groff_diff - differences between GNU troff and classical troff
This manual page describes the language differences between groff, the
GNU roff text processing system and the classical roff formatter of the
freely available Unix 7 of the 1970s, documented in the Troff User's
Manual by Osanna and Kernighan. This inludes the roff language as well
as the intermediate output format (troff output).
The section SEE ALSO gives pointers to both the classical roff and the
modern groff documentation.
In this section, all additional features of groff compared to the classical
Unix 7 troff are described in detail.
Long names [Toc] [Back]
The names of number registers, fonts, strings/macros/diversions, special
characters (glyphs), and colors can be of any length. In escape
sequences, additionally to the classical (xx construction for a twocharacter
name, you can use [xxx] for a name of arbitrary length.
\[xxx] Print the special character (glyph) called xxx.
\[comp1 comp2 ...]
Print composite glyph consisting of multiple components. Example:
`\[A ho]' is capital letter A with ogonek which finally
maps to glyph name `u0041_0328'. See the groff info file for
details how a glyph name for a composite glyph is constructed,
and groff_char(7) for list of glyph name components used composite
glyph names.
\f[xxx]
Set font xxx. Additionally, \f[] is a new syntax equal to \fP,
i.e., to return to the previous font.
\*[xxx arg1 arg2 ...]
Interpolate string xxx, taking arg1, arg2, ... as arguments.
\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 that 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 call .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. f indicates a scale of 65536
units, providing fractions for color definitions with the defcolor
request. For example, 0.5f = 32768u.
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 resp., depending on whether anything is
or is not acceptable as the name of a string, macro, diversion,
number register, environment, font, or color. 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 resp., depending on whether anything is
or is not a valid numeric expression. It will return 0 if any-
thing is empty.
\C'xxx'
Typeset glyph 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 is 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).
\Ff
\F(fm
\F[fam]
Change font family. This is the same as the fam request. \F[]
switches back to the previous color (note that \FP won't work;
it selects font family `P' instead).
\mx
\m(xx
\m[xxx]
Set drawing color. \m[] switches back to the previous color.
\Mx
\M(xx
\M[xxx]
Set background color for filled objects drawn with the \D'...'
commands. \M[] switches back to the previous color.
\N'n' Typeset the glyph with index n in the current font. n can be
any integer. Most devices only have glyphs with indices between
0 and 255. If the current font does not contain a glyph with
that code, special fonts will not be searched. The \N escape
sequence can be conveniently used in conjunction with the char
request, for example
.char \[phone] \f(ZD\N'37'
The index of each glyph is given in the fourth column in the
font description file after the charset command. It is possible
to include unnamed glyphs in the font description file by using
a name of ---; the \N escape sequence is the only way to use
these.
\On
\O[n] Suppressing troff output. The escapes \02, \O3, \O4, and \O5
are intended for internal use by grohtml.
\O0 Disable any ditroff glyphs from being emitted to the
device driver, provided that the escape occurs at the
outer level (see \O3 and \O4).
\O1 Enable output of glyphs, provided that the escape occurs
at the outer level.
\O0 and \O1 also reset the registers \n[opminx],
\n[opminy], \n[opmaxx], and \n[opmaxy] to -1. These four
registers mark the top left and bottom right hand corners
of a box which encompasses all written glyphs.
\O2 Provided that the escape occurs at the outer level,
enable output of glyphs and also write out to stderr the
page number and four registers encompassing the glyphs
previously written since the last call to \O.
\O3 Begin a nesting level. At start-up, troff is at outer
level. This is really an internal mechanism for grohtml
while producing images. They are generated by running
the troff source through troff to the postscript device
and ghostscript to produce images in PNG format. The \O3
escape will start a new page if the device is not html
(to reduce the possibility of images crossing a page
boundary).
\O4 End a nesting level.
\O5[Pfilename]
This escape is grohtml specific. Provided that this
escape occurs at the outer nesting level, write filename
to stderr. The position of the image, P, must be specified
and must be one of l, r, c, or i (left, right, centered,
inline). filename will be associated with the
production of the next inline image.
\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 or string, the concatenation of all the arguments
separated by spaces.
\$@ In a macro or string, the concatenation of all the arguments
with each surrounded by double quotes, and separated by spaces.
\$(nn
\$[nnn]
In a macro or string, this gives the nn-th or nnn-th argument.
Macros and strings 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 glyph so that the
spacing between that glyph and the following glyph will be correct
if the following glyph is a roman glyph. It is a good idea
to use this escape sequence whenever an italic glyph is immediately
followed by a roman glyph without any intervening space.
\, This modifies the spacing of the following glyph so that the
spacing between that glyph and the preceding glyph will correct
if the preceding glyph is a roman glyph. It is a good idea to
use this escape sequence whenever a roman glyph is immediately
followed by an italic glyph 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-ofsentence
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 \% within a word but without insertion of a soft hyphen
character.
\# Everything up to and including the next newline is ignored.
This is interpreted in copy mode. It 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.
.ami xx yy
Append to macro indirectly. See the dei request below for more
information.
.am1 xx yy
Similar to .am, but compatibility mode is switched off during
execution. To be more precise, a `compatibility save' token is
inserted at the beginning of the macro addition, and a `compatibility
restore' token at the end. As a consequence, the
requests am, am1, de, and de1 can be intermixed freely since the
compatibility save/restore tokens only affect the macro parts
defined by .am1 and .ds1.
.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.
.as1 xx yy
Similar to .as, but compatibility mode is switched off during
expansion. To be more precise, a `compatibility save' token is
inserted at the beginning of the string, and a `compatibility
restore' token at the end. As a consequence, the requests as,
as1, ds, and ds1 can be intermixed freely since the compatibility
save/restore tokens only affect the (sub)strings defined by
as1 and ds1.
.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]\[radicalex]\[sqrtex] 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 glyph c to be string. Every time glyph 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 glyphs in string.
A glyph defined by this request can be used just like a normal
glyph 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 glyph within
the glyph's definition will be handled like normal glyphs not
defined with char.
A glyph definition can be removed with the rchar request.
.chop xx
Chop the last element 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.
.composite glyph1 glyph2
Map glyph name glyph1 to glyph name glyph2 if it is used in
\[...] with more than one component.
.continue
Finish the current iteration of a while loop. See also the
while and break requests.
.color n
If n is non-zero or missing, enable colors (this is the
default), otherwise disable them.
.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.
.defcolor xxx scheme color_components
Define color. scheme can be one of the following values: rgb
(three components), cym (three components), cmyk (four components),
and gray or grey (one component). Color components can
be given either as a hexadecimal string or as positive decimal
integers in the range 0-65535. A hexadecimal string contains
all color components concatenated; it must start with either #
or ##. The former specifies hex values in the range 0-255
(which are internally multiplied by 257), the latter in the
range 0-65535. Examples: #FFC0CB (pink), ##ffff0000ffff
(magenta). A new scaling indicator f has been introduced which
multiplies its value by 65536; this makes it convenient to specify
color components as fractions in the range 0 to 1. Example:
.defcolor darkgreen rgb 0.1f 0.5f 0.2f
Note that f is the default scaling indicator for the defcolor
request, thus the above statement is equivalent to
.defcolor darkgreen rgb 0.1 0.5 0.2
The color named default (which is device-specific) can't be
redefined. It is possible that the default color for \M and \m
is not the same.
.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.
.ds1 xx yy
Similar to .ds, but compatibility mode is switched off during
expansion. To be more precise, a `compatibility save' token is
inserted at the beginning of the string, and a `compatibility
restore' token at the end.
.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 environments 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. The value at start-up is `T'. See the
description of the sty request for more information on font families.
.fchar c string
Define fallback glyph c to be string. The syntax of this
request is the same as the char request; the only difference is
that a glyph defined with char hides the glyph with the same
name in the current font, whereas a glyph defined with fchar is
checked only if the particular glyph isn't found in the current
font. This test happens before checking special fonts.
.fschar f c string
Define fallback glyph c for font f to be string. The syntax of
this request is the same as the char request (with an additional
argument to specify the font); a glyph defined with fschar is
searched after the list of fonts declared with the fspecial
request but before the list of fonts declared with special.
.fspecial f s1 s2...
When the current font is f, fonts s1, s2,... will be special,
that is, they will searched for glyphs not in the current font.
Any fonts specified in the special request will be searched
after fonts specified in the fspecial request. Without argument,
reset the list of global special fonts to be empty.
.ftr f g
Translate font f to g. Whenever a font named f is referred to
in an \f escape sequence, or in the ft, ul, bd, cs, tkf, spe-
cial, 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 a-z has a hyphenation code, which
is itself, and each upper-case letter A-Z 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 (simple)
TeX patterns files. More specifically, the following scanning
rules are implemented.
o A percent sign starts a comment (up to the end of the
line) even if preceded by a backslash.
o No support for `digraphs' like \$.
o ^^xx (x is 0-9 or a-f) and ^^x (character code of x in
the range 0-127) are recognized; other use of ^ causes an
error.
o No macro expansion.
o hpf checks for the expression \patterns{...} (possibly
with whitespace before and after the braces). Everything
between the braces is taken as hyphenation patterns.
Consequently, { and } are not allowed in patterns.
o Similarly, \hyphenation{...} gives a list of hyphenation
exceptions.
o \endinput is recognized also.
o For backwards compatibility, if \patterns is missing, the
whole file is treated as a list of hyphenation patterns
(only recognizing the % character as the start of a comment).
Use the hpfcode request to map the encoding used in hyphenation
patterns files to groff's input encoding.
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; a second call replaces the old patterns
with the new ones.
.hpfa file
The same as hpf except that the hyphenation patterns from file
are appended to the patterns already loaded in the current language.
.hpfcode a b c d ...
After reading a hyphenation patterns file with the hpf or hpfa
request, convert all characters with character code a in the
recently read patterns to character code b, character code c
to d, etc. Initially, all character codes map to themselves.
The arguments of hpfcode must be integers in the range 0 to 255.
Note that it is even possible to use character codes which are
invalid in groff otherwise.
.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.
.itc n macro
Variant of .it for which a line interrupted with \c counts as
one input line.
.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.
.output string
Emit string directly to the intermediate output (subject to
copy-mode interpretation); this is similar to \! used at the
top level. An initial double quote in string is stripped off to
allow initial blanks.
.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.
.pvs +-n
Set the post-vertical line space to n; default scale indicator
is p. This value will be added to each line after it has been
output. With no argument, the post-vertical line space is set
to its previous value.
The total vertical line spacing consists of four components: .vs
and \x with a negative value which are applied before the line
is output, and .pvs and \x with a positive value which are
applied after the line is output.
.rchar c1 c2...
Remove the definitions of glyphs c1, c2,... This undoes the
effect of a char request.
.return
Within a macro, return immediately. No effect otherwise.
.rfschar c1 c2...
Remove the font-specific definitions of glyphs c1, c2,... This
undoes the effect of a fschar request.
.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.
.schar c string
Define global fallback glyph c to be string. The syntax of this
request is the same as the char request; a glyph defined with
schar is searched after the list of fonts declared with the spe-
cial request but before the mounted special fonts.
.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 glyph 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 glyph 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.
.sizes s1 s2...sn [0]
This command is similar to the sizes command of a DESC file. It
sets the available font sizes for the current font to s1,
s2,..., sn scaled points. The list of sizes can be terminated
by an optional 0. Each si can also be a range of sizes m-n.
Contrary to the font file command, the list can't extend over
more than a single line.
.special s1 s2...
Fonts s1, s2, are special and will be searched for glyphs not in
the current font. Without arguments, reset the list of special
fonts to be empty.
.spreadwarn limit
Make troff emit a warning if the additional space inserted for
each space between words in an output line is larger or equal to
limit. A negative value is changed to zero; no argument toggles
the warning on and off without changing limit. The default
scaling indicator is m. At startup, spreadwarn is deactivated,
and limit is set to 3m. For example, .spreadwarn 0.2m will
cause a warning if troff must add 0.2m or more for each interword
space in a line. This request is active only if text is
justified to both margins (using .ad b).
.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 named xx with the substring defined by the
indices n1 and n2. The first character in the string has
index 0. If n2 is omitted, it is taken to be equal to the
string's length. If the index value n1 or n2 is negative, it
will be counted from the end of the string, going backwards: The
last character has index -1, the character before the last character
has index -2, etc.
.tkf f s1 n1 s2 n2
Enable track kerning for font f. When the current font is f the
width of every glyph 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 if 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.
.trin abcd
This is the same as the tr request except that the asciify
request will use the character code (if any) before the character
translation. Example:
.trin ax
.di xxx
a
.br
.di
.xxx
.trin aa
.asciify xxx
.xxx
The result is x a. Using tr, the result would be x x.
.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
troff(1). For example, .warn 0 will disable all warnings, and
.warn 1 will disable all warnings except that about missing
glyphs. If n is not given, all warnings will be enabled.
.warnscale si
Set the scaling indicator used in warnings to si. Valid values
for si are u, i, c, p, and P. At startup, it is set to i.
.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.
.writec stream anything
Similar to write but without writing a final newline.
.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 escape sequences [Toc] [Back]
\D'...'
All drawing commands of groff's intermediate output are
accepted. See subsection Drawing Commands below for more information.
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.
.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 glyph added to the current environment.
It is positive if the glyph extends below the baseline.
\n[.ce]
The number of lines remaining to be centered, as set by the ce
request.
\n[.cht]
The height of the last glyph added to the current environment.
It is positive if the glyph extends above the baseline.
\n[.color]
1 if colors are enabled, 0 otherwise.
\n[.csk]
The skew of the last glyph added to the current environment.
The skew of a glyph is how far to the right of the center of a
glyph the center of an accent over that glyph should be placed.
\n[.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[.fn]
The current (internal) real font name. This is a string-valued
register. If the current font is a style, the value of \n[.fn]
is the proper concatenation of family and style name.
\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[.height]
The current height of the font as set with \H.
\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[.pe]
1 during a page ejection caused by the bp request, 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[.pvs]
The current post-vertical line space as set with the pvs
request.
\n[.rj]
The number of lines to be right-justified as set by the rj
request.
\n[.slant]
The slant of the current font as set with \S.
\n[.sr]
The last requested pointsize in points as a decimal fraction.
This is a string-valued register.
\n[.ss]
\n[.sss]
These give the values of the parameters set by the first and
second arguments of the ss request.
\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[.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 troff(1).
\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 take account of the heights
and depths of glyphs.
\n[ssc]
The amount of horizontal space (possibly negative) that sh
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