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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 4.16 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/.