ROFF(7) OpenBSD Reference Manual ROFF(7)NAMEroff - roff language reference for mandoc
DESCRIPTION
The roff language is a general purpose text formatting language. In
particular, it serves as the basis for the mdoc(7) and man(7) manual
formatting macro languages. This manual describes the subset of the roff
language accepted by the mandoc(1) utility.
Input lines beginning with the control characters `.' or `'' are parsed
for requests and macros. These define the document structure, change the
processing state and manipulate the formatting. Some requests and macros
also produce formatted output, while others do not.
All other input lines provide free-form text to be printed; the
formatting of free-form text depends on the respective processing
context.
LANGUAGE SYNTAXroff documents may contain only graphable 7-bit ASCII characters, the
space character, and, in certain circumstances, the tab character. To
produce other characters in the output, use the escape sequences
documented in the mandoc_char(7) manual.
REQUEST SYNTAX
A request or macro line consists of:
1. the control character `.' or `'' at the beginning of the line,
2. optionally an arbitrary amount of whitespace,
3. the name of the request or the macro, which is one word of arbitrary
length, terminated by whitespace,
4. and zero or more arguments delimited by whitespace.
Thus, the following request lines are all equivalent:
.ig end
.ig end
. ig end
MACRO SYNTAX
Macros can be defined by the de request. When called, they follow the
same syntax as requests, except that macro arguments may optionally be
quoted by enclosing them in double quote characters (`"'). To be
recognized as the beginning of a quoted argument, the opening quote
character must be preceded by a space character.
A quoted argument may contain whitespace, and pairs of double quote
characters (`""') resolve to single double quote characters. A quoted
argument extends to the next double quote character that is not part of a
pair, or to the end of the input line, whichever comes earlier. Leaving
out the terminating double quote character at the end of the line is
discouraged. For clarity, if more arguments follow on the same input
line, it is recommended to follow the terminating double quote character
by a space character; in case the next character after the terminating
double quote character is anything else, it is regarded as the beginning
of the next, unquoted argument.
Both in quoted and unquoted arguments, pairs of backslashes (`\\')
resolve to single backslashes. In unquoted arguments, space characters
can alternatively be included by preceding them with a backslash (`\ '),
but quoting is usually better for clarity.
REQUEST REFERENCE
The mandoc(1)roff parser recognizes the following requests. Note that
the roff language defines many more requests not implemented in
mandoc(1).
ad
Set line adjustment mode. This line-scoped request is intended to have
one argument to select normal, left, right, or center adjustment for
subsequent text. Currently, it is ignored including its arguments, and
the number of arguments is not checked.
am
Append to a macro definition. The syntax of this request is the same as
that of de. It is currently ignored by mandoc(1), as are its children.
ami
Append to a macro definition, specifying the macro name indirectly. The
syntax of this request is the same as that of dei. It is currently
ignored by mandoc(1), as are its children.
am1
Append to a macro definition, switching roff compatibility mode off
during macro execution. The syntax of this request is the same as that
of de1. It is currently ignored by mandoc(1), as are its children.
de
Define a roff macro. Its syntax can be either
.de name
macro definition
..
or
.de name end
macro definition
.end
Both forms define or redefine the macro name to represent the macro
definition, which may consist of one or more input lines, including the
newline characters terminating each line, optionally containing calls to
roff requests, roff macros or high-level macros like man(7) or mdoc(7)
macros, whichever applies to the document in question.
Specifying a custom end macro works in the same way as for ig; namely,
the call to `.end' first ends the macro definition, and after that, it is
also evaluated as a roff request or roff macro, but not as a high-level
macro.
The macro can be invoked later using the syntax
.name [argument [argument ...]]
Regarding argument parsing, see MACRO SYNTAX above.
The line invoking the macro will be replaced in the input stream by the
macro definition, replacing all occurrences of \\$N, where N is a digit,
by the Nth argument. For example,
.de ZN
\fI\^\\$1\^\fP\\$2
..
.ZN XtFree .
produces
\fI\^XtFree\^\fP.
in the input stream, and thus in the output: XtFree.
Since macros and user-defined strings share a common string table,
defining a macro name clobbers the user-defined string name, and the
macro definition can also be printed using the `\*' string interpolation
syntax described below ds, but this is rarely useful because every macro
definition contains at least one explicit newline character.
In order to prevent endless recursion, both groff and mandoc(1) limit the
stack depth for expanding macros and strings to a large, but finite
number. Do not rely on the exact value of this limit.
dei
Define a roff macro, specifying the macro name indirectly. The syntax of
this request is the same as that of de. It is currently ignored by
mandoc(1), as are its children.
de1
Define a roff macro that will be executed with roff compatibility mode
switched off during macro execution. This is a GNU extension not
available in traditional roff implementations and not even in older
versions of groff. Since mandoc(1) does not implement roff compatibility
mode at all, it handles this request as an alias for de.
ds
Define a user-defined string. Its syntax is as follows:
.ds name ["]string
The name and string arguments are space-separated. If the string begins
with a double-quote character, that character will not be part of the
string. All remaining characters on the input line form the string,
including whitespace and double-quote characters, even trailing ones.
The string can be interpolated into subsequent text by using \*[name] for
a name of arbitrary length, or \*(NN or \*N if the length of name is two
or one characters, respectively. Interpolation can be prevented by
escaping the leading backslash; that is, an asterisk preceded by an even
number of backslashes does not trigger string interpolation.
Since user-defined strings and macros share a common string table,
defining a string name clobbers the macro name, and the name used for
defining a string can also be invoked as a macro, in which case the
following input line will be appended to the string, forming a new input
line passed to the roff parser. For example,
.ds badidea .S
.badidea
H SYNOPSIS
invokes the SH macro when used in a man(7) document. Such abuse is of
course strongly discouraged.
el
The "else" half of an if/else conditional. Pops a result off the stack
of conditional evaluations pushed by ie and uses it as its conditional.
If no stack entries are present (e.g., due to no prior ie calls) then
false is assumed. The syntax of this request is similar to if except
that the conditional is missing.
ft
Change the font. Its syntax is as follows:
.ft [font]
The following font arguments are supported:
B, BI, 3, 4
switches to bold font
I, 2 switches to underlined font
R, CW, 1
switches to normal font
P or no argument
switches back to the previous font
This request takes effect only locally, may be overridden by macros and
escape sequences, and is only supported in man(7) for now.
hy
Set automatic hyphenation mode. This line-scoped request is currently
ignored.
ie
The "if" half of an if/else conditional. The result of the conditional
is pushed into a stack used by subsequent invocations of el, which may be
separated by any intervening input (or not exist at all). Its syntax is
equivalent to if.
if
Begins a conditional. Right now, the conditional evaluates to true if
and only if it starts with the letter n, indicating processing in nroff
style as opposed to troff style. If a conditional is false, its children
are not processed, but are syntactically interpreted to preserve the
integrity of the input document. Thus,
.if t .ig
will discard the `.ig', which may lead to interesting results, but
.if t .if t \{\
will continue to syntactically interpret to the block close of the final
conditional. Sub-conditionals, in this case, obviously inherit the truth
value of the parent. This request has the following syntax:
.if COND \{\
BODY...
.\}
.if COND \{ BODY
BODY... \}
.if COND \{ BODY
BODY...
.\}
.if COND \
BODY
COND is a conditional statement. roff allows for complicated
conditionals; mandoc is much simpler. At this time, mandoc supports only
`n', evaluating to true; and `t', `e', and `o', evaluating to false. All
other invocations are read up to the next end of line or space and
evaluate as false.
If the BODY section is begun by an escaped brace `\{', scope continues
until a closing-brace escape sequence `.\}'. If the BODY is not enclosed
in braces, scope continues until the end of the line. If the COND is
followed by a BODY on the same line, whether after a brace or not, then
requests and macros must begin with a control character. It is generally
more intuitive, in this case, to write
.if COND \{\
.foo
bar
.\}
than having the request or macro follow as
.if COND \{ .foo
The scope of a conditional is always parsed, but only executed if the
conditional evaluates to true.
Note that text following an `.\}' escape sequence is discarded.
Furthermore, if an explicit closing sequence `\}' is specified in a free-
form line, the entire line is accepted within the scope of the prior
request, not only the text preceding the close, with the `\}' collapsing
into a zero-width space.
ig
Ignore input. Its syntax can be either
.ig
ignored text
..
or
.ig end
ignored text
.end
In the first case, input is ignored until a `..' request is encountered
on its own line. In the second case, input is ignored until the
specified `.end' macro is encountered. Do not use the escape character
`\' anywhere in the definition of end; it would cause very strange
behaviour.
When the end macro is a roff request or a roff macro, like in
.ig if
the subsequent invocation of if will first terminate the ignored text,
then be invoked as usual. Otherwise, it only terminates the ignored
text, and arguments following it or the `..' request are discarded.
ne
Declare the need for the specified minimum vertical space before the next
trap or the bottom of the page. This line-scoped request is currently
ignored.
nh
Turn off automatic hyphenation mode. This line-scoped request is
currently ignored.
rm
Remove a request, macro or string. This request is intended to have one
argument, the name of the request, macro or string to be undefined.
Currently, it is ignored including its arguments, and the number of
arguments is not checked.
nr
Define a register. A register is an arbitrary string value that defines
some sort of state, which influences parsing and/or formatting. Its
syntax is as follows:
.nr name value
The value may, at the moment, only be an integer. So far, only the
following register name is recognised:
nS If set to a positive integer value, certain mdoc(7) macros will
behave in the same way as in the SYNOPSIS section. If set to 0,
these macros will behave in the same way as outside the SYNOPSIS
section, even when called within the SYNOPSIS section itself.
Note that starting a new mdoc(7) section with the Sh macro will
reset this register.
ns
Turn on no-space mode. This line-scoped request is intended to take no
arguments. Currently, it is ignored including its arguments, and the
number of arguments is not checked.
ps
Change point size. This line-scoped request is intended to take one
numerical argument. Currently, it is ignored including its arguments,
and the number of arguments is not checked.
so
Include a source file. Its syntax is as follows:
.so file
The file will be read and its contents processed as input in place of the
`.so' request line. To avoid inadvertant inclusion of unrelated files,
mandoc(1) only accepts relative paths not containing the strings "../"
and "/..".
ta
Set tab stops. This line-scoped request can take an arbitrary number of
arguments. Currently, it is ignored including its arguments.
tr
Output character translation. This request is intended to have one
argument, consisting of an even number of characters. Currently, it is
ignored including its arguments, and the number of arguments is not
checked.
T&
Re-start a table layout, retaining the options of the prior table
invocation. See TS.
TE
End a table context. See TS.
TS
Begin a table, which formats input in aligned rows and columns. See
tbl(7) for a description of the tbl language.
COMPATIBILITY
This section documents compatibility between mandoc and other other roff
implementations, at this time limited to GNU troff ("groff"). The term
"historic groff" refers to groff version 1.15.
- The nS register is only compatible with OpenBSD's groff-1.15.
- Historic groff did not accept white-space before a custom end macro
for the ig request.
- The if and family would print funny white-spaces with historic groff
when using the next-line syntax.
SEE ALSOmandoc(1), man(7), mandoc_char(7), mdoc(7), tbl(7)
Joseph F. Ossanna and Brian W. Kernighan, Troff User's Manual, AT&T Bell
Laboratories, Computing Science Technical Report, 54, 1976 and 1992,
Murray Hill, New Jersey, http://www.kohala.com/start/troff/cstr54.ps.
Joseph F. Ossanna, Brian W. Kernighan, and Gunnar Ritter, Heirloom
Documentation Tools Nroff/Troff User's Manual, September 17, 2007,
http://heirloom.sourceforge.net/doctools/troff.pdf.
HISTORY
The RUNOFF typesetting system was written in PL/1 for the CTSS operating
system by Jerome ("Jerry") E. Saltzer in 1961. It was first used as the
main documentation tool by Multics since 1963. Robert ("Bob") H. Morris
ported it to the GE-635 and called it roff, Doug McIlroy rewrote it in
BCPL in 1969, Joseph F. Ossanna rewrote it in PDP-11 assembly in 1973,
and Brian W. Kernighan rewrote it in C in 1975.
AUTHORS
This partial roff reference was written by Kristaps Dzonsons
<kristaps@bsd.lv> and Ingo Schwarze <schwarze@openbsd.org>.
OpenBSD 4.9 January 25, 2011 OpenBSD 4.9
