groff(7) Miscellaneous Information Manual groff(7)
groff - a short reference for the GNU roff language
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 provides only short descriptions of roff language
elements. Groff: The GNU Implementation of troff, by Trent A. Fisher
and Werner Lemberg, is the primary groff manual, and is written in
Texinfo. You can browse it interactively with “info groff”.
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.
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
spaces (but not tab characters) from the command name and among
themselves, for example,
.command_name arg1 arg2
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 is 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 behaviour can be quite tricky, but there are some rules
that ensure a safe usage.
1. Printable backslashes must be denoted as \e. To be more
precise, \e represents the current escape character. To get a
backslash glyph, use \(rs or \[rs].
2. Double all backslashes.
3. Begin all text lines with the non-printing input break \&.
This does not produce the most efficient code, but it should work as
a first measure. For better strategies, see the groff Texinfo manual
and groff_tmac(5).
Reading roff source files is easier, just reduce all double
backslashes to a single one in all macro definitions.
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 .de
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
.ds request and retrieved by the \* 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
.nr request and retrieved by the \n 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 .ev request.
Fonts are identified either by a name or by an internal number. The
current font is chosen by the .ft request or by the \f 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
glyphs have a constant width anyway.
Glyphs are visual representation forms of characters. In groff, the
distinction between those two elements is not always obvious (and a
full discussion is beyond the scope of this man page). A first
approximation is that glyphs have a specific size and colour and are
taken from a specific font; they can't be modified any more –
characters are the input, and glyphs are the output. As soon as an
output line has been generated, it no longer contains characters but
glyphs. In this man page, we use either ‘glyph’ or ‘character’,
whatever is more appropriate. A few characters commonly seen on
keyboards are treated specially by roff languages and may not look
correct in output; they are the (double) quotation mark ("), the
apostrophe ('), the hyphen-minus (-), the backslash (\), the caret or
circumflex accent (^), the grave accent (`), and the tilde (~). All
are available if required; see groff_char(7).
Moreover, there are some advanced roff elements. A diversion stores
(formatted) information into a macro for later usage. See
groff_tmac(5) for more details. 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
Texinfo manual.
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 .if, .ie, .el, and .while. There it
is the control character that introduces a request (or macro).
By using the .cc 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 apostrophe 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 .c2 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 do work). In all other
positions, it denotes a single quote or apostrophe character,
depending on the output device's glyph repertoire. groff
provides a printable representation with the \(aq escape
sequence.
" The double quote can be used to enclose arguments to macros
and strings, but not requests. In the .ds, .ds1, .as, and
.as1 requests, a leading double quote in the second argument
is stripped off, enabling the inclusion of leading space
characters in the string definition or appendment. The
escaped double quote \" introduces a comment. Otherwise, it
is not special. groff provides a printable representation
with the \[dq] escape sequence.
\ The backslash usually introduces an escape sequence (this can
be changed with the .ec request). A printed version of the
escape character is the \e escape; a backslash glyph can be
obtained by \(rs.
( The open parenthesis is only special in escape sequences when
introducing an escape name or argument consisting of exactly
two characters. In groff, this behaviour 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 separate arguments in requests, macros, and
strings. In text, they separate words. When filling is
enabled (the default), a line may be broken at a space.
Further, in fill mode, multiple adjacent space characters
cause groff to attempt end-of-sentence detection on the
preceding word (and trailing punctuation). The amount of
space between sentences in fill mode is controlled by the .ss
request. When adjustment is enabled, a space's width may be
expanded to justify the line. To get a space of definite
width, use the escape sequences ‘\ ’ (this is the escape
character followed by a space), \0, \|, \^, or \h; see section
“Escape Sequences” below. An adjustable but non-breaking
space is available with \~.
newline
In text, newlines behave like space characters and trigger
end-of-sentence recognition on the preceding text.
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.
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 (approx. 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
s 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:
e1>?e2 The maximum of e1 and e2.
e1<?e2 The minimum of e1 and e2.
(c;e) Evaluate e using c as the default scaling indicator.
For details see the groff Texinfo manual.
Conditions are expressions tested by the .if, .ie, and the .while
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 N is ≤ 0 (see below).
's1's2' True if string s1 is identical to string s2.
!'s1's2' True if string s1 is not identical to string s2 (see
below).
c g True if a glyph g is available.
d name True if there is a string, macro, diversion, or
request called name.
e Current page number is even.
F font True if a font called font exists.
m color True if there is a color called color.
n Formatter is nroff.
o Current page number is odd.
r reg True if there is a number register called reg.
S style True if a style called style has been registered.
t Formatter is troff.
v Always false (for compatibilty with other troff
implementations).
Note that the ! operator may only appear at the beginning of an
expression, and negates the entire expression. This maintains bug-
compatibility with AT&T troff.
This section provides a short reference for the predefined requests.
In groff, request, macro, and string 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.
Some requests have optional arguments with a different behaviour.
Not all of these details are outlined here. Refer to the groff
Texinfo manual 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
\{ and \}.
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 is 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 is
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.
.\" anything
Complete line is a comment.
.ab string
Print string on standard error, exit program.
.ad Begin line adjustment for output lines in current adjust
mode.
.ad c Start line adjustment in mode c (c=l,r,c,b,n).
.af register c
Assign format c to register (c=l,i,I,a,A).
.aln new old
Create alias (additional name) new for existing number
register named old.
.als new old
Create alias (additional name) new for existing request,
string, macro, or diversion old.
.am macro Append to macro until .. is encountered.
.am macro end
Append to macro until .end is called.
.am1 macro
Same as .am but with compatibility mode switched off during
macro expansion.
.am1 macro end
Same as .am but with compatibility mode switched off during
macro expansion.
.ami macro
Append to a macro whose name is contained in the string
register macro until .. is encountered.
.ami macro end
Append to a macro indirectly. macro and end are string
registers whose contents are interpolated for the macro
name and the end macro, respectively.
.ami1 macro
Same as .ami but with compatibility mode switched off
during macro expansion.
.ami1 macro end
Same as .ami but with compatibility mode switched off
during macro expansion.
.as name [string]
Append string to the string name; no operation if string is
omitted.
.as1 name [string]
Same as .as but with compatibility mode switched off during
string expansion.
.asciify diversion
Unformat ASCII characters, spaces, and some escape
sequences in diversion.
.backtrace
Write a backtrace of the input stack to the standard error
stream. Also see the -b option of groff(1).
.bd font N
Embolden font by N-1 units.
.bd S font N
Embolden Special Font S when current font is font.
.blm Unset blank line macro (trap). Restore default handling of
blank lines.
.blm macro
Set blank line trap to macro.
.box End current diversion.
.box macro
Divert to macro, omitting a partially filled line.
.boxa End current diversion.
.boxa macro
Divert and append to macro, omitting a partially filled
line.
.bp Eject current page and begin new page.
.bp ±N Eject current page; next page number ±N.
.br Line break.
.brp Break output line; adjust if applicable.
.break Break out of a while loop.
.c2 Reset no-break control character to “'”.
.c2 c Set no-break control character to c.
.cc Reset control character to ‘.’.
.cc c Set control character to c.
.ce Center the next input line.
.ce N Center following N input lines.
.cf filename
Copy contents of file filename unprocessed to stdout or to
the diversion.
.cflags n c1 c2 ...
Assign properties encoded by the number n to characters c1,
c2, and so on.
.ch trap N
Change trap location to N.
.char c anything
Define entity c as string anything.
.chop object
Remove the last character from the macro, string, or
diversion named object.
.class name c1 c2 ...
Define a (character) class name comprising the characters
or range expressions c1, c2, and so on.
.close stream
Close the stream.
.color Enable colors.
.color N If N is zero disable colors, otherwise enable them.
.composite from to
Map glyph name from to glyph name to while constructing a
composite glyph name.
.continue Finish the current iteration of a while loop.
.cp Enable compatibility mode.
.cp N If N is zero disable compatibility mode, otherwise enable
it.
.cs font N M
Set constant character width mode for font to N/36 ems with
em M.
.cu N Continuous underline in nroff, like .ul in troff.
.da End current diversion.
.da macro Divert and append to macro.
.de macro Define or redefine macro until .. is encountered.
.de macro end
Define or redefine macro until .end is called.
.de1 macro
Same as .de but with compatibility mode switched off during
macro expansion.
.de1 macro end
Same as .de but with compatibility mode switched off during
macro expansion.
.defcolor color scheme component
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 f), 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.
.dei macro
Define or redefine a macro whose name is contained in the
string register macro until .. is encountered.
.dei macro end
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.
.dei1 macro
Same as .dei but with compatibility mode switched off
during macro expansion.
.dei1 macro end
Same as .dei but with compatibility mode switched off
during macro expansion.
.device anything
Write anything to the intermediate output as a device
control function.
.devicem name
Write contents of macro or string name uninterpreted to the
intermediate output as a device control function.
.di End current diversion.
.di macro Divert to macro. See groff_tmac(5) for more details.
.do name ...
Interpret the string, request, diversion, or macro name
(along with any arguments) with compatibility mode
disabled. Note that compatibility mode is restored (if and
only if it was active) when the expansion of name is
interpreted.
.ds name [string]
Define a string variable name with contents string, or as
empty if string is omitted.
.ds1 name [string]
Same as .ds but with compatibility mode switched off during
string expansion.
.dt N trap
Set diversion trap to position N (default scaling
indicator v).
.ec Reset escape character to ‘\’.
.ec c Set escape character to c.
.ecr Restore escape character saved with .ecs.
.ecs Save current escape character.
.el anything
Else part for if-else (.ie) request.
.em macro The macro is run after the end of input.
.eo Turn off escape character mechanism.
.ev Switch to previous environment and pop it off the stack.
.ev env Push down environment number or name env to the stack and
switch to it.
.evc env Copy the contents of environment env to the current
environment. No pushing or popping.
.ex Exit from roff processing.
.fam Return to previous font family.
.fam name Set the current font family to name.
.fc Disable field mechanism.
.fc a Set field delimiter to a and pad glyph to space.
.fc a b Set field delimiter to a and pad glyph to b.
.fchar c anything
Define fallback character (or glyph) c as string anything.
.fcolor Set fill color to previous fill color.
.fcolor c Set fill color to c.
.fi Fill output lines.
.fl Flush output buffer.
.fp n font
Mount font on position n.
.fp n internal external
Mount font with long external name to short internal name
on position n.
.fschar f c anything
Define fallback character (or glyph) c for font f as string
anything.
.fspecial font
Reset list of special fonts for font to be empty.
.fspecial font s1 s2 ...
When the current font is font, then the fonts s1, s2, ...
are special.
.ft Return to previous font. Same as \f[] or \fP.
.ft font Change to font name or number font; same as \f[font] escape
sequence.
.ftr font1 font2
Translate font1 to font2.
.fzoom font
Don't magnify font.
.fzoom font zoom
Set zoom factor for font (in multiples of 1/1000th).
.gcolor Set glyph color to previous glyph color.
.gcolor c Set glyph color to c.
.hc Reset the hyphenation character to \% (the default).
.hc char Change the hyphenation character to char.
.hcode c1 code1 [c2 code2] ...
Set the hyphenation code of character c1 to code1, that of
c2 to code2, and so on.
.hla lang Set the hyphenation language to lang.
.hlm n Set the maximum number of consecutive hyphenated lines to
n.
.hpf pattern-file
Read hyphenation patterns from pattern-file.
.hpfa pattern-file
Append hyphenation patterns from pattern-file.
.hpfcode a b [c d] ...
Define mapping values for character codes in pattern files
read with the .hpf and .hpfa requests.
.hw word ...
Define how each word is to be hyphenated, with each hyphen
“-” indicating a hyphenation point.
.hy Set hyphenation mode to 1 (the default).
.hy 0 Disable hyphenation; same as .nh.
.hy mode Set hyphenation mode to mode; see section “Hyphenation”
below.
.hym Set the (right) hyphenation margin to 0 (the default).
.hym length
Set the (right) hyphenation margin to length (default
scaling indicator m).
.hys Set the hyphenation space to 0 (the default).
.hys hyphenation-space
Suppress hyphenation of the line in adjustment modes “b” or
“n” if it can be justified by adding no more than
hyphenation-space extra space to each inter-word space
(default scaling indicator m).
.ie cond anything
If cond then anything, otherwise skip to .el.
.if cond anything
If cond then anything; otherwise do nothing.
.ig Ignore text until .. is encountered.
.ig end Ignore text until .end is called.
.in Change to previous indentation value.
.in ±N Change indentation according to ±N (default scaling
indicator m).
.it N trap
Set an input-line count trap for the next N lines.
.itc N trap
Same as .it but don't count lines interrupted with \c.
.kern Enable pairwise kerning.
.kern n If n is zero, disable pairwise kerning, otherwise enable
it.
.lc Remove leader repetition glyph.
.lc c Set leader repetition glyph to c.
.length reg anything
Compute the number of characters of anything and store the
count in the number register reg.
.linetabs Enable line-tabs mode (i.e., calculate tab positions
relative to output line).
.linetabs n
If n is zero, disable line-tabs mode, otherwise enable it.
.lf N Set input line number to N.
.lf N file
Set input line number to N and filename to file.
.lg N Ligature mode on if N>0.
.ll Change to previous line length.
.ll ±N Set line length according to ±N (default length 6.5i,
default scaling indicator m).
.lsm Unset the leading spaces macro.
.lsm macro
Set the leading spaces macro to macro.
.ls Change to the previous value of additional intra-line skip.
.ls N Set additional intra-line skip value to N, i.e., N-1 blank
lines are inserted after each text output line.
.lt ±N Length of title (default scaling indicator m).
.mc Margin glyph off.
.mc c Print glyph c after each text line at actual distance from
right margin.
.mc c N Set margin glyph to c and distance to N from right margin
(default scaling indicator m).
.mk [register]
Mark current vertical position in register, or in an
internal register used by .rt if no argument.
.mso file The same as .so except that file is searched in the tmac
directories.
.na No output-line adjusting.
.ne Need a one-line vertical space.
.ne N Need N vertical space (default scaling indicator v).
.nf No filling or adjusting of output lines.
.nh Disable hyphenation; same as “.hy 0”.
.nm Number mode off.
.nm ±N [M [S [I]]]
In line number mode, set number, multiple, spacing, and
indentation.
.nn Do not number next line.
.nn N Do not number next N lines.
.nop anything
Always process anything.
.nr register ±N [M]
Define or modify register using ±N with auto-increment M.
.nroff Make the built-in conditions n true and t false.
.ns Turn on no-space mode.
.nx Immediately jump to end of current file.
.nx filename
Immediately continue processing with file file.
.open stream filename
Open filename for writing and associate the stream named
stream with it.
.opena stream filename
Like .open but append to it.
.os Output vertical distance that was saved by the .sv request.
.output string
Emit string directly to intermediate output, allowing
leading whitespace if string starts with " (which is
stripped off).
.pc Reset page number character to ‘%’.
.pc c Page number character.
.pev Print the current environment and each defined environment
state to stderr.
.pi program
Pipe output to program (nroff only).
.pl Set page length to default 11i. The current page length is
stored in register .p.
.pl ±N Change page length to ±N (default scaling indicator v).
.pm Report, to the standard error stream, the names and sizes
in bytes of defined macros, strings, and diversions.
.pn ±N Next page number N.
.pnr Print the names and contents of all currently defined
number registers on stderr.
.po Change to previous page offset. The current page offset is
available in register .o.
.po ±N Page offset N.
.ps Return to previous point size.
.ps ±N Set/increase/decrease the point size to/by N scaled points
(a non-positive resulting point size is set to 1 u); also
see \s[±N].
.psbb filename
Get the bounding box of a PostScript image filename.
.pso command
This behaves like the .so request except that input comes
from the standard output of command.
.ptr Print the names and positions of all traps (not including
input line traps and diversion traps) on stderr.
.pvs Change to previous post-vertical line spacing.
.pvs ±N Change post-vertical line spacing according to ±N (default
scaling indicator p).
.rchar c1 c2 ...
Remove the definitions of entities c1, c2, ...
.rd prompt
Read insertion.
.return Return from a macro.
.return anything
Return twice, namely from the macro at the current level
and from the macro one level higher.
.rfschar f c1 c2 ...
Remove the font-specific definitions of glyphs c1, c2, ...
for font f.
.rj n Right justify the next n input lines.
.rm name Remove request, macro, diversion, or string name.
.rn old new
Rename request, macro, diversion, or string old to new.
.rnn reg1 reg2
Rename register reg1 to reg2.
.rr ident Remove name of number register ident.
.rs Restore spacing; turn no-space mode off.
.rt Return (upward only) to vertical position marked by .mk on
the current page.
.rt ±N Return (upward only) to specified distance from the top of
the page (default scaling indicator v).
.schar c anything
Define global fallback character (or glyph) c as string
anything.
.shc Reset soft hyphen glyph to \(hy.
.shc c Set the soft hyphen glyph to c.
.shift n In a macro, shift the arguments by n positions.
.sizes s1 s2 ... sn [0]
Set available font sizes similar to the sizes command in a
DESC file.
.so filename
Include source file.
.sp Skip one line vertically.
.sp N Space vertical distance N up or down according to sign of N
(default scaling indicator v).
.special Reset global list of special fonts to be empty.
.special s1 s2 ...
Fonts s1, s2, etc. are special and are searched for glyphs
not in the current font.
.spreadwarn
Toggle the spread warning on and off (the default) without
changing its value.
.spreadwarn N
Emit a break warning if the additional space inserted for
each space between words in an output line adjusted to both
margins is larger than or equal to N. A negative N is
treated as 0. The default scaling indicator is m. At
startup, .spreadwarn is inactive and N is 3 m.
.ss N Set minimal inter-word spacing to N 12ths of the space
width of the current font.
.ss N M As .ss N, and set additional inter-sentence spacing to
M 12ths of the space width of the current font.
.stringdown stringvar
Replace each byte in the string named stringvar with its
lowercase version.
.stringup stringvar
Replace each byte in the string named stringvar with its
uppercase version.
.sty n style
Associate style with font position n.
.substring str start [end]
Replace the string named str with its substring bounded by
the indices start and end, inclusive. Negative indices
count backwards from the end of the string.
.sv Save 1 v of vertical space.
.sv N Save the vertical distance N for later output with .os
request (default scaling indicator v).
.sy command-line
Execute program command-line.
.ta T N Set tabs after every position that is a multiple of N
(default scaling indicator m).
.ta n1 n2 ... nn T r1 r2 ... rn
Set tabs at positions n1, n2, ..., nn, then set tabs at
nn+m×rn+r1 through nn+m×rn+rn, where m increments from 0,
1, 2, ... to infinity.
.tc Remove tab repetition glyph.
.tc c Set tab repetition glyph to c.
.ti ±N Temporary indent next line (default scaling indicator m).
.tkf font s1 n1 s2 n2
Enable track kerning for font.
.tl 'left'center'right'
Three-part title.
.tm anything
Print anything on stderr.
.tm1 anything
Print anything on stderr, allowing leading whitespace if
anything starts with " (which is stripped off).
.tmc anything
Similar to .tm1 without emitting a final newline.
.tr abcd...
Translate a to b, c to d, etc. on output.
.trf filename
Transparently output the contents of file filename.
.trin abcd...
This is the same as the .tr request except that the asciify
request uses the character code (if any) before the
character translation.
.trnt abcd...
This is the same as the .tr request except that the
translations do not apply to text that is transparently
throughput into a diversion with \!.
.troff Make the built-in conditions t true and n false.
.uf font Set underline font to font (to be switched to by .ul).
.ul N Underline (italicize in troff) N input lines.
.unformat diversion
Unformat space characters and tabs in diversion, preserving
font information.
.vpt n Enable vertical position traps if n is non-zero, disable
them otherwise.
.vs Change to previous vertical base line spacing.
.vs ±N Set vertical base line spacing to ±N (default scaling
indicator p).
.warn Enable all warnings.
.warn n Set warnings code to n.
.warnscale si
Set scaling indicator used in warnings to si.
.wh N Remove (first) trap at position N.
.wh N trap
Set location trap; negative means from page bottom.
.while cond anything
While condition cond is true, accept anything as input.
.write stream anything
Write anything to the stream named stream.
.writec stream anything
Similar to .write without emitting a final newline.
.writem stream xx
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 recognize. They enclose their code
between a pair of characteristic macros.
┌─────────────┬─────────────────┬────────────────┐
│preprocessor │ start macro │ end macro │
├─────────────┼─────────────────┼────────────────┤
│ chem │ .cstart │ .cend │
│ eqn │ .EQ │ .EN │
│ grap │ .G1 │ .G2 │
│ grn │ .GS │ .GE │
│ ideal │ .IS │ .IE │
│ │ │ .IF │
│ pic │ .PS │ .PE │
│ refer │ .R1 │ .R2 │
│ soelim │ none │ none │
│ tbl │ .TS │ .TE │
├─────────────┼─────────────────┼────────────────┤
│ glilypond │ .lilypond start │ .lilypond stop │
│ gperl │ .Perl start │ .Perl stop │
│ gpinyin │ .pinyin start │ .pinyin stop │
└─────────────┴─────────────────┴────────────────┘
Note that the ‘ideal’ preprocessor is not available in groff yet.
Whereas requests must occur on control lines, escape sequences can
occur intermixed with text and appear in arguments to requests and
macros (and sometimes other escape sequences). An escape sequence
(or simply “escape”) is introduced by the escape character, a
backslash “\” (but see the .ec request). The next character
identifies the escape's function. Escapes vary in length. Some take
an argument, and of those, some have different syntactical forms for
a one-character, two-character, or arbitrary-length argument. Others
accept only an arbitrary-length argument. In the former convention,
a one-character argument follows the function character immediately,
an opening parenthesis “(” introduces a two-character argument (no
closing parenthesis is used), and an argument of arbitrary length is
enclosed in brackets “[]”. In the latter convention, the user
selects a delimiter character; the neutral apostrophe “'” is a
popular choice and shown in this document. Some characters cannot be
used as delimiters; see section “Escapes” in the groff Texinfo manual
for details. A few escapes are idiosyncratic, and support both of
the foregoing conventions (“\s”), designate their own terminating
character (“\?”), consume input until the next newline (“\!”, “\"”,
“\#”), or support an additional modifier character (“\s” again).
Once an escape sequence terminates, input processing resumes with the
next character.
Escape sequences serve a variety of purposes. Widespread uses
include commenting the source document; changing the font style;
setting the point size; interpolating special characters, number
registers, and strings into the text; and placing or suppressing
break and hyphenation points. As with requests, use of escapes in
source documents may interact poorly with a macro package you use;
consult its documentation to learn of “safe” escapes or alternative
facilities it provides to achieve the desired result.
Escape short reference
\" Start 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 \" except that
the terminating newline is ignored as well.
\*s The string stored in the string variable with one-character
name s.
\*(st The string stored in the string variable with two-character
name st.
\*[string]
The string stored in the string variable with name string
(with arbitrary length).
\*[stringvar arg1 arg2 ...]
The string stored in the string variable with arbitrarily long
name stringvar, taking arg1, arg2, ... as arguments.
\$0 The name by which the current macro was invoked. The .als
request can make a macro have more than one name.
\$x Macro or string argument with one-digit number x in the range
1 to 9.
\$(xy Macro or string argument with two-digit number xy (larger than
zero).
\$[nexp]
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.
\$^ In a macro, the representation of all parameters as if they
were an argument to the .ds request.
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode. For a
printable backslash, use \e, or even better \[rs], to be
independent from the current escape character.
\' The acute accent ´; same as \(aa.
\` The grave accent `; same as \(ga.
\- The - (minus) sign in the current font.
\_ The same as \(ul, the underline character.
\. The same as a dot (‘.’). Necessary in nested macro
definitions so that ‘\\..’ expands to ‘..’.
\% Default hyphenation character.
\! Transparent line indicator.
\?anything?
In a diversion, this transparently embeds anything in the
diversion. anything is read in copy mode. See also the
escape sequences \! and \?.
\space Unpaddable space size space glyph (no line break).
\0 Digit-width unbreakable space.
\| 1/6 em narrow unbreakable space glyph; zero-width in nroff.
\^ 1/12 em half-narrow unbreakable space glyph; zero-width in
nroff.
\& Non-printing input break.
\) Like \& except that it behaves like a glyph declared with the
.cflags request to be transparent for the purposes of end-of-
sentence recognition.
\/ Increases the width of the preceding glyph so that the spacing
between that glyph and the following glyph is correct if the
following glyph is a roman glyph.
\, Modifies the spacing of the following glyph so that the
spacing between that glyph and the preceding glyph is correct
if the preceding glyph is a roman glyph.
\~ Unbreakable space that stretches like a normal inter-word
space when a line is adjusted.
\: Insert a non-printing break point (similar to \% but without a
soft hyphen character).
\newline
Ignored newline, for continuation lines.
\{ Begin conditional input.
\} End conditional input.
\(sc A glyph with two-character name sc; see section “Special
Characters” below.
\[name]
A glyph with name name (of arbitrary length).
\[comp1 comp2 ...]
A composite glyph with components comp1, comp2, ...
\a Non-interpreted leader character.
\A'anything'
If anything is acceptable as a name of a string, macro,
diversion, register, environment or font it expands to 1, and
to 0 otherwise.
\b'abc...'
Bracket building function.
\B'anything'
If anything is acceptable as a valid numeric expression it
expands to 1, and to 0 otherwise.
\c Continue output line at next input line. Anything after this
escape on the same line is ignored except \R (which works as
usual). Anything before \c on the same line is appended to
the current partial output line. The next non-command line
after a line interrupted with \c counts as a new input line.
\C'glyph'
The glyph called glyph; same as \[glyph], but compatible to
other roff versions.
\d Forward (down) 1/2 em (1/2 line in nroff).
\D'charseq'
Draw a graphical element defined by the characters in charseq;
see the groff Texinfo manual for details.
\e Printable version of the current escape character.
\E Equivalent to an escape character, but is not interpreted in
copy mode.
\fF Change to font with one-character name or one-digit number F.
\fP Switch back to previous font.
\f(fo Change to font with two-character name or two-digit number fo.
\f[font]
Change to font with arbitrarily long name or number expression
font.
\f[] Switch back to previous font.
\Ff Change to font family with one-character name f.
\F(fm Change to font family with two-character name fm.
\F[fam]
Change to font family with arbitrarily long name fam.
\F[] Switch back to previous font family.
\gr Return format of register with one-character name r suitable
for .af request.
\g(rg Return format of register with two-character name rg suitable
for .af request.
\g[reg]
Return format of register with arbitrarily long name reg
suitable for .af request.
\h'N' Local horizontal motion; move right N (left if negative).
\H'N' Set height of current font to N.
\kr Mark horizontal position in one-character register r.
\k(rg Mark horizontal position in two-character register rg.
\k[reg]
Mark horizontal position in register with arbitrarily long
name reg.
\l'Nc' Horizontal line drawing function (optionally using character
c).
\L'Nc' Vertical line drawing function (optionally using character c).
\mc Change to color with one-character name c.
\m(cl Change to color with two-character name cl.
\m[color]
Change to color with arbitrarily long name color.
\m[] Switch back to previous color.
\Mc Change filling color for closed drawn objects to color with
one-character name c.
\M(cl Change filling color for closed drawn objects to color with
two-character name cl.
\M[color]
Change filling color for closed drawn objects to color with
arbitrarily long name color.
\M[] Switch to previous fill color.
\nr The numerical value stored in the register variable with the
one-character name r.
\n(re The numerical value stored in the register variable with the
two-character name re.
\n[reg]
The numerical value stored in the register variable with
arbitrarily long name reg.
\N'n' Typeset the glyph with index n in the current font. No
special fonts are searched. Useful for adding (named)
entities to a document using the .char request and friends.
\o'abc...'
Overstrike glyphs a, b, c, etc.
\O0 Disable glyph output. Mainly for internal use.
\O1 Enable glyph output. Mainly for internal use.
\p Break output line at next word boundary; adjust if applicable.
\r Reverse 1 em vertical motion (reverse line in nroff).
\R'name ±n'
The same as .nr name ±n.
\s±N Set/increase/decrease the point size to/by N scaled points. N
must be a single digit; 0 restores the previous point size.
(In compatibility mode only, a non-zero N must be in the range
4–39.) Otherwise, same as .ps request.
\s(±N
\s±(N Set/increase/decrease the point size to/by N scaled points; N
is a two-digit number ≥1. Same as .ps request.
\s[±N]
\s±[N]
\s'±N'
\s±'N' Set/increase/decrease the point size to/by N scaled points.
Same as .ps request.
\S'N' Slant output by N degrees.
\t Non-interpreted horizontal tab.
\u Reverse (up) 1/2 em vertical motion (1/2 line in nroff).
\v'N' Local vertical motion; move down N (up if negative).
\Ve The contents of the environment variable with one-character
name e.
\V(ev The contents of the environment variable with two-character
name ev.
\V[env]
The contents of the environment variable with arbitrarily long
name env.
\w'string'
The width of the glyph sequence string.
\x'N' Extra line-space function (negative before, positive after).
\X'string'
Output string as device control function.
\Yn Output string variable or macro with one-character name n
uninterpreted as device control function.
\Y(nm Output string variable or macro with two-character name nm
uninterpreted as device control function.
\Y[name]
Output string variable or macro with arbitrarily long name
name uninterpreted as device control function.
\zc Print c with zero width (without spacing).
\Z'anything'
Print anything and then restore the horizontal and vertical
position; anything may not contain tabs or leaders.
The escape sequences \e, \., \", \$, \*, \a, \n, \t, \g, and \newline
are interpreted in copy mode.
Escape sequences starting with \( or \[ 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
[Note: ‘Special Characters’ is a misnomer; those entities are
(output) glyphs, not (input) characters.]
Common special characters are predefined by escape sequences of the
form \(xy with characters x and y. In groff, it is also possible to
use the form \[xy].
Some of these special characters exist in the usual font while most
of them are only available in the special font. Below you can see a
small selection of the most important glyphs; a complete list can be
found in groff_char(7).
\(Do Dollar $
\(Eu Euro €
\(Po British pound sterling £
\(aq Apostrophe quote '
\(bu Bullet sign ·
\(co Copyright ©
\(cq Single closing quote (right) ’
\(ct Cent ¢
\(dd Double dagger ‡
\(de Degree sign °
\(dg Dagger †
\(dq Double quote "
\(em Em-dash —
\(en En-dash –
\(ha Caret/spacing circumflex accent (“hat”) ^
\(hy Hyphen ‐
\(lq Double quote left “
\(oq Single opening quote (left) ‘
\(rg Registered sign ®
\(rq Double quote right ”
\(rs Reverse solidus/backslash \
\(sc Section sign §
\(ti Tilde (spacing) ~
\(tm Trademark symbol ™
\(ul Underline character _
\(== Identical ≡
\(>= Larger or equal ≥
\(<= Less or equal ≤
\(!= Not equal ≠
\(-> Right arrow →
\(<- Left arrow ←
\(+- Plus-minus sign ±
Unicode characters
The extended escape u allows the inclusion of all available Unicode
characters into a roff file.
\[uxxxx]
u is the escape name. xxxx is a hexadecimal number of four
hex digits, such as 0041 for the letter A, thus \[u0041].
\[uyyyyy]
u is the escape name. yyyyy is a hexadecimal number of five
hex digits, such as 2FA1A for a Chinese-looking character from
the Unicode block CJK Compatibility Ideographs Supplement,
thus \[u2FA1A].
The hexadecimal value indicates the corresponding Unicode code point
for a character.
\[uhex1_hex2]
\[uhex1_hex2_hex3]
hex1, hex2, and hex3 are all Unicode hexadecimal codes (4 or 5
hex digits) that are used for overstriking, e.g.,
\[u0041_0301] is A acute, which can also be specified as Á;
see groff_char(7).
The availability of the Unicode characters depends on the font used.
For text mode, the device -Tutf8 is quite complete; for troff modes
it might happen that some or many characters will not be displayed.
Please check your fonts.
Strings
groff has string variables primarily for user convenience. Only one
string is predefined by the language.
\*[.T] This string contains the current output device (for
example, “utf8” or “pdf”).
The .ds request creates a string with a specified name and contents
and the \* escape dereferences its name, retrieving the contents.
Dereferencing an undefined string name defines it as empty.
The .as request is similar to .ds but appends to a string instead of
redefining it. If .as is called with only one argument, no operation
is performed (beyond dereferencing it).
The .ds1 request defines a string such that compatibility mode is off
when the string is later interpolated. To be more precise, a
compatibility save input token is inserted at the beginning of the
string, and a compatibility restore input token at the end.
Likewise, the .as1 request is similar to .as, but compatibility mode
is switched off when the appended portion of the string is later
interpolated.
Caution: Unlike other requests, the second argument to these requests
consumes the remainder of the input line, including trailing spaces.
It is good style to end string definitions (and appendments) with a
comment, even an empty one, to prevent unwanted space from creeping
into them during source document maintenance.
To store leading space in a string, start it with a double quote. A
double quote is special only in that position; double quotes in any
other location are included in the string (the effects of escape
sequences notwithstanding).
Strings, macros, and diversions (and boxes) share the same name
space. Internally, the same mechanism is used to store them.
Several requests exist to perform rudimentary string operations.
Strings can be queried (.length) and modified (.chop, .substring,
.stringup, .stringdown), and their names can be manipulated through
renaming, removal, and aliasing (.rn, .rm, .als).
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 .nr request.
The value stored in a register can be retrieved by the escape
sequences introduced by \n.
Most useful are predefined registers. In the following the notation
name is used to refer to register name to make clear that we speak
about registers. Please keep in mind that the \n[] 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 are
read-only). Mostly, they provide information on the current settings
or store results from request calls.
\n[$$] The process ID of troff.
\n[.$] Number of arguments in the current macro or string.
\n[.a] Post-line extra line-space most recently utilized using \x.
\n[.A] Set to 1 in troff if option -A is used; always 1 in nroff.
\n[.b] The emboldening offset while .bd is active.
\n[.br] Within a macro, set to 1 if macro called with the ‘normal’
control character, and to 0 otherwise.
\n[.c] Current input line number.
\n[.C] 1 if compatibility mode is in effect, 0 otherwise.
Always 0 in a .do request; see register .cp below.
\n[.cdp] The depth of the last glyph added to the current
environment. It is positive if the glyph extends below the
baseline.
\n[.ce] The number of lines remaining to be centered, as set by the
.ce request.
\n[.cht] The height of the last glyph added to the current
environment. It is positive if the glyph extends above the
baseline.
\n[.color]
1 if colors are enabled, 0 otherwise.
\n[.cp] Within a .do request, the saved value of compatibility mode
(see register .C above).
\n[.csk] The skew of the last glyph added to the current
environment. The skew of a glyph is how far to the right
of the center of a glyph the center of an accent over that
glyph should be placed.
\n[.d] Current vertical place in current diversion; equal to
register nl.
\n[.ev] The name or number of the current environment (string-
valued).
\n[.f] Current font number.
\n[.F] The name of the current input file (string-valued).
\n[.fam] The current font family (string-valued).
\n[.fn] The current (internal) real font name (string-valued).
\n[.fp] The number of the next free font position.
\n[.g] Always 1 in GNU troff. Macros should use it to test if
running under groff.
\n[.h] Text base-line high-water mark on current page or
diversion.
\n[.H] Number of basic units per horizontal unit of output device
resolution.
\n[.height]
The current font height as set with \H.
\n[.hla] The hyphenation language in the current environment.
\n[.hlc] The count of immediately preceding consecutive hyphenated
lines in the current environment.
\n[.hlm] The maximum number of consecutive hyphenated lines allowed
in the current environment.
\n[.hy] The hyphenation mode in the current environment.
\n[.hym] The hyphenation margin in the current environment.
\n[.hys] The hyphenation space adjustment threshold in the current
environment.
\n[.i] Current indentation.
\n[.in] The indentation that applies to the current output line.
\n[.int] Positive if last output line contains \c.
\n[.j] The current adjustment mode. It can be stored and used to
set adjustment. (n = 1, b = 1, l = 0, r = 5, c = 3).
\n[.k] The current horizontal output position (relative to the
current indentation).
\n[.kern] 1 if pairwise kerning is enabled, 0 otherwise.
\n[.l] Current line length.
\n[.L] The current line spacing setting as set by .ls.
\n[.lg] The current ligature mode (as set by the .lg request).
\n[.linetabs]
The current line-tabs mode (as set by the .linetabs
request).
\n[.ll] The line length that applies to the current output line.
\n[.lt] The title length (as set by the .lt request).
\n[.m] The current drawing color (string-valued).
\n[.M] The current background color (string-valued).
\n[.n] Length of text portion on previous output line.
\n[.ne] The amount of space that was needed in the last .ne request
that caused a trap to be sprung. Useful in conjunction
with register .trunc.
\n[.ns] 1 if in no-space mode, 0 otherwise.
\n[.o] Current page offset.
\n[.O] The suppression nesting level (see \O).
\n[.p] Current page length.
\n[.P] 1 if the current page is being printed, 0 otherwise (as
determined by the -o command-line option).
\n[.pe] 1 during page ejection, 0 otherwise.
\n[.pn] The number of the next page: either the value set by a .pn
request, or the number of the current page plus 1.
\n[.ps] The current point size in scaled points.
\n[.psr] The last-requested point size in scaled points.
\n[.pvs] The current post-vertical line spacing.
\n[.R] The number of unused number registers. Always 10000 in GNU
troff.
\n[.rj] The number of lines to be right-justified as set by the .rj
request.
\n[.s] Current point size as a decimal fraction.
\n[.slant]
The slant of the current font as set with \S.
\n[.sr] The last requested point size in points as a decimal
fraction (string-valued).
\n[.ss] Size of minimal inter-word spacing in twelfths of the space
width of the current font.
\n[.sss] Size of additional inter-sentence spacing in twelfths of
the space width of the current font.
\n[.sty] The current font style (string-valued).
\n[.t] Vertical distance to the next trap.
\n[.T] Set to 1 if option -T is used.
\n[.tabs] A string representation of the current tab settings
suitable for use as an argument to the .ta request.
\n[.trunc]
The amount of vertical space truncated by the most recently
sprung vertical position trap, or, if the trap was sprung
by an .ne request, minus the amount of vertical motion
produced by .ne. Useful in conjunction with the register
.ne.
\n[.u] Equal to 1 in fill mode and 0 in no-fill mode.
\n[.U] Equal to 1 in safer mode and 0 in unsafe mode.
\n[.v] Current vertical line spacing.
\n[.V] Number of basic units per vertical unit of output device
resolution.
\n[.vpt] 1 if vertical position traps are enabled, 0 otherwise.
\n[.w] Width of previous glyph.
\n[.warn] The sum of the number codes of the currently enabled
warnings.
\n[.x] The major version number.
\n[.y] The minor version number.
\n[.Y] The revision number of groff.
\n[.z] Name of current diversion.
\n[.zoom] Zoom factor for current font (in multiples of 1/1000th;
zero if no magnification).
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.
\n[%] Current page number.
\n[c.] Current input line number.
\n[ct] Character type (set by width function \w).
\n[dl] Maximal width of last completed diversion.
\n[dn] Height of last completed diversion.
\n[dw] Current day of week (1–7).
\n[dy] Current day of month (1–31).
\n[hours] The number of hours past midnight. Initialized at start-
up.
\n[hp] Current horizontal position at input line.
\n[llx] Lower left x-coordinate (in PostScript units) of a given
PostScript image (set by .psbb).
\n[lly] Lower left y-coordinate (in PostScript units) of a given
PostScript image (set by .psbb).
\n[ln] Output line number.
\n[lsn] The number of leading spaces of an input line.
\n[lss] The horizontal space corresponding to the leading spaces of
an input line.
\n[minutes]
The number of minutes after the hour. Initialized at
start-up.
\n[mo] Current month (1–12).
\n[nl] Vertical position of last printed text base-line.
\n[opmaxx]
\n[opmaxy]
\n[opminx]
\n[opminy]
These four registers mark the top left and bottom right
hand corners of a box which encompasses all written glyphs.
They are reset to -1 by \O0 or \O1.
\n[rsb] Like register sb, but takes account of the heights and
depths of glyphs.
\n[rst] Like register st, but takes account of the heights and
depths of glyphs.
\n[sb] Depth of string below base line (generated by width
function \w).
\n[seconds]
The number of seconds after the minute. Initialized at
start-up.
\n[skw] Right skip width from the center of the last glyph in the
\w argument.
\n[slimit]
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.
\n[ssc] The amount of horizontal space (possibly negative) that
should be added to the last glyph before a subscript
(generated by width function \w).
\n[st] Height of string above base line (generated by width
function \w).
\n[systat]
The return value of the system() function executed by the
last .sy request.
\n[urx] Upper right x-coordinate (in PostScript units) of a given
PostScript image (set by .psbb).
\n[ury] Upper right y-coordinate (in PostScript units) of a given
PostScript image (set by .psbb).
\n[year] The current year (year 2000 compliant).
\n[yr] Current year minus 1900. For Y2K compliance use register
year instead.
Several requests influence hyphenation. Because conventions vary, a
variety of hyphenation modes are available to the .hy request; these
determine whether automatic hyphenation will apply to a word prior to
breaking a line at the end of a page (more or less; see below for
details), and at which positions within that word hyphenation is
permissible. The default is “1” for historical reasons, but this is
not an appropriate value for the U.S. English hyphenation patterns
used by groff, and macro packages often override it.
0 disables hyphenation.
1 enables hyphenation except after the first and before the last
character of a word.
The remaining values “imply” 1; that is, they enable hyphenation
under the same conditions as “.hy 1”, and then apply or lift
restrictions relative to that basis.
2 disables hyphenation of the last word on a page.
(Technically, this value prevents hyphenation if the next page
position trap is closer than the next line of text would be.
groff automatically inserts an implicit page position trap at
the end of each page to cause a page transition. This value
can be used in traps planted by users or macro packages to
prevent hyphenation of the last word in a column in multi-
column page layouts or before floating figures or tables.)
4 disables hyphenation before the last two characters of a word.
8 disables hyphenation after the first two characters of a word.
16 enables hyphenation before the last character of a word.
32 enables hyphenation after the first character of a word.
Note that any restrictions imposed by the hyphenation mode are not
respected for words whose hyphenations have been explicitly specified
with the hyphenation character (“\%” by default) or the .hw request.
The nonzero values above are additive. For example, value 12 causes
groff to hyphenate neither the last two nor the first two characters
of a word. Some values cannot be used together because they
contradict; for instance, values 4 and 16, and values 8 and 32. As
noted, it is superfluous to add 1 to any other positive value.
The places within a word that are eligible for hyphenation are
determined by language-specific data (.hla, .hpf, and .hpfa) and
lettercase relationships (.hcode and .hpfcode). Furthermore,
hyphenation of a word might be suppressed because too many previous
lines have been hyphenated (.hlm), the line has not reached a certain
minimum length (.hym), or the line can instead be adjusted with up to
a certain amount of additional inter-word space (.hys). See
groff_diff(7) or the groff Texinfo manual for further details.
In the RUNOFF language, the underlining was quite easy. But in roff
this is much more difficult.
Underlining with .ul
There exists a groff request .ul (see above) that can underline the
next or further source lines in nroff, but in troff it produces only
a font change into italic. So this request is not really useful.
Underlining with .UL from ms
In the ‘ms’ macro package in tmac/s.tmac groff_ms(7), there is the
macro .UL. But this works only in troff, not in nroff.
Underlining macro definitions
So one can use the italic nroff idea from .ul and the troff
definition in ms for writing a useful new macro, something like
.de UNDERLINE
. ie n \\$1\f[I]\\$2\f[P]\\$3
. el \\$1\Z'\\$2'\v'.25m'\D'l \w'\\$2'u 0'\v'-.25m'\\$3
..
If doclifter(1) makes trouble, change the macro name UNDERLINE into
some 2-letter word, like Ul. Moreover, change the form of the font
escape from \f[P] to \fP.
Underlining without macro definitions
If one does not want to use macro definitions, e.g., when doclifter
gets lost, use the following:
.ds u1 before
.ds u2 in
.ds u3 after
.ie n \*[u1]\f[I]\*[u2]\f[P]\*[u3]
.el \*[u1]\Z'\*[u2]'\v'.25m'\D'l \w'\*[u2]'u 0'\v'-.25m'\*[u3]
When using doclifter, it might be necessary to change syntax forms
such as \[xy] and \*[xy] to those supported by AT&T troff: \*(xy and
\(xy, and so on.
Then these lines could look like
.ds u1 before
.ds u2 in
.ds u3 after
.ie n \*[u1]\fI\*(u2\fP\*(u3
.el \*(u1\Z'\*(u2'\v'.25m'\D'l \w'\*(u2'u 0'\v'-.25m'\*(u3
The result looks like
before _i_n after
Underlining with overstriking \z and \(ul
There is another possibility for underlining by using overstriking
with \zc (print c with zero width without spacing) and \(ul (under‐
line character). This produces the underlining of 1 character, both
in nroff and in troff.
For example the underlining of a character say t looks like \z\[ul]t
or \z\(ult
Longer words look then a bit strange, but a useful mode is to write
each character into a whole own line. To underlines the 3 character
part "tar" of the word "start":
before s\
\z\[ul]t\
\z\[ul]a\
\z\[ul]r\
t after
or
before s\
\z\(ult\
\z\(ula\
\z\(ulr\
t after
The result looks like
before s_t_a_rt after
The differences between the groff language and 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.
This document was written by Bernd Warken ⟨groff-bernd.warken-72@
web.de⟩.
Groff: The GNU Implementation of troff, by Trent A. Fisher and Werner
Lemberg, is the primary groff manual. You can browse it
interactively with “info groff”. 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)
describes the differences between the groff language and
classical troff.
This is the authoritative document for the predefined language
elements that are specific to groff.
groff_char(7)
the predefined groff special characters (glyphs).
groff_font(5)
the specification of fonts and the DESC file.
groff_tmac(5)
contains an overview of available groff macro packages,
instructions on how to interface them with a document,
guidance on writing macro packages and using diversions, and
historical information on macro package naming conventions.
roff(7)
the history of roff, the common parts shared by all roff
systems, and pointers to further documentation.
[CSTR #54]
Nroff/Troff User's Manual by Ossanna & Kernighan
⟨http://cm.bell-labs.com/cm/cs/cstr/54.ps.gz⟩ — the bible for
classical troff.
Wikipedia
article about groff
⟨https://en.wikipedia.org/wiki/Groff_%28software%29⟩.
Tutorial about groff
Manas Laha - An Introduction to the GNU Groff Text Processing
System ⟨dl.dropbox.com/u/4299293/grofftut.pdf⟩
troff.org
This is a collection of internet sites with classical roff
documentations and other information.
This page is part of the groff (GNU troff) project. Information
about the project can be found at
⟨http://www.gnu.org/software/groff/⟩. If you have a bug report for
this manual page, see ⟨http://www.gnu.org/software/groff/⟩. This
page was obtained from the project's upstream Git repository
⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2020-09-18. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-09-19.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
groff 1.22.4.234-3ba6 18 September 2020 groff(7)
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