|
|
zeros zeroes
|
|
.TE
|
|
.PP
|
|
See also the discussion
|
|
.IR "Hyphenation of attributive compounds"
|
|
below.
|
|
.SS Terms to avoid
|
|
The following table lists some terms to avoid using in man pages,
|
|
along with some suggested alternatives,
|
|
mainly to ensure consistency across pages.
|
|
.ad l
|
|
.TS
|
|
l l l
|
|
---
|
|
l l l.
|
|
Avoid Use instead Notes
|
|
|
|
32bit 32-bit T{
|
|
same for 8-bit, 16-bit, etc.
|
|
T}
|
|
current process calling process T{
|
|
A common mistake made by kernel programmers when writing man pages
|
|
T}
|
|
manpage T{
|
|
man page, manual page
|
|
T}
|
|
minus infinity negative infinity
|
|
non-root unprivileged user
|
|
non-superuser unprivileged user
|
|
nonprivileged unprivileged
|
|
OS operating system
|
|
plus infinity positive infinity
|
|
pty pseudoterminal
|
|
tty terminal
|
|
Unices UNIX systems
|
|
Unixes UNIX systems
|
|
.TE
|
|
.ad
|
|
.\"
|
|
.SS Trademarks
|
|
Use the correct spelling and case for trademarks.
|
|
The following is a list of the correct spellings of various
|
|
relevant trademarks that are sometimes misspelled:
|
|
.PP
|
|
DG/UX
|
|
HP-UX
|
|
UNIX
|
|
UnixWare
|
|
.SS NULL, NUL, null pointer, and null byte
|
|
A
|
|
.IR "null pointer"
|
|
is a pointer that points to nothing,
|
|
and is normally indicated by the constant
|
|
.IR NULL .
|
|
On the other hand,
|
|
.I NUL
|
|
is the
|
|
.IR "null byte",
|
|
a byte with the value 0, represented in C via the character constant
|
|
.IR \(aq\e0\(aq .
|
|
.PP
|
|
The preferred term for the pointer is "null pointer" or simply "NULL";
|
|
avoid writing "NULL pointer".
|
|
.PP
|
|
The preferred term for the byte is "null byte".
|
|
Avoid writing "NUL", since it is too easily confused with "NULL".
|
|
Avoid also the terms "zero byte" and "null character".
|
|
The byte that terminates a C string should be described
|
|
as "the terminating null byte";
|
|
strings may be described as "null-terminated",
|
|
but avoid the use of "NUL-terminated".
|
|
.SS Hyperlinks
|
|
For hyperlinks, use the
|
|
.IR .UR / .UE
|
|
macro pair
|
|
(see
|
|
.BR groff_man (7)).
|
|
This produces proper hyperlinks that can be used in a web browser,
|
|
when rendering a page with, say:
|
|
.PP
|
|
BROWSER=firefox man -H pagename
|
|
.SS Use of e.g., i.e., etc., a.k.a., and similar
|
|
In general, the use of abbreviations such as "e.g.", "i.e.", "etc.",
|
|
"cf.", and "a.k.a." should be avoided,
|
|
in favor of suitable full wordings
|
|
("for example", "that is", "and so on", "compare to", "also known as").
|
|
.PP
|
|
The only place where such abbreviations may be acceptable is in
|
|
.I short
|
|
parenthetical asides (e.g., like this one).
|
|
.PP
|
|
Always include periods in such abbreviations, as shown here.
|
|
In addition, "e.g." and "i.e." should always be followed by a comma.
|
|
.SS Em-dashes
|
|
The way to write an em-dash\(emthe glyph that appears
|
|
at either end of this subphrase\(emin *roff is with the macro "\e(em".
|
|
(On an ASCII terminal, an em-dash typically renders as two hyphens,
|
|
but in other typographical contexts it renders as a long dash.)
|
|
Em-dashes should be written
|
|
.I without
|
|
surrounding spaces.
|
|
.SS Hyphenation of attributive compounds
|
|
Compound terms should be hyphenated when used attributively
|
|
(i.e., to qualify a following noun). Some examples:
|
|
.PP
|
|
32-bit value
|
|
command-line argument
|
|
floating-point number
|
|
run-time check
|
|
user-space function
|
|
wide-character string
|
|
.SS Hyphenation with multi, non, pre, re, sub, and so on
|
|
The general tendency in modern English is not to hyphenate
|
|
after prefixes such as "multi", "non", "pre", "re", "sub", and so on.
|
|
Manual pages should generally follow this rule when these prefixes are
|
|
used in natural English constructions with simple suffixes.
|
|
The following list gives some examples of the preferred forms:
|
|
.PP
|
|
interprocess
|
|
multithreaded
|
|
multiprocess
|
|
nonblocking
|
|
nondefault
|
|
nonempty
|
|
noninteractive
|
|
nonnegative
|
|
nonportable
|
|
nonzero
|
|
preallocated
|
|
precreate
|
|
prerecorded
|
|
reestablished
|
|
reinitialize
|
|
rearm
|
|
reread
|
|
subcomponent
|
|
subdirectory
|
|
subsystem
|
|
.PP
|
|
Hyphens should be retained when the prefixes are used in nonstandard
|
|
English words, with trademarks, proper nouns, acronyms, or compound terms.
|
|
Some examples:
|
|
.PP
|
|
non-ASCII
|
|
non-English
|
|
non-NULL
|
|
non-real-time
|
|
.PP
|
|
Finally, note that "re-create" and "recreate" are two different verbs,
|
|
and the former is probably what you want.
|
|
.\"
|
|
.SS Generating optimal glyphs
|
|
Where a real minus character is required (e.g., for numbers such as \-1,
|
|
for man page cross references such as
|
|
.BR utf\-8 (7),
|
|
or when writing options that have a leading dash, such as in
|
|
.IR "ls\ \-l"),
|
|
use the following form in the man page source:
|
|
.PP
|
|
\e\-
|
|
.PP
|
|
This guideline applies also to code examples.
|
|
.PP
|
|
The use of real minus signs serves the following purposes:
|
|
.\" https://lore.kernel.org/linux-man/20210121061158.5ul7226fgbrmodbt@localhost.localdomain/
|
|
.IP * 3
|
|
To provide better renderings on various targets other than
|
|
ASCII terminals,
|
|
notably in PDF and on Unicode/UTF\-8-capable terminals.
|
|
.IP *
|
|
To generate glyphs that when copied from rendered pages will
|
|
produce real minus signs when pasted into a terminal.
|
|
.PP
|
|
To produce unslanted single quotes that render well in ASCII, UTF-8, and PDF,
|
|
use "\e(aq" ("apostrophe quote"); for example
|
|
.PP
|
|
\e(aqC\e(aq
|
|
.PP
|
|
where
|
|
.I C
|
|
is the quoted character.
|
|
This guideline applies also to character constants used in code examples.
|
|
.PP
|
|
Where a proper caret (\(ha) that renders well in both a terminal and PDF
|
|
is required, use "\\(ha".
|
|
This is especially necessary in code samples,
|
|
to get a nicely rendered caret when rendering to PDF.
|
|
.PP
|
|
Using a naked "\(ti" character results in a poor rendering in PDF.
|
|
Instead use "\\(ti".
|
|
This is especially necessary in code samples,
|
|
to get a nicely rendered tilde when rendering to PDF.
|
|
.\"
|
|
.SS Example programs and shell sessions
|
|
Manual pages may include example programs demonstrating how to
|
|
use a system call or library function.
|
|
However, note the following:
|
|
.IP * 3
|
|
Example programs should be written in C.
|
|
.IP *
|
|
An example program is necessary and useful only if it demonstrates
|
|
something beyond what can easily be provided in a textual
|
|
description of the interface.
|
|
An example program that does nothing
|
|
other than call an interface usually serves little purpose.
|
|
.IP *
|
|
Example programs should ideally be short
|
|
(e.g., a good example can often be provided in less than 100 lines of code),
|
|
though in some cases longer programs may be necessary
|
|
to properly illustrate the use of an API.
|
|
.IP *
|
|
Expressive code is appreciated.
|
|
.IP *
|
|
Comments should included where helpful.
|
|
Complete sentences in free-standing comments should be
|
|
terminated by a period.
|
|
Periods should generally be omitted in "tag" comments
|
|
(i.e., comments that are placed on the same line of code);
|
|
such comments are in any case typically brief phrases
|
|
rather than complete sentences.
|
|
.IP *
|
|
Example programs should do error checking after system calls and
|
|
library function calls.
|
|
.IP *
|
|
Example programs should be complete, and compile without
|
|
warnings when compiled with \fIcc\ \-Wall\fP.
|
|
.IP *
|
|
Where possible and appropriate, example programs should allow
|
|
experimentation, by varying their behavior based on inputs
|
|
(ideally from command-line arguments, or alternatively, via
|
|
input read by the program).
|
|
.IP *
|
|
Example programs should be laid out according to Kernighan and
|
|
Ritchie style, with 4-space indents.
|
|
(Avoid the use of TAB characters in source code!)
|
|
The following command can be used to format your source code to
|
|
something close to the preferred style:
|
|
.IP
|
|
indent \-npro \-kr \-i4 \-ts4 \-sob \-l72 \-ss \-nut \-psl prog.c
|
|
.IP *
|
|
For consistency, all example programs should terminate using either of:
|
|
.IP
|
|
exit(EXIT_SUCCESS);
|
|
exit(EXIT_FAILURE);
|
|
.IP
|
|
Avoid using the following forms to terminate a program:
|
|
.IP
|
|
exit(0);
|
|
exit(1);
|
|
return n;
|
|
.IP *
|
|
If there is extensive explanatory text before the
|
|
program source code, mark off the source code
|
|
with a subsection heading
|
|
.IR "Program source" ,
|
|
as in:
|
|
.IP
|
|
.SS Program source
|
|
.IP
|
|
Always do this if the explanatory text includes a shell session log.
|
|
.PP
|
|
If you include a shell session log demonstrating the use of a program
|
|
or other system feature:
|
|
.IP * 3
|
|
Place the session log above the source code listing
|
|
.IP *
|
|
Indent the session log by four spaces.
|
|
.IP *
|
|
Boldface the user input text,
|
|
to distinguish it from output produced by the system.
|
|
.PP
|
|
For some examples of what example programs should look like, see
|
|
.BR wait (2)
|
|
and
|
|
.BR pipe (2).
|
|
.SH EXAMPLES
|
|
For canonical examples of how man pages in the
|
|
.I man-pages
|
|
package should look, see
|
|
.BR pipe (2)
|
|
and
|
|
.BR fcntl (2).
|
|
.SH SEE ALSO
|
|
.BR man (1),
|
|
.BR man2html (1),
|
|
.BR attributes (7),
|
|
.BR groff (7),
|
|
.BR groff_man (7),
|
|
.BR man (7),
|
|
.BR mdoc (7)
|