Provided by: manpages_3.15-1_all

#### 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

.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.

(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.

#### SEEALSO

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 3.15 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/.