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 line length (see the -dAD option). roff(7) details these processes.

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. We refer to macros in this document using this leading dot. Some macros interpret arguments, words that follow the macro name. A newline, unless escaped (see subsection “Portability” below), marks the end of the macro call. An input line consisting of a dot followed by a newline is called the 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 topic. 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 topic section [footer-middle] [footer-inside] [header-middle]

Determine the contents of the page header and footer. roff systems refer to these collectively as “titles”. The subject of the man page is topic and the section of the manual to which it belongs is section. 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. topic and section are positioned together at the left and right in the header (with section in parentheses immediately appended to topic). 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 topic 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. The macro package may also abbreviate topic and footer-inside with ellipses (...) if they would overrun the space available in the header and footer, respectively. For 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 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, a one-line input trap is planted; text on the next line becomes heading-text. The left margin is reset to zero to set the heading text in bold (or the font specified by the string HF), and, on typesetting devices, 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, setting the left margin to the value of the IN register. 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

.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, a one-line input trap is planted; text on the next line becomes subheading-text. The left margin is reset to the value of the SN register to set the heading text 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, setting the left margin to the value of the IN register. 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 ~, and 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.

These macros are extensions introduced in Ninth Edition Research Unix. Systems running that troff, or those from Documenter's Workbench, Heirloom Doctools, or Plan 9 troff support them. To be certain your page will be portable to systems that do not, copy their definitions from the an-ext.tmac file of a groff installation.

.RS [inset-amount]

Start a new relative inset level. The position of the left margin is saved, then moved right by inset-amount, if specified, 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 [level]

End a relative inset. The left margin corresponding to inset level level is restored. If no argument is given, the inset level is reduced by 1.

Paragraphing macros¶

An ordinary paragraph (.P) like this one is set without a first-line indentation at the current left margin. In man pages and other technical literature, definition lists are frequently encountered; 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. The indentation is reset to the default value; the left margin, as affected by .RS and .RE, is not.

.TP [indentation]

Set a paragraph with a leading tag, and the remainder of the paragraph indented. A one-line input trap is planted; text on the next line, which can be formatted with a macro, becomes the tag, which is placed at the current left margin. The tag can be extended with the \c escape sequence. Subsequent text is indented by indentation, if specified, and by the amount of the IN register otherwise. 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. Otherwise, the descriptive part of the paragraph begins on the line following 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. An input trap is planted as with .TP.

This macro is a GNU extension not defined on systems running AT&T, Plan 9, or Solaris troff; see an-ext.tmac in section “Files” below.

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

.IP [tag] [indentation]

Set an indented paragraph with an optional tag. The tag and indentation arguments, if present, are handled as with .TP, with the exception that the tag argument to .IP cannot include a macro call.

Two convenient uses for .IP are

Command synopsis macros¶

.SY and .YS aid you to construct a command synopsis that has the classical Unix appearance. They break the output line.

These macros are GNU extensions not defined on systems running AT&T, Plan 9, or Solaris troff; see an-ext.tmac in section “Files” below.

.SY command

Begin synopsis. A new paragraph begins at the left margin (as with .P) unless .SY has already been called without a corresponding .YS, in which case only a break is performed. Adjustment and automatic hyphenation are disabled. command is set in bold. If a break is required, lines after the first are indented by the width of command plus a space.

.YS

End synopsis. Indentation, adjustment, and hyphenation are restored to their previous states.

Multiple .SY/.YS blocks can be specified, for instance to distinguish differing modes of operation of a complex command like tar(1); each will be vertically separated as paragraphs are.

.SY can be repeated before .YS to indicate synonymous ways of invoking a particular mode of operation.

groff's own command-line interface serves to illustrate most of the specimens of synopsis syntax one is likely to encounter.

.SY groff
.RB [ \-abcCeEgGijklNpRsStUVXzZ ]
.RB [ \-d\~\c
.IR cs ]
.RB [ \-d\~\c
.IB name =\c
.IR string ]
.RB [ \-D\~\c
.IR enc ]
    

(and so on similarly)

.RI [ file\~ .\|.\|.]
.YS
.
.
.SY groff
.B \-h
.
.SY groff
.B \-\-help
.YS
.
.
.SY groff
.B \-v
.RI [ option\~ .\|.\|.\&]
.RI [ file\~ .\|.\|.]
.
.SY groff
.B \-\-version
.RI [ option\~ .\|.\|.\&]
.RI [ file\~ .\|.\|.]
.YS
    

produces the following output.

Several features of the above example are of note.

• The empty request (.), which does nothing, is used to vertically space 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 text.
• 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 syntactical element may be repeated arbitrarily.
• The non-breaking adjustable space escape sequence \~ is used to prevent the output line from being broken 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.

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. Hyperlinked text is supported on HTML and terminal output devices; 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 not defined on systems running AT&T, Plan 9, or Solaris troff; see an-ext.tmac in section “Files” below. Plan 9 from User Space's troff implements .MR.

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

.MR topic manual-section [trailing-text]

(since groff 1.23) Set a man page cross reference as “topic(manual-section)”. 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. The cross reference hyperlinks to a URI of the form “man:topic(manual-section)”.

.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,

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,

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

The hyperlinking of .TP paragraph tags with .UR/.UE and .MT/.ME is not yet supported; if attempted, the hyperlink will be typeset at the beginning of the indented paragraph even on hyperlink-supporting devices.

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 terminal devices. The .SM and .SB macros set text in roman or bold, respectively, at a smaller type size; these differ visually from regular-sized roman or bold text only on typesetting devices. 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 typesetting devices 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, a one-line input trap is planted; 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, a one-line input trap is planted; 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 typesetting devices. If no argument is given, a one-line input trap is planted; 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.

.SB [text]

Set text in bold and (on typesetting devices) one point smaller than the default type size. If no argument is given, a one-line input trap is planted; text on the next line, which can be further formatted with a macro, is set smaller and in bold. This macro is an extension introduced in SunOS 4.0.

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.

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. Italic corrections are applied 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.

.BR bold-text roman-text ...

Set each argument in bold and roman, alternately.

.IB italic-text bold-text ...

Set each argument in italics and bold, alternately.

.IR italic-text roman-text ...

Set each argument in italics and roman, alternately.

.RB roman-text bold-text ...

Set each argument in roman and bold, alternately.

.RI roman-text italic-text ...

Set each argument in roman and italics, alternately.

Horizontal and vertical spacing¶

The indentation argument accepted by .IP, .TP, and the deprecated .HP is a number plus an optional scaling unit, as is .RS's inset-amount. If no scaling unit 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 “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 left margin used by ordinary paragraphs set with .P (and its synonyms) not within an .RS/.RE relative inset is 7.2n for typesetting devices and 7n for terminal devices (but see the -rIN option). Headers, footers (both set with .TH), and section headings (.SH) are set at the page offset (see groff(7)) and subsection headings (.SS) indented from it by 3n (but see the -rSN option).

It may be helpful to think of the left margin and indentation as related but distinct concepts; groff's implementation of the man macro package tracks them separately. The left margin 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.

Finally, we have ended the relative inset by using .RE, which (because we used only one .RS/.RE pair) has reset the left margin to the default. 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 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.

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 is 1v for terminal devices and 0.4v for typesetting devices (“v” is a unit of vertical distance, where 1v is the distance between adjacent text baselines in a single-spaced document). (The deprecated macro .PD can change this vertical spacing, but its use is discouraged.) 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 terminal devices 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 a man page author is aiming for a pathological level of portability, such as the composition of pages for consumption on simulators of 1980s Unix systems (or Solaris troff, though even it supports \(rg), the above strings should be avoided.

Portability¶

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. A similar restriction applied to the .B, .I, .SM, and font style alternation macros.

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

However, using raw groff requests (apart from the empty request “.”) is likely to make your page render poorly when processed by other tools; many of these attempt to interpret page sources directly for conversion 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 omitted or presented incomprehensibly.

For portability to modern viewers, it is best to write your page solely with the macros described in this page (except for the ones identified as deprecated, which should be avoided). The macros we have described as extensions (.EX/.EE, .SY/.YS, .TQ, .UR/.UE, .MT/.ME, .MR, and .SB) should be used with caution, as they may not be built in to some viewer that is important to your audience. See an-ext.tmac in section “Files” below.

Similar caveats apply to escape sequences. 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 syntactically—namely, any of the set ' - \ ^ ` ~ (apostrophe, dash or 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. This escape sequence 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.

This escape sequence is a groff extension also supported by Heirloom Doctools troff 050915 (September 2005), mandoc 1.14.5 (2019-03-10), 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).

This escape sequence is a groff extension also supported by Heirloom Doctools troff 050915 (September 2005), mandoc 1.9.5 (2009-09-21), 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 typesetting devices 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 be broken there (if not, an adjustable space is inserted); if filling is disabled, the line will be broken 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.

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

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 current 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.

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, 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).

\-

Minus sign or basic Latin hyphen-minus. This escape sequence produces the Unix command-line option dash in the output. “-” is a hyphen in the roff language; some output devices replace it with U+2010 (hyphen) or similar.

\(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.

\(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) or similar.

\(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) or similar.

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

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.

system can be any of the following.

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 is desirable to restore them, you should probably be composing a table using tbl(1) instead.

.HP [indentation]

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

Use of this presentation-oriented macro is deprecated. A hanging indentation cannot be expressed naturally under HTML, 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]

Define the 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.

.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.

version can be any of the following.

History¶

M. Douglas McIlroy 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 Research Unix (1986) introduced .EX and .EE. SunOS 4.0 (1988) added .SB.

The foregoing features were what James Clark implemented 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.