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GROFF_MAN(7)                      Miscellaneous Information Manual                      GROFF_MAN(7)



NAME
       groff_man - GNU roff macro package for formatting man pages

SYNOPSIS
       groff -man [option ...] [input-file ...]
       groff -m man [option ...] [input-file ...]

DESCRIPTION
       The  man  macro  package for groff is used to produce manual pages (“man pages”) like the one
       you are reading.  GNU roff's implementation was written by James Clark.

       This document presents the macros thematically to aid learners;  for  those  needing  only  a
       quick  reference, the following table lists them alphabetically, with cross-references to ap‐
       propriate subsections below.

       Macro   Meaning                         Subsection
       ───────────────────────────────────────────────────────────────────
       .B      Bold                            Font style macros
       .BI     Bold, italic alternating        Font style macros
       .BR     Bold, roman alternating         Font style macros
       .EE     Example end                     Document structure macros
       .EX     Example begin                   Document structure macros
       .I      Italic                          Font style macros
       .IB     Italic, bold alternating        Font style macros
       .IP     Indented paragraph              Paragraph macros
       .IR     Italic, roman alternating       Font style macros
       .LP     (Left) paragraph                Paragraph macros
       .ME     Mail-to end                     Hyperlink and email macros
       .MT     Mail-to start                   Hyperlink and email macros
       .OP     (Command-line) option           Command synopsis macros
       .P      Paragraph                       Paragraph macros
       .PP     Paragraph                       Paragraph macros
       .RB     Roman, bold alternating         Font style macros
       .RE     Relative-indent end             Document structure macros
       .RI     Roman, italic alternating       Font style macros
       .RS     Relative-indent start           Document structure macros
       .SB     Small bold                      Font style macros
       .SH     Section heading                 Document structure macros
       .SM     Small                           Font style macros
       .SS     Subection heading               Document structure macros
       .SY     Synopsis start                  Command synopsis macros
       .TH     Title heading                   Document structure macros
       .TP     Tagged paragraph                Paragraph macros
       .TQ     Tagged paragraph continuation   Paragraph macros
       .UE     URL end                         Hyperlink and email macros
       .UR     URL start                       Hyperlink and email macros
       .YS     Synopsis end                    Command synopsis macros

       Macros whose use we discourage (.AT, .BT, .DT, .HP, .PD, .PT, and .UC) are described in  sub‐
       section “Deprecated features”, below.

   Macro reference preliminaries
       Each  macro is described in a tagged paragraph.  Closely related macros, such as .EX and .EE,
       are grouped together.

       Optional macro arguments are indicated by surrounding them with square brackets.  If a  macro
       accepts  multiple  arguments,  arguments  containing  whitespace  must be double-quoted ("one
       two"), to be interpreted correctly.  Most macro arguments are strings that will be output  as
       text; exceptions are noted.

       Bear in mind that groff is fundamentally a programming system for typesetting.  Consequently,
       the verb “to set” is frequently used below in the sense “to typeset”.

   Document structure macros
       The highest level of organization of a man page is determined by this group of  macros.   .TH
       (title  heading)  identifies  the document as a man page and defines information enabling its
       indexing by mandb(8) or a similar tool.  Sections (.SH), one of which is mandatory  and  many
       of  which  are standardized, facilitate quick location of relevant material by the reader and
       aid the man page writer to discuss all essential aspects of the topic.  Subsections (.SS) are
       optional  and  permit sections that grow long to develop in a controlled way.  Many technical
       discussions require examples; lengthy ones, especially those reflecting multiple lines of in‐
       put  to  or  output from the system, are usefully bracketed by .EX and .EE.  When none of the
       foregoing meets a structural demand, a section of the discussion  can  be  manually  indented
       within .RS and .RE macros.

       .TH title section [footer-middle] [footer-outside] [header-middle]
              Define  the title of the man page as title and the section as section.  See man(1) for
              details on the section numbers and suffixes applicable to your system.  title and section are positioned together at the left and right in the header line (with section in
              parentheses immediately appended to title).  footer-middle is centered in  the  footer
              line.   footer-outside is positioned at the left in the footer line (or at the left on
              even pages and at the right on odd pages if double-sided printing is active).  header-
              middle is centered in the header line.  If section is a simple integer between 1 and 9
              (inclusive), or is exactly “3p”, there is no need to specify header-middle; the  macro
              package will supply text for it.

              For HTML output, headers and footers are completely suppressed.

              Additionally,  this macro starts a new page; the page number is reset to 1 (unless the
              -rC1 option is given on the command line).  This feature is intended only for  format‐
              ting multiple man pages.

              A  man  page should contain exactly one .TH call at or near the beginning of the file,
              prior to any other macro calls.

              By convention, footer-middle is the most recent modification  date  of  the  man  page
              source  document, and footer-outside is the name and version or release of the project
              providing it.

       .SH [heading-text]
              Set heading-text as a section heading flush left.  The text following .SH  up  to  the
              end  of  the line, or the text on the next input line if .SH is given no arguments, is
              set in bold (or the font specified by the string register HF) slightly larger than the
              base  font  size.   Additionally, the left margin and indentation affecting subsequent
              text are reset to their default values.  Text on input lines after heading-text is set
              as a normal paragraph (.PP).

              The  content  of heading-text and ordering of sections has been standardized by common
              practice, as has much of the layout of material within sections.  For example, a  sec‐
              tion called “Name” or “NAME” must exist, must be the first section after the .TH call,
              and must contain only a line of the form
                     page-topic[, ...] \- summary-description
              for a man page to be properly indexed.  See man(7) for the conventions  prevailing  on
              your system.

       .SS [subheading-text]
              Set  subheading-text  as  a subsection heading indented (by default) partway between a
              section heading and a normally-indented paragraph (.PP).  The text following .SS up to
              the  end of the line, or the text on the next input line if .SS is given no arguments,
              is set in bold (or the font specified by the string register  HF)  at  the  base  font
              size.  Additionally, the left margin and indentation affecting subsequent text are re‐
              set to their default values.  Text on input lines after subheading-text is  set  as  a
              normal paragraph (.PP).

       .EX
       .EE    Begin  and  end  example.   After .EX, filling and hyphenation are disabled and a con‐
              stant-width (monospaced) font is selected.  Calling .EE enables filling  and  restores
              the previous hyphenation setting and font.

              Example  regions  are  useful  for formatting code, shell sessions, and text file con‐
              tents.

              These macros are defined on many (but not all) legacy  Unix  systems  running  classic
              troff.   To be certain your page will be portable to those systems, copy their defini‐
              tions from the an-ext.tmac file of a groff installation.

       .RS [indent]
              Move the left margin to the right by the value indent, if specified, and by a  default
              amount  otherwise;  see  subsection “Horizontal and vertical spacing” below.  Calls to
              .RS can be nested; each call increments by 1 the indentation level used by  .RE.   The
              indentation level prior to any .RS calls is 1.

       .RE [level]
              Move the left margin back to that corresponding to indentation level level.  If no ar‐
              gument is given, move the left margin one level back.

   Paragraph macros
       A typical paragraph (.PP) is set at the current left margin, which  by  default  is  indented
       from the left margin of the output device.  In man pages and other technical literature, def‐
       inition lists are frequently encountered; these can be set as “tagged  paragraphs”  (.TP  and
       .TQ), which have one or more leading tags followed by a paragraph that has an additional left
       indent.  The indented paragraph (.IP) macro is useful to continue the indented content  of  a
       narrative started with .TP, or to present an itemized or ordered list.

       .LP
       .PP
       .P     Begin a new paragraph; these macros are synonymous.  They break the output line at the
              current position, followed by a vertical space downward by a default amount (which can
              be  changed  by  the  deprecated .PD macro).  The font size and style are reset to de‐
              faults; see subsection “Font style macros” below.  Finally, the left margin and inden‐
              tation are reset to default values.

       .TP [indent]
              Set  a  tagged, indented paragraph.  The input line following this macro, known as the
              tag, is printed at the current left margin.  Subsequent text is indented by indent, if
              specified,  and by a default amount otherwise; see subsection “Horizontal and vertical
              spacing” below.

              If the tag is not as wide as the indentation, the paragraph starts on the same line as
              the  tag, at the applicable indentation, and continues on the following lines.  Other‐
              wise, the descriptive part of the paragraph begins on the line following the tag,  en‐
              tirely  indented.   The line containing the tag can include a macro call, for instance
              to set the tag in bold with .B.

              .TP was used to write the first paragraph of this description of .TP, and .IP the sub‐
              sequent ones.

       .TQ    Set  an  additional  tag  for a paragraph tagged with .TP.  The pending output line is
              broken.  The tag on the input line following this macro and subsequent lines are  han‐
              dled as with .TP.

              This macro is not defined on legacy Unix systems running classic troff.  To be certain
              your page will be portable to those systems, copy its definition from the  an-ext.tmac
              file of a groff installation.

              The descriptions of .LP, .PP, and .P above were written using .TP and .TQ.

       .IP [tag] [indent]
              Set  an  indented  paragraph  with  an optional tag.  The tag and indent arguments, if
              present, are handled as with .TP, with the exception that the tag argument to .IP can‐
              not include a macro call.

              Two convenient use cases for .IP are

                     (1) to  start  a new paragraph with the same indentation as the previous .IP or
                         .TP paragraph, if no indent argument is given; and

                     (2) to set a paragraph with a short tag that  is  not  semantically  important,
                         such as a bullet (•)—obtained with the ‘\(bu’ character escape—or list enu‐
                         merator, as seen in this very paragraph.

   Command synopsis macros
       Command synopses are a staple of section 1 and 8 man pages.  These macros  aid  you  to  con‐
       struct  one  that has the classical Unix appearance.  Furthermore, some tools are able to in‐
       terpret these macros semantically and treat them appropriately for localization  and/or  pre‐
       sentation.  A command synopsis is wrapped in .SY/.YS calls, with command-line options of some
       formats indicated by .OP.

       These macros are not defined on legacy Unix systems running classic  troff.   To  be  certain
       your page will be portable to those systems, copy their definitions from the an-ext.tmac file
       of a groff installation.

       .SY command
              Begin synopsis.  Hyphenation is turned off.  The command argument is set in bold.  The
              output  line  is filled as normal, but if a break is required, subsequent output lines
              are indented by the width of command plus a space.

       .OP option-name [option-argument]
              Indicate an optional command parameter called option-name, which is set in  bold.   If
              the  option  takes an argument, specify option-argument using a noun, abbreviation, or
              hyphenated noun phrase.  If present, option-argument is preceded by a space and set in
              italics.  Square brackets (in roman) surround both arguments.

       .YS    End synopsis.  Restore indentation and hyphenation to previous values.

       Multiple  .SY/.YS blocks can be specified, for instance to distinguish differing modes of op‐
       eration of a complex command like tar(1); each will be separated by a paragraph space.

       .SY can also be repeated multiple times before a closing .YS, which  is  useful  to  indicate
       synonymous ways of invoking a particular mode of operation.

       For example,

              .SY groff
              .OP \-abcegiklpstzCEGNRSUVXZ
              .OP \-d cs
              .OP \-f fam
              .OP \-F dir
              .OP \-I dir
              .OP \-K arg
              .OP \-L arg
              .OP \-m name
              .OP \-M dir
              .OP \-n num
              .OP \-o list
              .OP \-P arg
              .OP \-r cn
              .OP \-T dev
              .OP \-w name
              .OP \-W name
              .RI [ file
              \&.\|.\|.\&]
              .YS
              .
              .SY groff
              .B \-h
              .SY groff
              .B \-\-help
              .YS

       produces the following output.

              groff [-abcegiklpstzCEGNRSUVXZ] [-d cs] [-f fam] [-F dir] [-I dir] [-K arg] [-L arg]
                    [-m name] [-M dir] [-n num] [-o list] [-P arg] [-r cn] [-T dev] [-w name]
                    [-W name] [file ...]

              groff -h
              groff --help

       Several features of the above example are of note.

       •      The  empty  request (.), which does nothing, is used for vertical spacing in the input
              file for readability by the document maintainer.  Do not put empty  lines  in  a  roff
              source document.

       •      The command and option names are presented in bold to cue the user that they should be
              input literally.

       •      Option dashes are specified with the ‘\-’ escape sequence; this is an important  prac‐
              tice  to  make  them clearly visible and to facilitate cut-and-paste from the rendered
              man page to a shell prompt or text file.

       •      Option arguments and command operands are presented in  italics  (underlined  on  some
              output  devices,  such  as terminals and emulators), to cue the user that they must be
              replaced with appropriate text.

       •      Symbols that are neither to be typed literally nor simply replaced appear in the roman
              style; brackets surround optional arguments, and an ellipsis indicates that the previ‐
              ous syntactical element may be repeated arbitrarily.

              Some man pages use a brace-and-pipe notation such as “{--diff|--compare}” to  indicate
              that  one and only one of the ‘|’-separated items within the braces must be input.  If
              this braced construct is furthermore surrounded by square brackets, it means  that  at
              most one of the items is accepted.

              Authors  of man pages should note the use of the zero-width space escape sequence ‘\&’
              on both sides of the ellipsis; this is a good practice to avoid surprises in the event
              the  ellipsis  gets refilled in your text editor.  See “Portability”, below.  The mor‐
              bidly curious may consult groff(7) regarding the narrow-space escape sequence ‘\|’.

   Hyperlink and email macros
       Email addresses are bracketed with .MT/.ME and URL hyperlinks with .UR/.UE.

       These macros are not defined on legacy Unix systems running classic  troff.   To  be  certain
       your page will be portable to those systems, copy their definitions from the an-ext.tmac file
       of a groff installation.

       .MT address
       .ME [punctuation]
              Identify address as an RFC 6068 addr-spec for a “mailto:” URI with  the  text  between
              the  two macro calls as the link text.  A punctuation argument to .ME is placed at the
              end of the link text without intervening space.  Note that address may not be  visible
              in the output text, particularly if the man page is being viewed as HTML.  On a device
              that is not a browser, address is set in angle brackets after the link text and before
              punctuation.

              When rendered by groff to a TTY or PostScript output device,

                     Contact
                     .MT fred.foonly@\:fubar.net
                     Fred Foonly
                     .ME
                     for more information.

              displays as: “Contact Fred Foonly ⟨fred.foonly AT fubar.net⟩ for more information.”.

              The use of ‘\:’ to insert hyphenless discretionary breaks is a groff extension and can
              be omitted.

       .UR URL
       .UE [punctuation]
              Identify URL as an RFC 3986 URI hyperlink with the text between the two macro calls as
              the  link  text.   A punctuation argument to .UE is placed at the end of the link text
              without intervening space.  Note that URL may not be visible in the output text,  par‐
              ticularly if the man page is being viewed as HTML.  On a device that is not a browser,
              URL is set in angle brackets after the link text and before punctuation.

              When rendered by groff to a TTY or PostScript output device,

                     The GNU Project of the Free Software Foundation hosts the
                     .UR https://\:www.gnu.org/\:software/\:groff/
                     Groff home page
                     .UE .

              displays as: “The GNU Project of the Free Software Foundation  hosts  the  Groff  home
              page ⟨https://www.gnu.org/software/groff/⟩.”.

              The use of ‘\:’ to insert hyphenless discretionary breaks is a groff extension and can
              be omitted.

   Font style macros
       The man macro package is limited in its  font  styling  options,  offering  only  bold  (.B),
       italic (.I), and roman (the default).  Italic text is usually set underscored instead on ter‐
       minals and other classical nroff-style output devices.  The .SM and .SB macros  set  text  in
       roman  or  bold,  respectively,  at a smaller point size; these differ visually from regular-
       sized roman or bold text only on troff-style output devices.  The foregoing macros cause word
       breaks  before  and after their arguments, but it is often necessary to set text in different
       styles without intervening whitespace.  The macros .BI, .BR, .IB, .IR, .RB,  and  .RI,  where
       ‘B’,  ‘I’,  and  ‘R’ indicate bold, italic, and roman, respectively, set their odd- and even-
       numbered arguments in alternating styles, with no whitespace separating them.

       Because font styles are presentational rather  than  semantic,  conflicting  traditions  have
       arisen  regarding  which  font  styles should be used to mark file or path names, environment
       variables, in-line literals, and even man page cross-references.

       The default font size and family (for troff output devices) is 10-point Times.   The  default
       style is roman.

       .B [text]
              Set text in bold.  If the macro is given no arguments, the text of the next input line
              is set in bold.

              Use bold for literal portions of syntax synopses, for command-line options in  running
              text,  and for literals that are major topics of the subject under discussion; for ex‐
              ample, this page uses bold for macro and register names.  In .EX/.EE examples  of  in‐
              teractive I/O (such as a shell session), set only the user-typed input in bold.

       .I [text]
              Set  text  in italics.  If the macro is given no arguments, the text of the next input
              line is set in italics.

              Use italics for file and path names, for environment  variables,  for  enumeration  or
              preprocessor  constants  in  C, for variable (user-determined) portions of syntax syn‐
              opses, for the first occurrence only of a  technical  concept  being  introduced,  for
              names  of  works of software (including commands and functions, but excluding names of
              operating systems or their kernels), and anywhere a parameter requiring replacement by
              the user is encountered.  An exception involves variable text in a context that is al‐
              ready marked up in italics, such as file or path names with  variable  components;  in
              such  cases,  follow  the  convention of mathematical typography: set the file or path
              name in italics as usual (see .IR below), but use roman for  the  variable  part,  and
              italics again in running roman text when referring to the variable material.

       .SM [text]
              Set text one point size smaller than the default size.  If the macro is given no argu‐
              ments, the text of the next input line is set smaller.

              Note: nroff-style output devices, such as terminals, will render text  at  the  normal
              font  size instead.  Do not rely upon .SM to communicate semantic information distinct
              from using roman style at the normal size; it will be hidden from readers  using  such
              devices.

       .SB [text]
              Set text in bold, one point size smaller than the default size.  If the macro is given
              no arguments, the text of the next input line is set smaller and in bold.

              Note: nroff-style output devices, such as terminals, will render text in bold  at  the
              normal  font  size  instead.  Do not rely upon .SB to communicate semantic information
              distinct from using bold style at the normal size; it will be hidden from readers  us‐
              ing such devices.

       Note  what is not prescribed for setting in bold or italics above: elements of “synopsis lan‐
       guage” such as ellipses and brackets around options; proper names and adjectives;  titles  of
       anything  other  than works of literature or software; identifiers for standards documents or
       technical reports such as CSTR #54, RFC 1918, Unicode 11.0, or  POSIX.1-2017;  acronyms;  and
       occurrences  after the first of a technical term or piece of jargon.  Again, the names of op‐
       erating systems and their kernels are, by practically universal convention, set in roman.

       Be frugal with the use of italics for emphasis, and particularly with the use of bold.  Brief
       runs of literal text, such as references to individual characters or short strings, including
       section and subsection headings of man pages, are suitable objects  for  quotation;  see  the
       ‘\(lq’, ‘\(rq’, ‘\(oq’, and ‘\(cq’ escapes in subsection “Portability” below.

       Unlike  the  above font style macros, the font alternation macros below accept only arguments
       on the same line as the macro call.  If whitespace is required within one of  the  arguments,
       first  consider  whether  the same result could be achieved with as much clarity by using the
       single-style macros on separate input lines.  When it cannot, double-quote an  argument  with
       one  or more embedded space characters.  Setting all three different styles within one white‐
       space-delimited word presents challenges; it is possible with the ‘\c’ and/or  ‘\f’  escapes,
       but see subsection “Portability” below for caveats.

       .BI bold-text italic-text ...
              Set each argument in bold and italics, alternately.

                     .BI \-r name = n

       .BR bold-text roman-text ...
              Set each argument in bold and roman, alternately.

                     Any such change becomes effective with the first use of
                     .BR .NH ,
                     .I after
                     the new alias is defined.

       .IB italic-text bold-text ...
              Set each argument in italics and bold, alternately.

                     All macro package files must be named
                     .IB name .tmac
                     to fully use the
                     .I tmac
                     mechanism.

       .IR italic-text roman-text ...
              Set each argument in italics and roman, alternately.

                     This is the first command of the
                     .IR prologue .

       .RB roman-text bold-text ...
              Set each argument in roman and bold, alternately.

                     Also, the statement
                     .RB \(oq "delim on" \(cq
                     is not handled specially.

       .RI roman-text italic-text ...
              Set each argument in roman and italics, alternately.

                     .RI [ file
                     \&.\|.\|.\&]

   Horizontal and vertical spacing
       The indent argument accepted by .RS, .IP, .TP, and the deprecated .HP is a number plus an op‐
       tional scaling indicator.  If no scaling indicator is given, the  man  package  assumes  ‘n’;
       that is, the width of a letter “n” in the font current when the macro is called.  See section
       “Numerical Expressions” in groff(7) for further details.  An indent specified in  a  call  to
       .IP,  .TP, or the deprecated .HP persists until (1) another of these macros is called with an
       explicit indent argument, or (2) .SH, .SS, or .PP or its synonyms is called; these clear  the
       indent entirely.

       Indents  set  by  .RS move the left margin and persist until .RS, .RE, .SH, or .SS is called.
       The default indentation, exhibited by ordinary .PP paragraphs not within an .RS/.RE  relative
       indent,  is 7.2n in troff mode and 7n in nroff mode.  The HTML output device is an exception;
       it ignores indentation completely.  This same indentation is used again (additively) for  the
       defaults of .IP, .TP, .RS, and the deprecated .HP.  Section headings (.SH) are set flush with
       the left margin of the output device, and subsection headings (.SS) are indented 3n.

       Resist the temptation to mock up tabular or multi-column output with ASCII tab characters  or
       the  indentation arguments to .IP, .TP, .RS, or the deprecated .HP; the result may not render
       comprehensibly on an output device you fail to check, or which is developed  in  the  future.
       The table preprocessor tbl(1) can likely meet your needs.

       The  following macros cause a line break with the insertion of vertical space: .SH, .SS, .TP,
       .TQ, .PP (and its synonyms), .IP, and the deprecated .HP.  The default inter-section and  in‐
       ter-paragraph spacing is 1 line in nroff mode, and 0.4v in troff mode.  (The deprecated macro
       .PD can change this vertical spacing, but its use is discouraged.)  The macros .RS, .RE, .EX,
       and .EE also cause a break but no insertion of vertical space.

   Number registers
       Number registers are described in section “Options” below.

   String registers
       The following strings are defined.

       \*R    expands to the character escape for the “registered sign” glyph, ‘\(rg’, if available,
              and “(Reg.)” otherwise.

       \*S    expands to an escape setting the font size to the document default.

       \*(HF  expands to the font identifier used to print headings and subheadings.  The default is
              ‘B’.

       \*(lq
       \*(rq  expand  to the character escapes for left and right double-quotation marks, ‘\(lq’ and
              ‘\(rq’, respectively.

       \*(Tm  expands to the character escape for the “trade mark sign” glyph, ‘\(tm’, if available,
              and “(TM)” otherwise.

   Interaction with preprocessors
       When  a preprocessor like tbl or eqn is needed, a hint can be given to the man page formatter
       by making the first line of a man page look like this:

              '\" word

       Note that the line starts with an apostrophe ('), not a dot, and that a single space  charac‐
       ter  follows the double quote.  The word consists of one letter for each needed preprocessor:
       ‘e’ for eqn, ‘r’ for refer, and ‘t’ for tbl.  Modern implementations of the man  program  in‐
       terpret this first line and automatically call the right preprocessor(s).

       The  usual  tbl and eqn macros for table and equation inclusion, .TS, .T&, .TE, .EQ, and .EN,
       may be used freely.  Note that nroff output devices are extremely limited in presentation  of
       mathematical equations.

   Portability
       The  two  major syntactical categories of roff languages are requests and escapes.  Since the
       man macros are implemented in terms of groff requests and escapes,  one  can,  in  principle,
       supplement the functionality of man with these lower-level elements where necessary.

       Note, however, that using raw groff requests is likely to make your page render poorly on the
       class of viewers that transform it to HTML.  Some requests make  implicit  assumptions  about
       things  like character and page sizes that may not hold in an HTML environment; also, many of
       these viewers don't interpret the full groff vocabulary, a problem that can lead to  portions
       of your text being silently dropped.

       For portability to modern viewers, it is best to write your page entirely with the macros de‐
       scribed in this page (except for the ones identified as deprecated, which should be avoided).
       The  macros  we  have  described  as  extensions (.EX/.EE, .SY/.OP/.YS, .UR/.UE, and .MT/.ME)
       should be used with caution, as they may not yet be built in to some viewer that is important
       to your audience.  If in doubt, copy the implementation into your page—after the .TH call and
       the “Name” section, to accommodate timid mandb implementations.

       Similar caveats apply to escapes.  Some escape sequences are  however  required  for  correct
       typesetting even in man pages and usually do not cause portability problems:

       \"     Comment.   Everything  after the double-quote to the end of the input line is ignored.
              Whole-line comments are frequently placed immediately after the empty request ‘.’.

       \newline
              Join the next input line to the current one.  Except for the update of the input  line
              counter  (used for diagnostic messages and related purposes), a series of lines ending
              in backslash-newline is transparent to groff.  Use this escape  to  break  excessively
              input long lines for document maintenance.

       \~     Adjustable, non-breaking space character.  Use this escape to prevent a break inside a
              short phrase or between a numerical quantity and its corresponding unit(s).

                     Before starting the motor, set the output speed to\~1.
                     There are 1,024\~bytes in 1\~kiB.
                     CSTR\~#8 documents the B language.

       \&     Zero-width space.  Append to an input line to prevent an  end-of-sentence  punctuation
              sequence from being recognized as such, or insert at the beginning of an input line to
              prevent a dot or apostrophe from being interpreted as the beginning of a roff request.

       \(aq   ASCII apostrophe.  Use for syntax elements of programming languages because some  out‐
              put devices might replace unescaped apostrophes with right single quotation marks.

       \(oq   Opening single quotation mark.
       \(cq   Closing single quotation mark.

              Use these for paired directional single quotes, ‘like this’.

       \(dq   ASCII  double-quote.  Sometimes needed after macro calls to prevent the interpretation
              of the ASCII quotation mark character ‘"’ as the beginning or end of a macro argument.

       \(lq   Left double quotation mark.
       \(rq   Right double quotation mark.

              Use these for paired directional double quotes, “like this”.

       \(em   Em-dash.  Use for an interruption in a sentence—such as this one.

       \(en   En-dash.  Use to separate the two ends of a range, in particular between numbers,  for
              example: the digits 1–9.

       \(ga   ASCII  grave  accent.   Use  for syntax elements of programming languages, for example
              shell command substitutions, because some output devices might replace unescaped grave
              accents with left single quotation marks.

       \(ha   ASCII  circumflex  accent.   Use  for syntax elements of programming languages because
              some output devices might replace unescaped circumflex accents with  non-ASCII  glyphs
              like the Unicode U+02C6 modifier letter circumflex.

       \(ti   ASCII tilde.  Use for syntax elements of programming languages because some output de‐
              vices might replace unescaped tildes with non-ASCII glyphs  like  the  Unicode  U+02DC
              small tilde.

       \-     Minus  sign.   Also use this to display syntax elements that require the ASCII hyphen-
              minus character, for example command-line options and C language operators.   The  un‐
              escaped  ‘-’  input character is not appropriate for these cases because it may render
              as a hyphen on some output devices.

       \c     If this escape sequence occurs at the end of an input line, no white space is inserted
              between  the  last glyph on it and the first glyph resulting from the next input line.
              This is occasionally useful when three different fonts are needed in a single word.

                     Normally, the final output file should be named
                     .IB file .pdf\c
                     \&.

              Note that when using this trick with the .BI or .RI macros, you will need to  manually
              add  an  italic  correction escape ‘\/’ before the ‘\c’ due to way macros expand their
              arguments.

                     Files processed with
                     .B groff \-mom
                     (or
                     .BI "\-m " mom\/\c
                     ) produce PostScript output by default.

              Alternatively, and perhaps with better portability, the ‘\f’ font escape sequence  can
              be  used;  see  below.  Using ‘\c’ to include the output from more than one input line
              into the next-line argument of a .TP macro will render incorrectly with groff  1.22.3,
              mandoc  1.14.1,  older versions of these programs, and perhaps with some other format‐
              ters.

       \e     Widely used in man pages to represent a backslash output glyph.  It works reliably  as
              long as the .ec request is not used, which should never happen in man pages, and it is
              slightly more portable than the more exact ‘\(rs’ (“reverse solidus”) escape sequence.

       \fB, \fI, \fR, \fP
              Switch to bold, italic, roman, or back to the  previous  font,  respectively.   Either
              these  or  ‘\c’  is  needed when three different fonts are required in a single white‐
              space-delimited word.

                     .RB [ \-\-reference\-dictionary=\fI\,name\/\fP ]

                     .RB [ \-\-reference\-dictionary=\c
                     .IR name ]

              Font escapes may be more portable than ‘\c’.  As shown above, it is up to you  to  ac‐
              count  for  italic  corrections  with ‘\/’ and ‘\,’, which are themselves groff exten‐
              sions, if desired and if supported by your implementation.

              Note that ‘\fP’ reliably returns to the style in use immediately preceding the  previ‐
              ous ‘\f’ escape only if no sectioning, paragraph, or font face macro calls have inter‐
              vened.

              As long as only two fonts are needed in any single whitespace-delimited word, font al‐
              ternation  macros  like  .BI usually result in more readable source code than ‘\f’ es‐
              capes do.

       For maximum portability, escape sequences and special characters not listed above are  better
       avoided in man pages.

   Deprecated features
       Use of the following is discouraged.

       .AT [system [release]]
              Alter the footer for use with AT&T man pages, overriding any definition of the footer-
              outside argument to .TH.  This macro exists only for compatibility; don't use it.

              The first argument system can be:

                     3      7th edition (default)

                     4      System III

                     5      System V

              The optional second argument release specifies the release number, such as in  “System
              V Release 3”.

       .BT    Set the page footer.  Redefine this macro to get control of the footer.

       .DT    Set  tabs  every 0.5 inches.  Since this macro is always called during a .TH macro, it
              makes sense to call it only if the tab positions have been changed.

              Use of this presentation-level macro is deprecated.  It translates poorly to HTML, un‐
              der  which  exact whitespace control and tabbing are not readily available.  Thus, in‐
              formation or distinctions that you use .DT to express are likely to be lost.   If  you
              feel  tempted  to use it, you should probably be composing a table using tbl(1) markup
              instead.

       .HP [indent]
              Set up a paragraph with a hanging left indentation.  The indent argument, if  present,
              is handled as with .TP.

              Use  of this presentation-level macro is deprecated.  While it is universally portable
              to legacy Unix systems, a hanging indentation  cannot  be  expressed  naturally  under
              HTML, and many HTML-based manual viewers simply interpret it as a starter for a normal
              paragraph.  Thus, any information or distinction you tried to express with the  inden‐
              tation may be lost.

       .PD [vertical-space]
              Define  the vertical space between paragraphs or (sub)sections.  The optional argument
              vertical-space specifies the amount of space; the default scaling is ‘v’).  Without an
              argument,  the  spacing  is  reset  to its default value; see “Horizontal and vertical
              spacing” above.

              Use of this presentation-level macro is deprecated.  It translates poorly to HTML, un‐
              der  which  exact  control of inter-paragraph spacing is not readily available.  Thus,
              information or distinctions that you use .PD to express are likely to be lost.

       .PT    Set the page header.  Redefine this macro to get control of the header.

       .UC [version]
              Alter the footer for use with BSD man pages, overriding any definition of the  footer-
              outside argument to .TH.  This macro exists only for compatibility; don't use it.

              The argument version can be:

                     3      3rd Berkeley Distribution (default)

                     4      4th Berkeley Distribution

                     5      4.2 Berkeley Distribution

                     6      4.3 Berkeley Distribution

                     7      4.4 Berkeley Distribution

   History
       According to its own man(7) page, Version 7 Unix (1979) supported all of the macros described
       in this page not listed as GNU extensions, except .P, .SB, .SS, and the deprecated .AT,  .BT,
       .PT, and .UC.  The only string registers defined were R and S; no number registers were docu‐
       mented.

OPTIONS
       The following groff options set number registers recognized and used by the man  macro  pack‐
       age.

       -rcR=1 Continuous  rendering.   Create  a  single,  very long page instead of multiple pages.
              This is the default in nroff mode.  Use -rcR=0 to disable it.

       -rC1   Number pages continuously.  If more than one man page is given on  the  command  line,
              number the pages continuously, rather than starting each at 1.

       -rD1   Enable  double-sided  printing.   Footers for even and odd pages are formatted differ‐
              ently; see the description of .TH in “Document structure macros”, above.

       -rFT=footer-distance
              Set distance of the footer, relative to the bottom of the page if negative or relative
              to the top if positive, to footer-distance.  The default is -0.5i.

       -rHY=flags
              Set hyphenation flags.  Permissible values of flags are documented in section “Hyphen‐
              ation” of groff(7).  The default is 4  if  continuous  rendering  is  enabled  (-rcR=1
              above), and 6 otherwise.

       -rIN=indent
              Set  the body text indentation (for normal paragraphs) to indent.  See “Horizontal and
              vertical spacing” above for the default indentation value.  For nroff,  indent  should
              always be an integer multiple of unit ‘n’ to get consistent indentation.

       -rLL=line-length
              Set  line  length.  If this option is not given, the line length is set to respect any
              value set by a prior “.ll” request (which must be in effect when the .TH macro is  in‐
              voked),  if this differs from the built-in default for the formatter; otherwise it de‐
              faults to 78n in nroff mode and 6.5i in troff mode.

              Note that the use of a “.ll” request to initialize the line length  is  supported  for
              backward compatibility with some versions of the man program; direct initialization of
              the LL register should always be preferred to the use of such a request.  In  particu‐
              lar,  note  that  a  “.ll 65n” request does not preserve the normal nroff default line
              length (the man default initialization to 78n prevails), whereas the -rLL=65n  option,
              or  an  equivalent “.nr LL 65n” request preceding the use of the .TH macro, does set a
              line length of 65n.

       -rLT=title-length
              Set title length.  If this option is not given, the title length defaults to the  line
              length.

       -rPn   Start enumeration of pages at n rather than 1.

       -rSpoint-size
              Use  point-size  as the base document font size.  Acceptable values are 10, 11, or 12.
              See subsection “Font style macros” above for the default.

       -rSN=subsection-indent
              Set subsection indentation to subsection-indent.  See “Horizontal and  vertical  spac‐
              ing” above for the default indentation value.

       -rXp   After  page p, number pages as pa, pb, pc, and so forth.  For example, the option -rX2
              produces the following page numbers: 1, 2, 2a, 2b, 2c, and so on.

FILES
       /usr/share/groff/1.22.4/tmac/man.tmac
       /usr/share/groff/1.22.4/tmac/an.tmac
              These are wrapper files to call andoc.tmac.

       /usr/share/groff/1.22.4/tmac/andoc.tmac
              This brief groff program detects whether the man or mdoc macro package is  being  used
              by  a  document  and loads the correct macro definitions, taking advantage of the fact
              that pages using them must call .TH or .Dd, respectively, as their first  macro.   Be‐
              cause  the  wrappers  above load this file, a man program or user typing, for example,
              “groff -man page.1”, need not know which package the file page.1 uses.   Multiple  man
              pages, in either format, can be handled.

       /usr/share/groff/1.22.4/tmac/an-old.tmac
              Most  man  macros  are  contained in this file.  It also loads the GNU extensions from
              an-ext.tmac (see below).

       /usr/share/groff/1.22.4/tmac/an-ext.tmac
              The extension macro definitions for .SY, .OP, .YS, .TQ, .EX/.EE, .UR/.UE, and  .MT/.ME
              are  contained  in  this  file, which is written in classic troff and permissively li‐
              censed—not copylefted.  Man page authors concerned about portability  to  legacy  Unix
              systems  are encouraged to copy these definitions into their pages, and maintainers of
              troff implementations or work-alike systems that format man pages  are  encouraged  to
              re-use them.

              Note  that  the  definitions  for these macros are read after the call of .TH, so they
              will replace any macros of the same names preceding it in your file.  If you use  your
              own  implementations  of  these macros, they must be defined after calling .TH to have
              any effect.

       /usr/share/groff/site-tmac/man.local
              Local changes and customizations should be put into this file.

NOTES
       Some tips on troubleshooting your man pages follow.

       • .RS doesn't indent relative to my indented paragraph
              The .RS macro sets the indentation relative to the amount of a normal  paragraph  (.PP
              and its synonyms).  The same default indentation amount is used for .RS, .IP, .TP, and
              the deprecated .HP.  If you need to start an indent relative to an indented paragraph,
              call .RS repeatedly until an acceptable indentation is achieved, or give .RS an inden‐
              tation argument that is at least as much as the paragraph's indentation  amount  rela‐
              tive  to  an  adjacent .PP paragraph.  See “Horizontal and vertical spacing” above for
              the values.

       • .RE doesn't reset the indent to the expected level
       • warning: scale indicator invalid in this context
       • warning: number register 'an-saved-marginn' not defined
       • warning: number register 'an-saved-prevailing-indentn' not defined
              The .RS macro takes an indentation amount as an argument; the .RE macro's argument  is
              a  specific  indentation  level.   .RE  1 goes to the level before any .RS macros were
              called, .RE 2 goes to the level of the first .RS call you made, and so forth.  If  you
              desire symmetry in your macro calls, simply issue one .RE without an argument for each
              .RS that precedes it.

              After calls to the .SH and .SS sectioning macros, all relative indents are cleared and
              calls to .RE have no effect.

AUTHORS
       The  GNU  version  of the man macro package was written by James Clark and contributors.  The
       extension macros were written by Werner  Lemberg  ⟨wl AT gnu.org⟩  and  Eric  S.  Raymond  ⟨esr@
       thyrsus.com⟩.

       This  document  was  originally written for the Debian GNU/Linux system by Susan G. Kleinmann
       ⟨sgk AT debian.org⟩.  It was corrected and updated by Werner Lemberg and  G.  Branden  Robinson.
       The  extension  macros were documented by Eric S. Raymond; he also originated the portability
       section, to which Ingo Schwarze contributed most of the material on escape sequences.

SEE ALSO
       Groff: The GNU Implementation of troff, by Trent A. Fisher and Werner Lemberg,  is  the  main
       groff documentation.  You can browse it interactively with “info groff”.

       tbl(1), eqn(1), and refer(1) are preprocessors used with man pages.

       man(1) describes the man page formatter on your system.

       groff_mdoc(7) describes the groff version of the BSD-originated alternative macro package for
       man pages.

       groff(7), groff_char(7), man(7)



groff 1.22.4                                23 March 2022                               GROFF_MAN(7)
groff_man(7)
NAME SYNOPSIS DESCRIPTION
Macro reference preliminaries Document structure macros .EX Paragraph macros .LP .PP Command synopsis macros Hyperlink and email macros Font style macros Horizontal and vertical spacing Number registers String registers Interaction with preprocessors Portability Deprecated features History
OPTIONS
-rcR=1 Continuous rendering. Create a single, very long page instead of multiple pages. -rC1 Number pages continuously. If more than one man page is given on the command line, -rD1 Enable double-sided printing. Footers for even and odd pages are formatted differ‐ -rFT=footer-distance -rHY=flags -rIN=indent -rLL=line-length -rLT=title-length -rPn Start enumeration of pages at n rather than 1. -rSpoint-size -rSN=subsection-indent -rXp After page p, number pages as pa, pb, pc, and so forth. For example, the option -rX2
FILES NOTES AUTHORS SEE ALSO

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