groff man page on UnixWare
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GROFF(7) GROFF(7)
NAME
groff - a short reference for the GNU roff language
DESCRIPTION
groff stands for GNU roff and is the free implementation of the roff
type-setting system. See roff(7) for a survey and the background of
the groff system.
This document gives only short descriptions of the predefined roff lan‐
guage elements as used in groff. Both the classical features and the
groff extensions are provided.
Historically, the roff language was called troff. groff is compatible
with the classical system and provides proper extensions. So in GNU,
the terms roff, troff, and groff language could be used as synonyms.
However troff slightly tends to refer more to the classical aspects,
whereas groff emphasizes the GNU extensions, and roff is the general
term for the language.
This file is only a short version of the complete documentation that is
found in the groff info(1) file, which contains more detailed, actual,
and concise information.
The general syntax for writing groff documents is relatively easy, but
writing extensions to the roff language can be a bit harder.
The roff language is line-oriented. There are only two kinds of lines,
control lines and text lines. The control lines start with a control
character, by default a period “.” or a single quote “'”; all other
lines are text lines.
Control lines represent commands, optionally with arguments. They have
the following syntax. The leading control character can be followed by
a command name; arguments, if any, are separated by blanks from the
command name and among themselves, for example,
.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 modi‐
fied by escape sequences, which are recognized by a leading backslash
‘\’. These are in-line or even in-word formatting elements or func‐
tions. Some of these take arguments separated by single quotes “'”,
others are regulated by a length encoding introduced by an open paren‐
thesis ‘(’ or enclosed in brackets ‘[’ and ‘]’.
The roff language provides flexible instruments for writing language
extension, such as macros. When interpreting macro definitions, the
roff system enters a special operating mode, called the copy mode.
The copy mode behavior can be quite tricky, but there are some rules
that ensure a safe usage.
1. Printable backslashes must be denoted as \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 double backslashes
to a single one in all macro definitions.
GROFF ELEMENTS
The roff language elements add formatting information to a text file.
The fundamental elements are predefined commands and variables that
make roff a full-blown programming language.
There are two kinds of roff commands, possibly with arguments.
Requests are written on a line of their own starting with a dot ‘.’ or
a “'”, whereas Escape sequences are in-line functions and in-word for‐
matting 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 her‐
self 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.
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 diversion stores
information into a macro for later usage. A trap is a positional con‐
dition 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 character. In text
paragraphs, it is advantageous to start each sentence at a line
of its own.
' The single quote has two controlling tasks. At the beginning of
a line and in the conditional requests it is the non-breaking
control character. That means that it introduces a request like
the dot, but with the additional property that this request
doesn't cause a linebreak. By using the .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 separa‐
tor in some functional escape sequences (but any pair of charac‐
ters not part of the argument will work). In all other posi‐
tions, it denotes the single quote or apostrophe character.
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 after‐
wards 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 argument consisting of exactly two
characters. In groff, this behavior can be replaced by the []
construct.
[ The opening bracket is only special in groff escape sequences;
there it is used to introduce a long escape name or long escape
argument. Otherwise, it is non-special, e.g. in macro calls.
] The closing bracket is only special in groff escape sequences;
there it terminates a long escape name or long escape argument.
Otherwise, it is non-special.
space Space characters are only functional characters. They separate
the arguments in requests or macros, and the words in text
lines. They are subject to groff's horizontal spacing calcula‐
tions. 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 charac‐
ters. Continuation lines can be specified by an escaped new‐
line, i.e., by specifying a backslash ‘\’ as the last character
of a line.
tab If a tab character occurs during text the interpreter makes a
horizontal jump to the next pre-defined tab position. There is
a sophisticated interface for handling tab positions.
NUMERICAL EXPRESSIONS
A numerical value is a signed or unsigned integer or float with or
without an appended scale indicator. A scale indicator is a one-char‐
acter abbreviation for a unit of measurement. A number followed by a
scale indicator signifies 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 numerical expres‐
sions:
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 re‐
quests. The following table characterizes the different types of con‐
ditions.
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 arbitrarily long. No bracket‐
ing or marking of long names is needed.
Most requests take one or more arguments. The arguments are separated
by space characters (no tabs!); there is no inherent limit for their
length or number. An argument can be enclosed by a pair of double
quotes: This is very handy if an argument contains space characters,
e.g., "arg with space" denotes a single argument.
Some requests have optional arguments with a different behaviour. Not
all of these details are outlined here. Refer to the groff info file
for all details.
In the following request specifications, most argument names were cho‐
sen to be descriptive. Only the following denotations need clarifica‐
tion.
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 already existing value in‐
herent 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 current 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 escape 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 ob‐
ject.
.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, 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 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 contained 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 disabled.
.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 current environ‐
ment. 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 internal 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 character.
.hc c Set up additional hyphenation indicator character 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 indicator 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, otherwise 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 register.
.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 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 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 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 indicator 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, spacing, and in‐
dent.
.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-increment 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 indicator 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 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 in‐
put 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 char‐
acters 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 substring 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 re‐
quest.
.sy command-line
Execute program command-line.
.ta T N Set tabs after every position that is a multiple of N (de‐
fault 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 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 terminal (UNIX standard message output).
.tm1 anything
Print anything on terminal (UNIX standard message output),
allowing leading whitespace if anything starts with " (which
will be 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.
.trnt abcd....
This is the same as the .tr request except that the transla‐
tions 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 informa‐
tion 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 bottom.
.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 further macro
calls. They can originate from a macro package (see roff(7) for an
overview) or from a preprocessor.
Preprocessor macros are easy to be recognized. They enclose their code
into a pair of characteristic macros.
┌─────────────┬─────────────┬────────────┐
│preprocessor │ start macro │ end macro │
├─────────────┼─────────────┼────────────┤
│ eqn │ .PS │ .PE │
│ grap │ .G1 │ .G2 │
│ grn │ .GS │ .GE │
│ pic │ .PS │ .PE │
│ refer │ .R1 │ .R2 │
│ soelim │ none │ none │
│ tbl │ .TS │ .TE │
└─────────────┴─────────────┴────────────┘
ESCAPE SEQUENCES
Escape sequences are in-line language elements usually introduced by a
backslash ‘\’ and followed by an escape name and sometimes by a re‐
quired argument. Input processing is continued directly after the es‐
caped character or the argument resp. without an intervening separation
character. So there must be a way to determine the end of the escape
name and the end of the argument.
This is done by enclosing names (escape name and arguments consisting
of a variable name) by a pair of brackets \[name] and constant argu‐
ments (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 apostrophes, too,
but there is no two-character analogue.
While 1-character escape sequences are mainly used for in-line func‐
tions and system related tasks, the 2-letter names following the \(
construct are used for special characters predefined by the roff sys‐
tem. 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 arbitrary length
name stringvar.
\$0 The name by which the current macro was invoked. The .als re‐
quest 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 ex‐
pression 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 separated by spaces.
\\ reduces to a single backslash; useful to delay its interpreta‐
tion as escape character in copy mode. For a printable back‐
slash, use \e.
\’ The acute accent ´; same as \(aa. Unescaped: apostrophe, right
quotation mark, single quote (ASCII 0x27).
\` The grave accent `; same as \(ga. Unescaped: left quote, back‐
quote (ASCII 0x60).
\- The - sign in the current font.
\. An uninterpreted dot (period), even at start of line.
\% Default optional hyphenation character.
\! Transparent line indicator.
\?anything?
In a diversion, this will transparently embed anything in the
diversion. anything is read in copy mode. See also the escape
sequences \! and \?.
\space Unpaddable space-size space character (no line break).
\0 Digit width.
\| 1/6 em narrow space character; zero width in nroff.
\^ 1/12 em half-narrow space character; zero width in nroff.
\& Non-printable, zero width character.
\) Like \& except that it behaves like a character declared with
the cflags request to be transparent for the purposes of end of
sentence recognition.
\/ Increases the width of the preceding character so that the spac‐
ing between that character and the following character will be
correct if the following character is a roman character.
\, Modifies the spacing of the following character so that the
spacing between that character and the preceding character will
correct if the preceding character is a roman character.
\~ Unbreakable space that stretches like a normal inter-word space
when a line is adjusted.
\: Inserts a zero-width break point (similar to \% 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 SPE‐
CIAL 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, diver‐
sion, register, environment or font it expands to 1, and 0 oth‐
erwise.
\b’abc...’
Bracket building function.
\B’anything’
If anything is acceptable as a valid numeric expression it ex‐
pands 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 interpreted 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 number 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. Alter‐
native forms \g(xy and \gx.
\h’N’ Local horizontal motion; move right N (left if negative).
\H’N’ Set height of current font to N.
\k[reg]
Mark horizontal input place in register with arbitrary 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 arbi‐
trary lenght name reg.
\N’n’ Typeset the character with code n in the current font, no spe‐
cial fonts are searched. Useful for adding characters to a font
using the .char request.
\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, \s±x. 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 negative).
\V[env]
The contents of the environment variable env. Alternative forms
\V(xy and \Vx.
\w’string’
The width of the character sequence string.
\x’N’ Extra line-space function (negative before, positive 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 po‐
sition; 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 charac‐
ter escape sequences, but introduce escape names with two or more char‐
acters.
If a backslash is followed by a character that does not constitute a
defined escape sequence the backslash is silently ignored and the char‐
acter maps to itself.
SPECIAL CHARACTERS
Common special characters are predefined by escape sequences of the
form \(xy with characters x and y. Some of these exist in the usual
font while most of them are only available in the special font. Below
you'll find a selection of the most important glyphs; a complete list
can be found in groff_char(7).
\(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 NUMERICAL EXPRESSIONS above), but
some can also hold a string value.
Each register is given a name. Arbitrary registers can be defined and
set with the request .nr register.
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 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 modi‐
fied by the user (usually, registers starting with a dot a read-only).
Mostly, they provide information on the current settings or store re‐
sults from request calls.
\n[.$] Number of arguments in the current macro.
\n[.a] Post-line extra line-space most recently utilized 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 otherwise.
\n[.cdp] The depth of the last character added to the current environ‐
ment. 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 envi‐
ronment. It is positive if the character extends above the
baseline.
\n[.csk] The skew of the last character added to the current environ‐
ment. The skew of a character is how far to the right of the
center of a character the center of an accent over that char‐
acter should be placed.
\n[.d] Current vertical place in current diversion; equal to regis‐
ter nl.
\n[.ev] The name or number of the current environment (string-val‐
ued).
\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 run‐
ning 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 hyphenated 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 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[.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 current 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 decimal 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 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
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 po‐
sition would have been but for the trap, and what the verti‐
cal position actually is. Useful in conjunction with the .ne
register.
\n[.ss] The value of the parameters set by the first argument 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 otherwise.
\n[.w] Width of previous character.
\n[.warn] The sum of the number codes of the currently enabled warn‐
ings.
\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 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[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 char‐
acters.
\n[rst] Like st, but takes account of the heights and depths of char‐
acters.
\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 memory is exhausted.
\n[ssc] The amount of horizontal space (possibly negative) 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 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.
WARNINGS
Each warning generated by groff is identified by a name and a code num‐
ber. The codes are powers of 2 to allow bit-encoding with a single in‐
teger. 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] regis‐
ter.
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 cur‐
rent 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 default.
ig 262144
Illegal escapes in text ignored with the .ig request.
These are conditions that are errors when they occur out‐
side of ignored text.
mac 512
Use of undefined strings, macros, and diversions. Automat‐
ically handled as empty. Usually, only one warning per
name.
missing 8192
Request that is missing non-optional arguments.
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. Automatically defined as
having value 0. Usually, only 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 number 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 │ │
└────────────────────┴──────────────────────────┴──────────────────────┘
COMPATIBILITY
groff provides a compatibility mode that allows to process roff code
written for classical or for other implementations of roff in a consis‐
tent 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 inter‐
pret this as a call of a macro named dsabcd.
Also classical troff will interpret \*[ or \n[ as references to a
string or number register called [. In GNU native mode, however, this
will normally be interpreted as the start of a long name.
In compatibility mode, groff will interpret these things in the tradi‐
tional 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 se‐
quence can be helpful in avoiding these escape sequences in names.
Fractional pointsizes cause one noteworthy incompatibility. In classi‐
cal troff, the .ps request ignores scale indicators and so
.ps 10u
will set the pointsize to 10 points, whereas in groff native 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 characters. Everything that af‐
fects how an output character will be output is stored with the charac‐
ter; once an output 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 characters
in any combination.
An output character does not behave like an input character for the
purposes of macro processing; it does not inherit any of the special
properties that the input character 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 back‐
slashes ‘\\’ is turned into a single output backslash ‘\’ and the re‐
sulting 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 se‐
quence. 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 traditional \! transparent
output facility or the new \? escape 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 inconsisten‐
cies between different documents 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 doc‐
umentation, but the gory details are found in the groff info file.
SEE ALSO
The main source of information for the groff language is the groff in‐
fo(1) file.
For a survey of roff and the groff system and further documentation
pointers see roff(7).
The formatter programs are described in groff(1) and troff(1); a com‐
plete 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)
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