troff - format documents
troff [ -abivzCERU ] [ -wname ] [ -Wname ] [ -dcs ] [ -ffam ]
[ -mname ] [ -nnum ] [ -olist ] [ -rcn ] [ -Tname ] [ -Fdir ]
[ -Mdir ] [ files... ]
It is possible to have whitespace between a command line option and its
parameter.
This manual page describes the GNU version of troff, which is part of
the groff document formatting system. It is highly compatible with
UNIX troff. Usually it should be invoked using the groff command,
which will also run preprocessors and postprocessors in the appropriate
order and with the appropriate options.
-a Generate an ASCII approximation of the typeset output.
-b Print a backtrace with each warning or error message. This
backtrace should help track down the cause of the error. The
line numbers given in the backtrace may not always be correct:
troff's idea of line numbers gets confused by as or am
requests.
-i Read the standard input after all the named input files have
been processed.
-v Print the version number.
-wname Enable warning name. Available warnings are described in the
Warnings subsection below. Multiple -w options are allowed.
-Wname Inhibit warning name. Multiple -W options are allowed.
-E Inhibit all error messages of troff. Note that this doesn't
affect messages output to standard error by macro packages
using the .tm or .tm1 requests.
-z Suppress formatted output.
-C Enable compatibility mode.
-dcs
-dname=s Define c or name to be a string s; c must be a one letter
name.
-ffam Use fam as the default font family.
-mname Read in the file name.tmac. If it isn't found, try tmac.name
instead. It will be first searched for in directories given
with the -M command line option, then in directories given in
the GROFF_TMAC_PATH environment variable, then in the current
directory (only if in unsafe mode), the home directory,
/usr/lib/groff/site-tmac, /usr/share/groff/site-tmac, and
/usr/share/groff/1.17.2/tmac.
-U Unsafe mode. This will enable the following requests: .open,
.opena, .pso, .sy, and .pi. For security reasons, these
potentially dangerous requests are disabled otherwise. It
will also add the current directory to the macro search path.
-R Don't load troffrc and troffrc-end.
-nnum Number the first page num.
-olist Output only pages in list, which is a comma-separated list of
page ranges; n means print page n, m-n means print every page
between m and n, -n means print every page up to n, n- means
print every page from n. Troff will exit after printing the
last page in the list.
-rcn
-rname=n Set number register c or name to n; c must be a one character
name; n can be any troff numeric expression.
-Tname Prepare output for device name, rather than the default ps.
-Fdir Search in directory (or directory path) dir for subdirectories
devname (name is the name of the device) and there for
the DESC file and font files. dir is scanned before all
other font directories.
-Mdir Search directory (or directory path) dir for macro files.
This is scanned before all other macro directories.
Only the features not in UNIX troff are described here.
Long names [Toc] [Back]
The names of number registers, fonts, strings/macros/diversions, special
characters can be of any length. In escape sequences, where you
can use (xx for a two character name, you can use [xxx] for a name of
arbitrary length:
\[xxx] Print the special character called xxx.
\f[xxx]
Set font xxx.
\*[xxx]
Interpolate string xxx.
\n[xxx]
Interpolate number register xxx.
Fractional pointsizes [Toc] [Back]
A scaled point is equal to 1/sizescale points, where sizescale is specified
in the DESC file (1 by default). There is a new scale indicator
z which has the effect of multiplying by sizescale. Requests and
escape sequences in troff interpret arguments that represent a pointsize
as being in units of scaled points, but they evaluate each such
argument using a default scale indicator of z. Arguments treated in
this way are the argument to the ps request, the third argument to the
cs request, the second and fourth arguments to the tkf request, the
argument to the \H escape sequence, and those variants of the \s escape
sequence that take a numeric expression as their argument.
For example, suppose sizescale is 1000; then a scaled point will be
equivalent to a millipoint; the request .ps 10.25 is equivalent to .ps
10.25z and so sets the pointsize to 10250 scaled points, which is equal
to 10.25 points.
The number register \n[.s] returns the pointsize in points as decimal
fraction. There is also a new number register \n[.ps] that returns the
pointsize in scaled points.
It would make no sense to use the z scale indicator in a numeric
expression whose default scale indicator was neither u nor z, and so
troff disallows this. Similarly it would make no sense to use a scaling
indicator other than z or u in a numeric expression whose default
scale indicator was z, and so troff disallows this as well.
There is also new scale indicator s which multiplies by the number of
units in a scaled point. So, for example, \n[.ps]s is equal to 1m. Be
sure not to confuse the s and z scale indicators.
Numeric expressions [Toc] [Back]
Spaces are permitted in a number expression within parentheses.
M indicates a scale of 100ths of an em.
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. If c is
missing, ignore scaling indicators in the evaluation of e.
New escape sequences [Toc] [Back]
\A'anything'
This expands to 1 or 0 according as anything is or is not
acceptable as the name of a string, macro, diversion, number
register, environment or font. It will return 0 if anything is
empty. This is useful if you want to lookup user input in some
sort of associative table.
\B'anything'
This expands to 1 or 0 according as anything is or is not a
valid numeric expression. It will return 0 if anything is
empty.
\C'xxx'
Typeset character named xxx. Normally it is more convenient to
use \[xxx]. But \C has the advantage that it is compatible with
recent versions of UNIX and is available in compatibility mode.
\E This is equivalent to an escape character, but it's not interpreted
in copy-mode. For example, strings to start and end
superscripting could be defined like this:
.ds { \v'-.3m'\s'\En[.s]*6u/10u'
.ds } \s0\v'.3m'
The use of \E ensures that these definitions will work even if
\*{ gets interpreted in copy-mode (for example, by being used in
a macro argument).
\N'n' Typeset the character with code n in the current font. n can be
any integer. Most devices only have characters with codes
between 0 and 255. If the current font does not contain a character
with that code, special fonts will not be searched. The
\N escape sequence can be conveniently used on conjunction with
the char request:
.char \[phone] \f(ZD\N'37'
The code of each character is given in the fourth column in the
font description file after the charset command. It is possible
to include unnamed characters in the font description file by
using a name of ---; the \N escape sequence is the only way to
use these.
\R'name +-n'
This has the same effect as
.nr name +-n
\s(nn
\s+-(nn
Set the point size to nn points; nn must be exactly two digits.
\s[+-n]
\s+-[n]
\s'+-n'
\s+-'n'
Set the point size to n scaled points; n is a numeric expression
with a default scale indicator of z.
\Vx
\V(xx
\V[xxx]
Interpolate the contents of the environment variable xxx, as
returned by getenv(3). \V is interpreted in copy-mode.
\Yx
\Y(xx
\Y[xxx]
This is approximately equivalent to \X'\*[xxx]'. However the
contents of the string or macro xxx are not interpreted; also it
is permitted for xxx to have been defined as a macro and thus
contain newlines (it is not permitted for the argument to \X to
contain newlines). The inclusion of newlines requires an extension
to the UNIX troff output format, and will confuse drivers
that do not know about this extension.
\Z'anything'
Print anything and then restore the horizontal and vertical
position; anything may not contain tabs or leaders.
\$0 The name by which the current macro was invoked. The als
request can make a macro have more than one name.
\$* 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.
\$(nn
\$[nnn]
In a macro, this gives the nn-th or nnn-th argument. Macros can
have an unlimited number of arguments.
\?anything\?
When used in a diversion, this will transparently embed anything
in the diversion. anything is read in copy mode. When the
diversion is reread, anything will be interpreted. anything may
not contain newlines; use \! if you want to embed newlines in a
diversion. The escape sequence \? is also recognised in copy
mode and turned into a single internal code; it is this code
that terminates anything. Thus
.nr x 1
.nf
.di d
\?\\?\\\\?\\\\\\\\nx\\\\?\\?\?
.di
.nr x 2
.di e
.d
.di
.nr x 3
.di f
.e
.di
.nr x 4
.f
will print 4.
\/ This increases the width of the preceding character so that the
spacing between that character and the following character will
be correct if the following character is a roman character. For
example, if an italic f is immediately followed by a roman right
parenthesis, then in many fonts the top right portion of the f
will overlap the top left of the right parenthesis producing f),
which is ugly. Inserting \/ produces f) and avoids this problem.
It is a good idea to use this escape sequence whenever an
italic character is immediately followed by a roman character
without any intervening space.
\, This 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. For
example, inserting \, between the parenthesis and the f changes
(f to (f. It is a good idea to use this escape sequence whenever
a roman character is immediately followed by an italic
character without any intervening space.
\) Like \& except that it behaves like a character declared with
the cflags request to be transparent for the purposes of end of
sentence recognition.
\~ This produces an unbreakable space that stretches like a normal
inter-word space when a line is adjusted.
\: This causes the insertion of a zero-width break point. It is
equal to \% but without insertion of a soft hyphen character.
\# Everything up to and including the next newline is ignored.
This is interpreted in copy mode. This is like \" except that
\" does not ignore the terminating newline.
New requests [Toc] [Back]
.aln xx yy
Create an alias xx for number register object named yy. The new
name and the old name will be exactly equivalent. If yy is
undefined, a warning of type reg will be generated, and the
request will be ignored.
.als xx yy
Create an alias xx for request, string, macro, or diversion
object named yy. The new name and the old name will be exactly
equivalent (it is similar to a hard rather than a soft link).
If yy is undefined, a warning of type mac will be generated, and
the request will be ignored. The de, am, di, da, ds, and as
requests only create a new object if the name of the macro,
diversion or string diversion is currently undefined or if it is
defined to be a request; normally they modify the value of an
existing object.
.am1 xx yy
Similar to .am, but compatibility mode is switched off during
execution. On entry, the current compatibility mode is saved
and restored at exit.
.asciify xx
This request `unformats' the diversion xx in such a way that
ASCII and space characters (and some escape sequences) that were
formatted and diverted into xx will be treated like ordinary
input characters when xx is reread. Useful for diversions in
conjunction with the .writem request. It can be also used for
gross hacks; for example, this
.tr @.
.di x
@nr n 1
.br
.di
.tr @@
.asciify x
.x
will set register n to 1. Note that glyph information (font,
font size, etc.) is not preserved; use .unformat instead.
.backtrace
Print a backtrace of the input stack on stderr.
.blm xx
Set the blank line macro to xx. If there is a blank line macro,
it will be invoked when a blank line is encountered instead of
the usual troff behaviour.
.box xx
.boxa xx
These requests are similar to the di and da requests with the
exception that a partially filled line will not become part of
the diversion (i.e., the diversion always starts with a new
line) but restored after ending the diversion, discarding the
partially filled line which possibly comes from the diversion.
.break Break out of a while loop. See also the while and continue
requests. Be sure not to confuse this with the br request.
.brp This is the same as \p.
.cflags n c1 c2...
Characters c1, c2,... have properties determined by n, which is
ORed from the following:
1 the character ends sentences (initially characters .?!
have this property);
2 lines can be broken before the character (initially no
characters have this property); a line will not be broken
at a character with this property unless the characters
on each side both have non-zero hyphenation codes.
4 lines can be broken after the character (initially characters
-\(hy\(em have this property); a line will not be
broken at a character with this property unless the characters
on each side both have non-zero hyphenation codes.
8 the character overlaps horizontally (initially characters
\(ul\(rn\(ru have this property);
16 the character overlaps vertically (initially character
\(br has this property);
32 an end of sentence character followed by any number of
characters with this property will be treated as the end
of a sentence if followed by a newline or two spaces; in
other words the character is transparent for the purposes
of end of sentence recognition; this is the same as having
a zero space factor in TeX (initially characters
"')]*\(dg\(rq have this property).
.char c string
Define character c to be string. Every time character c needs
to be printed, string will be processed in a temporary environment
and the result will be wrapped up into a single object.
Compatibility mode will be turned off and the escape character
will be set to \ while string is being processed. Any emboldening,
constant spacing or track kerning will be applied to this
object rather than to individual characters in string. A character
defined by this request can be used just like a normal
character provided by the output device. In particular other
characters can be translated to it with the tr request; it can
be made the leader character by the lc request; repeated patterns
can be drawn with the character using the \l and \L escape
sequences; words containing the character can be hyphenated correctly,
if the hcode request is used to give the character a
hyphenation code. There is a special anti-recursion feature:
use of character within the character's definition will be handled
like normal characters not defined with char. A character
definition can be removed with the rchar request.
.chop xx
Chop the last character off macro, string, or diversion xx.
This is useful for removing the newline from the end of diversions
that are to be interpolated as strings.
.close stream
Close the stream named stream; stream will no longer be an
acceptable argument to the write request. See the open request.
.continue
Finish the current iteration of a while loop. See also the
while and break requests.
.cp n If n is non-zero or missing, enable compatibility mode, otherwise
disable it. In compatibility mode, long names are not
recognised, and the incompatibilities caused by long names do
not arise.
.dei xx yy
Define macro indirectly. The following example
.ds xx aa
.ds yy bb
.dei xx yy
is equivalent to
.de aa bb
.de1 xx yy
Similar to .de, but compatibility mode is switched off during
execution. On entry, the current compatibility mode is saved
and restored at exit.
.do xxx
Interpret .xxx with compatibility mode disabled. For example,
.do fam T
would have the same effect as
.fam T
except that it would work even if compatibility mode had been
enabled. Note that the previous compatibility mode is restored
before any files sourced by xxx are interpreted.
.ecs Save current escape character.
.ecr Restore escape character saved with ecs. Without a previous
call to ecs, `\' will be the new escape character.
.evc xx
Copy the contents of environment xx to the current environment.
No pushing or popping of environents will be done.
.fam xx
Set the current font family to xx. The current font family is
part of the current environment. If xx is missing, switch back
to previous font family. See the description of the sty request
for more information on font families.
.fspecial f s1 s2...
When the current font is f, fonts s1, s2,... will be special,
that is, they will searched for characters not in the current
font. Any fonts specified in the special request will be
searched after fonts specified in the fspecial request.
.ftr f g
Translate font f to g. Whenever a font named f is referred to
in \f escape sequence, or in the ft, ul, bd, cs, tkf, special,
fspecial, fp, or sty requests, font g will be used. If g is
missing, or equal to f then font f will not be translated.
.hcode c1 code1 c2 code2...
Set the hyphenation code of character c1 to code1 and that of c2
to code2. A hyphenation code must be a single input character
(not a special character) other than a digit or a space. Initially
each lower-case letter has a hyphenation code, which is
itself, and each upper-case letter has a hyphenation code which
is the lower case version of itself. See also the hpf request.
.hla lang
Set the current hyphenation language to lang. Hyphenation
exceptions specified with the hw request and hyphenation patterns
specified with the hpf request are both associated with
the current hyphenation language. The hla request is usually
invoked by the troffrc file.
.hlm n Set the maximum number of consecutive hyphenated lines to n. If
n is negative, there is no maximum. The default value is -1.
This value is associated with the current environment. Only
lines output from an environment count towards the maximum associated
with that environment. Hyphens resulting from \% are
counted; explicit hyphens are not.
.hpf file
Read hyphenation patterns from file; this will be searched for
in the same way that name.tmac is searched for when the -mname
option is specified. It should have the same format as the
argument to the \patterns primitive in TeX; the letters appearing
in this file are interpreted as hyphenation codes. A %
character in the patterns file introduces a comment that continues
to the end of the line. The set of hyphenation patterns is
associated with the current language set by the hla request.
The hpf request is usually invoked by the troffrc file.
.hym n Set the hyphenation margin to n: when the current adjustment
mode is not b, the line will not be hyphenated if the line is no
more than n short. The default hyphenation margin is 0. The
default scaling indicator for this request is m. The hyphenation
margin is associated with the current environment. The
current hyphenation margin is available in the \n[.hym] register.
.hys n Set the hyphenation space to n: when the current adjustment mode
is b don't hyphenate the line if the line can be justified by
adding no more than n extra space to each word space. The
default hyphenation space is 0. The default scaling indicator
for this request is m. The hyphenation space is associated with
the current environment. The current hyphenation space is
available in the \n[.hys] register.
.kern n
If n is non-zero or missing, enable pairwise kerning, otherwise
disable it.
.length xx string
Compute the length of string and return it in the number register
xx (which is not necessarily defined before).
.linetabs n
If n is non-zero or missing, enable line-tabs mode, otherwise
disable it (which is the default). In line-tabs mode, tab distances
are computed relative to the (current) output line. Otherwise
they are taken relative to the input line. For example,
the following
.ds x a\t\c
.ds y b\t\c
.ds z c
.ta 1i 3i
\*x
\*y
\*z
yields
a b c
In line-tabs mode, the same code gives
a b c
Line-tabs mode is associated with the current environment; the
read-only number register \n[.linetabs] is set to 1 if in linetabs
mode, and 0 otherwise.
.mso file
The same as the so request except that file is searched for in
the same directories as macro files for the the -m command line
option. If the file name to be included has the form name.tmac
and it isn't found, mso tries to include tmac.name instead and
vice versa.
.nop anything
Execute anything. This is similar to `.if 1'.
.nroff Make the n built-in condition true and the t built-in condition
false. This can be reversed using the troff request.
.open stream filename
Open filename for writing and associate the stream named stream
with it. See also the close and write requests.
.opena stream filename
Like open, but if filename exists, append to it instead of truncating
it.
.pnr Print the names and contents of all currently defined number
registers on stderr.
.psbb filename
Get the bounding box of a PostScript image filename. This file
must conform to Adobe's Document Structuring Conventions; the
command looks for a %%BoundingBox comment to extract the bounding
box values. After a successful call, the coordinates (in
PostScript units) of the lower left and upper right corner can
be found in the registers \n[llx], \n[lly], \n[urx], and
\n[ury], respectively. If some error has occurred, the four
registers are set to zero.
.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. Empty slots in the
page trap list are printed as well, because they can affect the
priority of subsequently planted traps.
.rchar c1 c2...
Remove the definitions of characters c1, c2,... This undoes the
effect of a char request.
.return
Within a macro, return immediately. No effect otherwise.
.rj
.rj n Right justify the next n input lines. Without an argument right
justify the next input line. The number of lines to be right
justified is available in the \n[.rj] register. This implicitly
does .ce 0. The ce request implicitly does .rj 0.
.rnn xx yy
Rename number register xx to yy.
.shc c Set the soft hyphen character to c. If c is omitted, the soft
hyphen character will be set to the default \(hy. The soft
hyphen character is the character which will be inserted when a
word is hyphenated at a line break. If the soft hyphen character
does not exist in the font of the character immediately preceding
a potential break point, then the line will not be broken
at that point. Neither definitions (specified with the char
request) nor translations (specified with the tr request) are
considered when finding the soft hyphen character.
.shift n
In a macro, shift the arguments by n positions: argument i
becomes argument i-n; arguments 1 to n will no longer be available.
If n is missing, arguments will be shifted by 1. Shifting
by negative amounts is currently undefined.
.special s1 s2...
Fonts s1, s2, are special and will be searched for characters
not in the current font.
.sty n f
Associate style f with font position n. A font position can be
associated either with a font or with a style. The current font
is the index of a font position and so is also either a font or
a style. When it is a style, the font that is actually used is
the font the name of which is the concatenation of the name of
the current family and the name of the current style. For example,
if the current font is 1 and font position 1 is associated
with style R and the current font family is T, then font TR will
be used. If the current font is not a style, then the current
family is ignored. When the requests cs, bd, tkf, uf, or fspe-
cial are applied to a style, then they will instead be applied
to the member of the current family corresponding to that style.
The default family can be set with the -f option. The styles
command in the DESC file controls which font positions (if any)
are initially associated with styles rather than fonts.
.substring xx n1 [n2]
Replace the string in register xx with the substring defined by
the indices n1 and n2. The first character in the string has
index one. If n2 is omitted, it is taken to be equal to the
string's length. If the index value n1 or n2 is negative or
zero, it will be counted from the end of the string, going backwards:
The last character has index 0, the character before the
last character has index -1, etc.
.tkf f s1 n1 s2 n2
Enable track kerning for font f. When the current font is f the
width of every character will be increased by an amount between
n1 and n2; when the current point size is less than or equal to
s1 the width will be increased by n1; when it is greater than or
equal to s2 the width will be increased by n2; when the point
size is greater than or equal to s1 and less than or equal to s2
the increase in width is a linear function of the point size.
.tm1 string
Similar to the tm request, string is read in copy mode and written
on the standard error, but an initial double quote in string
is stripped off to allow initial blanks.
.tmc string
Similar to tm1 but without writing a final newline.
.trf filename
Transparently output the contents of file filename. Each line
is output as it would be were it preceded by \!; however, the
lines are not subject to copy-mode interpretation. If the file
does not end with a newline, then a newline will be added. For
example, you can define a macro x containing the contents of
file f, using
.di x
.trf f
.di
Unlike with the cf request, the file cannot contain characters
such as NUL that are not legal troff input characters.
.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 \!. For example,
.tr ab
.di x
\!.tm a
.di
.x
will print b; if trnt is used instead of tr it will print a.
.troff Make the n built-in condition false, and the t built-in condition
true. This undoes the effect of the nroff request.
.unformat xx
This request `unformats' the diversion xx. Contrary to the
.asciify request, which tries to convert formatted elements of
the diversion back to input tokens as much as possible, .unfor-
mat will only handle tabs and spaces between words (usually
caused by spaces or newlines in the input) specially. The former
are treated as if they were input tokens, and the latter are
stretchable again. Note that the vertical size of lines is not
preserved. Glyph information (font, font size, space width,
etc.) is retained. Useful in conjunction with the .box and
.boxa requests.
.vpt n Enable vertical position traps if n is non-zero, disable them
otherwise. Vertical position traps are traps set by the wh or
dt requests. Traps set by the it request are not vertical position
traps. The parameter that controls whether vertical position
traps are enabled is global. Initially vertical position
traps are enabled.
.warn n
Control warnings. n is the sum of the numbers associated with
each warning that is to be enabled; all other warnings will be
disabled. The number associated with each warning is listed in
the `Warnings' section. For example, .warn 0 will disable all
warnings, and .warn 1 will disable all warnings except that
about missing characters. If n is not given, all warnings will
be enabled.
.while c anything
While condition c is true, accept anything as input; c can be
any condition acceptable to an if request; anything can comprise
multiple lines if the first line starts with \{ and the last
line ends with \}. See also the break and continue requests.
.write stream anything
Write anything to the stream named stream. stream must previously
have been the subject of an open request. anything is
read in copy mode; a leading " will be stripped.
.writem stream xx
Write the contents of the macro or string xx to the stream named
stream. stream must previously have been the subject of an open
request. xx is read in copy mode.
Extended requests [Toc] [Back]
.cf filename
When used in a diversion, this will embed in the diversion an
object which, when reread, will cause the contents of filename
to be transparently copied through to the output. In UNIX
troff, the contents of filename is immediately copied through to
the output regardless of whether there is a current diversion;
this behaviour is so anomalous that it must be considered a bug.
.ev xx If xx is not a number, this will switch to a named environment
called xx. The environment should be popped with a matching ev
request without any arguments, just as for numbered environments.
There is no limit on the number of named environments;
they will be created the first time that they are referenced.
.fp n f1 f2
The fp request has an optional third argument. This argument
gives the external name of the font, which is used for finding
the font description file. The second argument gives the internal
name of the font which is used to refer to the font in troff
after it has been mounted. If there is no third argument then
the internal name will be used as the external name. This feature
allows you to use fonts with long names in compatibility
mode.
.ss m n
When two arguments are given to the ss request, the second argument
gives the sentence space size. If the second argument is
not given, the sentence space size will be the same as the word
space size. Like the word space size, the sentence space is in
units of one twelfth of the spacewidth parameter for the current
font. Initially both the word space size and the sentence space
size are 12. Contrary to UNIX troff, GNU troff handles this
request in nroff mode also; a given value is then rounded down
to the nearest multiple of 12. The sentence space size is used
in two circumstances: if the end of a sentence occurs at the end
of a line in fill mode, then both an inter-word space and a sentence
space will be added; if two spaces follow the end of a
sentence in the middle of a line, then the second space will be
a sentence space. Note that the behaviour of UNIX troff will be
exactly that exhibited by GNU troff if a second argument is
never given to the ss request. In GNU troff, as in UNIX troff,
you should always follow a sentence with either a newline or two
spaces.
.ta n1 n2...nn T r1 r2...rn
Set tabs at positions n1, n2,..., nn and then set tabs at nn+r1,
nn+r2,...., nn+rn and then at nn+rn+r1, nn+rn+r2,..., nn+rn+rn,
and so on. For example,
.ta T .5i
will set tabs every half an inch.
New number registers [Toc] [Back]
The following read-only registers are available:
\n[.C] 1 if compatibility mode is in effect, 0 otherwise.
\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 current environment.
The skew of a character is how far to the right of the center of
a character the center of an accent over that character should
be placed.
\n[.ev]
The name or number of the current environment. This is a
string-valued register.
\n[.fam]
The current font family. This is a string-valued register.
\n[.fp]
The number of the next free font position.
\n[.g] Always 1. Macros should use this to determine whether they are
running under GNU troff.
\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[.in]
The indent that applies to the current output line.
\n[.int]
Set to a positive value if last output line is interrupted
(i.e., if it contains \c).
\n[.kern]
1 if pairwise kerning is enabled, 0 otherwise.
\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[.ne]
The amount of space that was needed in the last ne request that
caused a trap to be sprung. Useful in conjunction with the
\n[.trunc] register.
\n[.ns]
1 if no-space mode is active, 0 otherwise.
\n[.pn]
The number of the next page: either the value set by a pn
request, or the number of the current page plus 1.
\n[.ps]
The current 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[.sr]
The last requested pointsize in points as a decimal fraction.
This is a string-valued register.
\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 the
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 \n[.ne] register.
\n[.ss]
\n[.sss]
These give the values of the parameters set by the first and
second arguments of the ss request.
\n[.vpt]
1 if vertical position traps are enabled, 0 otherwise.
\n[.warn]
The sum of the numbers associated with each of the currently
enabled warnings. The number associated with each warning is
listed in the `Warnings' subsection.
\n[.x] The major version number. For example, if the version number is
1.03 then \n[.x] will contain 1.
\n[.y] The minor version number. For example, if the version number is
1.03 then \n[.y] will contain 03.
\n[.Y] The revision number of groff.
\n[llx]
\n[lly]
\n[urx]
\n[ury]
These four registers are set by the .psbb request and contain
the bounding box values (in PostScript units) of a given PostScript
image.
The following read/write registers are set by the \w escape sequence:
\n[rst]
\n[rsb]
Like the st and sb registers, but takes account of the heights
and depths of characters.
\n[ssc]
The amount of horizontal space (possibly negative) that should
be added to the last character before a subscript.
\n[skw]
How far to right of the center of the last character in the \w
argument, the center of an accent from a roman font should be
placed over that character.
Other available read/write number registers are:
\n[c.] The current input line number. \n[.c] is a read-only alias to
this register.
\n[hp] The current horizontal position at input line.
\n[systat]
The return value of the system() function executed by the last
sy request.
\n[slimit]
If greater than 0, the maximum number of objects on the input
stack. If less than or equal to 0, there is no limit on the
number of objects on the input stack. With no limit, recursion
can continue until virtual memory is exhausted.
\n[year]
The current year. Note that the traditional troff number register
\n[yr] is the current year minus 1900.
Miscellaneous [Toc] [Back]
troff predefines a single (read/write) string-based register, \*(.T,
which contains the argument given to the -T command line option, namely
the current output device (for example, latin1 or ascii). Note that
this is not the same as the (read-only) number register \n[.T] which is
defined to be 1 if troff is called with the -T command line option, and
zero otherwise. This behaviour is different to UNIX troff.
Fonts not listed in the DESC file are automatically mounted on the next
available font position when they are referenced. If a font is to be
mounted explicitly with the fp request on an unused font position, it
should be mounted on the first unused font position, which can be found
in the \n[.fp] register; although troff does not enforce this strictly,
it will not allow a font to be mounted at a position whose number is
much greater than that of any currently used position.
Interpolating a string does not hide existing macro arguments. Thus in
a macro, a more efficient way of doing
.xx \\$@
is
\\*[xx]\\
If the font description file contains pairwise kerning information,
characters from that font will be kerned. Kerning between two characters
can be inhibited by placing a \& between them.
In a string comparison in a condition, characters that appear at different
input levels to the first delimiter character will not be recognised
as the second or third delimiters. This applies also to the tl
request. In a \w escape sequence, a character that appears at a different
input level to the starting delimiter character will not be
recognised as the closing delimiter character. When decoding a macro
argument that is delimited by double quotes, a character that appears
at a different input level to the starting delimiter character will not
be recognised as the closing delimiter character. The implementation
of \$@ ensures that the double quotes surrounding an argument will
appear the same input level, which will be different to the input level
of the argument itself. In a long escape name ] will not be recognized
as a closing delimiter except when it occurs at the same input level as
the opening ]. In compatibility mode, no attention is paid to the
input-level.
There are some new types of condition:
.if rxxx
True if there is a number register named xxx.
.if dxxx
True if there is a string, macro, diversion, or request named
xxx.
.if cch
True if there is a character ch available; ch is either an ASCII
character or a special character \(xx or \[xxx]; the condition
will also be true if ch has been defined by the char request.
The tr request can now map characters onto \~.
Warnings [Toc] [Back]
The warnings that can be given by troff are divided into the following
categories. The name associated with each warning is used by the -w
and -W options; the number is used by the warn request, and by the
.warn register.
char 1 Non-existent characters. This is enabled by
default.
number 2 Invalid numeric expressions. This is enabled by
default.
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.
delim 8 Missing or mismatched closing delimiters.
el 16 Use of the el request with no matching ie request.
scale 32 Meaningless scaling indicators.
range 64 Out of range arguments.
syntax 128 Dubious syntax in numeric expressions.
di 256 Use of di or da without an argument when there is no
current diversion.
mac 512 Use of undefined strings, macros and diversions.
When an undefined string, macro or diversion is
used, that string is automatically defined as empty.
So, in most cases, at most one warning will be given
for each name.
reg 1024 Use of undefined number registers. When an undefined
number register is used, that register is
automatically defined to have a value of 0. a definition
is automatically made with a value of 0. So,
in most cases, at most one warning will be given for
use of a particular name.
tab 2048 Inappropriate use of a tab character. Either use of
a tab character where a number was expected, or use
of tab character in an unquoted macro argument.
right-brace 4096 Use of \} where a number was expected.
missing 8192 Requests that are missing non-optional arguments.
input 16384 Illegal input characters.
escape 32768 Unrecognized escape sequences. When an unrecognized
escape sequence is encountered, the escape character
is ignored.
space 65536 Missing space between a request or macro and its
argument. This warning will be given when an undefined
name longer than two characters is encountered,
and the first two characters of the name make
a defined name. The request or macro will not be
invoked. When this warning is given, no macro is
automatically defined. This is enabled by default.
This warning will never occur in compatibility mode.
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 do
not occur in ignored text.
There are also names that can be used to refer to groups of warnings:
all All warnings except di, mac and reg. It is intended that this
covers all warnings that are useful with traditional macro packages.
w All warnings.
Incompatibilities [Toc] [Back]
Long names cause some incompatibilities. UNIX troff will interpret
.dsabcd
as defining a string ab with contents cd. Normally, GNU troff will
interpret this as a call of a macro named dsabcd. Also UNIX troff will
interpret \*[ or \n[ as references to a string or number register
called [. In GNU troff, however, this will normally be interpreted as
the start of a long name. In compatibility mode GNU troff will interpret
these things in the traditional way. In compatibility mode, however,
long names are not recognised. 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.
GNU troff does not allow the use of the escape sequences
\\|\^\&\}\{\(space)\'\`\-\_\!\%\c in names of strings, macros, diversions,
number registers, fonts or environments; UNIX troff does. The
\A escape sequence may be helpful in avoiding use of these escape
sequences in names.
Fractional pointsizes cause one noteworthy incompatibility. In UNIX
troff the ps request ignores scale indicators and so
.ps 10u
will set the pointsize to 10 points, whereas in GNU troff it will set
the pointsize to 10 scaled points.
In GNU troff there is a fundamental difference between unformatted,
input characters, and formatted, output characters. Everything that
affects how an output character will be output is stored with the character;
once an output character has been constructed it is unaffected
by any subsequent requests that are executed, including 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. For
example,
.di x
\\\\
.br
.di
.x
will print \\ in GNU troff; each pair of input \s is turned into one
output \ and the resulting output \s are not interpreted as escape
characters when they are reread. UNIX troff would interpret them as
escape characters when they were reread and would end up printing one
\. The correct way to obtain 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 troff and UNIX troff. If you wish
for some reason to store in a diversion an escape sequence that will be
interpreted when the diversion is reread, you can either use the traditional
\! transparent output facility, or, if this is unsuitable, the
new \? escape sequence.
GROFF_TMAC_PATH
A colon separated list of directories in which to search for
macro files. troff will scan directories given in the -M option
before these, and in standard directories (current directory if
in unsafe mode, home directory, /usr/share/groff/site-tmac,
/usr/lib/groff/site-tmac, /usr/share/groff/1.17.2/tmac) after
these.
GROFF_TYPESETTER [Toc] [Back]
Default device.
GROFF_FONT_PATH [Toc] [Back]
A colon separated list of directories in which to search for the
devname directory. troff will scan directories given in the -F
option before these, and in standard directories
(/usr/share/groff/1.17.2/font:/usr/lib/font) after these.
/usr/share/groff/1.17.2/tmac/troffrc
Initialization file (called before any other macro package).
/usr/share/groff/1.17.2/tmac/troffrc-end
Initialization file (called after any other macro package).
/usr/share/groff/1.17.2/tmac/name.tmac
/usr/share/groff/1.17.2/tmac/tmac.name
Macro files
/usr/share/groff/1.17.2/font/devname/DESC
Device description file for device name.
/usr/share/groff/1.17.2/font/devname/F
Font file for font F of device name.
Note that troffrc and troffrc-end are neither searched in the current
nor in the home directory by default for security reasons (even if the
-U option is given). Use the -M command line option or the
GROFF_TMAC_PATH environment variable to add these directories to the
search path if necessary.
groff(7) -- This is a short but complete reference of all requests,
registers, and escapes.
groff(1), tbl(1), pic(1), eqn(1), refer(1), soelim(1), grn(1),
grops(1), grodvi(1), grotty(1), grohtml(1),
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