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#### 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   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.

(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.

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

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: (R)

\*S    Change to default font size

\*(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
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.

#### 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 3.24 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/.