# man

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 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

.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
item \- description

It is extremely important that this format is followed, and that there is
a backslash before the single dash which follows the item name.  This
syntax is used by the mandb(8) program to create a database of short
descriptions for the whatis(1) and apropos(1) commands.  (See lexgrog(1)
for further details on the syntax of the NAME section.)

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
respecifying the indent value.  A normal (nonindented) 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.

.UR url
Insert a hypertext link to the URI (URL) url, with all text up to
the following .UE macro as the link text.

.UE [trailer]
Terminate the link text of the preceding .UR macro, with the
optional trailer (if present, usually a closing parenthesis and/or
end-of-sentence punctuation) immediately following.  For non-HTML
output devices (e.g., man -Tutf8), the link text is followed by
the URL in angle brackets; if there is no link text, the URL is
printed as its own link text, surrounded by angle brackets.
(Angle brackets may not be available on all output devices.)  For
the HTML output device, the link text is hyperlinked to the URL;
if there is no link text, the URL is printed as its own link text.

These macros have been supported since GNU Troff 1.20 (2009-01-05) and
Heirloom Doctools Troff since 160217 (2016-02-17).

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 UR and UE macros to identify links to related
information.  If you include URLs, use the full URL (e.g.,
⟨http://www.kernel.org⟩) to ensure that tools can automatically find the
URLs.

Tools processing these files should open the file and examine the first
nonwhitespace 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.