GROFF(7)GROFF(7)NAMEgroff - a short reference for the GNU roff language
DESCRIPTIONgroff 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 prede
fined 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 documen
tation that is found in the groffinfo(1) file, which con
tains more detailed, actual, and concise information.
The general syntax for writing groff documents is rela
tively 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 argu
ments. They have the following syntax. The leading con
trol character can be followed by a command name; argu
ments, if any, are separated by blanks 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 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 regu
lated by a length encoding introduced by an open parenthe
sis `(' or enclosed in brackets `[' and `]'.
The roff language provides flexible instruments for writ
ing language extension, such as macros. When interpreting
macro definitions, the roff system enters a special oper
ating 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 \e. To be
more precise, \e represents the current escape
character. To get a backslash glyph, use \(rs.
2. Double all backslashes.
3. Begin all text lines with the special non-spacing
character \&.
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 dou
ble 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 com
mands and variables that make roff a full-blown program
ming language.
There are two kinds of roff commands, possibly with argu
ments. Requests are written on a line of their own start
ing 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 vari
ables, 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.
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 is everywhere
available, but on text devices, it is displayed as an
underlined Roman font. For the graphical output devices,
there exist constant-width pendants of these font, CR, CI,
and CB. On text devices, all characters have a constant
width anyway.
Moreover, there are some advanced roff elements. A diver
sion 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 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 .if, .ie, .el,
and .while. There it is the control character that
introduces a request (or macro). The special
behavior can be delayed by using the \. escape. 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 charac
ter. 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 .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 will work). In all other positions,
it denotes the single quote or apostrophe charac
ter. Groff provides a printable representation
with the \(cq escape sequence.
" The double quote is used to enclose arguments in
requests and macros. In the .ds and .as 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 \" 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 argu
ment consisting of exactly two characters. In
groff, this behavior can be replaced by the [] con
struct.
[ 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-spe
cial.
space Space characters are only functional characters.
They separate the arguments in requests or macros,
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),
\|, \^, or \h should be used.
newline
In text paragraphs, newlines mostly behave like
space characters. Continuation lines can be speci
fied 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 inter
preter 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 scale indicator. A scale
indicator is a one-character abbreviation for a unit of
measurement. A number followed by a scale indicator sig
nifies a size value. By default, numerical values do not
have a scale indicator, i.e., they are normal numbers.
The roff language defines the following scale 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
z scaled point = 1/sizescale of a point
(defined in font DESC file)
Numerical expressions are combinations of the numerical
values defined above with the arithmetical operators `+',
`-', `*', `/', `%' (modulo), the comparative operators
`==' (this is the same as `='), `<=', `>=', `<', `>', the
logical operators `&' (and), `:' (or), `!' (not), and the
parentheses `(' and `)'.
Moreover, groff added the following operators for numeri
cal 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 info file.
CONDITIONS
Conditions occur in tests raised 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 >0.
!N True if the value of N 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.
n Formatter is nroff.
rreg True if there is a register named reg.
t Formatter is troff.
REQUESTS
This section provides a short reference for the predefined
requests. In groff, request and macro names can be arbi
trarily 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 be
haviour. Not all of these details are outlined here. Re
fer to the groff info file 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 will be added to an al
ready 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.
.\" anything
Complete line is a comment.
.ab string
Print string on standard error, exit program.
.ad Begin line adjustment for output lines in cur
rent adjust mode.
.ad c Start line adjustment in mode c (c=l,r,b,n).
.af register c
Assign format c to register (c=l,i,I,a,A).
.aln alias register
Create alias name for register.
.als alias object
Create alias name for request, string, macro, or
diversion object.
.am macro Append to macro until .. is called.
.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.
.as stringvar anything
Append anything to stringvar.
.asciify diversion
Unformat ASCII characters, spaces, and some es
cape sequences in diversion.
.backtrace
Print a backtrace of the input on stderr.
.bd font N
Embolden font by N-1 units.
.bd S font N
Embolden Special Font S when current font is
font.
.blm Unset the blank line macro.
.blm macro
Set the blank line macro 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 and spread output line. Same as \p.
.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 mode c1 c2 ...
Treat characters c1, c2, ... according to mode
number.
.ch trap N
Change trap location to N.
.char c anything
Define character c to string anything.
.chop object
Chop the last character off macro, string, or
diversion object.
.close stream
Close the stream.
.continue
Finish the current iteration of a while loop.
.cp Enable compatibility mode.
.cp N If N is zero disable compatibility mode, other
wise 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 called.
.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.
.dei macro
Define or redefine a macro whose name is con
tained in the string register macro until .. is
called.
.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.
.di End current diversion.
.di macro Divert to macro.
.do name Interpret .name with compatibility mode dis
abled.
.ds stringvar anything
Set stringvar to anything.
.dt N trap
Set diversion trap to position N (default scale
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 will be run after the end of input.
.eo Turn off escape character mechanism.
.ev Switch to previous environment.
.ev env Push down environment number or name env and
switch to it.
.evc env Copy the contents of environment env to the cur
rent 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 character to
space.
.fc a b Set field delimiter to a and pad character to b.
.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 in_
ternal name on position n.
.fspecial font s1 s2...
When the current font is font, then the fonts
s1, s2, ... will be special.
.ft Return to previous font. Same as \fP.
.ft font Change to font name or number font; same as
\f[font] escape sequence.
.ftr font1 font2
Translate font1 to font2.
.hc Remove additional hyphenation indicator charac
ter.
.hc c Set up additional hyphenation indicator charac
ter c.
.hcode c1 code1 c2 code2 ...
Set the hyphenation code of character c1 to
code1, that of c2 to code2, etc.
.hla lang Set the current hyphenation language to lang.
.hlm n Set the maximum number of consecutive hyphenated
lines to n.
.hpf file Read hyphenation patterns from file.
.hw words List of words with exceptional hyphenation.
.hy N Switch to hyphenation mode N.
.hym n Set the hyphenation margin to n (default scale
indicator m).
.hys n Set the hyphenation space to n.
.ie cond anything
If cond then anything else goto .el.
.if cond anything
If cond then anything; otherwise do nothing.
.ig Ignore text until .. is called.
.ig end Ignore text until .end.
.in Change to previous indent value.
.in N Change indent according to N (default scale in
dicator m).
.it N trap
Set an input-line count trap at position N.
.kern Enable pairwise kerning.
.kern n If n is zero, disable pairwise kerning, other
wise enable it.
.lc Remove leader repetition character.
.lc c Set leader repetition character to c.
.length register anything
Write the length of the string anything in reg_
ister.
.linetabs
Enable line-tabs mode (i.e., calculate tab posi
tions relative to output line).
.linetabs n
If n is zero, disable line-tabs mode, otherwise
enable it.
.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 size
6.5i, default scale indicator m).
.ls Change to the previous value of additional in
tra-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 scale indicator m).
.mc Margin character off.
.mc c Print character c after each text line at actual
distance from right margin.
.mc c N Set margin character to c and distance to N from
right margin (default scale indicator m).
.mk register
Mark current vertical position in register.
.mso file The same as the .so request 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 scale indica
tor v).
.nf No filling or adjusting of output-lines.
.nh No hyphenation.
.nm Number mode off.
.nm N M S I
In line number mode, set number, multiple, spac
ing, and indent.
.nn Do not number next line.
.nn N Do not number next N lines.
.nop anything
Always execute anything.
.nr register N M
Define or modify register using N with auto-in
crement M.
.nroff Make the built-in condition n true and t false.
.ns Turn no-space mode on.
.nx filename
Next 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.
.pc Reset page number character to `%'.
.pc c Page number character.
.pi program
Pipe output to program (nroff only).
.pl Set page length to default 11i. The current page
length is stored in .p.
.pl N Change page length to N (default scale indica
tor v).
.pm Print macro names and sizes (number of blocks of
128 bytes).
.pm t Print only total of sizes of macros (number of
128 bytes blocks).
.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 .o.
.po N Page offset N.
.ps Return to previous point-size.
.ps N Point size; same as \s[N].
.psbb filename
Get the bounding box of a PostScript image file_
name.
.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.
.rchar c1 c2...
Remove the definitions of characters c1, c2, ...
.rd prompt
Read insertion.
.return Return from a macro.
.rj n Right justify the next n input lines.
.rm name Remove request, macro, or string name.
.rn old new
Rename request, macro, or string old to new.
.rnn reg1 reg2
Rename register reg1 to reg2.
.rr register
Remove register.
.rs Restore spacing; turn no-space mode off.
.rt N Return (upward only) to marked vertical place
(default scale indicator v).
.shc Reset soft hyphen character to \(hy.
.shc c Set the soft hyphen character to c.
.shift n In a macro, shift the arguments by n positions.
.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 s1 s2 ...
Fonts s1, s2, etc. are special and will be
searched for characters not in the current font.
.ss N Space-character size set to N/12 of the
spacewidth in the current font.
.ss N M 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).
.sty n style
Associate style with font position n.
.substring register n1 n2
Replace the string in register with the sub
string defined by the indices n1 and n2.
.sv Save 1v of vertical space.
.sv N Save the vertical distance N for later output
with .os request.
.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+r1, nn+r2, ..., nn+rn, then at
nn+rn+r1, nn+rn+r2, ..., nn+rn+rn, and so on.
.tc Remove tab repition character.
.tc c Set tab repetition character to c.
.ti N Temporary indent next line (default scaling in
dicator m).
.tkf font s1 n1 s2 n2
Enable track kerning for font.
.tl 'left'center'right'
Three-part title.
.tm anything
Print anything on terminal (UNIX standard mes
sage output).
.tm1 anything
Print anything on terminal (UNIX standard mes
sage output), allowing leading whitespace if
anything starts with " (which will be stripped
off).
.tmc anything
Similar to .tm1 without emitting a final new
line.
.tr abcd....
Translate a to b, c to d, etc. on output.
.trf filename
Transparently output the contents of file file_
name.
.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 condition t true and n false.
.uf font Underline font set to font (to be switched to by
.ul).
.ul N Underline (italicize in troff) N input lines.
.unformat diversion
Unformat space characters and tabs, preserving
font information in diversion.
.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
value is 12p.
.warn n Set warnings code to n.
.wh N trap
Set location trap; negative means from page bot
tom.
.while cond anything
While condition cond is true, accept anything as
input.
.write stream anything
Write anything to the stream named stream.
Besides these standard groff requests, there might be fur
ther 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 en
close 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 in
troduced 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 ar
gument 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 \(xy 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
\c.
Constant arguments of length 1 can omit the marker apos
trophes, 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 \( construct are used for special
characters predefined by the roff system. Names with more
than two characters \[name] mostly denote user defined
named characters (see the .char 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 \" except the ignoring of the terminating
newline.
\*s The string stored in the string variable with
1-character name s.
\*(st The string stored in the string variable with
2-character name st.
\*[stringvar]
The string stored in the string variable with arbi
trary length name stringvar.
\$0 The name by which the current macro was invoked.
The .als request can make a macro have more than
one name.
\$x Macro argument with 1-place number x, where x is a
digit between 1 and 9.
\$(xy Macro argument with 2-digit number xy.
\$[nexp]
Macro argument with number nexp, where nexp is a
numerical expression evaluating to an integer >=1.
\$* In a macro, the concatenation of all the arguments
separated by spaces.
\$@ In a macro, the concatenation of all the arguments
with each surrounded by double quotes, and separat
ed by spaces.
\\ reduces to a single backslash; useful to delay its
interpretation as escape character in copy mode.
For a printable backslash, use \e.
\' The acute accent ; same as \(aa. Unescaped: apos
trophe, right quotation mark, single quote (ASCII
0x27).
\` The grave accent `; same as \(ga. Unescaped: left
quote, backquote (ASCII 0x60).
\- The - sign in the current font.
\. An uninterpreted dot (period), even at start of
line.
\% Default optional hyphenation character.
\! Transparent line indicator.
\?anything?
In a diversion, this will transparently embed any_
thing in the diversion. anything is read in copy
mode. See also the escape sequences \! and \?.
\space Unpaddable space-size space character (no line
break).
\0 Digit width.
\| 1/6 em narrow space character; zero width in nroff.
\^ 1/12 em half-narrow space character; zero width in
nroff.
\& Non-printable, zero width character.
\) Like \& except that it behaves like a character de
clared 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 follow
ing 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 in
ter-word space when a line is adjusted.
\: Inserts a zero-width break point (similar to \% but
without a soft hyphen character).
\newline
Ignored newline, for continuation lines.
\{ Begin conditional input.
\} End conditional input.
\(st The special character with 2-character name st, see
section SPECIAL CHARACTERS.
\[name]
The named character with arbitrary length name
name.
\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 0 otherwise.
\b'abc...'
Bracket building function.
\B'anything'
If anything is acceptable as a valid numeric ex
pression it expands to 1, and 0 otherwise.
\c Interrupt text processing.
\C'char'
The character called char; same as \[char], but
compatible to other roff versions.
\d Forward (down) 1/2 em vertical unit (1/2 line in
nroff).
\D'charseq'
Draw a graphical element defined by the characters
in charseq; see groff info file for details.
\e Printable version of the current escape character.
\E Equivalent to an escape character, but is not in
terpreted in copy-mode.
\fF Change to font with 1-character name or 1-digit
number F.
\f(fo Change to font with 2-characer name or 2-digit num
ber fo.
\f[font]
Change to font with arbitrary length name or number
expression font.
\g[reg]
Return format of register with name reg suitable
for .af. Alternative forms \g(xy and \gx.
\h'N' Local horizontal motion; move right N (left if neg
ative).
\H'N' Set height of current font to N.
\k[reg]
Mark horizontal input place in register with arbi
trary length name reg. Alternative forms \k(xy and
\kx.
\l'Nc' Horizontal line drawing function (optionally using
character c).
\L'Nc' Vertical line drawing function (optionally using
character c).
\nr The numerical value stored in the register variable
with the 1-character name r.
\n(re The numerical value stored in the register variable
with the 2-character name re.
\n[reg]
The numerical value stored in the register variable
with arbitrary lenght name reg.
\N'n' Typeset the character with code n in the current
font, no special fonts are searched. Useful for
adding characters to a font using the .char re
quest.
\o'abc...'
Overstrike characters a, b, c, etc.
\p Break and spread output line.
\r Reverse 1 em vertical motion (reverse line in
nroff).
\R'name n'
The same as .nr name n.
\s[N] Set the point size to N scaled points. Note the
alternative forms \s[N], \s'N', \s'N', \s(xy,
\s(xy, \sx. Same as .ps request.
\S'N' Slant output 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 nega
tive).
\V[env]
The contents of the environment variable env. Al
ternative forms \V(xy and \Vx.
\w'string'
The width of the character sequence string.
\x'N' Extra line-space function (negative before, posi
tive after).
\X'string'
Output string as device control function.
\Y[name]
Output string variable or macro name uninterpreted
as device control function. Alternative forms
\Y(xy and \Yx.
\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
Common special characters are predefined by escape se
quences 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 selec
tion of the most important glyphs; a complete list can be
found in groff_char(7).
\(bu Bullet sign.
\(co Copyright.
\(ct Cent.
\(dd = Double dagger.
\(de Degree.
\(dg - Dagger.
\(em -- Em-dash.
\(hy - Hyphen.
\(rg Registered sign.
\(sc Section sign.
\(ul _ Underline character.
\(== == Identical.
\(>= >= Larger or equal.
\(<= <= Less or equal.
\(!= != Not equal.
\(-> -> Right arrow.
\(<- <- Left arrow.
\(+- Plus-minus sign.
REGISTERS
Registers are variables that store a value. In groff,
most registers store numerical values (see section NUMERI
CAL 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 .nr register.
The value stored in a register can be retrieved by the es
cape sequences introduced by \n.
Most useful are predefined registers. In the following
the notation name is used to refer to a register called
name to make clear that we speak about registers. Please
keep in mind that the \en[] 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.
\n[.$] Number of arguments in the current macro.
\n[.a] Post-line extra line-space most recently uti
lized using \x'N'.
\n[.A] Set to 1 in troff if option -A is used; always 1
in nroff.
\n[.c] Current input line number.
\n[.C] 1 if compatibility mode is in effect, 0 other
wise.
\n[.cdp] The depth of the last character added to the
current environment. It is positive if the
character 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 character added to the
current environment. It is positive if the
character extends above the baseline.
\n[.csk] The skew of the last character added to the cur
rent environment. The skew of a character is
how far to the right of the center of a charac
ter the center of an accent over that character
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[.fam] The current font family (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] Available horizontal resolution in basic units.
\n[.hla] The current hyphenation language as set by the
.hla request.
\n[.hlc] The number of immediately preceding consecutive
hyphenated lines.
\n[.hlm] The maximum allowed number of consecutive hy
phenated lines, as set by the .hlm request.
\n[.hy] The current hyphenation flags (as set by the .hy
request).
\n[.hym] The current hyphenation margin (as set by the
.hym request).
\n[.hys] The current hyphenation space (as set by the
.hys request).
\n[.i] Current ident.
\n[.in] The indent that applies to the current output
line.
\n[.int] Positive if last output line contains \c.
\n[.kern] 1 if pairwise kerning is enabled, 0 otherwise.
\n[.l] Current line length.
\n[.lg] The current ligature mode (as set by the .lg re
quest).
\n[.linetabs]
The current line-tabs mode (as set by the
.linetabs request).
\n[.ll] The line length that applies to the current out
put line.
\n[.lt] The title length (as set by the .lt request).
\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 .trunc.
\n[.ns] 1 if in no-space mode, 0 otherwise.
\n[.o] Current page offset.
\n[.p] Current page length.
\n[.pn] The number of the next page: either the value
set by a .pn request, or the number of the cur
rent page plus 1.
\n[.ps] The current pointsize in scaled points.
\n[.psr] The last-requested pointsize in scaled points.
\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[.sr] The last requested pointsize in points as a dec
imal fraction (string-valued).
\n[.t] Distance to the next trap.
\n[.T] Set to 1 if option -T is used.
\n[.tabs] A string representation of the current tab set
tings 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 a .ne request, minus
the amount of vertical motion produced by .ne.
request. 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 .ne regis
ter.
\n[.ss] The value of the parameters set by the first ar
gument of the .ss request.
\n[.sss] The value of the parameters set by the second
argument of the .ss request.
\n[.u] Equal to 1 bin fill mode and 0 in nofill mode.
\n[.v] Current vertical line spacing.
\n[.V] Available vertical resolution in basic units.
\n[.vpt] 1 if vertical position traps are enabled, 0 oth
erwise.
\n[.w] Width of previous character.
\n[.warn] The sum of the number codes of the currently en
abled 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.
WRITABLE REGISTERS
The following registers can be read and written by the us
er. 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[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[mo] Current month (1-12).
\n[nl] Vertical position of last printed text base-
line.
\n[rsb] Like sb, but takes account of the heights and
depths of characters.
\n[rst] Like st, but takes account of the heights and
depths of characters.
\n[sb] Depth of string below base line (generated by
width function \w).
\n[skw] Right skip width from the center of the last
character 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 memo
ry is exhausted.
\n[ssc] The amount of horizontal space (possibly nega
tive) that should be added to the last character
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 exe
cuted 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.
WARNINGS
Each warning generated by groff is identified by a name
and a code number. The codes are powers of 2 to allow
bit-encoding with a single integer. There are also names
that can be used to refer to groups of warnings.
The name associated with a warning is used by the -w and
-W options; the number code is used by the .warn request
and by the \n[warn] register.
all group
All warnings except di, mac and reg. Intended
to cover all warnings with traditional macro
packages.
break 4
In fill mode, lines which could not be broken
so that their length was less than the line
length. This is enabled by default.
char 1
Non-existent characters. This is enabled by
default.
delim 8
Missing or mismatched closing delimiters.
di 256
Use of .di or .da without an argument when
there is no current diversion.
el 16
Use of the .el request with no matching .ie
request.
escape 32768
Unrecognized escape sequence. Then the escape
character is ignored.
font 131072
Non-existent fonts. This is enabled by de
fault.
ig 262144
Illegal escapes in text ignored with the .ig
request. These are conditions that are errors
when they occur outside of ignored text.
mac 512
Use of undefined strings, macros, and diver
sions. Automatically handled as empty. Usu
ally, only one warning per name.
missing 8192
Request that is missing non-optional argu
ments.
input 16384
Illegal input character.
number 2
Invalid numeric expressions. This is enabled
by default.
range 64
Out of range arguments.
reg 1024
Use of undefined number register. Automati
cally defined as having value 0. Usually, on
ly one warning per name.
right-brace 4096
Use of \} where a number was expected.
scale 32
Meaningless scaling indicators.
space 65536
Missing space between a request or macro and
its argument. Then no macro is automatically
defined. This is enabled by default. This
warning will never occur in compatibility
mode.
syntax 128
Dubious syntax in numeric expressions.
tab 2048
Inappropriate use of a tab character (either
in an unquoted macro argument or where a num
ber was expected).
w group
All warnings.
+----------------+---------------------+------------------+
Bit Code Warning Bit Code Warning Bit Code Warning |
+----------------+---------------------+------------------+
| 0 1 char | 8 256 di |16 65536 space |
| 1 2 number | 9 512 mac |17 131072 font |
| 2 4 break |10 1024 reg |18 262144 ig |
| 3 8 delim |11 2048 tab | |
| 4 16 el |12 4096 right-brace | |
| 5 32 scale |13 8192 missing | |
| 6 64 range |14 16384 input | |
| 7 128 syntax |15 32768 escape | |
+----------------+---------------------+------------------+
COMPATIBILITYgroff provides a compatibility mode that allows to process
roff code written for classical or for other implementa
tions of roff in a consistent way.
Compatibility mode can be turned on with the -C command
line option, and turned on or off with the .cp request.
The number register \n(.C is 1 if compatibility mode is
on, 0 otherwise.
This became necessary because the GNU concept for long
names causes some incompatibilities. Classical troff will
interpret
.dsabcd
as defining a string ab with contents cd. Normally, groff
will interpret this as a call of a macro named dsabcd.
Also classical troff will interpret \*[ or \n[ as refer
ences to a string or number register called [. In GNU na_
tive mode, however, this will normally be interpreted as
the start of a long name.
In compatibility mode, groff will interpret these things
in the traditional way, but long names are not recognized.
On the other hand, groff in GNU native mode does not allow
to use the escape sequences \e, \|, \^, \&, \}, \{,
\ (space), \', \`, \-, \_, \!, \%, and \c in names of
strings, macros, diversions, number registers, fonts or
environments, whereas classical troff does. The \A escape
sequence can be helpful in avoiding these escape sequences
in names.
Fractional pointsizes cause one noteworthy incompatibili
ty. In classical troff, the .ps request ignores scale in
dicators and so
.ps 10u
will set the pointsize to 10 points, whereas in groff na
tive mode the pointsize will be set to 10 scaled points.
In groff mode, there is a fundamental difference between
unformatted input characters, and formatted output charac
ters. Everything that affects how an output character
will be output is stored with the character; once an out
put character has been constructed it is unaffected by any
subsequent requests that are executed, including the .bd,
.cs, .tkf, .tr, or .fp requests.
Normally output characters are constructed from input
characters at the moment immediately before the character
is added to the current output line. Macros, diversions
and strings are all, in fact, the same type of object;
they contain lists of input characters and output charac
ters in any combination.
An output character does not behave like an input charac
ter for the purposes of macro processing; it does not in
herit any of the special properties that the input charac
ter from which it was constructed might have had. The
following example will make things clearer.
.di x
\\\\
.br
.di
.x
In GNU mode this will be printed as \\. So each pair of
input backslashes `\\' is turned into a single output
backslash `\' and the resulting output backslashes are not
interpreted as escape characters when they are reread.
Classical troff would interpret them as escape characters
when they were reread and would end up printing a single
backslash `\'.
The correct way to get a printable `\' is to use the \e
escape sequence. This will always print a single instance
of the current escape character, regardless of whether or
not it is used in a diversion. It will also work in both
GNU mode and compatibility mode.
To store an escape sequence in a diversion that will be
interpreted when the diversion is reread, either the tra
ditional \! transparent output facility or the new \? es
cape sequence can be used.
BUGS
At the moment, the documentation of the groff system is in
a state of change and evolution. It is possible that
there are small inconsistencies between different docu
ments temporarily.
The WARNINGS section belongs to troff(1).
AUTHOR
This document is part of groff, the GNU roff distribution.
It was written by Bernd Warken <bwarken@mayn.de>.
It 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 under
http://www.gnu.org/copyleft/fdl.html.
Formerly, the extensions of the groff language were kept
in the manual page troff(1). This document contains the
essential parts of that documentation, but the gory de
tails are found in the groff info file.
SEE ALSO
The main source of information for the groff language is
the groffinfo(1) file.
For a survey of roff and the groff system and further doc
umentation pointers see roff(7).
The formatter programs are described in groff(1) and
troff(1); a complete of all predefined glyph names can be
found in groff_char(7).
The classical troff documentation is available on-line at
http://cm.bell-labs.com/cm/cs/cstr.html
and
http://www.kohala.com/start/troff/.
Groff Version 1.17.2 27 June 2001 GROFF(7)
