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 an.tmac macro package (often called
the man macro package). 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.
For conventions that should be employed when writing man pages for the
Linux man-pages package, see man-pages(7).
Title line
The first command in a man page (after comment lines, that is, lines
that start with .\") should be
.TH title section date source manual
For details of the arguments that should be supplied to the TH command,
see man-pages(7).
Note that BSD mdoc-formatted pages begin with the Dd command, not the
TH command.
Sections
Sections are started with .SH followed by the heading name.
The only mandatory 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
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.
For a list of other sections that might appear in a manual page, see
man-pages(7).
Fonts
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 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
"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 paragraph(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 visible.
Here’s an example:
.de URL
\\$2 \(laURL: \\$1 \(ra\\$3
..
.if \n[.g] .mso www.tmac
.TH ...
(later in the page)
This software comes from the
.URL "http://www.gnu.org/" "GNU Project" " of the"
.URL "http://www.fsf.org/" "Free Software Foundation" .
In the above, if groff is being used, the www.tmac macro
package’s definition of the URL macro will supersede the
locally defined one.
A number of other link macros are available. See groff_www(7) for more
details.
Miscellaneous Macros
.DT Reset tabs to default tab values (every 0.5 inches); does not
cause a break.
.PD d Set inter-paragraph vertical distance to d (if omitted,
d=0.4v); does not cause a break.
.SS t Subheading t (like .SH, but used for a subsection inside a
section).
Predefined Strings
The man package has the following predefined strings:
\*R Registration Symbol: ®
\*S Change to default font size
\*(Tm Trademark Symbol: ™
\*(lq Left angled double quote: “
\*(rq Right angled double quote: ”
Safe Subset
Although technically man is a troff macro package, in reality a large
number of other tools process man page files that don’t implement all
of troff’s abilities. Thus, it’s best to avoid some of troff’s more
exotic abilities where possible to permit these other tools to work
correctly. Avoid using the various troff preprocessors (if you must,
go ahead and use tbl(1), but try to use the IP and TP commands instead
for two-column tables). Avoid using computations; most other tools
can’t process them. Use simple commands that are easy to translate to
other formats. The following troff macros are believed to be safe
(though in many cases they will be ignored by translators): \", ., ad,
bp, br, ce, de, ds, el, ie, if, fi, ft, hy, ig, in, na, ne, nf, nh, ps,
so, sp, ti, tr.
You may also use many troff escape sequences (those sequences beginning
with \). When you need to include the backslash character as normal
text, use \e. Other sequences you may use, where x or xx are any
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.
FILES
/usr/share/groff/[*/]tmac/an.tmac
/usr/man/whatis
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 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:
e eqn(1)
g grap(1)
p pic(1)
r refer(1)
t tbl(1)
v vgrind(1)
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.
SEE ALSO
apropos(1), groff(1), man(1), man2html(1), groff_mdoc(7), whatis(1),
groff_man(7), groff_www(7), man-pages(7), mdoc(7)
COLOPHON
This page is part of release 3.23 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/.