Usage

An mdoc macro is called by placing the roff control character, ‘.’ (dot) at the beginning of a line followed by its name. In this document, we often discuss a macro name with this leading dot to identify it clearly, but the dot is not part of its name. Space or tab characters can separate the dot from the macro name. Arguments may follow, separated from the macro name and each other by spaces, but not tabs. The dot at the beginning of the line prepares the formatter to expect a macro name. A dot followed immediately by a newline is ignored; this is called the empty request. To begin an input line with a dot (or a neutral apostrophe ‘'’) in some context other than a macro call, precede it with the ‘\&’ escape sequence; this is a dummy character, not formatted for output. The backslash is the roff escape character; it can appear anywhere and it always followed by at least one more character. If followed by a newline, the backslash escapes the input line break; you can thus keep input lines to a reasonable length without affecting their interpretation.

Macros in GNU troff accept an unlimited number of arguments, in contrast to other troffs that often can't handle more than nine. In limited cases, arguments may be continued or extended on the next input line without resort to the ‘\newline’ escape sequence; see subsection Extended arguments below. Neutral double quotes " can be used to group multiple words into an argument; see subsection Passing space characters in an argument below.

Most of mdoc's general text and manual domain macros parse their argument lists for callable macro names. This means that an argument in the list matching a general text or manual domain macro name (and defined to be callable) will be called with the remaining arguments when it is encountered. In such cases, the argument, although the name of a macro, is not preceded by a dot. Macro calls can thus be nested. This approach to macro argument processing is a unique characteristic of the mdoc package, not a general feature of roff syntax.

For example, the option macro, .Op, may call the flag and argument macros, .Fl and .Ar, to specify an optional flag with an argument.

In this document, macros whose argument lists are parsed for callable arguments are referred to as parsed, and those that may be called from an argument list are referred to as callable. This usage is a technical faux pas, since all mdoc macros are in fact interpreted (unless prevented with ‘\&’), but as it is cumbersome to constantly refer to macros as “being able to call other macros”, we employ the term “parsed” instead. Except where explicitly stated, all mdoc macros are parsed and callable.

In the following, we term an mdoc macro that starts a line (with a leading dot) a command if a distinction from those appearing as arguments of other macros is necessary.

Passing space characters in an argument

Sometimes it is desirable to give a macro an argument containing one or more space characters, for instance to specify a particular arrangement of arguments demanded by the macro. Additionally, quoting multi-word arguments that are to be treated the same makes mdoc work faster; macros that parse arguments do so once (at most) for each. For example, the function command .Fn expects its first argument to be the name of a function and any remaining arguments to be function parameters. Because C language standards mandate the inclusion of types and identifiers in the parameter lists of function definitions, each ‘Fn’ parameter after the first will be at least two words in length, as in “int foo”.

There are a few ways to embed a space in a macro argument. One is to use the unadjustable space escape sequence \space. The formatter treats this escape sequence as if it were any other printable character, and will not break a line there as it would a word space when the output line is full. This method is useful for macro arguments that are not expected to straddle an output line boundary, but has a drawback: this space does not adjust as others do when the output line is formatted. An alternative is to use the unbreakable space escape sequence, ‘\~’, which cannot break but does adjust. This groff extension is widely but not perfectly portable. Another method is to enclose the string in double quotes.

Trailing space characters

It is wise to remove trailing spaces from the ends of input lines. Should the need arise to put a formattable space at the end of a line, do so with the unadjustable or unbreakable space escape sequences.

Formatting the backslash glyph

When you need the roff escape character ‘\’ to appear in the output, use ‘\e’ or ‘\(rs’ instead. Technically, ‘\e’ formats the current escape character; it works reliably as long as no roff request is used to change it, which should never happen in man pages. ‘\(rs’ is a groff special character escape sequence that explicitly formats the “reverse solidus” (backslash) glyph.

Other possible pitfalls

groff mdoc warns when an empty input line is found outside of a display, a topic presented in subsection Examples and displays below. Use empty requests to space the source document for maintenance.

Leading spaces cause a break and are formatted. Avoid this behaviour if possible. Similarly, do not put more than one space between words in an ordinary text line; they are not “normalized” to a single space as other text formatters might do.

Don't try to use the neutral double quote character ‘"’ to represent itself in an argument. Use the special character escape sequence ‘\(dq’ to format it. Further, this glyph should not be used for conventional quotation; mdoc offers several quotation macros. See subsection Enclosure and quoting macros below.

The formatter attempts to detect the ends of sentences and by default puts the equivalent of two spaces between sentences on the same output line; see roff(7). To defeat this detection in a parsed list of macro arguments, put ‘\&’ before the punctuation mark. Thus,

The
.Ql .
character.
.Pp
The
.Ql \&.
character.
.Pp
.No test .
test
.Pp
.No test.
test

A comment in the source file of a man page can begin with ‘.\"’ at the start of an input line, ‘\"’ after other input, or ‘\#’ anywhere (the last is a groff extension); the remainder of any such line is ignored.

What's in a Name...

The manual domain macro names are derived from the day to day informal language used to describe commands, subroutines and related files. Slightly different variations of this language are used to describe the three different aspects of writing a man page. First, there is the description of mdoc macro command usage. Second is the description of a UNIX command with mdoc macros, and third, the description of a command to a user in the verbal sense; that is, discussion of a command in the text of a man page.

In the first case, troff macros are themselves a type of command; the general syntax for a troff command is:

‘.Xx’ is a macro command, and anything following it are arguments to be processed. In the second case, the description of a UNIX command using the manual domain macros is a bit more involved; a typical Synopsis command line might be displayed as:

Here, filter is the command name and the bracketed string -flag is a flag argument designated as optional by the option brackets. In mdoc terms, ⟨infile⟩ and ⟨outfile⟩ are called meta arguments; in this example, the user has to replace the meta expressions given in angle brackets with real file names. Note that in this document meta arguments are used to describe mdoc commands; in most man pages, meta variables are not specifically written with angle brackets. The macros that formatted the above example:

.Nm filter
.Op Fl flag
.Ao Ar infile Ac Ao Ar outfile Ac

In the third case, discussion of commands and command syntax includes both examples above, but may add more detail. The arguments ⟨infile⟩ and ⟨outfile⟩ from the example above might be referred to as operands or file arguments. Some command-line argument lists are quite long:

Here one might talk about the command make and qualify the argument, makefile, as an argument to the flag, -f, or discuss the optional file operand target. In the verbal context, such detail can prevent confusion, however the mdoc package does not have a macro for an argument to a flag. Instead the ‘Ar’ argument macro is used for an operand or file argument like target as well as an argument to a flag like variable. The make command line was produced from:

.Nm make
.Op Fl eiknqrstv
.Op Fl D Ar variable
.Op Fl d Ar flags
.Op Fl f Ar makefile
.Op Fl I Ar directory
.Op Fl j Ar max_jobs
.Op Ar variable Ns = Ns Ar value
.Bk
.Op Ar target ...
.Ek

The ‘.Bk’ and ‘.Ek’ macros are explained in Keeps.

General Syntax

The manual domain and general text domain macros share a similar syntax with a few minor deviations; most notably, ‘.Ar’, ‘.Fl’, ‘.Nm’, and ‘.Pa’ differ only when called without arguments; and ‘.Fn’ and ‘.Xr’ impose an order on their argument lists. All manual domain macros are capable of recognizing and properly handling punctuation, provided each punctuation character is separated by a leading space. If a command is given:

The result is:

The punctuation is not recognized and all is output in the font used by ‘.Ar’. If the punctuation is separated by a leading white space:

The result is:

The punctuation is now recognized and output in the default font distinguishing it from the argument strings. To remove the special meaning from a punctuation character, escape it with ‘\&’.

The following punctuation characters are recognized by mdoc:

troff is limited as a macro language, and has difficulty when presented with a string containing certain mathematical, logical, or quotation character sequences:

{+,-,/,*,%,<,>,<=,>=,=,==,&,`,',"}

The problem is that troff may assume it is supposed to actually perform the operation or evaluation suggested by the characters. To prevent the accidental evaluation of these characters, escape them with ‘\&’. Typical syntax is shown in the first manual domain macro displayed below, ‘.Ad’.

Addresses

The address macro identifies an address construct.

The default width is 12n.

Author Name

The ‘.An’ macro is used to specify the name of the author of the item being documented, or the name of the author of the actual manual page.

The default width is 12n.

In a section titled “Authors”, ‘An’ causes a break, allowing each new name to appear on its own line. If this is not desirable,

.An -nosplit

call will turn this off. To turn splitting back on, write

.An -split

Arguments

The .Ar argument macro may be used whenever an argument is referenced. If called without arguments, ‘file ...’ is output. This places the ellipsis in italics, which is ugly and incorrect, and will be noticed on terminals that underline text instead of using an oblique typeface. We recommend using ‘.Ar file No ...’ instead.

The default width is 12n.

Configuration Declaration (Section Four Only)

The ‘.Cd’ macro is used to demonstrate a config(8) declaration for a device interface in a section four manual.

In a section titled “Synopsis”, ‘Cd’ causes a break before and after its arguments.

The default width is 12n.

Command Modifiers

The command modifier is identical to the ‘.Fl’ (flag) command with the exception that the ‘.Cm’ macro does not assert a dash in front of every argument. Traditionally flags are marked by the preceding dash, however, some commands or subsets of commands do not use them. Command modifiers may also be specified in conjunction with interactive commands such as editor commands. See Flags.

The default width is 10n.

Defined Variables

A variable (or constant) that is defined in an include file is specified by the macro ‘.Dv’.

The default width is 12n.

Errnos

The ‘.Er’ errno macro specifies the error return value for section 2, 3, and 9 library routines. The second example below shows ‘.Er’ used with the ‘.Bq’ general text domain macro, as it would be used in a section two manual page.

The default width is 17n.

Environment Variables

The ‘.Ev’ macro specifies an environment variable.

The default width is 15n.

Flags

The ‘.Fl’ macro handles command-line flags. It prepends a dash, ‘-’, to the flag. For interactive command flags that are not prepended with a dash, the ‘.Cm’ (command modifier) macro is identical, but without the dash.

The ‘.Fl’ macro without any arguments results in a dash representing stdin/stdout. Note that giving ‘.Fl’ a single dash will result in two dashes.

The default width is 12n.

Function Declarations

The ‘.Fd’ macro is used in the Synopsis section with section two or three functions. It is neither callable nor parsed.

In a section titled “Synopsis”, ‘Fd’ causes a break if a function has already been presented and a break has not occurred, leaving vertical space between one function declaration and the next.

In a section titled “Synopsis”, the ‘In’ macro represents the #include statement, and is the short form of the above example. It specifies the C header file as being included in a C program. It also causes a break.

While not in the “Synopsis” section, it represents the header file enclosed in angle brackets.

Function Types

This macro is intended for the “Synopsis” section. It may be used anywhere else in the man page without problems, but its main purpose is to present the function type (in BSD kernel normal form) for the “Synopsis” of sections two and three. (It causes a break, allowing the function name to appear on the next line.)

Functions (Library Routines)

The ‘.Fn’ macro is modeled on ANSI C conventions.

Note that any call to another macro signals the end of the ‘.Fn’ call (it will insert a closing parenthesis at that point).

For functions with many parameters (which is rare), the macros ‘.Fo’ (function open) and ‘.Fc’ (function close) may be used with ‘.Fa’ (function argument).

Example:

.Ft int
.Fo res_mkquery
.Fa "int op"
.Fa "char *dname"
.Fa "int class"
.Fa "int type"
.Fa "char *data"
.Fa "int datalen"
.Fa "struct rrec *newrr"
.Fa "char *buf"
.Fa "int buflen"
.Fc

Produces:

Typically, in a “Synopsis” section, the function delcaration will begin the line. If more than one function is presented in the “Synopsis” section and a function type has not been given, a break will occur, leaving vertical space between the current and prior function names.

The default width values of ‘.Fn’ and ‘.Fo’ are 12n and 16n, respectively.

Function Arguments

The ‘.Fa’ macro is used to refer to function arguments (parameters) outside of the Synopsis section of the manual or inside the Synopsis section if the enclosure macros ‘.Fo’ and ‘.Fc’ instead of ‘.Fn’ are used. ‘.Fa’ may also be used to refer to structure members.

The default width is 12n.

Return Values

The ‘.Rv’ macro generates text for use in the Return values section.

For example, ‘.Rv -std atexit’ produces:

The -std option is valid only for manual page sections 2 and 3. Currently, this macro does nothing if used without the -std flag.

Exit Status

The ‘.Ex’ macro generates text for use in the Diagnostics section.

For example, ‘.Ex -std cat’ produces:

The -std option is valid only for manual page sections 1, 6 and 8. Currently, this macro does nothing if used without the -std flag.

Interactive Commands

The ‘.Ic’ macro designates an interactive or internal command.

The default width is 12n.

Library Names

The ‘.Lb’ macro is used to specify the library where a particular function is compiled in.

Available arguments to ‘.Lb’ and their results are:

Site-specific additions might be found in the file mdoc.local; see section Files below.

In a section titled “Library”, ‘Lb’ causes a break before and after its arguments.

Literals

The ‘Li’ literal macro may be used for special characters, symbolic constants, and other syntactical items that should be typed exactly as displayed.

The default width is 16n.

Names

The ‘Nm’ macro is used for the document title or page topic. Upon its first call, it has the peculiarity of remembering its argument, which should always be the topic of the man page. When subsequently called without arguments, ‘Nm’ regurgitates this initial name for the sole purpose of making less work for the author. Use of ‘Nm’ is also appropriate when presenting a command synopsis for the topic of a man page in section 1, 6, or 8. Its behavior changes when presented with arguments of various forms.

By default, the topic is set in boldface to reflect its prime importance in the discussion. Cross references to other man page topics should use ‘Xr’; including a second argument for the section number enables them to be hyperlinked. By default, cross-referenced topics are set in italics to avoid cluttering the page with boldface.

The default width is 10n.

Options

The ‘.Op’ macro places option brackets around any remaining arguments on the command line, and places any trailing punctuation outside the brackets. The macros ‘.Oo’ and ‘.Oc’ (which produce an opening and a closing option bracket, respectively) may be used across one or more lines or to specify the exact position of the closing parenthesis.

Here a typical example of the ‘.Oo’ and ‘.Oc’ macros:

.Oo
.Op Fl k Ar kilobytes
.Op Fl i Ar interval
.Op Fl c Ar count
.Oc

Produces:

The default width values of ‘.Op’ and ‘.Oo’ are 14n and 10n, respectively.

Pathnames

The ‘.Pa’ macro formats file specifications. If called without arguments, ‘~’ (recognized by many shells) is output, representing the user's home directory.

The default width is 32n.

Standards

The ‘.St’ macro replaces standard abbreviations with their formal names.

Available pairs for “Abbreviation/Formal Name” are:

ANSI/ISO C

POSIX Part 1: System API

POSIX Part 2: Shell and Utilities

X/Open

Miscellaneous

Variable Types

The ‘.Vt’ macro may be used whenever a type is referenced. In a section titled “Synopsis”, ‘Vt’ causes a break (useful for old-style C variable declarations).

Variables

Generic variable reference.

The default width is 12n.

Manual Page Cross References

The ‘.Xr’ macro expects the first argument to be a manual page name. The optional second argument, if a string (defining the manual section), is put into parentheses.

The default width is 10n.

AT&T Macro

The following values for ⟨version⟩ are possible:

BSD Macro

⟨version⟩ will be prepended to the string ‘BSD’. The following values for ⟨release⟩ are possible:

NetBSD Macro

For possible values of ⟨version⟩ see the description of the ‘.Os’ command above in section Title macros.

FreeBSD Macro

For possible values of ⟨version⟩ see the description of the ‘.Os’ command above in section Title macros.

DragonFly Macro

For possible values of ⟨version⟩ see the description of the ‘.Os’ command above in section Title macros.

OpenBSD Macro

BSD/OS Macro

Unix Macro

Emphasis Macro

Text may be stressed or emphasized with the ‘.Em’ macro. The usual font for emphasis is italic.

The default width is 10n.

Font Mode

The ‘.Bf’ font mode must be ended with the ‘.Ef’ macro (the latter takes no arguments). Font modes may be nested within other font modes.

‘.Bf’ has the following syntax:

⟨font mode⟩ must be one of the following three types:

Both macros are neither callable nor parsed.

Enclosure and Quoting Macros

The concept of enclosure is similar to quoting. The object being to enclose one or more strings between a pair of characters like quotes or parentheses. The terms quoting and enclosure are used interchangeably throughout this document. Most of the one-line enclosure macros end in small letter ‘q’ to give a hint of quoting, but there are a few irregularities. For each enclosure macro, there is a pair of opening and closing macros that end with the lowercase letters ‘o’ and ‘c’ respectively.

All macros ending with ‘q’ and ‘o’ have a default width value of 12n.

.Eo, .Ec

These macros expect the first argument to be the opening and closing strings, respectively.

.Es, .En

To work around the nine-argument limit in the original troff program, mdoc supports two other macros that are now obsolete. ‘.Es’ uses its first and second parameters as opening and closing marks which are then used to enclose the arguments of ‘.En’. The default width value is 12n for both macros.

.Eq

The first and second arguments of this macro are the opening and closing strings respectively, followed by the arguments to be enclosed.

.Ql

The quoted literal macro behaves differently in troff and nroff modes. If formatted with nroff(1), a quoted literal is always quoted. If formatted with troff, an item is only quoted if the width of the item is less than three constant-width characters. This is to make short strings more visible where the font change to literal (constant-width) is less noticeable.

The default width is 16n.

.Pf

The prefix macro suppresses the whitespace between its first and second argument:

.Pf ( Fa name2

(name2

The default width is 12n.

The ‘.Ns’ macro (see below) performs the analogous suffix function.

.Ap

The ‘.Ap’ macro inserts an apostrophe and exits any special text modes, continuing in ‘.No’ mode.

Examples of quoting:

For a good example of nested enclosure macros, see the ‘.Op’ option macro. It was created from the same underlying enclosure macros as those presented in the list above. The ‘.Xo’ and ‘.Xc’ extended argument list macros are discussed below.

Normal text macro

‘No’ formats subsequent argument(s) normally, ending the effect of ‘Em’ and similar. Parsing is not suppressed, so you must prefix words like ‘No’ with ‘\&’ to avoid their interpretation as mdoc macros.

The default width is 12n.

No-Space Macro

The ‘.Ns’ macro suppresses insertion of a space between the current position and its first parameter. For example, it is useful for old style argument lists where there is no space between the flag and argument:

Note: The ‘.Ns’ macro always invokes the ‘.No’ macro after eliminating the space unless another macro name follows it. If used as a command (i.e., the second form above in the ‘Usage’ line), ‘.Ns’ is identical to ‘.No’.

(Sub)section cross references

Use the ‘.Sx’ macro to cite a (sub)section heading within the given document.

The default width is 16n.

Symbolics

The symbolic emphasis macro is generally a boldface macro in either the symbolic sense or the traditional English usage.

The default width is 6n.

Mathematical Symbols

Use this macro for mathematical symbols and similar things.

The default width is 6n.

References and Citations

The following macros make a modest attempt to handle references. At best, the macros make it convenient to manually drop in a subset of refer(1) style references.

Macros beginning with ‘%’ are not callable but accept multiple arguments in the usual way. Only the ‘.Tn’ macro is handled properly as a parameter; other macros will cause strange output. ‘.%B’ and ‘.%T’ can be used outside of the ‘.Rs/.Re’ environment.

Example:

.Rs
.%A "Matthew Bar"
.%A "John Foo"
.%T "Implementation Notes on foobar(1)"
.%R "Technical Report ABC-DE-12-345"
.%Q "Drofnats College"
.%C "Nowhere"
.%D "April 1991"
.Re

produces

Trade Names or Acronyms

The trade name macro prints its arguments at a smaller type size. It is intended to imitate a small caps fonts for fully capitalized acronyms.

The default width is 10n.

Extended Arguments

The .Xo and .Xc macros allow one to extend an argument list on a macro boundary for the ‘.It’ macro (see below). Note that .Xo and .Xc are implemented similarly to all other macros opening and closing an enclosure (without inserting characters, of course). This means that the following is true for those macros also.

Here is an example of ‘.Xo’ using the space mode macro to turn spacing off:

.Bd -literal -offset indent
.Sm off
.It Xo Sy I Ar operation
.No \en Ar count No \en
.Xc
.Sm on
.Ed

produces

Another one:

.Bd -literal -offset indent
.Sm off
.It Cm S No / Ar old_pattern Xo
.No / Ar new_pattern
.No / Op Cm g
.Xc
.Sm on
.Ed

produces

Another example of ‘.Xo’ and enclosure macros: Test the value of a variable.

.Bd -literal -offset indent
.It Xo
.Ic .ifndef
.Oo \&! Oc Ns Ar variable Oo
.Ar operator variable No ...
.Oc Xc
.Ed

produces

Section headings

The following ‘.Sh’ section heading macros are required in every man page. The remaining section headings are recommended at the discretion of the author writing the manual page. The ‘.Sh’ macro is parsed but not generally callable. It can be used as an argument in a call to ‘.Sh’ only; it then reactivates the default font for ‘.Sh’.

The default width is 8n.

.Sh Name

The ‘.Sh Name’ macro is mandatory. If not specified, headers, footers, and page layout defaults will not be set and things will be rather unpleasant. The Name section consists of at least three items. The first is the ‘.Nm’ name macro naming the subject of the man page. The second is the name description macro, ‘.Nd’, which separates the subject name from the third item, which is the description. The description should be the most terse and lucid possible, as the space available is small.

‘.Nd’ first prints ‘-’, then all its arguments.

.Sh Library

This section is for section two and three function calls. It should consist of a single ‘.Lb’ macro call; see Library Names.

.Sh Synopsis

The Synopsis section describes the typical usage of the subject of a man page. The macros required are either ‘.Nm’, ‘.Cd’, or ‘.Fn’ (and possibly ‘.Fo’, ‘.Fc’, ‘.Fd’, and ‘.Ft’). The function name macro ‘.Fn’ is required for manual page sections 2 and 3; the command and general name macro ‘.Nm’ is required for sections 1, 5, 6, 7, and 8. Section 4 manuals require a ‘.Nm’, ‘.Fd’ or a ‘.Cd’ configuration device usage macro. Several other macros may be necessary to produce the synopsis line as shown below:

cat [-benstuv] [-] file ...

The following macros were used:

.Nm cat

.Op Fl benstuv

.Op Fl

.Ar file No ...

.Sh Description

In most cases the first text in the Description section is a brief paragraph on the command, function or file, followed by a lexical list of options and respective explanations. To create such a list, the ‘.Bl’ (begin list), ‘.It’ (list item) and ‘.El’ (end list) macros are used (see Lists and Columns below).

.Sh Implementation notes

Implementation specific information should be placed here.

.Sh Return values

Sections 2, 3 and 9 function return values should go here. The ‘.Rv’ macro may be used to generate text for use in the Return values section for most section 2 and 3 library functions; see Return Values.

The following ‘.Sh’ section headings are part of the preferred manual page layout and must be used appropriately to maintain consistency. They are listed in the order in which they would be used.

.Sh Environment

The Environment section should reveal any related environment variables and clues to their behavior and/or usage.

.Sh Files

Files which are used or created by the man page subject should be listed via the ‘.Pa’ macro in the Files section.

.Sh Examples

There are several ways to create examples. See subsection Examples and Displays below for details.

.Sh Diagnostics

Diagnostic messages from a command should be placed in this section. The ‘.Ex’ macro may be used to generate text for use in the Diagnostics section for most section 1, 6 and 8 commands; see Exit Status.

.Sh Compatibility

Known compatibility issues (e.g. deprecated options or parameters) should be listed here.

.Sh Errors

Specific error handling, especially from library functions (man page sections 2, 3, and 9) should go here. The ‘.Er’ macro is used to specify an error (errno).

.Sh See also

References to other material on the man page topic and cross references to other relevant man pages should be placed in the See also section. Cross references are specified using the ‘.Xr’ macro. Currently refer(1) style references are not accommodated.

It is recommended that the cross references be sorted by section number, then alphabetically by name within each section, then separated by commas. Example:

ls(1), ps(1), group(5), passwd(5)

.Sh Standards

If the command, library function, or file adheres to a specific implementation such as IEEE Std 1003.2 (“POSIX.2”) or ANSI X3.159-1989 (“ANSI C89”) this should be noted here. If the command does not adhere to any standard, its history should be noted in the History section.

.Sh History

Any command which does not adhere to any specific standards should be outlined historically in this section.

.Sh Authors

Credits should be placed here. Use the ‘.An’ macro for names and the ‘.Aq’ macro for email addresses within optional contact information. Explicitly indicate whether the person authored the initial manual page or the software or whatever the person is being credited for.

.Sh Bugs

Blatant problems with the topic go here.

User-specified ‘.Sh’ sections may be added; for example, this section was set with:

.Sh "Page structure domain"

Subsection headings

Subsection headings have exactly the same syntax as section headings: ‘.Ss’ is parsed but not generally callable. It can be used as an argument in a call to ‘.Ss’ only; it then reactivates the default font for ‘.Ss’.

The default width is 8n.

Paragraphs and Line Spacing

.Pp

The ‘.Pp’ paragraph command may be used to specify a line space where necessary. The macro is not necessary after a ‘.Sh’ or ‘.Ss’ macro or before a ‘.Bl’ or ‘.Bd’ macro (which both assert a vertical distance unless the -compact flag is given).

The macro is neither callable nor parsed and takes no arguments; an alternative name is ‘.Lp’.

Keeps

The only keep that is implemented at this time is for words. The macros are ‘.Bk’ (begin keep) and ‘.Ek’ (end keep). The only option that ‘.Bk’ currently accepts is -words (also the default); this prevents breaks in the middle of options. In the example for make command-line arguments (see What's in a Name), the keep prevents nroff from placing the flag and the argument on separate lines.

Neither macro is callable or parsed.

More work needs to be done on the keep macros; specifically, a -line option should be added.

Examples and Displays

There are seven types of displays.

.D1

(This is D-one.) Display one line of indented text. This macro is parsed but not callable.

-ldghfstru

The above was produced by: .D1 Fl ldghfstru.

.Dl

(This is D-ell.) Display one line of indented literal text. The ‘.Dl’ example macro has been used throughout this file. It allows the indentation (display) of one line of text. Its default font is set to constant width (literal). ‘.Dl’ is parsed but not callable.

% ls -ldg /usr/local/bin

The above was produced by: .Dl % ls \-ldg /usr/local/bin.

.Bd

Begin display. The ‘.Bd’ display must be ended with the ‘.Ed’ macro. It has the following syntax:

.Bd {-literal | -filled | -unfilled | -ragged | -centered} [-offset ⟨string⟩] [-file ⟨file name⟩] [-compact]

 

-ragged

Fill, but do not adjust the right margin (only left-justify).

-centered

Center lines between the current left and right margin. Note that each single line is centered.

-unfilled

Do not fill; break lines where their input lines are broken. This can produce overlong lines without warning messages.

-filled

Display a filled block. The block of text is formatted (i.e., the text is justified on both the left and right side).

-literal

Display block with literal font (usually fixed-width). Useful for source code or simple tabbed or spaced text.

-file ⟨file name⟩

The file whose name follows the -file flag is read and displayed before any data enclosed with ‘.Bd’ and ‘.Ed’, using the selected display type. Any troff/mdoc commands in the file will be processed.

-offset ⟨string⟩

If -offset is specified with one of the following strings, the string is interpreted to indicate the level of indentation for the forthcoming block of text:

left

Align block on the current left margin; this is the default mode of ‘.Bd’.

center

Supposedly center the block. At this time unfortunately, the block merely gets left aligned about an imaginary center margin.

indent

Indent by one default indent value or tab. The default indent value is also used for the ‘.D1’ and ‘.Dl’ macros, so one is guaranteed the two types of displays will line up. The indentation value is normally set to 6n or about two thirds of an inch (six constant width characters).

indent-two

Indent two times the default indent value.

right

This left aligns the block about two inches from the right side of the page. This macro needs work and perhaps may never do the right thing within troff.

If ⟨string⟩ is a valid numeric expression instead (with a scaling indicator other than ‘u’), use that value for indentation. The most useful scaling indicators are ‘m’ and ‘n’, specifying the so-called Em and En square. This is approximately the width of the letters ‘m’ and ‘n’ respectively of the current font (for nroff output, both scaling indicators give the same values). If ⟨string⟩ isn't a numeric expression, it is tested whether it is an mdoc macro name, and the default offset value associated with this macro is used. Finally, if all tests fail, the width of ⟨string⟩ (typeset with a fixed-width font) is taken as the offset.

-compact

Suppress insertion of vertical space before begin of display.

.Ed

End display (takes no arguments).

Lists and Columns

There are several types of lists which may be initiated with the ‘.Bl’ begin-list macro. Items within the list are specified with the ‘.It’ item macro, and each list must end with the ‘.El’ macro. Lists may be nested within themselves and within displays. The use of columns inside of lists or lists inside of columns is untested.

In addition, several list attributes may be specified such as the width of a tag, the list offset, and compactness (blank lines between items allowed or disallowed). Most of this document has been formatted with a tag style list (-tag).

It has the following syntax forms:

And now a detailed description of the list types.

-bullet

A bullet list.

.Bl -bullet -offset indent -compact
.It
Bullet one goes here.
.It
Bullet two here.
.El

Produces:

• Bullet one goes here.
• Bullet two here.

-dash (or -hyphen)

A dash list.

.Bl -dash -offset indent -compact
.It
Dash one goes here.
.It
Dash two here.
.El

Produces:

• Dash one goes here.
• Dash two here.

-enum

An enumerated list.

.Bl -enum -offset indent -compact
.It
Item one goes here.
.It
And item two here.
.El

The result:

1. Item one goes here.
2. And item two here.

If you want to nest enumerated lists, use the -nested flag (starting with the second-level list):

.Bl -enum -offset indent -compact
.It
Item one goes here
.Bl -enum -nested -compact
.It
Item two goes here.
.It
And item three here.
.El
.It
And item four here.
.El

Result:

1. Item one goes here.
   1. Item two goes here.
   2. And item three here.
2. And item four here.

-item

A list of type -item without list markers.

.Bl -item -offset indent
.It
Item one goes here.
Item one goes here.
Item one goes here.
.It
Item two here.
Item two here.
Item two here.
.El

Produces:

• Item one goes here. Item one goes here. Item one goes here.
• Item two here. Item two here. Item two here.

-tag

A list with tags. Use -width to specify the tag width.

SL

sleep time of the process (seconds blocked)

PAGEIN

number of disk I/O operations resulting from references by the process to pages not loaded in core.

UID

numerical user-id of process owner

PPID

numerical id of parent of process priority (non-positive when in non-interruptible wait)

The raw text:

.Bl -tag -width "PPID" -compact -offset indent
.It SL
sleep time of the process (seconds blocked)
.It PAGEIN
number of disk I/O operations resulting from references
by the process to pages not loaded in core.
.It UID
numerical user-id of process owner
.It PPID
numerical id of parent of process priority
(non-positive when in non-interruptible wait)
.El

-diag

Diag lists create section four diagnostic lists and are similar to inset lists except callable macros are ignored. The -width flag is not meaningful in this context.

Example:

.Bl -diag
.It You can't use Sy here.
The message says all.
.El

produces

You can't use Sy here.

The message says all.

-hang

A list with hanging tags.

Hanged

labels appear similar to tagged lists when the label is smaller than the label width.

Longer hanged list labels

blend into the paragraph unlike tagged paragraph labels.

And the unformatted text which created it:

.Bl -hang -offset indent
.It Em Hanged
labels appear similar to tagged lists when the
label is smaller than the label width.
.It Em Longer hanged list labels
blend into the paragraph unlike
tagged paragraph labels.
.El

-ohang

Lists with overhanging tags do not use indentation for the items; tags are written to a separate line.

SL

sleep time of the process (seconds blocked)

PAGEIN

number of disk I/O operations resulting from references by the process to pages not loaded in core.

UID

numerical user-id of process owner

PPID

numerical id of parent of process priority (non-positive when in non-interruptible wait)

The raw text:

.Bl -ohang -offset indent
.It Sy SL
sleep time of the process (seconds blocked)
.It Sy PAGEIN
number of disk I/O operations resulting from references
by the process to pages not loaded in core.
.It Sy UID
numerical user-id of process owner
.It Sy PPID
numerical id of parent of process priority
(non-positive when in non-interruptible wait)
.El

-inset

Here is an example of inset labels:

Tag

The tagged list (also called a tagged paragraph) is the most common type of list used in the Berkeley manuals. Use a -width attribute as described below.

Diag

Diag lists create section four diagnostic lists and are similar to inset lists except callable macros are ignored.

Hang

Hanged labels are a matter of taste.

Ohang

Overhanging labels are nice when space is constrained.

Inset

Inset labels are useful for controlling blocks of paragraphs and are valuable for converting mdoc manuals to other formats.

Here is the source text which produced the above example:

.Bl -inset -offset indent
.It Em Tag
The tagged list (also called a tagged paragraph)
is the most common type of list used in the
Berkeley manuals.
.It Em Diag
Diag lists create section four diagnostic lists
and are similar to inset lists except callable
macros are ignored.
.It Em Hang
Hanged labels are a matter of taste.
.It Em Ohang
Overhanging labels are nice when space is constrained.
.It Em Inset
Inset labels are useful for controlling blocks of
paragraphs and are valuable for converting
.Xr mdoc
manuals to other formats.
.El

-column

This list type generates multiple columns. The number of columns and the width of each column is determined by the arguments to the -column list, ⟨string1⟩, ⟨string2⟩, etc. If ⟨stringN⟩ starts with a ‘.’ (dot) immediately followed by a valid mdoc macro name, interpret ⟨stringN⟩ and use the width of the result. Otherwise, the width of ⟨stringN⟩ (typeset with a fixed-width font) is taken as the Nth column width.

Each ‘.It’ argument is parsed to make a row, each column within the row is a separate argument separated by a tab or the ‘.Ta’ macro.

The table:

String	Nroff	Troff
<=	<=	≤
>=	>=	≥

was produced by:

.Bl -column -offset indent ".Sy String" ".Sy Nroff" ".Sy Troff"
.It Sy String Ta Sy Nroff Ta Sy Troff
.It Li <= Ta <= Ta \*(<=
.It Li >= Ta >= Ta \*(>=
.El

Don't abuse this list type! For more complicated cases it might be far better and easier to use tbl(1), the table preprocessor.

Other keywords:

-width ⟨string⟩

If ⟨string⟩ starts with a ‘.’ (dot) immediately followed by a valid mdoc macro name, interpret ⟨string⟩ and use the width of the result. Almost all lists in this document use this option.

Example:

.Bl -tag -width ".Fl test Ao Ar string Ac"
.It Fl test Ao Ar string Ac
This is a longer sentence to show how the
.Fl width
flag works in combination with a tag list.
.El

gives:

-test ⟨string⟩

This is a longer sentence to show how the -width flag works in combination with a tag list.

(Note that the current state of mdoc is saved before ⟨string⟩ is interpreted; afterwards, all variables are restored again. However, boxes (used for enclosures) can't be saved in GNU troff(1); as a consequence, arguments must always be balanced to avoid nasty errors. For example, do not write ‘.Ao Ar string’ but ‘.Ao Ar string Xc’ instead if you really need only an opening angle bracket.)

Otherwise, if ⟨string⟩ is a valid numeric expression (with a scaling indicator other than ‘u’), use that value for indentation. The most useful scaling indicators are ‘m’ and ‘n’, specifying the so-called Em and En square. This is approximately the width of the letters ‘m’ and ‘n’ respectively of the current font (for nroff output, both scaling indicators give the same values). If ⟨string⟩ isn't a numeric expression, it is tested whether it is an mdoc macro name, and the default width value associated with this macro is used. Finally, if all tests fail, the width of ⟨string⟩ (typeset with a fixed-width font) is taken as the width.

If a width is not specified for the tag list type, ‘6n’ is used.

-offset ⟨string⟩

If ⟨string⟩ is indent, a default indent value (normally set to 6n, similar to the value used in ‘.Dl’ or ‘.Bd’) is used. If ⟨string⟩ is a valid numeric expression instead (with a scaling indicator other than ‘u’), use that value for indentation. The most useful scaling indicators are ‘m’ and ‘n’, specifying the so-called Em and En square. This is approximately the width of the letters ‘m’ and ‘n’ respectively of the current font (for nroff output, both scaling indicators give the same values). If ⟨string⟩ isn't a numeric expression, it is tested whether it is an mdoc macro name, and the default offset value associated with this macro is used. Finally, if all tests fail, the width of ⟨string⟩ (typeset with a fixed-width font) is taken as the offset.

-compact

Suppress insertion of vertical space before the list and between list items.