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.
The first command in a man page (after comment lines) should be
.THtitle section date source manual,
The title of the man page (e.g., MAN).
The section number the man page should be placed in (e.g.,
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.
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, BSD
4.3, Linux DLL 4.4.1.
The title of the manual (e.g., Linux Programmer's
Note that BSD mdoc-formatted pages begin with the Dd command, not the
The manual sections are traditionally defined as follows:
Those commands that can be executed by the user from within
2 System calls
Those functions which must be performed by the kernel.
3 Library calls
Most of the libc functions, such as
4 Special files
Files found in /dev.
5 File formats and conventions
The format for /etc/passwd and other human-readable
7 Conventions and miscellaneous
A description of the standard file system layout, network
protocols, ASCII and other character codes, this man page, and other
8 System management commands
Commands like mount(8), many of which only root can
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been documented, and the documentation that exists is outdated already.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.
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:
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:
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.
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
gives a list of the values the library routine will return
to the caller and the conditions that cause these values to be
lists the possible exit status values or a program and the
conditions that cause these values to be returned.
describes the options accepted by the program and how they
change its behavior.
describes the grammar of any sublanguage this
provides one or more examples describing how this function,
file or command is used.
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.
lists all environment variables that affect your program or
function and how they affect it.
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.
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). However, please include
security information somewhere!
describes any standards or conventions this
provides miscellaneous notes.
lists limitations, known defects or inconveniences, and
other questionable activities.
lists authors of the documentation or program so you can
mail in bug reports.
lists related man pages in alphabetical order, possibly
followed by other related pages or documents. Conventionally this is the
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
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
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.,
The commands to select the type face are:
Bold alternating with italics (especially useful for
Bold alternating with Roman (especially useful for
referring to other manual pages)
Italics alternating with bold
Italics alternating with Roman
Roman alternating with bold
Roman alternating with italics
Small alternating with bold
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 followed
by a mark of punctuation in Roman. If no arguments are given, the command is
applied to the following line of text.
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 ens or ems as units for
indents, since these will automatically adjust to font size changes. The other
key macro definitions are:
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 corresponding
End relative margin indent and restores the previous value
of the prevailing indent.
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 \(em (em dash) as the
tag, and for numbered lists, use the number or letter followed by a period
as the tag; this simplifies translation to other formats.
Begin paragraph with hanging tag. The tag is given on the
next line, but its results are like those of the .IP command.
(Feature supported with groff only.) In order to use hypertext link macros, it
is necessary to load the www.tmac macro package. Use the request
.mso www.tmac to do this.
.URL url link trailer
Inserts a hypertext link to the URI (URL) url, with
link as the text of the link. The trailer will be printed
immediately afterwards. When generating HTML this should translate into
the HTML command <A
This and other related macros are new, and many tools won't
do anything with them, but since many tools (including troff) will simply
ignore undefined macros (or at worst insert their text) these are safe to
A number of other link macros are available. See groff_www(7) for more
Although technically man is a troff macro package, in reality a large
number of other tools process man page files that don't implement all of
troff's abilities. Thus, it's best to avoid some of troff's more exotic
abilities where possible to permit these other tools to work correctly. Avoid
using the various troff preprocessors (if you must, go ahead and use
tbl(1), but try to use the IP and TP commands instead for
two-column tables). Avoid using computations; most other tools can't process
them. Use simple commands that are easy to translate to other formats. The
following troff macros are believed to be safe (though in many cases they will
be ignored by translators): \", ., ad, bp,
br, ce, de, ds, el, ie, if,
fi, ft, hy, ig, in, na, ne,
nf, nh, ps, so, sp, ti, tr.
You may also use many troff escape sequences (those sequences beginning with \).
When you need to include the backslash character as normal text, use \e. Other
sequences you may use, where x or xx are any 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.
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 preprocessed. 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:
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.