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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.  For the macros that produce  alternating  type
       faces,  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 5.09 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/.