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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: ®

       \*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 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/.