groff-specific options

The following options either do not exist in GNU troff or are interpreted differently by groff.

-D enc

Use enc as preconv(1)'s fallback input encoding; implies -k.

-e

Run eqn(1) preprocessor.

-g

Run grn(1) preprocessor.

-G

Run grap(1) preprocessor; implies -p.

-I dir

Works as troff's option (see below), but also implies -g and -s. groff passes -I options and their arguments to soelim(1), troff(1), and output drivers; with the option letter changed to -M, it passes the same arguments to grn(1).

-j

Run chem(1) preprocessor; implies -p.

-k

Run preconv(1) preprocessor. Refer to its man page for its behavior if neither of groff's -K or -D options is also specified.

-K enc

Set input encoding used by preconv(1) to enc; implies -k.

-l

Send the output to a spooler program for printing. The “print” directive in the device description file specifies the default command to be used; see groff_font(5). If no such directive is present for the output device, this option is ignored. See options -L and -X.

-L arg

Pass arg to the print spooler. If multiple args are required, pass each with a separate -L option. groff does not prefix an option dash to arg before passing it to the spooler.

-M

Works as troff's option (see below), but is also passed to eqn(1), grap(1), and grn(1).

-N

Prohibit newlines between eqn delimiters: pass -N to eqn(1).

-p

Run pic(1) preprocessor.

-P arg

Pass arg to the postprocessor. If multiple args are required, pass each with a separate -P option. groff does not prefix an option dash to arg before passing it to the postprocessor.

-R

Run refer(1) preprocessor. No mechanism is provided for passing arguments to it; most refer options have equivalent language elements that can be specified within the document.

-s

Run soelim(1) preprocessor.

-S

Enable safer mode and ignore any subsequent -U option. groff passes the -S option to pic(1) and troff(1).

-t

Run tbl(1) preprocessor.

-T dev

Prepare output for device dev. groff passes the -T option and its argument to troff, then (unless the -Z option is used) runs an output driver to convert troff's output to a form appropriate for dev; see subsection “Output devices” below.

-U

Operate in unsafe mode. groff passes the -U option to pic(1) and troff(1).

--version

-v

Write version information for groff and all programs run by it to the standard output stream; that is, the given command line is processed in the usual way, passing -v to the formatter and any pre- or postprocessors invoked.

-V

Output the pipeline that groff would run to the standard output stream and exit. If given more than once, groff both writes the pipeline to the standard error stream and runs it.

-X

Use gxditview(1) instead of the usual postprocessor to (pre)view a document on an X11 display. Combining this option with “-T ps” uses the font metrics of the PostScript device, whereas the “-T X75”, “-T X75-12” “-T X100”, and “-T X100-12” options use the metrics of X11 fonts.

-Z

Disable postprocessing. troff output appears on the standard output stream (unless suppressed with -z); see groff_out(5) for a description of this format.

Transparent options

The following options are passed as-is to the formatter program troff(1) and described in more detail in its man page.

-a

Generate a plain text approximation of the typeset output.

-b

Write a backtrace to the standard error stream on each error or warning.

-c

Start with color output disabled.

-C

Enable AT&T troff compatibility mode; implies -c.

-d ctext

-d string=text

Define string.

-E

Inhibit troff error messages; implies -Ww.

-f fam

Set default font family.

-F dir

Search in directory dir for the selected output device's directory of device and font description files.

-i

Process standard input after the specified input files.

-I dir

Search dir for input files.

-m mac

Read macro package mac before input. groff passes -m options and their arguments to eqn(1), grap(1), and grn(1).

-M dir

Search directory dir for macro files. groff passes -M options and their arguments to eqn(1), grap(1), and grn(1).

-n num

Begin numbering pages at num.

-o list

Output only pages in list.

-r cnumeric-expression

-r register=numeric-expression

Define register.

-S

Enable safer mode and ignore any subsequent -U option.

-U

Operate in unsafe mode.

-w cat

-W cat

Enable and inhibit, respectively, warnings in category cat.

-z

Suppress formatted device-independent output of troff.

Getting started

Those who prefer to learn by experimenting or are desirous of rapid feedback from the system may wish to start with a “Hello, world!” document.

$ 
echo "Hello, world!" | groff -Tascii | sed '/^$/d'
Hello, world!

We used a sed(1) command only to eliminate the 65 blank lines that would otherwise flood the terminal screen. (roff systems were developed in the days of paper-based terminals with 66 lines to a page.)

Today's users may prefer output to a UTF-8-capable terminal.

$ 
echo "Hello, world!" | groff -Tutf8 | sed '/^$/d'

Producing PDF, HTML, or TeX's DVI is also straightforward. The hard part may be selecting a viewer program for the output.

$ 
echo "Hello, world!" | groff -Tpdf > hello.pdf
$ 
evince hello.pdf
$ 
echo "Hello, world!" | groff -Thtml > hello.html
$ 
firefox hello.html
$ 
echo "Hello, world!" | groff -Tdvi > hello.dvi
$ 
xdvi hello.dvi

Using groff as a REPL

Those with a programmer's bent may be pleased to know that they can use groff in a read-evaluate-print loop (REPL). Doing so can be handy to verify one's understanding of the formatter's behavior and/or the syntax it accepts. Turning on all warnings with -ww can aid this goal.

$ 
groff -ww -Tutf8
\# This is a comment. Let's define a register.
.nr a 1
\# Do integer arithmetic with operators evaluated left-to-right.
.nr b \n[a]+5/2
\# Let's get the result on the standard error stream.
.tm \n[b]
3
\# Now we'll define a string.
.ds name Leslie\" This is another form of comment.
.nr b (\n[a] + (7/2))
\# Center the next two text input lines.
.ce 2
Hi, \*[name].
Your secret number is \n[b].
\# We will see that the division rounded toward zero.
It is
\# Here's an if-else control structure.
.ie (\n[b] % 2) odd.
.el even.
\# This trick sets the page length to the current vertical
\# position, so that blank lines don't spew when we're done.
.pl \n[nl]u
<Control-D>
                           Hi, Leslie.
                    Your secret number is 4.
It is even.

Paper format

The formatter reads the device description file DESC for the selected output device when it starts; page dimensions declared there are used if present. groff's build process configures a default page format and writes it to typesetters' DESC files. This installation defaults to “A4”. If the DESC file lacks this information, the formatter and output driver use a page length of “11i” (eleven inches) for compatibility with AT&T troff. See groff_font(5).

In the formatter, the pl request changes the page length, but macro packages often do not support alteration of the paper format within a document. One might, for instance, want to switch between portrait and landscape orientations. Macro packages lack a consistent approach to configuration of parameters dependent on the paper format; some, like ms, benefit from a preamble in the document prior to the first macro call, while others, like mm, instead require the specification of registers on the command line, or otherwise before its macro file is interpreted, to configure page dimensions.

Output drivers for typesetters also recognize command-line options -p to override the default page dimensions and -l to use landscape orientation. The output driver's man page, such as grops(1), may be helpful.

groff's “-d paper” command-line option is a convenient means of setting the paper format; see groff_tmac(5). Combine it with appropriate -P options for the output driver, overriding its defaults. The following command formats for PostScript on A4 paper in landscape orientation.

$ 
groff -T ps -d paper=a4l -P -pa4 -P -l -ms my.ms >my.ps

Front end

The groff program wraps troff(1), allowing one to specify preprocessors via command-line options and running the appropriate output driver for the selected output device. This convenience avoids the manual construction of pipelines or management of temporary files required of users of traditional roff(7) systems. Use grog(1) to infer an appropriate groff command line to format a document.

Language

Input to a roff system is in plain text interleaved with control lines and escape sequences. The combination constitutes a document in one of a family of languages we also call roff; see roff(7) for background. An overview of GNU roff language syntax and features, including lists of all supported escape sequences, requests, and predefined registers, can be found in groff(7). GNU roff extensions to the AT&T troff language, a common subset of roff dialects extant today, are detailed in groff_diff(7).

Preprocessors

A preprocessor interprets a domain-specific language that produces roff language output. Frequently, such input is confined to sections or regions of roff input (bracketed with macro calls specific to each preprocessor), which it replaces. Preprocessors therefore often interpret a subset of roff syntax along with their own language. GNU roff provides reimplementations of most preprocessors familiar to users of AT&T troff; these routinely have extended features and/or require GNU troff to format their output.

A preprocessor unique to GNU roff is preconv(1), which converts various input encodings to something GNU troff can understand. When used, it is run before any other preprocessors.

Most preprocessors enclose content between a pair of characteristic tokens. Such a token must occur at the beginning of an input line and use the dot control character. Spaces and tabs must not follow the control character or precede the end of the input line. Deviating from these rules defeats a token's recognition by the preprocessor. Tokens are generally preserved in preprocessor output and interpreted as macro calls subsequently by troff. The ideal preprocessor is not yet available in groff.

Macro packages

Macro files are roff input files designed to produce no output themselves but instead ease the preparation of other roff documents. When a macro file is installed at a standard location and suitable for use by a general audience, it is termed a macro package.

The -m option loads a macro package prior to any roff input documents, and after performing any string and register assignments directed by -d and -r options. The GNU roff system implements most well-known macro packages for AT&T troff in a compatible way and extends them. These have one- or two-letter names arising from intense practices of naming economy in early Unix culture, a laconic approach that led to many of the packages being identified in general usage with the nroff and troff option letter used to invoke them, sometimes to punning effect, as with “man” (short for “manual”), and even with the option dash, as in the case of the s package, much better known as ms or even -ms.

Macro packages serve a variety of purposes. Some are “full-service” packages, adopting responsibility for page layout among other fundamental tasks, and defining their own lexicon of macros for document composition; each such package stands alone and a given document can use at most one.

an

is used to compose man pages in the format originating in Version 7 Unix (1979); see groff_man(7). It can be specified on the command line as -man.

doc

is used to compose man pages in the format originating in 4.3BSD-Reno (1990); see groff_mdoc(7). It can be specified on the command line as -mdoc.

e

is the Berkeley general-purpose macro suite, developed as an alternative to AT&T's s; see groff_me(7). It can be specified on the command line as -me.

m

implements the format used by the second-generation AT&T macro suite for general documents, a successor to s; see groff_mm(7). It can be specified on the command line as -mm.

om

(invariably called “mom”) is a modern package written by Peter Schaffter specifically for GNU roff. Consult the mom HTML manual for extensive documentation. She—for mom takes the female pronoun—can be specified on the command line as -mom.

s

is the original AT&T general-purpose document format; see groff_ms(7). It can be specified on the command line as -ms.

Others are supplemental. For instance, andoc is a wrapper package specific to GNU roff that recognizes whether a document uses man or mdoc format and loads the corresponding macro package. It can be specified on the command line as -mandoc. A man(1) librarian may use this macro file to delegate loading of the correct macro package; it is thus unnecessary for man itself to scan the contents of a document to decide the issue.

Many macro files augment the function of the full-service packages, or of roff documents that do not employ such a package—the latter are sometimes characterized as “raw”. These auxiliary packages are described, along with details of macro file naming and placement, in groff_tmac(5).

Formatters

The formatter, the program that interprets roff language input, is troff(1). It provides the features of the AT&T troff and nroff programs as well as many extensions. The command-line option -C switches troff into compatibility mode, which tries to emulate AT&T troff as closely as is practical to enable the formatting of documents written for the older system.

A shell script, nroff(1), emulates the behavior of AT&T nroff. It attempts to correctly encode the output based on the locale, relieving the user of the need to specify an output device with the -T option and is therefore convenient for use with terminal output devices, described in the next subsection.

GNU troff generates output in a device-independent, but not device-agnostic, page description language detailed in groff_out(5).

Output devices

troff output is formatted for a particular output device, typically specified by the -T option to the formatter or a front end. If neither this option nor the GROFF_TYPESETTER environment variable is used, the default output device is ps. An output device may be any of the following.

ascii

for terminals using the ISO 646 1991:IRV character set and encoding, also known as US-ASCII.

dvi

for TeX DVI format.

html

xhtml

for HTML and XHTML output, respectively.

latin1

for terminals using the ISO Latin-1 (8859-1) character set and encoding.

lbp

for Canon CaPSL printers (LBP-4 and LBP-8 series laser printers).

lj4

for HP LaserJet4-compatible (or other PCL5-compatible) printers.

pdf

for PDF output.

ps

for PostScript output.

utf8

for terminals using the ISO 10646 (“Unicode”) character set in UTF-8 encoding.

X75

for previewing with gxditview using 75 dpi resolution and a 10-point base type size.

X75-12

for previewing with gxditview using 75 dpi resolution and a 12-point base type size.

X100

for previewing with gxditview using 100 dpi resolution and a 10-point base type size.

X100-12

for previewing with gxditview using 100 dpi resolution and a 12-point base type size.

Postprocessors

Any program that interprets the output of GNU troff is a postprocessor. The postprocessors provided by GNU roff are output drivers, which prepare a document for viewing or printing. Postprocessors for other purposes, such as page resequencing or statistical measurement of a document, are conceivable.

An output driver supports one or more output devices, each with its own device description file. A device determines its postprocessor with the postpro directive in its device description file; see groff_font(5). The -X option overrides this selection, causing gxditview to serve as the output driver.

grodvi(1)

provides dvi.

grohtml(1)

provides html and xhtml.

grolbp(1)

provides lbp.

grolj4(1)

provides lj4.

gropdf(1)

provides pdf.

grops(1)

provides ps.

grotty(1)

provides ascii, latin1, and utf8.

gxditview(1)

provides X75, X75-12, X100, and X100-12, and additionally can preview ps.

Utilities

GNU roff includes a suite of utilities.

gdiffmk(1)

marks differences between a pair of roff input files.

grog(1)

infers the groff command a document requires.

Several utilities prepare descriptions of fonts, enabling the formatter to use them when producing output for a given device.

addftinfo(1)

adds information to AT&T troff font description files to enable their use with GNU troff.

afmtodit(1)

creates font description files for PostScript Type 1 fonts.

pfbtops(1)

translates a PostScript Type 1 font in PFB (Printer Font Binary) format to PFA (Printer Font ASCII), which can then be interpreted by afmtodit.

hpftodit(1)

creates font description files for the HP LaserJet 4 family of printers.

tfmtodit(1)

creates font description files for the TeX DVI device.

xtotroff(1)

creates font description files for X Window System core fonts.

A trio of tools transform material constructed using roff preprocessor languages into graphical image files.

eqn2graph(1)

converts an eqn equation into a cropped image.

grap2graph(1)

converts a grap diagram into a cropped image.

pic2graph(1)

converts a pic diagram into a cropped image.

Another set of programs works with the bibliographic data files used by the refer(1) preprocessor.

indxbib(1)

makes inverted indices for bibliographic databases, speeding lookup operations on them.

lkbib(1)

searches the databases.

lookbib(1)

interactively searches the databases.

groff macro directory

Most macro files supplied with GNU roff are stored in /usr/share/groff/1.24.0/tmac for the installation corresponding to this document. As a rule, multiple directories are searched for macro files; see troff(1). For a catalog of macro files GNU roff provides, see groff_tmac(5).

groff device and font description directory

Device and font description files supplied with GNU roff are stored in /usr/share/groff/1.24.0/font for the installation corresponding to this document. As a rule, multiple directories are searched for device and font description files; see troff(1). For the formats of these files, see groff_font(5).