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GROFF(7) Miscellaneous Information Manual GROFF(7)
NAME
groff - a short reference for the GNU roff language
DESCRIPTION
The name groff stands for GNU roff and is the free implementation of
the roff type-setting system. See roff(7) for a survey and the
background of the groff system.
This document gives only short descriptions of the predefined roff
language elements as used in groff. Both the classical features and
the groff extensions are provided.
Historically, the roff language was called troff. groff is compatible
with the classical system and provides proper extensions. So in GNU,
the terms roff, troff, and groff language could be used as synonyms.
However troff slightly tends to refer more to the classical aspects,
whereas groff emphasizes the GNU extensions, and roff is the general
term for the language.
This file is only a short version of the complete documentation that is
found in the groff info(1) file, which contains more detailed, actual,
and concise information.
The general syntax for writing groff documents is relatively easy, but
writing extensions to the roff language can be a bit harder.
The roff language is line-oriented. There are only two kinds of lines,
control lines and text lines. The control lines start with a control
character, by default a period or a single quote all other lines are
text lines.
Control lines represent commands, optionally with arguments. They have
the following syntax. The leading control character can be followed by
a command name; arguments, if any, are separated by blanks from the
command name and among themselves, for example,
\)\$*
For indentation, any number of space or tab characters can be inserted
between the leading control character and the command name, but the
control character must be on the first position of the line.
Text lines represent the parts that will be printed. They can be
modified by escape sequences, which are recognized by a leading
backslash These are in-line or even in-word formatting elements or
functions. Some of these take arguments separated by single quotes
others are regulated by a length encoding introduced by an open
parenthesis or enclosed in brackets and
The roff language provides flexible instruments for writing language
extension, such as macros. When interpreting macro definitions, the
roff system enters a special operating mode, called the copy mode.
The copy mode behavior can be quite tricky, but there are some rules
that ensure a safe usage.
1. Printable backslashes must be denoted as \[rs]\$1\$2 To be more
precise, \[rs]\$1\$2 represents the current escape character.
To get a backslash glyph, use \[rs]\$1\$2 or \[rs]\$1\$2
2. Double all backslashes.
3. Begin all text lines with the special non-spacing character
\[rs]\$1\$2
This does not produce the most efficient code, but it should work as a
first measure. For better strategies, see the groff info file and
groff_tmac(5).
Reading roff source files is easier, just reduce all double backslashes
to a single one in all macro definitions.
GROFF ELEMENTS
The roff language elements add formatting information to a text file.
The fundamental elements are predefined commands and variables that
make roff a full-blown programming language.
There are two kinds of roff commands, possibly with arguments.
Requests are written on a line of their own starting with a dot or a
whereas Escape sequences are in-line functions and in-word formatting
elements starting with a backslash
The user can define her own formatting commands using the \$* request.
These commands are called macros, but they are used exactly like
requests. Macro packages are pre-defined sets of macros written in the
groff language. A user's possibilities to create escape sequences
herself is very limited, only special characters can be mapped.
The groff language provides several kinds of variables with different
interfaces. There are pre-defined variables, but the user can define
her own variables as well.
String variables store character sequences. They are set with the \$*
request and retrieved by the \[rs]\$1\$2 escape sequences. Strings can
have variables.
Register variables can store numerical values, numbers with a scale
unit, and occasionally string-like objects. They are set with the \$*
request and retrieved by the \[rs]\$1\$2 escape sequences.
Environments allow the user to temporarily store global formatting
parameters like line length, font size, etc. for later reuse. This is
done by the \$* request.
Fonts are identified either by a name or by an internal number. The
current font is chosen by the \$* request or by the \[rs]\$1\$2 escape
sequences. Each device has special fonts, but the following fonts are
available for all devices. R is the standard font Roman. B is its
bold counterpart. The italic font is called I and is available
everywhere, but on text devices it is displayed as an underlined Roman
font. For the graphical output devices, there exist constant-width
pendants of these fonts, CR, CI, and CB. On text devices, all
characters have a constant width anyway.
Moreover, there are some advanced roff elements. A diversion stores
information into a macro for later usage. A trap is a positional
condition like a certain number of lines from page top or in a
diversion or in the input. Some action can be prescribed to be run
automatically when the condition is met.
More detailed information and examples can be found in the groff info
file.
CONTROL CHARACTERS
There is a small set of characters that have a special controlling task
in certain conditions.
A dot is only special at the beginning of a line or after the
condition in the requests \$* \$* \$* and \$* There it is the
control character that introduces a request (or macro). The
special behavior can be delayed by using the \[rs]\$1\$2 escape.
By using the \$* request, the control character can be set to a
different character, making the dot a non-special character.
In all other positions, it just means a dot character. In text
paragraphs, it is advantageous to start each sentence at a line
of its own.
The single quote has two controlling tasks.
At the beginning of a line and in the conditional requests it is
the non-breaking control character. That means that it
introduces a request like the dot, but with the additional
property that this request doesn't cause a linebreak. By using
the \$* request, the non-break control character can be set to a
different character.
As a second task, it is the most commonly used argument
separator in some functional escape sequences (but any pair of
characters not part of the argument will work). In all other
positions, it denotes the single quote or apostrophe character.
Groff provides a printable representation with the \[rs]\$1\$2
escape sequence.
The double quote is used to enclose arguments in requests, macros, and
strings. In the \$* and \$* requests, a leading double quote in
the argument will be stripped off, making everything else
afterwards the string to be defined (enabling leading
whitespace). The escaped double quote \[rs]\$1\$2 introduces a
comment. Otherwise, it is not special. Groff provides a
printable representation with the \[rs]\$1\$2 escape sequence.
The backslash usually introduces an escape sequence (this can be
changed with the \$* request). A printed version of the escape
character is the \[rs]\$1\$2 escape; a backslash glyph can be
obtained by \[rs]\$1\$2
The open parenthesis is only special in escape sequences when
introducing an escape name or argument consisting of exactly two
characters. In groff, this behavior can be replaced by the []
construct.
The opening bracket is only special in groff escape sequences; there
it is used to introduce a long escape name or long escape
argument. Otherwise, it is non-special, e.g. in macro calls.
The closing bracket is only special in groff escape sequences; there
it terminates a long escape name or long escape argument.
Otherwise, it is non-special.
space Space characters are only functional characters. They separate
the arguments in requests, macros, and strings, and the words in
text lines. They are subject to groff's horizontal spacing
calculations. To get a defined space width, escape sequences
like (this is the escape character followed by a space),
\[rs]\$1\$2 \[rs]\$1\$2 or \[rs]\$1\$2 should be used.
newline
In text paragraphs, newlines mostly behave like space
characters. Continuation lines can be specified by an escaped
newline, i.e., by specifying a backslash as the last character
of a line.
tab If a tab character occurs during text the interpreter makes a
horizontal jump to the next pre-defined tab position. There is
a sophisticated interface for handling tab positions.
NUMERICAL EXPRESSIONS
A numerical value is a signed or unsigned integer or float with or
without an appended scaling indicator. A scaling indicator is a one-
character abbreviation for a unit of measurement. A number followed by
a scaling indicator signifies a size value. By default, numerical
values do not have a scaling indicator, i.e., they are normal numbers.
The roff language defines the following scaling indicators.
c Centimeter
i Inch
P Pica = 1/6 inch
p Point = 1/72 inch
m Em = the font size in points (width of letter `m')
M 100th of an Em
n En = Em/2
u Basic unit for actual output device
v Vertical line space in basic units scaled
point = 1/sizescale of a point (defined in font DESC
file)
f Scale by 65536.
Numerical expressions are combinations of the numerical values defined
above with the following arithmetical operators already defined in
classical troff.
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulo
= Equals
== Equals
< Less than
> Greater than
<= Less or equal
>= Greater or equal
& Logical and
: Logical or
! Logical not
( Grouping of expressions
) Close current grouping
Moreover, groff added the following operators for numerical
expressions:
The maximum of
e1 and e2.
The minimum of
e1 and e2.
Evaluate e using c as the default scaling indicator.
For details see the groff info file.
CONDITIONS
Conditions occur in tests raised by the \$* \$* and the \$* requests.
The following table characterizes the different types of conditions.
N A numerical expression N yields true if its value is
greater than 0.
!N True if the value of I is 0.
's1's2' True if string s1 is identical to string s2.
!'s1's2' True if string s1 is not identical to string s2.
cch True if there is a character ch available.
dname True if there is a string, macro, diversion, or
request called name.
e Current page number is even.
o Current page number is odd.
mname True if there is a color called name.
n Formatter is nroff.
rreg True if there is a register named reg.
t Formatter is troff.
Ffont True if there exists a font named font.
Sstyle True if a style named style has been registered.
REQUESTS
This section provides a short reference for the predefined requests.
In groff, request and macro names can be arbitrarily long. No
bracketing or marking of long names is needed.
Most requests take one or more arguments. The arguments are separated
by space characters (no tabs!); there is no inherent limit for their
length or number. An argument can be enclosed by a pair of double
quotes. This is very handy if an argument contains space characters,
e.g., "arg with space" denotes a single argument.
Some requests have optional arguments with a different behaviour. Not
all of these details are outlined here. Refer to the groff info file
and groff_diff(7) for all details.
In the following request specifications, most argument names were
chosen to be descriptive. Only the following denotations need
clarification.
c denotes a single character.
font a font either specified as a font name or a font
number.
anything all characters up to the end of the line or within
\[rs]\$1\$2 and \[rs]\$1\$2
n is a numerical expression that evaluates to an integer
value.
N is an arbitrary numerical expression, signed or
unsigned.
+-N has three meanings depending on its sign, described
below.
If an expression defined as +-N starts with a sign the resulting value
of the expression will be added to an already existing value inherent
to the related request, e.g. adding to a number register. If the
expression starts with a the value of the expression will be subtracted
from the request value.
Without a sign, N replaces the existing value directly. To assign a
negative number either prepend 0 or enclose the negative number in
parentheses.
Request Short Reference
Empty line, ignored. Useful for structuring documents. Complete line
is a comment. Print string on standard error, exit program. Begin
line adjustment for output lines in current adjust mode. Start line
adjustment in mode c (c=l,r,b,n). Assign format c to register
(c=l,i,I,a,A). Create alias name for register. Create alias name for
request, string, macro, or diversion object. Append to macro until ..
is encountered. Append to macro until \$* is called. Same as \$* but
with compatibility mode switched off during macro expansion. Same as
\$* but with compatibility mode switched off during macro expansion.
Append to a macro whose name is contained in the string register macro
until .. is encountered. Append to a macro indirectly. macro and end
are string registers whose contents are interpolated for the macro name
and the end macro, respectively. Same as \$* but with compatibility
mode switched off during macro expansion. Same as \$* but with
compatibility mode switched off during macro expansion. Append
anything to stringvar. Same as \$* but with compatibility mode
switched off during string expansion. Unformat ASCII characters,
spaces, and some escape sequences in diversion. Print a backtrace of
the input on stderr. Embolden font by N-1 units. Embolden Special
Font S when current font is font. Unset the blank line macro. Set the
blank line macro to macro. End current diversion. Divert to macro,
omitting a partially filled line. End current diversion. Divert and
append to macro, omitting a partially filled line. Eject current page
and begin new page. Eject current page; next page number +-N. Line
break. Break and spread output line. Same as \[rs]\$1\$2 Break out of
a while loop. Reset no-break control character to Set no-break control
character to c. Reset control character to Set control character to c.
Center the next input line. Center following N input lines. Copy
contents of file filename unprocessed to stdout or to the diversion.
Treat characters c1, c2, ... according to mode number. Change trap
location to N . Define character c as string anything. Chop the last
character off macro, string, or diversion object. Close the stream.
Enable colors. If N is zero disable colors, otherwise enable them.
Map glyph name from to glyph name to while constructing a composite
glyph name. Finish the current iteration of a while loop. Enable
compatibility mode. If N is zero disable compatibility mode, otherwise
enable it. Set constant character width mode for font to N/36 ems with
em M. Continuous underline in nroff, like \$* in troff. End current
diversion. Divert and append to macro. Define or redefine macro until
.. is encountered. Define or redefine macro until \$* is called. Same
as \$* but with compatibility mode switched off during macro expansion.
Same as \$* but with compatibility mode switched off during macro
expansion. Define or redefine a color with name color. scheme can be
rgb, cym, cymk, gray, or grey. component can be single components
specified as fractions in the range 0 to 1 (default scaling
indicator \)\$* as a string of two-digit hexadecimal color components
with a leading #, or as a string of four-digit hexadecimal components
with two leading #. The color default can't be redefined. Define or
redefine a macro whose name is contained in the string register macro
until .. is encountered. Define or redefine a macro indirectly. macro
and end are string registers whose contents are interpolated for the
macro name and the end macro, respectively. Same as \$* but with
compatibility mode switched off during macro expansion. Same as \$*
but with compatibility mode switched off during macro expansion. End
current diversion. Divert to macro . Interpret \$* with compatibility
mode disabled. Set stringvar to anything. Same as \$* but with
compatibility mode switched off during string expansion. Set diversion
trap to position N (default scaling indicator \)\$* Reset escape
character to Set escape character to c. Restore escape character saved
with \$* Save current escape character. Else part for if-else (\$*
request. The macro will be run after the end of input. Turn off
escape character mechanism. Switch to previous environment. Push down
environment number or name env and switch to it. Copy the contents of
environment env to the current environment. No pushing or popping.
Exit from roff processing. Return to previous font family. Set the
current font family to name. Disable field mechanism. Set field
delimiter to a and pad character to space. Set field delimiter to a
and pad character to b. Define fallback character c as string
anything. Set fill color to previous fill color. Set fill color to c.
Fill output lines. Flush output buffer. Mount font on position n.
Mount font with long external name to short internal name on position
n. Define fallback character c for font f as string anything. Reset
list of special fonts for font to be empty. When the current font is
font, then the fonts s1, s2, ... will be special. Return to previous
font. Same as \$* or \$* Change to font name or number font; same as
\)\$* escape sequence. Translate font1 to font2. Set glyph color to
previous glyph color. Set glyph color to c. Remove additional
hyphenation indicator character. Set up additional hyphenation
indicator character c. Set the hyphenation code of character c1 to
code1, that of c2 to code2, etc. Set the current hyphenation language
to lang. Set the maximum number of consecutive hyphenated lines to n.
Read hyphenation patterns from file. Append hyphenation patterns from
file. Set input mapping for \$* List of words with exceptional
hyphenation. Switch to hyphenation mode N. Set the hyphenation margin
to n (default scaling indicator \)\$* Set the hyphenation space to n.
If cond then anything else goto \$* If cond then anything; otherwise do
nothing. Ignore text until .. is encountered. Ignore text until \$*
Change to previous indent value. Change indent according to +-N
(default scaling indicator \)\$* Set an input-line count trap for the
next N lines. Same as \$* but count lines interrupted with \[rs]\$1\$2
as one line. Enable pairwise kerning. If n is zero, disable pairwise
kerning, otherwise enable it. Remove leader repetition character. Set
leader repetition character to c. Write the length of the string
anything in register. Enable line-tabs mode (i.e., calculate tab
positions relative to output line). If n is zero, disable line-tabs
mode, otherwise enable it. Set input line number to N. Set input line
number to N and filename to file. Ligature mode on if N>0. Change to
previous line length. Set line length according to +-N (default size
\)\$* default scaling indicator \)\$* Change to the previous value of
additional intra-line skip. Set additional intra-line skip value to N,
i.e., N-1 blank lines are inserted after each text output line. Length
of title (default scaling indicator \)\$* Margin character off. Print
character c after each text line at actual distance from right margin.
Set margin character to c and distance to N from right margin (default
scaling indicator \)\$* Mark current vertical position in register.
The same as the .so request except that file is searched in the tmac
directories. No output-line adjusting. Need a one-line vertical
space. Need N vertical space (default scaling indicator \)\$* No
filling or adjusting of output-lines. No hyphenation. Number mode
off. In line number mode, set number, multiple, spacing, and indent.
Do not number next line. Do not number next N lines. Always execute
anything. Define or modify register using +-N with auto-increment M.
Make the built-in condition n true and t false. Turn no-space mode on.
Immediately jump to end of current file. Next file. Open \)\$* \$*
for writing and associate the stream named \)\$* \$* with it. Like \$*
but append to it. Output vertical distance that was saved by the \$*
request. Emit string directly to intermediate output, allowing leading
whitespace if string starts with (which will be stripped off). Reset
page number character to Page number character. Pipe output to program
(nroff only). Set page length to default \)\$* The current page length
is stored in \)\$* \$* Change page length to +-N (default scaling
indicator \)\$* Print macro names and sizes (number of blocks of 128
bytes). Print only total of sizes of macros (number of 128 bytes
blocks). Next page number N. Print the names and contents of all
currently defined number registers on stderr. Change to previous page
offset. The current page offset is available in \)\$* \$* Page offset
N. Return to previous point-size. Point size; same as \)\$* Get the
bounding box of a PostScript image filename. This behaves like the \$*
request except that input comes from the standard output of command.
Print the names and positions of all traps (not including input line
traps and diversion traps) on stderr. Change to previous post-vertical
line spacing. Change post-vertical line spacing according to +-N
(default scaling indicator \)\$* Remove the definitions of characters
c1, c2, ... Read insertion. Return from a macro. Return twice, namely
from the macro at the current level and from the macro one level
higher. Remove the definitions of characters c1, c2, ... for font f.
Right justify the next n input lines. Remove request, macro, or string
name. Rename request, macro, or string old to new. Rename register
reg1 to reg2. Remove register. Restore spacing; turn no-space mode
off. Return (upward only) to marked vertical place (default scaling
indicator \)\$* Define global fallback character c as string anything.
Reset soft hyphen character to \[rs]\$1\$2 Set the soft hyphen
character to c. In a macro, shift the arguments by n positions. Set
available font sizes similar to the sizes command in a DESC file.
Include source file. Skip one line vertically. Space vertical
distance N up or down according to sign of N (default scaling
indicator \)\$* Reset global list of special fonts to be empty. Fonts
s1, s2, etc. are special and will be searched for characters not in the
current font. Toggle the spread warning on and off without changing
its value. Emit a warning if each space in an output line is widened
by limit or more (default scaling indicator \)\$* Space-character size
set to N/12 of the spacewidth in the current font. Space-character
size set to N/12 and sentence space size set to M/12 of the spacewidth
in the current font (=1/3 em). Associate style with font position n.
Replace the string named xx with the substring defined by the indices
n1 and n2. Save \)\$* of vertical space. Save the vertical distance N
for later output with \$* request. Execute program command-line. Set
tabs after every position that is a multiple of N (default scaling
indicator \)\$* Set tabs at positions n1, n2, \)\$* nn, then set tabs
at nn+r1, nn+r2, \)\$* nn+rn, then at nn+rn+r1, nn+rn+r2, \)\$*
nn+rn+rn, and so on. Remove tab repition character. Set tab
repetition character to c. Temporary indent next line (default scaling
indicator \)\$* Enable track kerning for font. Three-part title.
Print anything on terminal (UNIX standard message output). Print
anything on terminal (UNIX standard message output), allowing leading
whitespace if anything starts with (which will be stripped off).
Similar to \$* without emitting a final newline. Translate a to b, c
to d, etc. on output. Transparently output the contents of file
filename. This is the same as the \$* request except that the asciify
request will use the character code (if any) before the character
translation. This is the same as the \$* request except that the
translations do not apply to text that is transparently throughput into
a diversion with \[rs]\$1\$2 Make the built-in condition t true and n
false. Underline font set to font (to be switched to by \$* Underline
(italicize in troff) N input lines. Unformat space characters and
tabs, preserving font information in diversion. Enable vertical
position traps if n is non-zero, disable them otherwise. Change to
previous vertical base line spacing. Set vertical base line spacing
according to +-N (default scaling indicator \)\$* Default value is
\)\$* Set warnings code to n. Set scaling indicator used in warnings
to si. Remove (first) trap at position N. Set location trap; negative
means from page bottom. While condition cond is true, accept anything
as input. Write anything to the stream named stream. Similar to \$*
without emitting a final newline. Write contents of macro or string xx
to the stream named stream.
Besides these standard groff requests, there might be further macro
calls. They can originate from a macro package (see roff(7) for an
overview) or from a preprocessor.
Preprocessor macros are easy to be recognized. They enclose their code
into a pair of characteristic macros.
+-------------+-------------+------------+
|preprocessor | start macro | end macro |
+=============+=============+============+
| eqn | .PS | .PE |
| grap | .G1 | .G2 |
| grn | .GS | .GE |
| pic | .PS | .PE |
| refer | .R1 | .R2 |
| soelim | none | none |
| tbl | .TS | .TE |
+-------------+-------------+------------+
ESCAPE SEQUENCES
Escape sequences are in-line language elements usually introduced by a
backslash and followed by an escape name and sometimes by a required
argument. Input processing is continued directly after the escaped
character or the argument resp. without an intervening separation
character. So there must be a way to determine the end of the escape
name and the end of the argument.
This is done by enclosing names (escape name and arguments consisting
of a variable name) by a pair of brackets [name] and constant arguments
(number expressions and characters) by apostrophes (ASCII 0x27) like
'constant'.
There are abbreviations for short names. Two character escape names
can be specified by an opening parenthesis like \[rs]\$1\$2 without a
closing counterpart. And all one-character names different from the
special characters and can even be specified without a marker in the
form \[rs]\$1\$2
Constant arguments of length 1 can omit the marker apostrophes, too,
but there is no two-character analogue.
While 1-character escape sequences are mainly used for in-line
functions and system related tasks, the 2-letter names following the
\[rs]\$1\$2 construct are used for special characters predefined by the
roff system. Escapes sequences with names of more than two characters
\)\$* denote user defined named characters (see the \$* request).
Single Character Escapes
Beginning of a comment. Everything up to the end of the line is
ignored. Everything up to and including the next newline is ignored.
This is interpreted in copy mode. This is like \[rs]\$1\$2 except that
the terminating newline is ignored as well. The string stored in the
string variable with 1-character name s. The string stored in the
string variable with 2-character name st. The string stored in the
string variable with arbitrary length name stringvar, taking arg1,
arg2, ... as arguments. The name by which the current macro was
invoked. The \$* request can make a macro have more than one name.
Macro or string argument with 1-place number x, where x is a digit
between 1 and 9. Macro or string argument with 2-digit number xy.
Macro or string argument with number nexp, where nexp is a numerical
expression evaluating to an integer >=1. In a macro or string, the
concatenation of all the arguments separated by spaces. In a macro or
string, the concatenation of all the arguments with each surrounded by
double quotes, and separated by spaces. reduces to a single backslash;
useful to delay its interpretation as escape character in copy mode.
For a printable backslash, use \[rs]\$1\$2 or even better \[rs]\$1\$2
to be independent from the current escape character. The acute accent
'; same as \[rs]\$1\$2 Unescaped: apostrophe, right quotation mark,
single quote (ASCII 0x27). The grave accent `; same as \[rs]\$1\$2
Unescaped: left quote, backquote (ASCII 0x60). The - sign in the
current font. An uninterpreted dot (period), even at start of line.
Default optional hyphenation character. Transparent line indicator.
In a diversion, this will transparently embed anything in the
diversion. anything is read in copy mode. See also the escape
sequences \[rs]\$1\$2 and \[rs]\$1\$2 Unpaddable space-size space
character (no line break). Digit width. 1/6 em narrow space
character; zero width in nroff. 1/12 em half-narrow space character;
zero width in nroff. Non-printable, zero width character. Like
\[rs]\$1\$2 except that it behaves like a character declared with the
cflags request to be transparent for the purposes of end of sentence
recognition. Increases the width of the preceding character so that
the spacing between that character and the following character will be
correct if the following character is a roman character. Modifies the
spacing of the following character so that the spacing between that
character and the preceding character will correct if the preceding
character is a roman character. Unbreakable space that stretches like
a normal inter-word space when a line is adjusted. Inserts a zero-
width break point (similar to \[rs]\$1\$2 but without a soft hyphen
character). Ignored newline, for continuation lines. Begin
conditional input. End conditional input. The special character with
2-character name sc, see section Special Characters. The named
character (or rather glyph) with arbitrary length name name. A
composite glyph with components comp1, comp2, ... Non-interpreted
leader character. If anything is acceptable as a name of a string,
macro, diversion, register, environment or font it expands to 1, and
to 0 otherwise. Bracket building function. If anything is acceptable
as a valid numeric expression it expands to 1, and to 0 otherwise.
Interrupt text processing. The character called char; same as \)\$*
but compatible to other roff versions. Forward (down) 1/2 em vertical
unit (1/2 line in nroff). Draw a graphical element defined by the
characters in charseq; see groff info file for details. Printable
version of the current escape character. Equivalent to an escape
character, but is not interpreted in copy-mode. Change to font with
1-character name or 1-digit number F. Switch back to previous font.
Change to font with 2-character name or 2-digit number fo. Change to
font with arbitrary length name or number expression font. Switch back
to previous font. Change to font family with 1-character name f.
Change to font family with 2-character name fm. Change to font family
with arbitrary length name fam. Switch back to previous font family.
Return format of register with name reg suitable for \$* Alternative
forms \)\$* and \)\$* Local horizontal motion; move right N (left if
negative). Set height of current font to N. Mark horizontal input
place in register with arbitrary length name reg. Alternative forms
\)\$* and \)\$* Horizontal line drawing function (optionally using
character c). Vertical line drawing function (optionally using
character c). Change to color color. Alternative forms \)\$* and
\)\$* Switch back to previous color. Change filling color for closed
drawn objects to color color. Alternative forms \)\$* and \)\$* Switch
to previous fill color. The numerical value stored in the register
variable with the 1-character name r. The numerical value stored in
the register variable with the 2-character name re. The numerical
value stored in the register variable with arbitrary length name reg.
Typeset the character with code n in the current font, no special fonts
are searched. Useful for adding characters to a font using the \$*
request. Overstrike characters a, b, c, etc. Disable glyph output.
Mainly for internal use. Enable glyph output. Mainly for internal
use. Break and spread output line. Reverse 1 em vertical motion
(reverse line in nroff). The same as \$* name +-n. Set the point size
to N scaled points. Note the alternative forms \s+-[N], \s'+-N'\)\$*
\s+-'N'\)\$* \)\$* \)\$* \s+-(xy\)\$* \)\$* Same as \$* request. Slant
output N degrees. Non-interpreted horizontal tab. Reverse (up) 1/2 em
vertical motion (1/2 line in nroff). Local vertical motion; move down
N (up if negative). The contents of the environment variable env.
Alternative forms \)\$* and \)\$* The width of the character sequence
string. Extra line-space function (negative before, positive after).
Output string as device control function. Output string variable or
macro name uninterpreted as device control function. Alternative forms
\)\$* and \)\$* Print c with zero width (without spacing). Print
anything and then restore the horizontal and vertical position;
anything may not contain tabs or leaders.
The escape sequences \[rs]\$1\$2 \[rs]\$1\$2 \[rs]\$1\$2 \[rs]\$1\$2
\[rs]\$1\$2 \[rs]\$1\$2 \[rs]\$1\$2 \[rs]\$1\$2 \[rs]\$1\$2 and \)\$*
are interpreted in copy mode.
Escape sequences starting with \[rs]\$1\$2 or \[rs]\$1\$2 do not
represent single character escape sequences, but introduce escape names
with two or more characters.
If a backslash is followed by a character that does not constitute a
defined escape sequence the backslash is silently ignored and the
character maps to itself.
Special Characters
Common special characters are predefined by escape sequences of the
form \(xy with characters x and y. Some of these exist in the usual
font while most of them are only available in the special font. Below
you'll find a selection of the most important glyphs; a complete list
can be found in groff_char(7).
Bullet sign Copyright Cent Double dagger Degree Dagger Printable
double quote Em-dash Hyphen Registered sign Printable backslash
character Section sign Underline character Identical Larger or
equal Less or equal Not equal Right arrow Left arrow Plus-minus
sign
Strings
Strings are defined by the \$* request and can be retrieved by the
\[rs]\$1\$2 escape sequence.
Strings share their name space with macros. So strings and macros
without arguments are roughly equivalent; it is possible to call a
string like a macro and vice-versa, but this often leads to
unpredictable results. The following strings are predefined in groff.
The name of the current output device as specified by the
\)\$* command line option.
REGISTERS
Registers are variables that store a value. In groff, most registers
store numerical values (see section NUMERICAL EXPRESSIONS above), but
some can also hold a string value.
Each register is given a name. Arbitrary registers can be defined and
set with the request \$* register.
The value stored in a register can be retrieved by the escape sequences
introduced by \[rs]\$1\$2
Most useful are predefined registers. In the following the notation
name is used to refer to a register called \)\$* \$* to make clear that
we speak about registers. Please keep in mind that the \)\$*
decoration is not part of the register name.
Read-only Registers
The following registers have predefined values that should not be
modified by the user (usually, registers starting with a dot a read-
only). Mostly, they provide information on the current settings or
store results from request calls.
Number of arguments in the current macro or string.
Post-line extra line-space most recently utilized using
\)\$*
Set to 1 in
troff if option -A is used; always 1 in nroff.
Current input line number.
1 if compatibility mode is in effect, 0 otherwise.
The depth of the last character added to the current environment.
It is positive if the character extends below the baseline.
The number of lines remaining to be centered, as set by the
\$* request.
The height of the last character added to the current environment.
It is positive if the character extends above the baseline.
1 if colors are enabled, 0 otherwise.
The skew of the last character added to the current environment.
The skew of a character is how far to the right of the center
of a character the center of an accent over that character
should be placed.
Current vertical place in current diversion; equal to
\)\$* \$*
The name or number of the current environment (string-valued).
Current font number.
The current font family (string-valued).
The current (internal) real font name (string-valued).
The number of the next free font position.
Always 1 in GNU troff.
Macros should use it to test if running under groff.
Text base-line high-water mark on current page or diversion.
Available horizontal resolution in basic units.
The current font height as set with
\$*
The current hyphenation language as set by the
.hla request.
The number of immediately preceding consecutive hyphenated lines.
The maximum allowed number of consecutive hyphenated lines, as set by
the \$* request.
The current hyphenation flags (as set by the
\$* request).
The current hyphenation margin (as set by the
\$* request).
The current hyphenation space (as set by the
\$* request).
Current ident.
The indent that applies to the current output line.
Positive if last output line contains
\[rs]\$1\$2
1 if pairwise kerning is enabled, 0 otherwise.
Current line length.
The current ligature mode (as set by the
\$* request).
The current line-tabs mode (as set by the
\$* request).
The line length that applies to the current output line.
The title length (as set by the
\$* request).
The current drawing color (string-valued).
The current background color (string-valued).
Length of text portion on previous output line.
The amount of space that was needed in the last
\$* request that caused a trap to be sprung. Useful in
conjunction with \)\$* \$*
1 if in no-space mode, 0 otherwise.
Current page offset.
Current page length.
1 during page ejection, 0 otherwise.
The number of the next page: either the value set by a
\$* request, or the number of the current page plus 1.
The current pointsize in scaled points.
The last-requested pointsize in scaled points.
The current post-vertical line spacing.
The number of lines to be right-justified as set by the rj request.
Current point size as a decimal fraction.
The slant of the current font as set with
\$*
The last requested pointsize in points as a decimal fraction
(string-valued).
The value of the parameters set by the first argument of the
\$* request.
The value of the parameters set by the second argument of the
\$* request.
The current font style (string-valued).
Distance to the next trap.
Set to 1 if option -T is used.
A string representation of the current tab settings suitable for use
as an argument to the \$* request.
The amount of vertical space truncated by the most recently sprung
vertical position trap, or, if the trap was sprung by a \$*
request, minus the amount of vertical motion produced by \$*
In other words, at the point a trap is sprung, it represents
the difference of what the vertical position would have been
but for the trap, and what the vertical position actually is.
Useful in conjunction with the \)\$* \$*
Equal to 1 in fill mode and 0 in nofill mode.
Equal to 1 in safer mode and 0 in unsafe mode.
Current vertical line spacing.
Available vertical resolution in basic units.
1 if vertical position traps are enabled, 0 otherwise.
Width of previous character.
The sum of the number codes of the currently enabled warnings.
The major version number.
The minor version number.
The revision number of groff.
Name of current diversion.
Writable Registers
The following registers can be read and written by the user. They have
predefined default values, but these can be modified for customizing a
document.
Current page number.
Current input line number.
Character type (set by width function
\[rs]\$1\$2
Maximal width of last completed diversion.
Height of last completed diversion.
Current day of week (1-7).
Current day of month (1-31).
The number of hours past midnight.
Initialized at start-up.
Current horizontal position at input line.
Lower left x-coordinate (in PostScript units) of a given PostScript
image (set by \$*
Lower left y-coordinate (in PostScript units) of a given PostScript
image (set by \$*
Output line number.
The number of minutes after the hour.
Initialized at start-up.
Current month (1-12).
Vertical position of last printed text base-line.
Like \)\$* \$* but takes account of the heights and depths of
characters.
Like \)\$* \$* but takes account of the heights and depths of
characters.
Depth of string below base line (generated by width function
\[rs]\$1\$2
The number of seconds after the minute.
Initialized at start-up.
Right skip width from the center of the last character in the
\[rs]\$1\$2 argument.
If greater than 0, the maximum number of objects on the input stack.
If <=0 there is no limit, i.e., recursion can continue until
virtual memory is exhausted.
The amount of horizontal space (possibly negative) that should be
added to the last character before a subscript (generated by
width function \[rs]\$1\$2
Height of string above base line (generated by width function
\[rs]\$1\$2
The return value of the
system() function executed by the last \$* request.
Upper right x-coordinate (in PostScript units) of a given PostScript
image (set by \$*
Upper right y-coordinate (in PostScript units) of a given PostScript
image (set by \$*
The current year (year 2000 compliant).
Current year minus 1900.
For Y2K compliance use \)\$* \$* instead.
COMPATIBILITY
The differences of the groff language in comparison to classical troff
as defined by [CSTR #54] are documented in groff_diff(7).
The groff system provides a compatibility mode, see groff(1) on how to
invoke this.
BUGS
Report bugs to the Include a complete, self-contained example that will
allow the bug to be reproduced, and say which version of groff you are
using.
AUTHORS
Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 Free Software
Foundation, Inc.
This document is distributed under the terms of the FDL (GNU Free
Documentation License) version 1.1 or later. You should have received
a copy of the FDL on your system, it is also available on-line at the
This document is part of groff, the GNU roff distribution. It was
written by it is maintained by
SEE ALSO
The main source of information for the groff language is the groff
info(1) file. Besides the gory details, it contains many examples.
groff(1)
the usage of the groff program and pointers to the documentation
and availability of the groff system.
groff_diff(7)
the differences of the groff language as compared to classical
roff. This is the authoritative document for the predefined
language elements that are specific to groff.
groff_char(7)
the predefined groff characters (glyphs).
groff_font(5)
the specification of fonts and the DESC file.
roff(7)
the history of roff, the common parts shared by all roff
systems, and pointers to further documentation.
[CSTR #54]
-- the bible for classical troff.
Groff Version 1.19.2 September 4, 2005 GROFF(7)