groff_man_style(7) — Linux manual page

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groff_man_style(7)  Miscellaneous Information Manual  groff_man_style(7)

Name top

       groff_man_style - GNU roff man page tutorial and style guide

Synopsis top

       groff -man [option ...] [file ...]

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

Description top

The GNU implementation of the man macro package is part of the
groff document formatting system. It is used to compose manual
pages (“man pages”) like the one you are reading. This document
presents the macros thematically; for those needing only a quick
reference, the following table lists them alphabetically, with
cross references to appropriate 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 Paragraphing macros
.IR Italic, roman alternating Font style macros
.LP Begin paragraph Paragraphing macros
.ME Mail-to end Hyperlink macros
.MR Man page cross reference Hyperlink macros
.MT Mail-to start Hyperlink macros
.P Begin paragraph Paragraphing macros
.PP Begin paragraph Paragraphing macros
.RB Roman, bold alternating Font style macros
.RE Relative inset end Document structure macros
.RI Roman, italic alternating Font style macros
.RS Relative inset start Document structure macros
.SH Section heading Document structure macros
.SM Small Font style macros
.SS Subsection heading Document structure macros
.SY Synopsis start Synopsis macros
.TH Title heading Document structure macros
.TP Tagged paragraph Paragraphing macros
.TQ Supplemental paragraph tag Paragraphing macros
.UE URI end Hyperlink macros
.UR URI start Hyperlink macros
.YS Synopsis end Synopsis macros

We discuss other macros (.AT, .DT, .HP, .OP, .PD, .SB, and .UC)
in subsection “Deprecated features” below.

Throughout Unix documentation, a manual entry is referred to
simply as a “man page”, regardless of its length, without
gendered implication, and irrespective of the macro package
selected for its composition.

A man page employs the Unix line-ending convention (U+000A only).
Some basic Latin characters have special meaning to roff; see
subsection “Portability” below.

Fundamental concepts
groff is a programming system for typesetting: we thus often use
the verb “to set” in the sense “to typeset”. The formatter
troff(1) collects words from the input and fills output lines
with as many as will fit. Words are separated by spaces and
newlines. A transition to a new output line is called a break.
When formatted, a word may be broken at hyphens, at \% or \:
escape sequences (see subsection “Portability” below), or at
predetermined locations if automatic hyphenation is enabled (see
the -rHY option in section “Options” below). An output line may
be supplemented with inter-sentence space, and then optionally
adjusted with more space to a consistent length (see the -dAD
option). roff(7) details these processes. Output is prepared
for terminals or for more capable typesetters that can change the
type size and font family.

An input line that starts with a dot (.) or neutral apostrophe
(') is a control line. To call a macro, put its name after a dot
on a control line. This document uses the leading dot to
identify macros. Some macros interpret arguments, words that
follow its name. A newline, unless escaped (see subsection
“Portability” below), marks the end of the macro call. A control
line with no macro name on it is called an empty request; it does
nothing. Text lines are input lines that are not control lines.

We describe below several man macros that plant one-line input
traps: the next input line that directly produces formatted
output is treated specially. For man documents that follow the
advice in section “Portability” below, this means that control
lines using the empty request and uncommented input lines ending
with an escaped newline do not spring the trap; anything else
does (but see the .TP macro description).

Macro reference preliminaries
A tagged paragraph describes each macro. We present coupled
pairs together, as with .EX and .EE. Optional macro arguments
are indicated by surrounding them with square brackets. If a
macro accepts multiple arguments, those containing space
characters must be double-quoted to be interpreted correctly. An
empty macro argument can be specified with a pair of double-
quotes (""), but the man package is designed such that this
should seldom be necessary. See section “Notes” below for
examples of cases where better alternatives to empty arguments in
macro calls are available. Most macro arguments will be
formatted as text in the output; exceptions are noted.

Document structure macros
Document structure macros organize a man page's content. All of
them break the output line. .TH (title heading) identifies the
document as a man page and configures the page headers and
footers. Section headings (.SH), one of which is mandatory and
many of which are conventionally expected, facilitate location of
material by the reader and aid the man page writer to discuss all
essential aspects of the subject. Subsection headings (.SS) are
optional and permit sections that grow long to develop in a
controlled way. Many technical discussions benefit from
examples; lengthy ones, especially those reflecting multiple
lines of input to or output from the system, are usefully
bracketed by .EX and .EE. When none of the foregoing meets a
structural demand, use .RS/.RE to inset a region within a
(sub)section.

.TH identifier section [footer-middle [footer-inside [header-
middle]]]
Populate the page header and footer. roff systems refer
to these collectively as “titles”. Together, identifier
and the section of the manual to which it belongs can
uniquely identify a man document on the system. This use
of “section” has nothing to do with the section headings
otherwise discussed in this page; it arises from the
organizational scheme of printed and bound Unix manuals.
See man(1) or intro(1) for the manual sectioning
applicable to your system. identifier and section are
positioned at the left and right in the header; the latter
is set after the former, in parentheses and without space.
footer-middle is centered in the footer. The arrangement
of the rest of the footer depends on whether double-sided
layout is enabled with the option -rD1. When disabled
(the default), footer-inside is positioned at the bottom
left. Otherwise, footer-inside appears at the bottom left
on recto (odd-numbered) pages, and at the bottom right on
verso (even-numbered) pages. The outside footer is the
page number, except in the continuous-rendering mode
enabled by the option -rcR=1, in which case it is the
identifier and section, as in the header. header-middle
is centered in the header. If section is an integer
between 1 and 9 (inclusive), there is no need to specify
header-middle; an.tmac will supply text for it. This
package may abbreviate identifier and footer-inside with
ellipses (...) if they would overrun the space available
in the header and footer, respectively. In HTML output,
headers and footers are suppressed.

Additionally, this macro breaks the page, resetting the
number to 1 (unless the -rC1 option is given). This
feature is intended only for formatting multiple man
documents in sequence.

A valid man document calls .TH only once, early in the
file, prior to any other macro calls.

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

.SH [heading-text]
Set heading-text as a section heading. If no argument is
given, the macro plants a one-line input trap; text on the
next line becomes heading-text. The heading text is set
in bold (or the font specified by the string HF), and, on
typesetters, slightly larger than the base type size. If
the heading font \*[HF] is bold, use of an italic style in
heading-text is mapped to the bold-italic style if
available in the font family. The inset level is reset to
1; see subsection “Horizontal and vertical spacing” below.
Text after heading-text is set as an ordinary paragraph
(.P).

The content of heading-text and ordering of sections
follows a set of common practices, as has much of the
layout of material within sections. For example, a
section called “Name” or “NAME” must exist, must be the
first section after the .TH call, and must contain only
text of the form
topic[, another-topic]... \- summary-description
for a man page in English to be properly indexed.

.SS [subheading-text]
Set subheading-text as a subsection heading indented
between a section heading and an ordinary paragraph (.P).
If no argument is given, the macro plants a one-line input
trap; text on the next line becomes subheading-text. The
subheading text is set in bold (or the font specified by
the string HF). If the heading font \*[HF] is bold, use
of an italic style in subheading-text is mapped to the
bold-italic style if available in the font family. The
inset level is reset to 1; see subsection “Horizontal and
vertical spacing” below. Text after subheading-text is
set as an ordinary paragraph (.P).

.EX
.EE Begin and end example. After .EX, filling is disabled and
a constant-width (monospaced) font is selected. Calling
.EE enables filling and restores the previous font.

Example regions are useful for formatting code, shell
sessions, and text file contents. An example region is
not a “literal mode” of any sort: special character escape
sequences must still be used to produce correct glyphs for
', -, \, ^, `, and ~ (see subsection “Portability” below).
Sentence endings are still detected and additional inter-
sentence space applied. If the amount of additional
inter-sentence spacing is altered, the rendering of, for
instance, regular expressions using . or ? followed by
multiple spaces can change. Use the dummy character
escape sequence \& before the spaces.

.EX and .EE are extensions introduced in Ninth Edition
Unix. Documenter's Workbench, Heirloom Doctools, and
Plan 9 troffs, and mandoc (since 1.12.2) also support
them. Solaris troff does not. See subsection “Use of
extensions” below.

.RS [inset-amount]
Start a new relative inset level. The current inset
amount is saved, then moved right by inset-amount, if
specified, by the indentation amount of the preceding .IP,
.TP, or (deprecated) .HP macro call if no (sub-)sectioning
or ordinary paragraphing macro has intervened, and by the
amount of the IN register otherwise. Calls to .RS can be
nested; each increments by 1 the inset level used by .RE.
The level prior to any .RS calls is 1.

.RE [inset-level]
End a relative inset. The inset amount corresponding to
inset-level is restored. If no argument is given, the
inset level is reduced by 1.

Paragraphing macros
An ordinary paragraph (.P) like this one indents all output lines
by the same amount. Definition lists frequently occur in man
pages; these can be set as tagged paragraphs, which have one
(.TP) or more (.TQ) leading tags followed by a paragraph that has
an additional indentation. 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. All of
these macros break the output line. If another paragraph macro
has occurred since the previous .SH or .SS, they (except for .TQ)
follow the break with a default amount of vertical space, which
can be changed by the deprecated .PD macro; see subsection
“Horizontal and vertical spacing” below. They also reset the
type size and font style to defaults (.TQ again excepted); see
subsection “Font style macros” below.

.P
.LP
.PP Begin a new paragraph; these macros are synonymous. Any
indentation from use of .IP, .TP, or the deprecated .HP is
cleared. The inset amount, as affected by .RS and .RE, is
not.

.TP [indentation]
Set a paragraph with a leading tag, and the remainder of
the paragraph indented. The macro plants a one-line input
trap that honors the \c escape sequence; text on the next
line becomes the tag, set without indentation. Text on
subsequent lines is indented by indentation, if specified,
and by the amount of the IN register otherwise. If the
tag, plus the “tag spacing” stored in the TS register (see
section “Options” below) is wider than the indentation,
the line is broken after the tag.

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 subsequent one.

.TQ Set an additional tag for a paragraph tagged with .TP,
planting a one-line input trap as with .TP.

.TQ is a GNU extension supported by Heirloom Doctools
troff and mandoc (since 1.14.5) but not by Documenter's
Workbench, Plan 9, or Solaris troffs. See subsection “Use
of extensions” below.

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

.IP [mark [indentation]]
Set an indented paragraph with an optional mark.
Arguments, if present, are handled as with .TP, except
that the mark argument to .IP cannot include a macro call,
and the tag separation amount stored in the TS register is
not enforced.

Two convenient uses for .IP are

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

(2) to set a paragraph with a short mark that is not
semantically important, such as a bullet
(•)—obtained with the \(bu special character
escape sequence—or list enumerator, as seen in
this very paragraph.

Synopsis macros
Use .SY and .YS to summarize syntax using familiar Unix
conventions. Heirloom Doctools troff and mandoc (since 1.14.5)
support these GNU extensions; Documenter's Workbench, Plan 9, and
Solaris troffs do not. See subsection “Use of extensions” below.

.SY keyword [suffix]
Begin synopsis. Adjustment and automatic hyphenation are
disabled. If .SY has already been called without a
corresponding .YS, a break is performed. keyword and
suffix (if any) are set in bold. If a break is required
in subsequent text (up to another paragraphing,
sectioning, or synopsis macro call), lines after the first
are indented. The indentation amount is the width of
keyword plus a space, if that is the only argument, and by
the sum of the widths of keyword and suffix otherwise.

.YS [reuse-indentation]
End synopsis, breaking the line and restoring indentation,
adjustment, and hyphenation to their previous states. If
an argument is given, the indentation corresponding to the
previous .SY call is reused by the next .SY call instead
of being computed.

Interleave multiple .SY/.YS blocks with paragraphing macros to
distinguish differing modes of operation of a complex command
like tar(1). Omit the paragraphing macro to indicate synonymous
ways of invoking a particular mode of operation.

groff's own command-line interface illustrates most specimens one
may encounter.

.SY groff
.RB [ \-abcCeEgGijklNpRsStUVXzZ ]
.RB [ \-d\~\c
.IR ctext ]
.RB [ \-d\~\c
.IB string =\c
.IR text ]
.RB [ \-D\~\c
.IR fallback-encoding ]
(and so on similarly)
.RI [ file\~ .\|.\|.]
.YS
.
.
.P
.SY groff
.B \-h
.YS
.
.SY groff
.B \-\-help
.YS
.
.
.P
.SY groff
.B \-v
.RI [ option\~ .\|.\|.\&]
.RI [ file\~ .\|.\|.]
.YS
.
.SY groff
.B \-\-version
.RI [ option\~ .\|.\|.\&]
.RI [ file\~ .\|.\|.]
.YS

produces the following output.

groff [-abcCeEgGijklNpRsStUVXzZ] [-d ctext]
[-d string=text] [-D fallback-encoding] [-f font-
family] [-F font-directory] [-I inclusion-directory]
[-K input-encoding] [-L spooler-argument] [-m macro-
package] [-M macro-directory] [-n page-number]
[-o page-list] [-P postprocessor-argument]
[-r cnumeric-expression] [-r register=numeric-
expression] [-T output-device] [-w warning-category]
[-W warning-category] [file ...]

groff -h

groff --help

groff -v [option ...] [file ...]

groff --version [option ...] [file ...]

Several features of the above example are of note.

• The empty request (.), which does nothing, vertically spaces
the input file for readability by the document maintainer. Do
not put blank (empty) lines in a man page source document.

• 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 practice to make them clearly visible and to
facilitate copy-and-paste from the rendered man page to a
shell prompt or text file.

• Option arguments and command operands are presented in italics
(but see subsection “Font style macros” below regarding
terminals) to cue the user that they must be replaced with
appropriate input.

• Symbols that are neither to be typed literally nor replaced at
the user's discretion appear in the roman style; brackets
surround optional arguments, and an ellipsis indicates that
the previous syntactic element may be repeated arbitrarily.
Where whitespace separates optional arguments, a space
precedes the ellipsis.

• The non-breaking adjustable space escape sequence \~ prevents
the output line from breaking within the option brackets; see
subsection “Portability” below.

• The output line continuation escape sequence \c is used with
font style alternation macros to allow all three font styles
to be set without (breakable) space among them; see subsection
“Portability” below.

• The dummy character escape sequence \& follows the ellipsis
when further text will follow after space on the output line,
keeping its last period from being interpreted as the end of a
sentence and causing additional inter-sentence space to be
placed after it. See subsection “Portability” below.

We might synopsize the standard C library function bsearch(3) as
follows.

.P
.B void *\c
.SY bsearch (
.BI const\~void\~* key ,
.BI const\~void\~* base ,
.BI size_t\~ nmemb ,
.BI int\~(* compar )\c
.B (const\~void\~*, const\~void\~*));
.YS

man produces the following result.

void *

bsearch const void *key, const void *base, size_t nmemb,
int (*compar)(const void *, const void *));

Hyperlink macros
Man page cross references like ls(1) are best presented with .MR.
Text may be hyperlinked to email addresses with .MT/.ME or other
URIs with .UR/.UE. Not all output devices support hyperlinking
of text; terminals and pager programs must support ECMA-48 OSC 8
escape sequences (see grotty(1)). When device support is
unavailable or disabled with the U register (see section
“Options” below), .MT and .UR URIs are rendered between angle
brackets after the linked text.

.MT, .ME, .UR, and .UE are GNU extensions supported by Heirloom
Doctools and mandoc (.UR/.UE since 1.12.3; .MT/.ME since 1.14.2)
but not by Documenter's Workbench, Plan 9, or Solaris troffs.
Plan 9 from User Space's troff implements .MR. See subsection
“Use of extensions” below.

The arguments to .MR, .MT, and .UR should be prepared for
typesetting since they can appear in the output. Use special
character escape sequences to encode Unicode basic Latin
characters where necessary, particularly the hyphen-minus. (See
section “Portability” below.) URIs can be lengthy; rendering
them can result in jarring adjustment or variations in line
length, or troff warnings when a hyperlink is longer than an
output line. The application of non-printing break point escape
sequences \: after each slash (or series thereof), and before
each dot (or series thereof) is recommended as a rule of thumb.
The former practice avoids forcing a trailing slash in a URI onto
a separate output line, and the latter helps the reader to avoid
mistakenly interpreting a dot at the end of a line as a period
(or multiple dots as an ellipsis). Thus,
.UR http://\:example\:.com/\:fb8afcfbaebc74e\:.cc
has several potential break points in the URI shown. Consider
adding break points before or after at signs in email addresses,
and question marks, ampersands, and number signs in HTTP(S) URIs.
The formatter removes \: escape sequences from hyperlinks when
supplying device control commands to output drivers.

.MR topic [manual-section [trailing-text]]
(since groff 1.23) Set a man page cross reference as
“topic(manual-section)”. If manual-section is absent, the
package omits the surrounding parentheses. If trailing-
text (typically punctuation) is specified, it follows the
closing parenthesis without intervening space.
Hyphenation is disabled while the cross reference is set.
topic is set in the font specified by the MF string. If
manual-section is present, the cross reference hyperlinks
to a URI of the form “man:topic(manual-section)”.

The output driver
.MR grops 1
produces PostScript from
.I troff
output.
.
The Ghostscript program (\c
.MR gs 1 )
interprets PostScript and PDF.

.MT address
.ME [trailing-text]
Identify address as an RFC 6068 addr-spec for a “mailto:”
URI with the text between the two macro calls as the link
text. An argument to .ME is placed after the link text
without intervening space. address may not be visible in
the rendered document if hyperlinks are enabled and
supported by the output driver. If they are not, address
is set in angle brackets after the link text and before
trailing-text. If hyperlinking is enabled but there is no
link text, address is formatted and hyperlinked without
angle brackets.

When rendered by groff to a PostScript device,

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

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

.UR uri
.UE [trailing-text]
Identify uri as an RFC 3986 URI hyperlink with the text
between the two macro calls as the link text. An argument
to .UE is placed after the link text without intervening
space. uri may not be visible in the rendered document if
hyperlinks are enabled and supported by the output driver.
If they are not, uri is set in angle brackets after the
link text and before trailing-text. If hyperlinking is
enabled but there is no link text, uri is formatted and
hyperlinked without angle brackets.

When rendered by groff to a PostScript device,

The GNU Project of the Free Software Foundation
hosts the
.UR https://\:www\:.gnu\:.org/\:software/\:groff/
.I 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/⟩.”.

If a .TP call is followed immediately by hyperlinking macros
.UR/.UE or .MT/.ME, and the device doesn't support hyperlinking,
the hyperlink is set at the beginning of the indented paragraph,
not as part of the tag.

Font style macros
The man macro package is limited in its font styling options,
offering only bold (.B), italic (.I), and roman. Italic text is
usually set underscored instead on terminals. .SM sets text at a
smaller type size, which differs visually from regular-sized text
only on typesetters. It is often necessary to set text in
different styles without intervening space. 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 space 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,
and inlined literals.

The default type size and family for typesetters is 10-point
Times, except on the X75-12 and X100-12 devices where the type
size is 12 points. The default style is roman.

.B [text]
Set text in bold. If no argument is given, the macro
plants a one-line input trap; text on the next line, which
can be further formatted with a macro, 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
example, this page uses bold for macro, string, and
register names. In an .EX/.EE example of interactive I/O
(such as a shell session), set only user input in bold.

.I [text]
Set text in an italic or oblique face. If no argument is
given, the macro plants a one-line input trap; text on the
next line, which can be further formatted with a macro, is
set in an italic or oblique face.

Use italics for file and path names, for environment
variables, for C data types, for enumeration or
preprocessor constants in C, for variant (user-
replaceable) portions of syntax synopses, for the first
occurrence (only) of a technical concept being introduced,
for names of journals and of literary works longer than an
article, and anywhere a parameter requiring replacement by
the user is encountered. An exception involves variant
text in a context already typeset in italics, such as file
or path names with replaceable components; in such cases,
follow the convention of mathematical typography: set the
file or path name in italics as usual but use roman for
the variant part (see .IR and .RI below), and italics
again in running roman text when referring to the variant
material.

.SM [text]
Set text one point smaller than the default type size on
typesetters. If no argument is given, the macro plants a
one-line input trap; text on the next line, which can be
further formatted with a macro, is set smaller.

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

Observe what is not prescribed for setting in bold or italics
above: elements of “synopsis language” such as ellipses and
brackets around options; proper names and adjectives; titles of
anything other than major works of literature; identifiers for
standards documents or technical reports such as CSTR #54,
RFC 1918, Unicode 13.0, or POSIX.1-2017; acronyms; and
occurrences after the first of a technical term.

Be frugal with italics for emphasis, and particularly with bold.
Article titles and 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 escape sequences in
subsection “Portability” below.

Unlike the above font style macros, the font style alternation
macros below set no input traps; they must be given arguments to
have effect. They apply italic corrections as appropriate. If a
space is required within an argument, first consider whether the
same result could be achieved with as much clarity by using
single-style macros on separate input lines. When it cannot,
double-quote an argument containing embedded space characters.
Setting all three different styles within a word presents
challenges; it is possible with the \c and/or \f escape
sequences. See subsection “Portability” below for approaches.

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

.BI -r\~ register = numeric-expression

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

Set an ellipsis on the math axis with the GNU extension macro
.BR cdots .

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

In places where
.IB n th
is allowed,

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

Use GNU
.IR pic 's
.B figname
command to change the name of the vbox.

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

.I file
is
.RB \[lq] - \[rq],
.I groff
reads the standard input stream.

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

.RI ( tpic
was a fork of AT&T
.I pic
by Tim Morgan of the University of California at Irvine

Horizontal and vertical spacing
All text is rendered with respect to the page offset; see
register PO in section “Options” below. Headers, footers (both
set with .TH), and section headings (.SH) are set with no further
indentation. Subsection headings (.SS) are indented by the
amount in the SN register.

Ordinary paragraphs not within an .RS/.RE inset region are inset
by the amount stored in the BP register; see section “Options”
below. The IN register configures the default indentation amount
used by .RS (as the inset-amount), .IP, .TP, and the deprecated
.HP; an overriding argument is a number plus an optional scaling
unit. If no scaling unit is given, the man package assumes “n”;
that is, roughly the width of a letter “n” in the font current
when the macro is called—see section “Measurements” in groff(7).
An indentation specified in a call to .IP, .TP, or the deprecated
.HP persists until (1) another of these macros is called with an
indentation argument, or (2) .SH, .SS, or .P or its synonyms is
called; these clear the indentation entirely.

The inset amount and indentation are related but distinct
parameters with the same defaults. The former is manipulated by
.RS and .RE (and by .SH and .SS, which reset it to the default).
Indentation is controlled by the paragraphing macros (though,
again, .SH and .SS reset it); it is imposed by the .TP, .IP, and
deprecated .HP macros, and cancelled by .P and its synonyms. An
extensive example follows.

This ordinary (.P) paragraph is not in a relative inset nor does
it possess an indentation.

Now we have created a relative inset with .RS and started
another ordinary paragraph with .P. We observe that all
of its lines are inset and indented the same; contrast
with a first-line indentation.

tag This tagged paragraph, set with .TP, is still
within the .RS region, but lines after the first
have a supplementary indentation that the tag
lacks.

A paragraph like this one, set with .IP, will
appear to the reader as also associated with the
tag above, because .IP re-uses the previous
paragraph's indentation unless given an argument to
change it. Both the inset amount (.RS) and
indentation (.IP) affect this paragraph.
┌───────────────────────────────────┐
│ This table is affected both by │
│ the inset amount and indentation. │
└───────────────────────────────────┘

• This indented paragraph is marked with a bullet,
contrasting the inset amount and the indentation;
only the former affects the mark, but both affect
the text of the paragraph.

This ordinary (.P) paragraph resets the indentation, but
the inset amount is unchanged.
┌─────────────────────────────┐
│ This table is affected only │
│ by the inset amount. │
└─────────────────────────────┘

Finally, we have ended the relative inset by using .RE, which
(because we used only one .RS/.RE pair) has restored the inset
amount to its initial value. This is an ordinary .P paragraph.

Resist the temptation to mock up tabular or multi-column output
with tab characters or the indentation arguments to .IP, .TP,
.RS, or the deprecated .HP; the result may not be comprehensible
on an output device you fail to check, or which is developed in
the future. Consider the table preprocessor tbl(1) instead.

Several macros insert vertical space: .SH, .SS, .TP, .P (and its
synonyms), .IP, and the deprecated .HP. The default inter-
section and inter-paragraph spacing is 1v for terminals and 0.4v
for typesetters. “v” is a unit of vertical distance, where 1v is
the distance between adjacent text baselines. (The deprecated
macro .PD can change this vertical spacing, but we discourage its
use.) Between .EX and .EE calls, the inter-paragraph spacing is
1v regardless of output device.

Registers
Registers are described in section “Options” below. They can be
set not only on the command line but in the site man.local file
as well; see section “Files” below.

Strings
The following strings are defined for use in man pages. Others
are supported for configuration of rendering parameters; see
section “Options” below.

\*R interpolates a special character escape sequence for the
“registered sign” glyph, \(rg, if available, and “(Reg.)”
otherwise.

\*S interpolates an escape sequence setting the type size to
the document default.

\*(lq
\*(rq interpolate special character escape sequences for left
and right double-quotation marks, \(lq and \(rq,
respectively.

\*(Tm interpolates a special character escape sequence for the
“trade mark sign” glyph, \(tm, if available, and “(TM)”
otherwise.

None of the above is necessary in a contemporary man page. \*S
is superfluous, since type size changes are invisible on
terminals and macros that change it restore its original value
afterward. Better alternatives exist for the rest; simply use
the \(rg, \(lq, \(rq, and \(tm special character escape sequences
directly. Unless you are aiming for a pathological level of
portability—perhaps composing a man page for consumption on
simulators of 1980s Unix systems (or Solaris troff, though even
it supports \(rg)—avoid using the above strings.

Use of extensions
To ensure that your man page formats reliably on a wide variety
of viewers, write it solely with the macros described in this
page (except for the ones identified as deprecated, which you
should avoid). The macros we have described as extensions might
not be supported by a formatter that is important to your
audience. Nevertheless, groff's extensions are present because
they perform tasks that are otherwise difficult or tedious to
achieve portably. If you require an extension but also expect
your man page to be rendered on a system that doesn't support it,
consider writing a configuration test that measures a property of
the system, and use m4(1), sed(1), or a similar tool to generate
a .man file from a .man.in file, defining page-local versions of
extension macros only where necessary. You can copy extension
macro definitions from groff; see an-ext.tmac in section “Files”
below.

For example, we might put a line
@DEFINE_MR@
in our man document at the end of the “Name” section, test a
system for the availability of the groff man .MR macro, remove
the line if the macro is present, and “inline” a definition
otherwise, as follows. (This version is slightly simplified and
does not attempt to disable hyphenation when setting arguments to
.MR.)
have_MR=$(echo .pm | troff -man 2>&1 | grep MR)
if [ -n "$have_MR" ]
then
sed '/@DEFINE_MR@/d' myprog.man.in > myprog.man
else
sed 's/@DEFINE_MR@/.de MR\
. ie \\\\n(.$=1 .I \\\\$1\
. el .IR \\\\$1 (\\\\$2)\\\\$3\
../' myprog.man.in > myprog.man
fi
(The profusion of backslashes is due to its status as an escape
character in both roff and sed.)

If the foregoing method is too much trouble, you could apply the
radical technique of reading your man page using every formatter
of interest, confirming satisfactory output from each. Test
documentation for syntactic validity and semantic correctness,
just as you would test code.

Portability
An installed man page should contain Unicode basic Latin code
points exclusively. One can maintain it in a more convenient
encoding, using preconv(1) to produce a basic Latin version that
employs special character escape sequences to access code points
necessary in non-English text.

The two major features that control formatting in the roff
language are requests and escape sequences. Since the man macros
are implemented in terms of these, one can, in principle,
supplement the functionality of man with these lower-level
elements where necessary.

However, use of roff requests (apart from the empty request “.”)
risks poor rendering when your page is processed by tools other
than roff formatters that attempt to interpret page sources.
(Historically, this was commonly attempted for HTML conversion.)
Requests might make assumptions about line length that do not
hold in an HTML environment. Many of these programs don't
interpret the full roff language (let alone extensions): they may
be incapable of handling numeric expressions, control structures,
or register, string, and macro definitions. Such limitations can
lead to portions of a document being presented incomprehensibly
or omitted altogether.

It is wise to quote multi-word section and subsection headings;
the .SH and .SS macros of man(7) implementations descended from
Seventh Edition Unix supported six arguments at most. This
restriction also applied to the .B, .I, .SM, and font style
alternation macros.

Exercise restraint with escape sequences as with requests. Some
escape sequences are however required for correct typesetting
even in man pages and usually do not cause portability problems.

Several of these render glyphs corresponding to punctuation code
points in the Unicode basic Latin range (U+0000–U+007F) that are
handled specially in roff input; the escape sequences below must
be used to render them correctly and portably when documenting
material that uses them as literals—namely, any of the set ' - \
^ ` ~ (apostrophe, dash or hyphen-minus, backslash, caret, grave
accent, tilde).

\" Comment. Everything after the double-quote to the end
of the input line is ignored. Whole-line comments
should be 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 appears to groff as a
single input line. Use this escape sequence to split
excessively long input lines for document maintenance.

\% Control hyphenation. The location of this escape
sequence within a word marks a hyphenation point,
supplementing groff's automatic hyphenation patterns.
At the beginning of a word, it suppresses any
hyphenation breaks within except those specified with
\%.

\: Insert a non-printing break point. A word can break at
such a point, but a hyphen glyph is not written to the
output if it does. \: is an input word boundary, so
the remainder of the word is subject to hyphenation as
normal. You can use \: and \% in combination to
control breaking of a file name or URI or to permit
hyphenation only after certain explicit hyphens within
a word. See subsection “Hyperlink macros” above for an
example.

\: is a GNU extension also supported by Heirloom
Doctools troff 050915 (September 2005), mandoc 1.13.1
(2014-08-10), and neatroff (commit 399a4936,
2014-02-17), but not by Plan 9, Solaris, or
Documenter's Workbench troffs.

\~ Adjustable non-breaking space. Use this escape
sequence 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.

\~ is a GNU extension also supported by Heirloom
Doctools troff 050915 (September 2005), mandoc 1.9.14
(2009-11-16), neatroff (commit 1c6ab0f6e, 2016-09-13),
and Plan 9 from User Space troff (commit 93f8143600,
2022-08-12), but not by Solaris or Documenter's
Workbench troffs.

\& Dummy character. Insert at the beginning of an input
line to prevent a dot or apostrophe from being
interpreted as beginning a roff control line. Append
to an end-of-sentence punctuation sequence to keep it
from being recognized as such.

\| Thin space (one-sixth em on typesetters, zero-width on
terminals); a non-breaking space. Used primarily in
ellipses (“.\|.\|.”) to space the dots more pleasantly
on typesetters like dvi, pdf, and ps.

\c End a text line without inserting space or attempting a
break. Normally, if filling is enabled, the end of a
text line is treated like a space; an output line may
break there (if it does not, troff inserts an
adjustable space); if filling is disabled, the line
will break there, as in .EX/.EE examples. The next
line is interpreted as usual and can include a macro
call (contrast with \newline). \c is useful when three
font styles are needed in a single word, as in a
command synopsis.

.RB [ \-\-stylesheet=\c
.IR name ]

It also helps when changing font styles in .EX/.EE
examples, since they are not filled.

.EX
$ \c
.B groff \-T utf8 \-Z \c
.I file \c
.B | grotty \-i
.EE

Alternatively, and perhaps with better portability, the
\f font selection escape sequence can be used; see
below. Using \c to continue a .TP paragraph tag across
multiple input lines will render incorrectly with groff
1.22.3, mandoc 1.14.1, older versions of these
programs, and perhaps with some other formatters.

\e Format the roff escape character on the output; widely
used in man pages to render a backslash 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 explicit \(rs
(“reverse solidus”) special character escape sequence.

\fB, \fI, \fR, \fP
Switch to bold, italic, roman, or back to the previous
style, respectively. Either \f or \c is needed when
three different font styles are required in a word.

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

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

Style escape sequences may be more portable than \c.
As shown above, it is up to you to account for italic
corrections with “\/” and “\,”, which are themselves
GNU extensions, if desired and if supported by your
implementation.

\fP reliably returns to the style in use immediately
preceding the previous \f escape sequence only if no
sectioning, paragraph, example, or style macro calls
have intervened.

As long as at most two styles are needed in a word,
style macros like .B and .BI usually result in more
readable roff source than \f escape sequences do.

Several special characters are also widely portable. Except for
\-, \(em, and \(ga, AT&T troff did not consistently define the
characters listed below, but its descendants, like Plan 9 or
Solaris troff, can be made to support them by defining them in
font description files, making them aliases of existing glyphs if
necessary; see groff_font(5). groff's extended notation for
special characters, \[xx], is also supported by mandoc(1),
Heirloom Doctools troff, and neatroff, but not Documenter's
Workbench, Plan 9, or Solaris troff.

\- Minus sign. \- produces the basic Latin hyphen-minus
(U+002D) specifying Unix command-line options and
frequently used in file names. “-” is a hyphen in roff;
some output devices format it as U+2010 (hyphen).

\(aq Basic Latin neutral apostrophe. Some output devices
format “'” as a right single quotation mark.

\(oq
\(cq Opening (left) and closing (right) single quotation marks.
Use these for paired directional single quotes, ‘like
this’.

\(dq Basic Latin quotation mark (double quote). Use in macro
calls to prevent ‘"’ from being interpreted as beginning a
quoted argument, or simply for readability.

.TP
.BI "split \(dq" text \(dq

\(lq
\(rq Left and right double quotation marks. Use these for
paired directional double quotes, “like this”.

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

\(en En dash. Use to separate the ends of a range,
particularly between numbers; for example, “the digits
1–9”.

\(ga Basic Latin grave accent. Some output devices format “`”
as a left single quotation mark.

\(ha Basic Latin circumflex accent (“hat”). Some output
devices format “^” as U+02C6 (modifier letter circumflex
accent).

\(rs Reverse solidus (backslash). The backslash is the default
escape character in the roff language, so it does not
represent itself in output. Also see \e above.

\(ti Basic Latin tilde. Some output devices format “~” as
U+02DC (small tilde).

For maximum portability, avoid escape sequences (including
special characters) not listed above.

Hooks
Two macros, both GNU extensions, are called internally by the
groff man package to format page headers and footers and can be
redefined by the administrator in a site's man.local file (see
section “Files” below). The presentation of .TH above describes
the default headers and footers. Because these macros are hooks
for groff man internals, man pages have no reason to call them.
Such hook definitions will likely consist of “.sp” and “.tl”
requests. They must also increase the page length with “.pl”
requests in continuous rendering mode; .PT furthermore has the
responsibility of emitting a PDF bookmark after writing the first
page header in a document. Consult the existing implementations
in an.tmac when drafting replacements.

.BT Set the page footer text (“bottom trap”).

.PT Set the page header text (“page trap”).

To remove a page header or footer entirely, define the
appropriate macro as empty rather than deleting it.

Deprecated features
Use of the following in man pages for public distribution is
discouraged.

.AT [system [release]]
Alter the footer for use with legacy AT&T man pages,
overriding any definition of the footer-inside argument to
.TH. This macro exists only to render man pages from
historical systems.

The inside footer is populated per the value of system.

3 7th edition (default)

4 System III

5 System V

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

.DT Reset tab stops to the default (every 0.5i [inches]).

Use of this presentation-oriented macro is deprecated. It
translates poorly to HTML, under which exact space control
and tabulation are not readily available. Thus,
information or distinctions that you use tab stops to
express are likely to be lost. If you feel tempted to
change the tab stops such that calling this macro later to
restore them is desirable, consider composing a table
using tbl(1) instead.

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

Use of this presentation-oriented macro is deprecated. A
hanging indentation cannot be expressed naturally in HTML,
a hanging paragraph is not distinguishable from an
ordinary one if it formats on only one output line, and
non-roff-based man page interpreters may treat .HP as an
ordinary paragraph. Thus, information or distinctions you
mean to express with indentation may be lost.

.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.

Use of this quasi-semantic macro, an extension originating
in Documenter's Workbench troff, is deprecated. It cannot
easily be used to annotate options that take optional
arguments or options whose arguments have internal
structure (such as a mixture of literal and variable
components). One could work around these limitations with
font selection escape sequences, but it is preferable to
use font style alternation macros, which afford greater
flexibility.

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

Use of this presentation-oriented macro is deprecated. It
translates poorly to HTML, under 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.

.SB [text]
Set text in bold and (on typesetters) one point smaller
than the default type size. If no argument is given, the
macro plants a one-line input trap; text on the next line,
which can be further formatted with a macro, is set
smaller and in bold. Use of this macro, an extension
originating in SunOS 4.0 troff, is deprecated. .SM
without an argument, followed immediately by “.B text”,
produces the same output more portably. The macros' order
is interchangeable; put text with the latter.

Note: terminals will render text in bold at the normal
size instead. Do not rely upon .SB to communicate
semantic information distinct from using bold style at
normal size; it will be hidden from readers using such
devices.

.UC [version]
Alter the footer for use with legacy BSD man pages,
overriding any definition of the footer-inside argument to
.TH. This macro exists only to render man pages from
historical systems.

The inside footer is populated per the value of version.

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
M. Douglas McIlroy ⟨m.douglas.mcilroy@dartmouth.edu⟩ designed,
implemented, and documented the AT&T man macros for Unix
Version 7 (1979) and employed them to edit the first volume of
its Programmer's Manual, a compilation of all man pages supplied
by the system. That man supported the macros listed in this page
not described as extensions, except .P and the deprecated .AT and
.UC. The only strings defined were R and S; no registers were
documented.

.UC appeared in 3BSD (1980). Unix System III (1980) introduced
.P and exposed the registers IN and LL, which had been internal
to Seventh Edition Unix man. PWB/UNIX 2.0 (1980) added the Tm
string. 4BSD (1980) added lq and rq strings. SunOS 2.0 (1985)
recognized C, D, P, and X registers. 4.3BSD (1986) added .AT and
.P. Ninth Edition Unix (1986) introduced .EX and .EE. SunOS 4.0
(1988) added .SB.

James Clark implemented the foregoing features in early versions
of groff. Later, groff 1.20 (2009) originated .SY/.YS, .TQ,
.MT/.ME, and .UR/.UE. Plan 9 from User Space's troff introduced
.MR in 2020.

Options top

       The following groff options set registers (with -r) and strings
       (with -d) recognized and used by the man macro package.  To
       ensure rendering consistent with output device capabilities and
       reader preferences, man pages should never manipulate them.

       -dAD=adjustment-mode
              Set line adjustment to adjustment-mode, which is typically
              “b” for adjustment to both margins (the default), or “l”
              for left alignment (ragged right margin).  Any valid
              argument to groff's “.ad” request may be used.  See
              groff(7) for less-common choices.

       -rBP=base-paragraph-inset
              Set the inset amount for ordinary paragraphs not within an
              .RS/.RE inset.  The default is 5n.

       -rcR=1 Enable continuous rendering.  Output is not paginated;
              instead, one (potentially very long) page is produced.
              This is the default for terminal and HTML devices.  Use
              -rcR=0 to disable it on terminals; on HTML devices, it
              cannot be disabled.

       -rC1   Number output pages consecutively, in strictly increasing
              sequence, rather than resetting the page number to 1 (or
              the value of register P) with each new man document.

       -rCS=1 Set section headings (the argument(s) to .SH) in full
              capitals.  This transformation is off by default because
              it discards case distinction information.

       -rCT=1 Set the man page identifier (the first argument to .TH) in
              full capitals in headers and footers.  This transformation
              is off by default because it discards case distinction
              information.

       -rD1   Enable double-sided layout, formatting footers for even
              and odd pages differently; see the description of .TH in
              subsection “Document structure macros” above.

       -rFT=footer-distance
              Set distance of the footer relative to the bottom of the
              page to footer-distance; this amount is always negative.
              At one half-inch above this location, the page text is
              broken before writing the footer.  Ignored if continuous
              rendering is enabled.  The default is “-0.5i - 1v”.

       -dHF=heading-font
              Select the font used for section and subsection headings;
              the default is “B” (bold style of the default family).
              Any valid argument to groff's “.ft” request may be used.
              See groff(7).

       -rHY=0 Disable automatic hyphenation.  Normally, it is
              enabled (1).  The hyphenation mode is determined by the
              groff locale; see section “Localization“ of groff(7).

       -rIN=standard-indentation
              Set the default indentation amount used by .IP, .TP, and
              the deprecated .HP, and the inset amount used by .RS.  The
              default is 7n on terminals and 7.2n on typesetters.  Use
              only integer multiples of unit “n” on terminals for
              consistent indentation.

       -rLL=line-length
              Set line length; the default is 80n on terminals and 6.5i
              on typesetters.

       -rLT=title-length
              Set the line length for titles.  (“Titles” is the roff
              term for headers and footers.)  By default, it is set to
              the line length (see -rLL above).

       -dMF=man-page-topic-font
              Select the font used for man page identifiers in .TH calls
              and topics named in .MR calls; the default is “I” (italic
              style of the default family).  Any valid argument to
              groff's “.ft” request may be used.  If the MF string ends
              in “I”, it is assumed to be an oblique typeface, and
              italic corrections are applied before and after man page
              topics and identifiers.

       -rPn   Start enumeration of pages at n.  The default is 1.

       -rPO=page-offset
              Set page offset; the default is 0 on terminals and 1i on
              typesetters.

       -rStype-size
              Use type-size for the document's body text; acceptable
              values are 10, 11, or 12 points.  See subsection “Font
              style macros” above for the default.

       -rSN=subsection-indentation
              Set indentation of subsection headings to subsection-
              indentation.  The default is 3n.

       -rTS=separation
              Require the given separation between a TP paragraph's tag
              and its body.  The default is 2n.

       -rU0   Disable generation of URI hyperlinks in output drivers
              capable of them, making the arguments to MT and UR calls
              visible as formatted text.  grohtml(1), gropdf(1), and
              grotty(1) enable hyperlinks by default (the last only if
              not in legacy output mode).

       -rXp   Number successors of page p as pa, pb, pc, and so forth.
              The register tracking the suffixed page letter uses format
              “a” (see the “.af” request in groff(7)).  For example, the
              option -rX2 produces the following page numbers: 1, 2, 2a,
              2b, ..., 2aa, 2ab, and so on.

Files top

       /usr/local/share/groff/1.23.0/tmac/an.tmac
              Most man macros are defined in this file.  It also loads
              extensions from an-ext.tmac (see below).

       /usr/local/share/groff/1.23.0/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,
              before any other macros.  A man program or a user typing,
              for example, “groff -mandoc page.1”, need not know which
              package the file page.1 uses.  Multiple man pages, in
              either format, can be handled; andoc reloads each macro
              package as necessary.  Page-local redefinitions of names
              used by the man or mdoc packages prior to .TH or .Dd calls
              will be “clobbered” by the reloading process.  If you want
              to provide your own definition of an extension macro to
              ensure its availability, the an-ext.tmac entry below
              offers advice.

       /usr/local/share/groff/1.23.0/tmac/an-ext.tmac
              Definitions of macros described above as extensions (and
              not deprecated) are contained in this file; in some cases,
              they are simpler versions of definitions appearing in
              an.tmac, and are ignored if the formatter is GNU troff.
              They are written to be compatible with AT&T troff and
              permissively licensed—not copylefted.  To reduce the risk
              of name space collisions, string and register names begin
              only with “m”.  We encourage man page authors who are
              concerned about portability to legacy Unix systems to copy
              these definitions into their pages, and maintainers of
              troff implementations or work-alike systems that format
              man pages to re-use them.  To ensure reliable rendering,
              define them after your page calls .TH; see the discussion
              of andoc.tmac above.  Further, it is wise to define such
              page-local macros (if at all) after the “Name” section to
              accommodate timid makewhatis(8) or mandb(8)
              implementations that easily give up scanning for indexing
              material.

       /usr/local/share/groff/1.23.0/tmac/man.tmac
              is a wrapper enabling the package to be loaded with the
              option “-m man”.

       /usr/local/share/groff/1.23.0/tmac/mandoc.tmac
              is a wrapper enabling andoc.tmac to be loaded with the
              option “-m mandoc”.

       /usr/local/share/groff/site-tmac/man.local
              Put site-local changes and customizations into this file.

                     .\" Put only one space after the end of a sentence.
                     .ss 12 0 \" See groff(7).
                     .\" Keep pages narrow even on wide terminals.
                     .if n .if \n[LL]>80n .nr LL 80n

              On multi-user systems, it is more considerate to users
              whose preferences may differ from the administrator's to
              be less aggressive with such settings, or to permit their
              override with a user-specific man.local file.  Place the
              requests below at the end of the site-local file to
              manifest courtesy.
                     .soquiet \V[XDG_CONFIG_HOME]/man.local
                     .soquiet \V[HOME]/.man.local
              However, a security-sandboxed man(1) program may lack
              permission to open such files.

Notes top

Some tips on composing and troubleshooting your man pages follow.

• What's the difference between a man page topic and identifier?

A single man page may document several related but distinct
topics. For example, printf(3) and fprintf(3) are often
presented together. Further, multiple programming languages
have functions named “printf”, and may document these in a man
page. The identifier is intended to (with the section)
uniquely identify a page on the system; it may furthermore
correspond closely to the file name of the document.

The man(1) librarian makes access to man pages convenient by
resolving topics to man page identifiers. Thus, you can type
“man fprintf”, and other pages can refer to it, without knowing
whether the installed document uses “printf”, “fprintf”, or
even “c_printf” as an identifier.

• Some ASCII characters look funny or copy and paste wrong.

On devices with large glyph repertoires, like UTF-8-capable
terminals and PDF, several keyboard glyphs are mapped to code
points outside the Unicode basic Latin range because that
usually results in better typography in the general case. When
documenting GNU/Linux command or C language syntax, however,
this translation is sometimes not desirable.

To get a “literal”... ...should be input.
────────────────────────────────────────────
' \(aq
- \-
\ \(rs
^ \(ha
` \(ga
~ \(ti
────────────────────────────────────────────

Additionally, if a neutral double quote (") is needed in a
macro argument, you can use \(dq to get it. You should not use
\(aq for an ordinary apostrophe (as in “can't”) or \- for an
ordinary hyphen (as in “word-aligned”). Review subsection
“Portability” above.

• Do I ever need to use an empty macro argument ("")?

Probably not. When this seems necessary, often a shorter or
clearer alternative is available.

Instead of... ...should be considered.
────────────────────────────────────────────────────────────────
.TP "" .TP
────────────────────────────────────────────────────────────────
.BI "" italic-text bold-text .IB italic-text bold-text
────────────────────────────────────────────────────────────────
.TH foo 1 "" "foo 1.2.3" .TH foo 1 yyyy-mm-dd "foo 1.2.3"
────────────────────────────────────────────────────────────────
.IP "" 4n .IP
────────────────────────────────────────────────────────────────
.IP "" 4n .RS 4n
paragraph .P
... paragraph
... .RE
────────────────────────────────────────────────────────────────
.B one two "" three .B one two three

In the title heading (.TH), the date of the page's last
revision is more important than packaging information; it
should not be omitted. Ideally, a page maintainer will keep
both up to date.

.IP is sometimes ill-understood and misused, especially when no
mark argument is supplied—an indentation argument is not
required. By setting an explicit indentation, you may be
overriding the reader's preference as set with the -rIN option.
If your page renders adequately without one, use the simpler
form. If you need to indent multiple (unmarked) paragraphs,
consider setting an inset region with .RS and .RE instead.

In the last example, the empty argument does have a subtly
different effect than its suggested replacement: the empty
argument causes an additional space character to be
interpolated between the arguments “two” and “three”—but it is
a regular breaking space, so it can be discarded at the end of
an output line. It is better not to be subtle, particularly
with space, which can be overlooked in source and rendered
forms.

• .RS doesn't indent relative to my indented paragraph.

The .RS macro determines the inset amount, the position at
which an ordinary paragraph (.P and its synonyms) will be set;
the value of the IN register determines its default amount.
This register also determines the default indentation used by
.IP, .TP, and the deprecated .HP. To create an inset relative
to an indented paragraph, call .RS repeatedly until an
acceptable indentation is achieved, or give .RS an indentation
argument that is at least as much as the paragraph's
indentation amount relative to an adjacent ordinary (.P)
paragraph.

Another approach to tagged paragraphs places an .RS call
immediately after the tag; this will also force a break
regardless of the tag's width, which some authors prefer.
Follow-up paragraphs under the tag can then be set with .P
instead of .IP. Remember to use .RE to end the indented region
before starting the next tagged paragraph (at the appropriate
nesting level).

• .RE doesn't move the inset back to the expected level.

The .RS macro takes an inset amount as an argument; the .RE
macro's argument is an inset 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.

Calling the .SH or .SS sectioning macros clears all relative
insets and .RE calls have no effect until .RS is used again.

• Do I need to keep typing the indentation in a series of .IP
calls?

Not if you don't want to change it. Review subsection
“Horizontal and vertical spacing” above.

Instead of... ...should be considered.
─────────────────────────────────────────────
.IP \(bu 4n .IP \(bu 4n
paragraph paragraph
.IP \(bu 4n .IP \(bu
another-paragraph another-paragraph
─────────────────────────────────────────────

• Why doesn't the package provide a string to insert an ellipsis?

Examples of ellipsis usage are shown above, in subsection
“Synopsis macros”. The idiomatic roff ellipsis is three dots
(periods) with thin space escape sequences \| internally
separating them. Since dots both begin control lines and are
candidate end-of-sentence characters, however, it is sometimes
necessary to prefix and/or suffix an ellipsis with the dummy
character escape sequence \&. That fact stands even if a
string is defined to contain the sequence; further, if the
string ends with \&, end-of-sentence detection is defeated when
you use the string at the end of an actual sentence. (Ending a
sentence with an ellipsis is often poor style, but not always.)
A hypothetical string EL that contained an ellipsis, but not
the trailing dummy character \&, would then need to be suffixed
with the latter when not ending a sentence.

Instead of... ...do this.
──────────────────────────────────────────────────
.ds EL \&.\|.\|. Arguments are
Arguments are .IR src-file\~ .\|.\|.\&
.IR src-file\~ \*(EL\& .IR dest-dir .
.IR dest-dir .
──────────────────────────────────────────────────

The first column practices a false economy; the savings in
typing is offset by the cost of obscuring even the suggestion
of an ellipsis to a casual reader of the source document, and
reduced portability to non-roff man page formatters that cannot
handle string definitions.

There is an ellipsis code point in Unicode, and some fonts have
an ellipsis glyph, which some man pages have accessed in a non-
portable way with the font-dependent \N escape sequence. We
discourage the use of these; on terminals, they may crowd the
dots into a half-width character cell, and will not render at
all if the output device doesn't have the glyph. In syntax
synopses, missing ellipses can mislead the reader. Dots and
space are universally supported.

Authors top

       The initial GNU implementation of the man macro package was
       written by James Clark.  Later, Werner Lemberg ⟨wl@gnu.org⟩
       supplied the S, LT, and cR registers, the last a 4.3BSD-Reno
       mdoc(7) feature.  Larry Kollar ⟨kollar@alltel.net⟩ added the FT,
       HY, and SN registers; the HF string; and the PT and BT macros.
       G. Branden Robinson ⟨g.branden.robinson@gmail.com⟩ implemented
       the AD and MF strings; BP, CS, CT, PO, TS, and U registers; and
       the MR macro.  Extension macros since groff 1.20 were written by
       Lemberg, Eric S. Raymond ⟨esr@thyrsus.com⟩, and Robinson.

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

COLOPHON top

       This page is part of the groff (GNU troff) project.  Information
       about the project can be found at 
       ⟨http://www.gnu.org/software/groff/⟩.  If you have a bug report
       for this manual page, see ⟨http://www.gnu.org/software/groff/⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2024-06-14.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2024-06-10.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

groff 1.23.0.1273-9d53-dirty   6 June 2024            groff_man_style(7)