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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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Name | Synopsis | Description | Options | Environment | Files | Limitations | Examples | See also | COLOPHON |
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grotty(1) General Commands Manual grotty(1)
grotty - groff output driver for typewriter-like (terminal)
devices
grotty [-dfho] [-i|-r] [-F font-directory] [file ...]
grotty -c [-bBdfhouU] [-F font-directory] [file ...]
grotty --help
grotty -v
grotty --version
The GNU roff TTY (“Teletype”) output driver translates the output
of troff(1) into a form suitable for typewriter-like devices,
including video terminal emulators. Normally, grotty is invoked
by groff(1) when the latter is given one of the “-T ascii”,
“-T latin1”, or “-T utf8” options on systems using ISO character
encoding standards, or with “-T cp1047” or “-T utf8” on EBCDIC-
based hosts. (In this installation, ps is the default output
device.) Use groff's -P option to pass any options shown above
to grotty. If no file arguments are given, or if file is “-”,
grotty reads the standard input stream. It writes to the
standard output stream.
By default, grotty emits SGR escape sequences (from ISO 6429,
popularly called “ANSI escapes”) to change text attributes (bold,
italic, underline, reverse video [“negative image”] and colors).
Devices supporting the appropriate sequences can view roff
documents using eight different background and foreground colors.
Following ISO 6429, the following colors are defined in tty.tmac:
black, white, red, green, blue, yellow, magenta, and cyan.
Unrecognized colors are mapped to the default color, which is
dependent on the settings of the terminal. OSC 8 hyperlinks are
produced for these devices.
In keeping with long-standing practice and the rarity of
terminals (and emulators) that support oblique or italic fonts,
italicized text is represented with underlining by default—but
see the -i option below.
SGR and OSC support in pagers
When paging grotty's output with less(1), the latter program must
be instructed to pass SGR and OSC sequences through to the
device; its -R option is one way to achieve this (less version
566 or later is required for OSC 8 support). Consequently,
programs like man(1) that page roff documents with less must call
it with an appropriate option.
Legacy output format
The -c option tells grotty to use an output format compatible
with paper terminals, like the Teletype machines for which roff
and nroff were first developed but which are no longer in wide
use. SGR escape sequences are not emitted; bold, italic, and
underlining character attributes are thus not manipulated.
Instead, grotty overstrikes, representing a bold character c with
the sequence “c BACKSPACE c”, an italic character c with the
sequence “_ BACKSPACE c”, and bold italics with “_ BACKSPACE c
BACKSPACE c”. This rendering is inherently ambiguous when the
character c is itself the underscore.
The legacy output format can be rendered on a video terminal (or
emulator) by piping grotty's output through ul(1), which may
render bold italics as reverse video. Some implementations of
more(1) are also able to display these sequences; you may wish to
experiment with that command's -b option. less renders legacy
bold and italics without requiring options. In contrast to the
terminal output drivers of some other roff implementations,
grotty never outputs reverse line feeds. There is therefore no
need to filter its output through col(1).
Device control commands
grotty supports a device control command accessed with the
“device” request or \X escape sequence.
\X'tty: link [uri [key=value] ...]'
Embed a hyperlink using the OSC 8 terminal escape
sequence. Specifying uri starts hyperlinked text, and
omitting it ends the hyperlink. When uri is present, any
number of additional key/value pairs can be specified;
their interpretation is the responsibility of the pager or
terminal. Spaces or tabs cannot appear literally in uri,
key, or value; they must be represented in an alternate
form.
Device description files
If the DESC file for the character encoding contains the
“unicode” directive, grotty emits Unicode characters in UTF-8
encoding. Otherwise, it emits characters in a single-byte
encoding depending on the data in the font description files.
See groff_font(5).
A font description file may contain a directive “internalname n”
where n is a decimal integer. If the 01 bit in n is set, then
the font is treated as an italic font; if the 02 bit is set, then
it is treated as a bold font.
Typefaces
grotty supports the standard four styles: R (roman), I (italic),
B (bold), and BI (bold-italic). Because the output driver
operates in nroff mode, attempts to set or change the font family
or type size are ignored.
--help displays a usage message, while -v and --version show
version information; all exit afterward.
-b Suppress the use of overstriking for bold characters in
legacy output format.
-B Use only overstriking for bold-italic characters in legacy
output format.
-c Use grotty's legacy output format (see subsection “Legacy
output format” above). SGR and OSC escape sequences are
not emitted.
-d Ignore all \D drawing escape sequences in the input. By
default, grotty renders \D'l...' escape sequences that
have at least one zero argument (and so are either
horizontal or vertical) using Unicode box drawing
characters (for the utf8 device) or the -, |, and +
characters (for all other devices). grotty handles
\D'p...' escape sequences that consist entirely of
horizontal and vertical lines similarly.
-f Emit a form feed at the end of each page having no output
on its last line.
-F dir Prepend directory dir/devname to the search path for font
and device description files; name describes the output
device's character encoding, one of ascii, latin1, utf8,
or cp1047.
-h Use literal horizontal tab characters in the output. Tabs
are assumed to be set every 8 columns.
-i Render oblique-styled fonts (I and BI) with the SGR
attribute for italic text rather than underlined text.
Many terminals don't support this attribute; however,
xterm(1), since patch #314 (2014-12-28), does. Ignored if
-c is also specified.
-o Suppress overstriking (other than for bold and/or
underlined characters when the legacy output format is in
use).
-r Render oblique-styled fonts (I and BI) with the SGR
attribute for reverse video text rather than underlined
text. Ignored if -c or -i is also specified.
-u Suppress the use of underlining for italic characters in
legacy output format.
-U Use only underlining for bold-italic characters in legacy
output format.
GROFF_FONT_PATH
A list of directories in which to seek the selected output
device's directory of device and font description files.
See troff(1) and groff_font(5).
GROFF_NO_SGR
If set, grotty's legacy output format is used just as if
the -c option were specified; see subsection “Legacy
output format” above.
/usr/local/share/groff/1.23.0/font/devascii/DESC
describes the ascii output device.
/usr/local/share/groff/1.23.0/font/devascii/F
describes the font known as F on device ascii.
/usr/local/share/groff/1.23.0/font/devcp1047/DESC
describes the cp1047 output device.
/usr/local/share/groff/1.23.0/font/devcp1047/F
describes the font known as F on device cp1047.
/usr/local/share/groff/1.23.0/font/devlatin1/DESC
describes the latin1 output device.
/usr/local/share/groff/1.23.0/font/devlatin1/F
describes the font known as F on device latin1.
/usr/local/share/groff/1.23.0/font/devutf8/DESC
describes the utf8 output device.
/usr/local/share/groff/1.23.0/font/devutf8/F
describes the font known as F on device utf8.
/usr/local/share/groff/1.23.0/tmac/tty.tmac
defines macros for use with the ascii, cp1047, latin1, and
utf8 output devices. It is automatically loaded by
troffrc when any of those output devices is selected.
/usr/local/share/groff/1.23.0/tmac/tty-char.tmac
defines fallback characters for use with grotty. See
nroff(1).
grotty is intended only for simple documents.
• There is no support for fractional horizontal or vertical
motions.
• roff \D escape sequences producing anything other than
horizontal and vertical lines are not supported.
• Color handling differs from other output drivers. The groff
requests and escape sequences that set the stroke and fill
colors instead set the foreground and background character
cell colors, respectively.
The \l and \L escape sequences on one hand, and the \D'l' line-
drawing escape sequence on the other, make different compromises
due to the first two factors. Specifically, (1) \l draws
horizontal lines with underscore characters; \D'l' uses ACS or
Unicode line-drawing characters if possible, and hyphen-minus
signs if not. (2) \D'l' draws vertical lines an extra character
cell high, and horizontal lines an extra cell to the right.
grotty does this to detect intersecting lines so that it can
replace them with glyphs of appropriate appearance (like “+”).
Observe the difference below.
The input
Hello,\L'1v'
world.\l'1n'
.sp 2v
Hello,\D'l 0 1v'
world.\D'l 1n 0'
.pl \n(nlu \" truncate page for convenience
rendered with “nroff -T ascii” produces the following output.
Hello,
| world._
Hello,|
|world.--
The following groff document exercises several features for which
output device support varies: (1) bold style; (2) italic
(underline) style; (3) bold-italic style; (4) character
composition by overstriking (“coöperate”); (5) foreground color;
(6) background color; and (7) horizontal and vertical line
drawing.
You might see \f[B]bold\f[] and \f[I]italic\f[].
Some people see \f[BI]both at once\f[].
If the output device does (not) co\z\[ad]operate,
you might see \m[red]red\m[].
Black on cyan can have a \M[cyan]\m[black]prominent\m[]\M[]
\D'l 1i 0'\D'l 0 2i'\D'l 1i 0' look.
.\" If in nroff mode, end page now.
.if n .pl \n[nl]u
Given the foregoing input, compare and contrast the output of the
following.
$ groff -T ascii file
$ groff -T utf8 -P -i file
$ groff -T utf8 -P -c file | ul
“Control Functions for Coded Character Sets” (ECMA-48)
5th edition, Ecma International, June 1991.
⟨http://www.ecma-international.org/publications/files/ECMA-ST/
Ecma-048.pdf⟩ A gratis version of ISO 6429, this document
includes a normative description of SGR escape sequences.
“Hyperlinks in Terminal Emulators”
⟨https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f
3cb5feda⟩, Egmont Koblinger.
groff(1), troff(1), groff_out(5), groff_font(5), groff_char(7),
ul(1), more(1), less(1), man(1)
This page is part of the groff (GNU troff) project. Information
about the project can be found at
⟨http://www.gnu.org/software/groff/⟩. If you have a bug report
for this manual page, see ⟨http://www.gnu.org/software/groff/⟩.
This page was obtained from the project's upstream Git repository
⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-06-10.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
groff 1.23.0.1273-9d53-dirty 6 June 2024 grotty(1)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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