NAME | SYNOPSIS | DESCRIPTION | EXAMPLE | SEE ALSO | COLOPHON
MAN-PAGES(7) Linux Programmer's Manual MAN-PAGES(7)
man-pages - conventions for writing Linux man pages
man [section] title
This page describes the conventions that should be employed when writing man
pages for the Linux man-pages project, which comprises Sections 2, 3, 4, 5,
and 7 of the Linux manual pages. The conventions described on this page may
also be useful for authors writing man pages for other projects.
The manual Sections are traditionally defined as follows:
1 Commands (Programs)
Those commands that can be executed by the user from within a shell.
2 System calls
Those functions which must be performed by the kernel.
3 Library calls
Most of the libc functions.
4 Special files (devices)
Files found in /dev.
5 File formats and conventions
The format for /etc/passwd and other human-readable files.
6 Games
7 Conventions and miscellaneous
Overviews of various topics, conventions and protocols, character
set standards, and miscellaneous other things.
8 System management commands
Commands like mount(8), many of which only root can execute.
New manual pages should be marked up using the groff an.tmac package described
in man(7). This choice is mainly for consistency: the vast majority of
existing Linux manual pages are marked up using these macros.
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.
New sentences should be started on new lines. This makes it easier to see the
effect of patches, which often operate at the level of individual sentences.
The first command in a man page should be a TH command:
.TH title section date source manual
where:
title The title of the man page, written in all caps (e.g., MAN-
PAGES).
section The section number in which the man page should be placed
(e.g., 7).
date The date of the last revision -- remember to change this
every time a change is made to the man page, since this is
the most general way of doing version control. Dates should
be written in the form YYYY-MM-DD.
source The source of the command, function, or system call.
For those few man-pages pages in Sections 1 and 8, probably
you just want to write GNU.
For system calls, just write 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.)
For library calls that are part of glibc or one of the other
common GNU libraries, just use GNU C Library, GNU, or an
empty string.
For Section 4 pages, use Linux.
In cases of doubt, just write Linux, or GNU.
manual The title of the manual (e.g., for Section 2 and 3 pages in
the man-pages package, use Linux Programmer's Manual).
The list below shows conventional or suggested sections. Most manual pages
should include at least the highlighted sections. Arrange a new manual page
so that sections are placed in the order shown in the list.
NAME
SYNOPSIS
CONFIGURATION [Normally only in Section 4]
DESCRIPTION
OPTIONS [Normally only in Sections 1, 8]
EXIT STATUS [Normally only in Sections 1, 8]
RETURN VALUE [Normally only in Sections 2, 3]
ERRORS [Typically only in Sections 2, 3]
ENVIRONMENT
FILES
VERSIONS [Normally only in Sections 2, 3]
CONFORMING TO
NOTES
BUGS
EXAMPLE
SEE ALSO
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 (.SS) within those sections.
The following list elaborates on the contents of each of the above sections.
NAME The name of this manual page. See man(7) for important details
of the line(s) that should follow the .SH NAME command.
SYNOPSIS briefly describes the command or function's interface. 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 #include directives, followed by
the function declaration.
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
feature_test_macros(7).
CONFIGURATION Configuration details for a device. This section normally only
appears in Section 4 pages.
DESCRIPTION gives an explanation of what the program, function, or format
does. 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 OPTIONS
section.
OPTIONS describes the command-line options accepted by a program and how
they change its behavior. This section should only appear for
Section 1 and 8 manual pages.
EXIT STATUS lists the possible exit status values of a program and the
conditions that cause these values to be returned. This section
should only appear for Section 1 and 8 manual pages.
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.
ERRORS For Section 2 and 3 manual pages, this is a list of the values
that may be placed in errno in the event of an error, along with
information about the cause of the errors. The error list
should be in alphabetical order.
ENVIRONMENT lists all environment variables that affect the program or
function and how they affect it.
FILES lists the files the program or function uses, such as
configuration files, startup files, and files the program
directly operates on. 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 /usr/local, so your base manual page
should use /usr/local as the base.
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. 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 only matters 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).
The syscalls(2) manual page also provides information about
kernel versions in which various system calls first appeared.
CONFORMING TO describes any standards or conventions that relate to the
function or command described by the manual page. 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.) (See standards(7).)
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.
If this section consists of just a list of standards (which it
commonly does), terminate the list with a period ('.').
NOTES provides miscellaneous notes. For Section 2 and 3 man pages you
may find it useful to include subsections (SS) named Linux Notes
and Glibc Notes.
BUGS lists limitations, known defects or inconveniences, and other
questionable activities.
EXAMPLE provides one or more examples describing how this function, file
or command is used. For details on writing example programs,
see Example Programs below.
AUTHORS lists authors of the documentation or program. Use of an
AUTHORS section is strongly discouraged. 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.
SEE ALSO provides a comma-seprated list of related man pages, ordered by
section number and then alphabetically by name, possibly
followed by other related pages or documents. Do not terminate
this with a period.
For functions, the arguments are always specified using italics, even in the
SYNOPSIS section, where the rest of the function is specified in bold:
int myfunction(int argc, char **argv);
Variable names should, like argument names, be specified in italics.
Filenames (whether pathnames, or references to files in the /usr/include
directory) are always in italics (e.g., <stdio.h>), except in the SYNOPSIS
section, where included files are in bold (e.g., #include <stdio.h>). When
referring to a standard include file under /usr/include, specify the header
file surrounded by angle brackets, in the usual C way (e.g., <stdio.h>).
Special macros, which are usually in upper case, are in bold (e.g., MAXINT).
Exception: don't boldface NULL.
When enumerating a list of error codes, the codes are in bold (this list
usually uses the .TP macro).
Complete commands should, if long, be written as in an indented line on their
own, for example
man 7 man-pages
If the comamnd is short, then it can be included inline in the text, in italic
format, for example, man 7 man-pages. In this case, it may be worth using
non-breaking spaces ("\ ") at suitable places in the command. Command options
should be written in italics, e.g., -l.
Expressions, if not written on a separate indented line, should be specified
in italics. Again, the use of non-breaking spaces may be appropriate if the
expression is inlined with normal text.
Any reference to the subject of the current manual page should be written with
the name in bold. If the subject is a function (i.e., this is a Section 2 or
3 page), then the name should be followed by a pair of parentheses in Roman
(normal) font. For example, in the fcntl(2) man page, references to the
subject of the page would be written as: fcntl(). The preferred way to write
this in the source file is:
.BR fcntl ()
(Using this format, rather than the use of "\fB...\fP()" makes it easier to
write tools that parse man page source files.)
Any reference to another man page should be written with the name in bold,
always followed by the section number, formatted in Roman (normal) font,
without any separating spaces (e.g., intro(2)). The preferred way to write
this in the source file is:
.BR intro (2)
(Including the section number in cross references lets tools like man2html(1)
create properly hyperlinked pages.)
Starting with release 2.59, man-pages follows American spelling conventions;
please write all new pages and patches according to these conventions.
Manual pages can include example programs demonstrating how to use a system
call or library function. However, note the following:
* Example programs should be written in C.
* An example program is only necessary and useful 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.
* Example programs should be fairly short (preferably less than 100 lines;
ideally less than 50 lines).
* Example programs should do error checking after system calls and library
function calls.
* Example programs should be complete, and compile without warnings when
compiled with cc -Wall.
* 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).
* 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!)
For some examples of what example programs should look like, see wait(2) and
pipe(2).
When structure definitions, shell session logs, etc. are included in running
text, indent them by 4 spaces (i.e., a block enclosed by .in +4n and .in).
For canonical examples of how man pages in the man-pages package should look,
see pipe(2) and fcntl(2).
man(1), man2html(1), groff(7), groff_man(7), man(7), mdoc(7)
This page is part of release 3.11 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
Linux 2008-06-12 MAN-PAGES(7)