MAN(7) Linux Programmer's Manual MAN(7)
NAME
man - macros to format man pages
SYNOPSIS
groff -Tascii -man file ...
groff -Tps -man file ...
man [section] title
DESCRIPTION
This manual page explains the groff tmac.an macro package (often called
the man macro package) and related conventions for creating manual
(man) pages. This macro package should be used by developers when
writing or porting man pages for Linux. It is fairly compatible with
other versions of this macro package, so porting man pages should not
be a major problem (exceptions include the NET-2 BSD release, which
uses a totally different macro package called mdoc; see mdoc(7)).
Note that NET-2 BSD mdoc man pages can be used with groff simply by
specifying the -mdoc option instead of the -man option. Using the
-mandoc option is, however, recommended, since this will automatically
detect which macro package is in use.
PREAMBLE
The first command in a man page (after comment lines) should be
.TH title section date source manual,
where:
title The title of the man page (e.g., MAN).
section The section number the man page should be placed in
(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.
source The source of the command.
For binaries, use something like: GNU, NET-2, SLS Dis-
tribution, MCC Distribution.
For system calls, use the version of the kernel that
you are currently looking at: Linux 0.99.11.
For library calls, use the source of the function:
GNU, 4.3BSD, Linux DLL 4.4.1.
manual The title of the manual (e.g., Linux Programmer's Man-
ual).
Note that BSD mdoc-formatted pages begin with the Dd command, not the
TH command.
The manual sections are traditionally defined as follows:
1 Commands
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, such as qsort(3).
4 Special files
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
A description of the standard file system layout, net-
work protocols, ASCII and other character codes, this
man page, and other things.
8 System management commands
Commands like mount(8), many of which only root can
execute.
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 develop-
ers.
SECTIONS
Sections are started with .SH followed by the heading name. If the
name contains spaces and appears on the same line as .SH, then place
the heading in double quotes. Traditional or suggested headings
include: NAME, SYNOPSIS, DESCRIPTION, RETURN VALUE, EXIT STATUS, ERROR
HANDLING, ERRORS, OPTIONS, USAGE, EXAMPLES, FILES, ENVIRONMENT, DIAG-
NOSTICS, SECURITY, CONFORMING TO, NOTES, BUGS, AUTHOR, and SEE ALSO.
Where a traditional heading would apply, please use it; this kind of
consistency can make the information easier to understand. However,
feel free to create your own headings if they make things easier to
understand. The only required heading is NAME, which should be the
first section and be followed on the next line by a one line descrip-
tion of the program:
.SH NAME
chess \- the game of chess
It is extremely important that this format is followed, and that there
is a backslash before the single dash which follows the command name.
This syntax is used by the makewhatis(8) program to create a database
of short command descriptions for the whatis(1) and apropos(1) com-
mands.
Some other traditional sections have the following contents:
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.
DESCRIPTION gives an explanation of what the command, 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
options use the OPTIONS section. If there is some kind
of input grammar or complex set of subcommands, consider
describing them in a separate USAGE section (and just
place an overview in the DESCRIPTION section).
RETURN VALUE gives a list of the values the library routine will
return to the caller and the conditions that cause these
values to be returned.
EXIT STATUS lists the possible exit status values or a program and
the conditions that cause these values to be returned.
OPTIONS describes the options accepted by the program and how
they change its behavior.
USAGE describes the grammar of any sublanguage this implements.
EXAMPLES provides one or more examples describing how this func-
tion, file or command is used.
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 pro-
grams, the default installation location is in
/usr/local, so your base manual page should use
/usr/local as the base.
ENVIRONMENT lists all environment variables that affect your program
or function and how they affect it.
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 your program.
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 sec-
tions (such as the DESCRIPTION or USAGE section). How-
ever, please include security information somewhere!
CONFORMING TO describes any standards or conventions this implements.
NOTES provides miscellaneous notes.
BUGS lists limitations, known defects or inconveniences, and
other questionable activities.
AUTHOR lists authors of the documentation or program so you can
mail in bug reports.
SEE ALSO lists related man pages in alphabetical order, possibly
followed by other related pages or documents.
Conventionally this is the last section.
FONTS
Although there are many arbitrary conventions for man pages in the UNIX
world, the existence of several hundred Linux-specific man pages
defines our font standards:
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);
Filenames are always in italics (e.g., /usr/include/stdio.h),
except in the SYNOPSIS section, where included files are in bold
(e.g., #include <stdio.h>).
Special macros, which are usually in upper case, are in bold
(e.g., MAXINT).
When enumerating a list of error codes, the codes are in bold
(this list usually uses the .TP macro).
Any reference to another man page (or to the subject of the cur-
rent man page) is in bold. If the manual section number is
given, it is given in Roman (normal) font, without any spaces
(e.g., man(7)).
The commands to select the type face are:
.B Bold
.BI Bold alternating with italics (especially useful for function spec-
ifications)
.BR Bold alternating with Roman (especially useful for referring to
other manual pages)
.I Italics
.IB Italics alternating with bold
.IR Italics alternating with Roman
.RB Roman alternating with bold
.RI Roman alternating with italics
.SB Small alternating with bold
.SM Small (useful for acronyms)
Traditionally, each command can have up to six arguments, but the GNU
implementation removes this limitation (you might still want to limit
yourself to 6 arguments for portability's sake). Arguments are delim-
ited by spaces. Double quotes can be used to specify an argument which
contains spaces. All of the arguments will be printed next to each
other without intervening spaces, so that the .BR command can be used
to specify a word in bold followed by a mark of punctuation in Roman.
If no arguments are given, the command is applied to the following line
of text.
OTHER MACROS AND STRINGS
Below are other relevant macros and predefined strings. Unless noted
otherwise, all macros cause a break (end the current line of text).
Many of these macros set or use the "prevailing indent." The "prevail-
ing indent" value is set by any macro with the parameter i below;
macros may omit i in which case the current prevailing indent will be
used. As a result, successive indented paragraphs can use the same
indent without re-specifying the indent value. A normal (non-indented)
paragraph resets the prevailing indent value to its default value (0.5
inches). By default a given indent is measured in ens; try to use ens
or ems as units for indents, since these will automatically adjust to
font size changes. The other key macro definitions are:
Normal Paragraphs
.LP Same as .PP (begin a new paragraph).
.P Same as .PP (begin a new paragraph).
.PP Begin a new paragraph and reset prevailing indent.
Relative Margin Indent
.RS i Start relative margin indent: moves the left margin i to the
right (if i is omitted, the prevailing indent value is used).
A new prevailing indent is set to 0.5 inches. As a result,
all following paragraph(s) will be indented until the corre-
sponding .RE.
.RE End relative margin indent and restores the previous value of
the prevailing indent.
Indented Paragraph Macros
.HP i Begin paragraph with a hanging indent (the first line of the
paragraph is at the left margin of normal paragraphs, and the
rest of the paragraph's lines are indented).
.IP x i Indented paragraph with optional hanging tag. If the tag x is
omitted, the entire following paragraph is indented by i. If
the tag x is provided, it is hung at the left margin before
the following indented paragraph (this is just like .TP except
the tag is included with the command instead of being on the
following line). If the tag is too long, the text after the
tag will be moved down to the next line (text will not be lost
or garbled). For bulleted lists, use this macro with \(bu
(bullet) or \(em (em dash) as the tag, and for numbered lists,
use the number or letter followed by a period as the tag; this
simplifies translation to other formats.
.TP i Begin paragraph with hanging tag. The tag is given on the
next line, but its results are like those of the .IP command.
Hypertext Link Macros
(Feature supported with groff only.) In order to use hypertext link
macros, it is necessary to load the www.tmac macro package. Use the
request .mso www.tmac to do this.
.URL url link trailer
Inserts a hypertext link to the URI (URL) url, with link as
the text of the link. The trailer will be printed immediately
afterwards. When generating HTML this should translate into
the HTML command <A HREF="url">link</A>trailer.
This and other related macros are new, and many tools won't do
anything with them, but since many tools (including troff)
will simply ignore undefined macros (or at worst insert their
text) these are safe to insert.
It can be useful to define your own URL macro in manual pages
for the benefit of those viewing it with a roff viewer other
than groff. That way, the URL, link text, and trailer text
(if any) are still visible.
Here's an example:
.de URL
\\$2 \(laURL: \\$1 \(ra\\$3
..
.if \n[.g] .mso www.tmac
.TH ...
(later in the page)
This software comes from the
.URL "http://www.gnu.org/" "GNU Project" " of the"
.URL "http://www.fsf.org/" "Free Software Foundation" .
In the above, if groff is being used, the www.tmac macro pack-
age's definition of the URL macro will supersede the locally
defined one.
A number of other link macros are available. See groff_www(7) for more
details.
Miscellaneous Macros
.DT Reset tabs to default tab values (every 0.5 inches); does not
cause a break.
.PD d Set inter-paragraph vertical distance to d (if omitted,
d=0.4v); does not cause a break.
.SS t Subheading t (like .SH, but used for a subsection inside a
section).
Predefined Strings
The man package has the following predefined strings:
\*R Registration Symbol: (R)
\*S Change to default font size
\*(Tm Trademark Symbol: tm
\*(lq Left angled doublequote: "
\*(rq Right angled doublequote: "
SAFE SUBSET
Although technically man is a troff macro package, in reality a large
number of other tools process man page files that don't implement all
of troff's abilities. Thus, it's best to avoid some of troff's more
exotic abilities where possible to permit these other tools to work
correctly. Avoid using the various troff preprocessors (if you must,
go ahead and use tbl(1), but try to use the IP and TP commands instead
for two-column tables). Avoid using computations; most other tools
can't process them. Use simple commands that are easy to translate to
other formats. The following troff macros are believed to be safe
(though in many cases they will be ignored by translators): \", ., ad,
bp, br, ce, de, ds, el, ie, if, fi, ft, hy, ig, in, na, ne, nf, nh, ps,
so, sp, ti, tr.
You may also use many troff escape sequences (those sequences beginning
with \). When you need to include the backslash character as normal
text, use \e. Other sequences you may use, where x or xx are any char-
acters and N is any digit, include: \', \`, \-, \., \", \%, \*x, \*(xx,
\(xx, \$N, \nx, \n(xx, \fx, and \f(xx. Avoid using the escape
sequences for drawing graphics.
Do not use the optional parameter for bp (break page). Use only posi-
tive values for sp (vertical space). Don't define a macro (de) with
the same name as a macro in this or the mdoc macro package with a dif-
ferent meaning; it's likely that such redefinitions will be ignored.
Every positive indent (in) should be paired with a matching negative
indent (although you should be using the RS and RE macros instead).
The condition test (if,ie) should only have 't' or 'n' as the
condition. Only translations (tr) that can be ignored should be used.
Font changes (ft and the \f escape sequence) should only have the val-
ues 1, 2, 3, 4, R, I, B, P, or CW (the ft command may also have no
parameters).
If you use capabilities beyond these, check the results carefully on
several tools. Once you've confirmed that the additional capability is
safe, let the maintainer of this document know about the safe command
or sequence that should be added to this list.
NOTES
By all means include full URLs (or URIs) in the text itself; some tools
such as man2html(1) can automatically turn them into hypertext links.
You can also use the new URL macro to identify links to related infor-
mation. If you include URLs, use the full URL (e.g., <http://www.ker-
nelnotes.org>) to ensure that tools can automatically find the URLs.
Tools processing these files should open the file and examine the first
non-whitespace character. A period (.) or single quote (') at the
beginning of a line indicates a troff-based file (such as man or mdoc).
A left angle bracket (<) indicates an SGML/XML-based file (such as HTML
or Docbook). Anything else suggests simple ASCII text (e.g., a "catman"
result).
Many man pages begin with '\" followed by a space and a list of charac-
ters, indicating how the page is to be preprocessed. For portability's
sake to non-troff translators we recommend that you avoid using any-
thing other than tbl(1), and Linux can detect that automatically. How-
ever, you might want to include this information so your man page can
be handled by other (less capable) systems. Here are the definitions
of the preprocessors invoked by these characters:
e eqn(1)
g grap(1)
p pic(1)
r refer(1)
t tbl(1)
v vgrind(1)
FILES
/usr/share/groff/[*/]tmac/tmac.an
/usr/man/whatis
BUGS
Most of the macros describe formatting (e.g., font type and spacing)
instead of marking semantic content (e.g., this text is a reference to
another page), compared to formats like mdoc and DocBook (even HTML has
more semantic markings). This situation makes it harder to vary the
man format for different media, to make the formatting consistent for a
given media, and to automatically insert cross-references. By sticking
to the safe subset described above, it should be easier to automate
transitioning to a different reference page format in the future.
The Sun macro TX is not implemented.
AUTHORS
-- James Clark (jjc@jclark.com) wrote the implementation of the macro
package.
-- Rickard E. Faith (faith@cs.unc.edu) wrote the initial version of
this manual page.
-- Jens Schweikhardt (schweikh@noc.fdn.de) wrote the Linux Man-Page
Mini-HOWTO (which influenced this manual page).
-- David A. Wheeler (dwheeler@ida.org) heavily modified this manual
page, such as adding detailed information on sections and macros.
SEE ALSO
apropos(1), groff(1), man(1), man2html(1), mdoc(7), groff_mdoc(7),
groff_man(7), groff_www(7), whatis(1)
Linux 2004-07-27 MAN(7)
