# man

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  develop-
ers when writing or porting man pages for Linux.  It is fairly compati-
ble 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 pro-
gram:

.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) com-
mands.

For a list of other sections that might appear in a  manual  page,  see
man-pages(7).
.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 delim-
ited 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 "prevail-
ing 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  corre-
sponding .RE.

.RE      End  relative margin indent and restores the previous value of
the prevailing indent.

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 pack-
age'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.

\*(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 char-
acters 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  posi-
tive  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  dif-
ferent  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  condi-
tion.  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 parame-
ters).

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 infor-
mation.  If you include URLs, use the full URL (e.g.,  <http://www.ker-
nelnotes.org>) to ensure that tools can automatically find the URLs.

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