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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
              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.

   Hypertext link macros
       .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.

SEE ALSO

       apropos(1), groff(1), lexgrog(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 4.13 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.