From Linux Man Pages
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 con-
ventions for creating manual (man) pages. This macro package should be used by developers when writing or port-
ing 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 Distribution, 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 Manual).
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, network 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 ker-
nel here, but in fact very little has been documented, and the documentation that exists is out-
dated already. There are better sources of information for kernel developers.
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,
DIAGNOSTICS, 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 description 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) commands.
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 inter-
nals 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 function, 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 programs, 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 sections (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 docu-
ments. 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 current 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 specifications)
.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 delimited 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 fol-
lowed 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 "prevailing 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 para-
graph(s) will be indented until the corresponding .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 visi-
ble.
Here's an example:
.de URL
\\$2 \(laURL: \\$1 \(ra\\$3
..
.if \n[.g] .mso www.tmac
.TH ...
(later in the page)
This software comes from the
.URL "http://www.gnu.org/" "GNU Project" " of the"
.URL "http://www.fsf.org/" "Free Software Foundation" .
In the above, if groff is being used, the www.tmac macro package's definition of the URL macro will
supersede the locally defined one.
A number of other link macros are available. See groff_www(7) for more details.
Miscellaneous Macros
.DT Reset tabs to default tab values (every 0.5 inches); does not cause a break.
.PD d Set inter-paragraph vertical distance to d (if omitted, d=0.4v); does not cause a break.
.SS t Subheading t (like .SH, but used for a subsection inside a section).
Predefined Strings
The man package has the following predefined strings:
\*R Registration Symbol: �
\*S Change to default font size
\*(Tm Trademark Symbol: tm
\*(lq Left angled doublequote: "
\*(rq Right angled doublequote: "
SAFE SUBSET
Although technically man is a troff macro package, in reality a large number of other tools process man page
files that don't implement all of troff's abilities. Thus, it's best to avoid some of troff's more exotic abili-
ties where possible to permit these other tools to work correctly. Avoid using the various troff preprocessors
(if you must, go ahead and use tbl(1), but try to use the IP and TP commands instead for two-column tables).
Avoid using computations; most other tools can't process them. Use simple commands that are easy to translate to
other formats. The following troff macros are believed to be safe (though in many cases they will be ignored by
translators): \", ., ad, bp, br, ce, de, ds, el, ie, if, fi, ft, hy, ig, in, na, ne, nf, nh, ps, so, sp, ti, tr.
You may also use many troff escape sequences (those sequences beginning with \). When you need to include the
backslash character as normal text, use \e. Other sequences you may use, where x or xx are any characters 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 positive 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 different 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 values 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 information. If
you include URLs, use the full URL (e.g., <http://www.kernelnotes.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 characters, indicating how the page is to be pre-
processed. For portability's sake to non-troff translators we recommend that you avoid using anything other than
tbl(1), and Linux can detect that automatically. However, 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.
RELATED
apropos(1), groff(1), man(1), man2html(1), mdoc(7), mdoc.samples(7), groff_man(7), groff_www(7), whatis(1)
CATEGORY