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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
       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   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.

   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
                afterward.  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: (R)

       \*S    Change to default font size

       \*(Tm  Trademark Symbol: tm

       \*(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.

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 3.35 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://man7.org/linux/man-pages/.