This Info file documents groff version 1.16, the GNU implementation of the troff typesetting system.
This is an in-progress document; contributions, comments, or contributions are welcome. Send them to bug-groff@gnu.org.
Next: Introduction, Previous: Top, Up: Top [Contents][Index]
Copyright © 1989, 1991 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
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Next: Invoking groff, Previous: Copying, Up: Top [Contents][Index]
GNU troff (or groff) is a system for typesetting
documents. troff is very flexible and has been in existence (and
use) for about 3 decades. It is quite widespread and firmly
entrenched in the UNIX community.
| • What Is groff? | ||
| • History | ||
| • groff Capabilities | ||
| • Macro Package Intro | ||
| • Preprocessor Intro | ||
| • Output device intro | ||
| • Credits |
Next: History, Previous: Introduction, Up: Introduction [Contents][Index]
groff?groff is of an older generation of document preparation systems,
which operate more like compilers than the more recent interactive
WYSIWYG1 systems.
groff and its contemporary counterpart, TeX, both work using a
batch paradigm: The input (or source) files are normal text
files with embedded formatting commands. These files can then be
processed by groff to produce a typeset document on a variety of
devices.
Likewise, groff should not be confused with a word
processor, since that term connotes an integrated system which includes
an editor and a text formatter. Also, many word processors follow the
WYSIWYG paradigm which was discussed earlier.
Although WYSIWYG systems may be easier to use, they have a
number of disadvantages compared to troff:
troff is firmly entrenched in all UNIX systems.
“GUIs normally make it simple to accomplish simple actions and impossible to accomplish complex actions.” –Doug Gwyn (22/Jun/91 in
comp.unix.wizards)
Next: groff Capabilities, Previous: What Is groff?, Up: Introduction [Contents][Index]
troff can trace its origins back to a formatting program called
runoff, written by J. E. Saltzer, which ran on MIT’s CTSS
operating system in the mid-sixties. This name came from the common
phrase of the time “I’ll run off a document.” Bob Morris ported it to
the 635 architecture and called the program roff (an abbreviation
of runoff). It has then been rewritten as rf for the
PDP-7 (before having UNIX), and at the same time (1969), Doug
McIllroy rewrote an extended and simplified version of roff in
the BCPL programming language.
The first version of UNIX was developed on a PDP-7 which was
sitting around Bell Labs. In 1971 the developers wanted to get a PDP-11
for further work on the operating system. In order to justify the cost
for this system, they proposed that they would implement a document
formatting system for the AT&T patents division. This first formatting
program was a reimplementation of McIllroy’s roff, written by
J. F. Ossanna.
When they needed a more flexible language, a new version of roff
called nroff (Newer roff) was written. It had a much more
complicated syntax, but provided the basis for all future versions.
When they got a Graphic Systems CAT Phototypesetter, Ossanna wrote a
version of nroff which would drive it. It was dubbed
troff for typesetter roff, although many people have
speculated that it actually means Times roff because of the use
of the Times font family in troff by default. As such, the name
troff is pronounced ‘t-roff’ rather than ‘trough’.
With troff came nroff (they were actually the same program
except for some ‘#ifdefs’), which was for producing output for line
printers and character terminals. It understood everything troff
did, and ignored the commands which were not applicable (e.g. font
changes).
Since there are several things which cannot be done easily in
troff, work on several preprocessors began. These programs would
transform certain parts of a document into troff, which made a
very natural use of pipes in UNIX.
The eqn preprocessor allowed mathematical formulæ to be
specified in a much simpler and more intuitive manner. tbl is a
preprocessor for formatting tables. The refer preprocessor (and
the similar program, bib) processes citations in a document
according to a bibliographic database.
Unfortunately, Ossanna’s troff was written in PDP-11 assembly
language and produced output specifically for the CAT phototypesetter.
He rewrote it in C, although it was now 7000 lines of uncommented
code and still dependent on the CAT. As the CAT became less common, and
was no longer supported by the manufacturer, the need to make it support
other devices became a priority. However, before this could be done, he
was killed in an auto accident.
So, Brian Kernighan took on the task of rewriting troff. The
newly rewritten version produced a device independent code which was
very easy for postprocessors to read and translate to the appropriate
printer codes. Also, this new version of troff (called
ditroff for ‘device independent troff’) had several
extensions, which included drawing functions.
Due to the additional abilities of the new version of troff,
several new preprocessors appeared. The pic preprocessor
provides a wide range of drawing functions. Likewise the ideal
preprocessor did the same, although via a much different paradigm. The
grap preprocessor took specifications for graphs, but, unlike
other preprocessors, produced pic code.
James Clark began work on a GNU implementation of ditroff in
early 1989. The first version, groff 0.3.1, was released
June 1990. groff included
ditroff with many extensions.
soelim, pic, tbl, and eqn preprocessors.
troff also eliminated the need for a separate
nroff program with a postprocessor which would produce
ASCII output.
Also, a front-end was included which could construct the, sometimes painfully long, pipelines required for all the post- and preprocessors.
Development of GNU troff progressed rapidly, and saw the
additions of a replacement for refer, an implementation of the
ms and mm macros, and a program to deduce how to format a
document (grog).
It was declared a stable (i.e. non-beta) package with the release of version 1.04 around November 1991.
Beginning in 1999, groff has new maintainers (the package was
an orphan for a few years). As a result, new features and programs like
grn, a preprocessor for gremlin images, and grohtml, an
output device to produce HTML output, have been added.
Next: Macro Package Intro, Previous: History, Up: Introduction [Contents][Index]
groff CapabilitiesSo what exactly is groff capable of doing? groff provides
a wide range of low-level text formatting operations. Using these, it
is possible to perform a wide range of formatting tasks, such as
footnotes, table of contents, multiple columns, etc.
Next: Preprocessor Intro, Previous: groff Capabilities, Up: Introduction [Contents][Index]
Since groff provides such low level facilities, it can be quite
difficult to use by itself. However, groff provides a
macro facility to specify how certain routine operations (e.g. starting paragraphs, printing headers and footers, etc.) should be
done. These macros can be collected together into a macro
package. There are a number of macro packages available; the most
common (and the ones described in this manual) are man,
mdoc, me, ms, and mm.
Next: Output device intro, Previous: Macro Package Intro, Up: Introduction [Contents][Index]
Although groff provides most functions needed to format a
document, some operations would be unwieldy (e.g. to draw pictures).
Therefore, programs called preprocessors were written which understand
their own language and produce the necessary groff operations.
These preprocessors are able to differentiate their own input from the
rest of the document via markers.
To use a preprocessor, UNIX pipes are used to feed the output
from the preprocessor into groff. Any number of preprocessors
may be used on a given document; in this case, the preprocessors are
linked together into one pipeline. However, in groff, the user
does not need to construct the pipe, but only tell groff what
preprocessors to use.
groff currently has preprocessors for producing tables
(tbl), typesetting equations (eqn), drawing pictures
(pic and grn), and for processing bibliographies
(refer). An associated program which is useful when dealing with
preprocessors is soelim.
A free implementation of grap, a preprocessor for drawing graphs,
can be obtained as an extra package; groff can use grap
also.
There are other preprocessors in existence, but, unfortunately, no free
implementations are available. Among them are preprocessors for drawing
mathematical pictures (ideal) and chemical structures
(chem).
Next: Credits, Previous: Preprocessor Intro, Up: Introduction [Contents][Index]
groff actually produces device independent code which may be fed
into a postprocessor which will produce output for a particular device.
Currently, groff has postprocessors for POSTSCRIPT,
character terminals, X Windows (for previewing), TeX DVI format,
HP LaserJet 4 and Canon LBP printers (which use CAPSL),
and HTML.
Previous: Output device intro, Up: Introduction [Contents][Index]
Large portions of this manual were taken from existing documents, most
notably, the manual pages for the groff package by James Clark,
and Eric Allman’s papers on the me macro package.
The section on the man macro package is partly based on Susan G. Kleinmann’s groff_man manual page written for the Debian GNU/Linux system.
Next: Tutorial for Macro Users, Previous: Introduction, Up: Top [Contents][Index]
groffThis section focuses on how to invoke the groff front end. This
front end takes care of the details of constructing the pipeline among
the preprocessors, gtroff and the postprocessor.
It has become a tradition that GNU programs get the prefix ‘g’ to
distinguish it from its original counterparts provided by the host
(see Environment, for more details). Thus, for example, geqn
is GNU eqn. On operating systems like Linux or the Hurd, which
don’t contain proprietary software, this prefix is omitted since GNU
troff is the only used incarnation of troff. Exception:
groff is never replaced by roff.
| • Groff Options | ||
| • Environment | ||
| • Invocation Examples |
Next: Environment, Previous: Invoking groff, Up: Invoking groff [Contents][Index]
groff normally runs the gtroff program and a postprocessor
appropriate for the selected device. The default device is ‘ps’.
It can optionally preprocess with any of gpic, geqn,
gtbl, ggrn, grap, grefer, or gsoelim.
This section only documents options to the groff front end. Many
of the arguments to groff are passed on to gtroff,
therefore those are also included. Arguments to pre- or postprocessors
can be found in Invoking gpic, Invoking geqn, Invoking gtbl, Invoking ggrn, Invoking grefer, Invoking gsoelim, Invoking grotty, Invoking grops, Invoking grohtml, Invoking grodvi, Invoking grolj4, Invoking grolbp, and Invoking gxditview.
The command line format for groff is:
groff [ -abeghilpstvzCEGNRSUVXZ ] [ -Fdir ] [ -mname ]
[ -Tdef ] [ -ffam ] [ -wname ] [ -Wname ]
[ -Mdir ] [ -dcs ] [ -rcn ] [ -nnum ]
[ -olist ] [ -Parg ] [ -Larg ] [ -Idir ]
[ files… ]
The command line format for gtroff is as follows. As can be
seen, many of the options to groff are actually passed on to
gtroff.
gtroff [ -abivzCERU ] [ -wname ] [ -Wname ] [ -dcs ]
[ -ffam ] [ -mname ] [ -nnum ]
[ -olist ] [ -rcn ] [ -Tname ]
[ -Fdir ] [ -Mdir ] [ files… ]
Options without an argument can be grouped behind a single -. A filename of ‘-’ denotes the standard input. It is possible to have whitespace between an option and its parameter.
The grog command can be used to guess the correct groff
command to format a file.
Print a help message.
Preprocess with geqn.
Preprocess with gtbl.
Preprocess with ggrn.
Preprocess with grap.
Preprocess with gpic.
Preprocess with gsoelim.
Preprocess with grefer. No mechanism is provided for passing
arguments to grefer because most grefer options have
equivalent commands which can be included in the file. See grefer,
for more details.
Note that gtroff also accepts a -R option, which is not
accessible via groff. This option prevents the loading of the
troffrc and troffrc-end files.
Make programs run by groff print out their version number.
Print the pipeline on stdout instead of executing it.
Suppress output from gtroff. Only error messages will be
printed.
Do not postprocess the output of gtroff. Normally groff
will automatically run the appropriate postprocessor.
Pass arg to the postprocessor. Each argument should be passed
with a separate -P option. Note that groff does not
prepend ‘-’ to arg before passing it to the postprocessor.
Send the output to a printer. The command used for this is specified by the print command in the device description file.
Pass arg to the spooler. Each argument should be passed with a
separate -L option. Note that groff does not prepend a
‘-’ to arg before passing it to the postprocessor.
Prepare output for device dev. The default device is ‘ps’. The following are the output devices currently available:
psFor POSTSCRIPT printers and previewers.
dviFor TeX DVI format.
X75For a 75dpi X11 previewer.
X100For a 100dpi X11 previewer.
asciiFor typewriter-like devices.
latin1For typewriter-like devices using the ISO Latin-1 (ISO 8859-1) character set.
utf8For typewriter-like devices which use the Unicode (ISO 10646) character set with UTF-8 encoding.
cp1047For typewriter-like devices which use the EBCDIC encoding IBM cp1047.
lj4For an HP LaserJet4-compatible (or other PCL5-compatible) printer.
lbpFor Canon CAPSL printers (LBP-4 and LBP-8 series laser printers).
htmlTo produce HTML output.
The predefined gtroff string register .T contains the
current output device; the read-only number register .T is set
to 1 if this option is used (which is always true if groff is
used to call gtroff). See Built-in Registers.
The postprocessor to be used for a device is specified by the
postpro command in the device description file. (See Font Files, for more info.) This can be overridden with the -X
option.
Preview with gxditview instead of using the usual postprocessor.
This is unlikely to produce good results except with -Tps.
Note that this is not the same as using -TX75 or
-TX100 to view a document with gxditview: The former
will us the metrics of the specified device, whereas the latter will use
X-specific fonts and metrics.
Don’t allow newlines with eqn delimiters. This is the same as
the -N option in geqn.
Safer mode. Pass the -S option to gpic and use the
-msafer macros with gtroff (enabled by default).
Unsafe mode. Reverts to the old unsafe behaviour.
Generate an ASCII approximation of the typeset output. The
read-only register .A is then set to 1. See Built-in Registers.
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: gtroff can get
confused by as or am requests while counting line numbers.
Read the standard input after all the named input files have been processed.
Enable warning name. Available warnings are described in Debugging. Multiple -w options are allowed.
Inhibit warning name. Multiple -W options are allowed.
Inhibit all error messages.
Enable compatibility mode.
Define c or name to be a string s. c must be a one-letter name; name can be of arbitrary length.
Use fam as the default font family.
Read in the file tmac.name. Normally this will be searched
for in the library directory of groff.
Number the first page num.
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. gtroff will exit after printing the last page in
the list.
Within gtroff, this information can be extracted with the
‘.P’ register. See Built-in Registers.
Set number register c or name to n. c must be a
one-letter name; name can be of arbitrary length. n can be
any gtroff numeric expression.
Search dir for subdirectories devname (name is the name of the device) for the DESC file and font files before the normal directory.
Search directory dir for macro files before the normal directory.
This option is as described in gsoelim. It implies the -s option.
Next: Invocation Examples, Previous: Groff Options, Up: Invoking groff [Contents][Index]
There are also several environment variables (of the operating system,
not within gtroff) which can modify the behavior of groff.
GROFF_COMMAND_PREFIXIf this is set to X, then groff will run
Xtroff instead of gtroff. This also applies to
tbl, pic, eqn, grn, refer, and
soelim. It does not apply to grops, grodvi,
grotty, grohtml, grolj4, and gxditview.
GROFF_TMAC_PATHA colon separated list of directories in which to search for macro files.
GROFF_TYPESETTERThe default output device.
GROFF_FONT_PATHA colon separated list of directories in which to search for the
devname directory.
PATHThe search path for commands executed by groff.
GROFF_TMPDIRThe directory in which temporary files will be created. If this is not
set and TMPDIR is set, temporary files will be created in that
directory. Otherwise temporary files will be created in /tmp.
The grops and grefer commands can create temporary files.
Previous: Environment, Up: Invoking groff [Contents][Index]
This section will list several common uses of groff and the
command line which will accomplish it.
groff file
This command processes file without a macro package or a preprocessor. The output device is the default, ps, and the output is sent to stdout.
groff -t -mandoc -Tascii file | less
This is basically what a call to the man program does. The
manual page file is processed with the mandoc macros (which
in turn either calls the man or the mdoc macro package),
using the tbl preprocessor and the ASCII output device.
Finally, the result is displayed with the less pager.
groff -X -m me file
Preview file with gxditview, using the me macro
package. Since no -T option is specified, use the default
device (‘ps’). Note that you can either say ‘-m me’ or
‘-me’; the latter is an anachronism from the early days of
UNIX.2
groff -man -rD1 -z file
Check file with the man macro package, forcing double-sided printing – don’t produce any output.
| • grog |
Previous: Invocation Examples, Up: Invocation Examples [Contents][Index]
groggrog reads files and guesses which of the groff
preprocessors and/or macro packages are are required for formatting
them, and prints the groff command including those options on the
standard output. The options generated are one of -e,
-man, -me, -mm, -ms, -p,
-R, -g, -G, -s, and -t.
A filename of ‘-’ is taken to refer to the standard input. If no files are specified the standard input will be read. Any specified options will be included in the printed command. No space is allowed between options and their arguments. For example,
grog -Tdvi paper.ms
will guess the appropriate command to print paper.ms and then
print it to the command line after adding the -Tdvi option.
For direct execution, enclose the call to grog in backquotes on
the UNIX shell prompt:
`grog -Tdvi paper.ms` > paper.dvi
As seen in the example, it is still necessary to redirect the output to
something meaningful (i.e. either a file or a pager program like
less).
Next: Macro Packages, Previous: Invoking groff, Up: Top [Contents][Index]
Most users tend to use a macro package to format their papers. This
means that the whole breadth of groff is not necessary for most
people. This chapter covers the material needed to efficiently use a
macro package.
| • Basics | ||
| • Common Features |
Next: Common Features, Previous: Tutorial for Macro Users, Up: Tutorial for Macro Users [Contents][Index]
This section covers some of the basic concepts necessary to understand how to use a macro package.3 References are made throughout to more detailed information, if desired.
gtroff reads an input file prepared by the user and outputs a
formatted document suitable for publication or framing. The input
consists of text, or words to be printed, and embedded commands
(requests and escapes), which tell gtroff how to
format the output. For more detail on this see Embedded Commands.
The word argument is used in this manual to mean a word or number which appears on the same line as a request which modifies the meaning of that request. For example, the request
.sp
spaces one line, but
.sp 4
spaces four lines. The number 4 is an argument to the sp
request which says to space four lines instead of one. Arguments are
separated from the request and from each other by spaces. More details
on this can be found in Request Arguments.
The primary function of gtroff is to collect words from input
lines, fill output lines with those words, justify the right hand margin
by inserting extra spaces in the line, and output the result. For
example, the input:
Now is the time for all good men to come to the aid of their party. Four score and seven years ago,...
will be read, packed onto output lines, and justified to produce:
Now is the time for all good men to come to the aid of their party. Four score and seven years ago,...
Sometimes a new output line should be started even though the current line is not yet full; for example, at the end of a paragraph. To do this it is possible to cause a break, which starts a new output line. Some requests cause a break automatically, as do blank input lines and input lines beginning with a space.
Not all input lines are text to be formatted. Some of the input lines are requests which describe how to format the text. Requests always have a period (‘.’) or an apostrophe (‘'’) as the first character of the input line.
The text formatter also does more complex things, such as automatically numbering pages, skipping over page boundaries, putting footnotes in the correct place, and so forth.
Here a few hints for preparing text for input to gtroff. First,
keep the input lines short. Short input lines are easier to edit, and
gtroff will pack words onto longer lines anyhow. In keeping with
this, it is helpful to begin a new line after every period, comma, or
phrase, since common corrections are to add or delete sentences or
phrases. Secondly, do not hyphenate words at the end of lines –
gtroff is smart enough to hyphenate words for the user as needed,
but is not smart enough to take hyphens out and join a word back
together. Also, words such as “mother-in-law” should not be broken
over a line, since then a space can occur where not wanted, such as
“mother- in-law”.
gtroff will double space output text automatically if using the
request ‘.ls 2’. Single spaced mode can be reactivated by
typing ‘.ls 1’.
A number of requests allow to change the way the output looks, sometimes called the layout of the output page. Most of these requests adjust the placing of white space (blank lines or spaces).
The ‘.bp’ request starts a new page, causing a line break.
The request ‘.sp N’ leaves N lines of blank space. N can be omitted (meaning skip a single line) or can be of the form Ni (for N inches) or Nc (for N centimeters). For example, the input:
.sp 1.5i My thoughts on the subject .sp
leaves one and a half inches of space, followed by the line “My thoughts on the subject”, followed by a single blank line.
Text lines can be centered by using the ce request. The line
after ce is centered (horizontally) on the page. To center more
than one line, use ‘.ce N’ (where N is the number
of lines to center), followed by the N lines. To center many
lines without counting them, type:
.ce 1000 lines to center .ce 0
The ‘.ce 0’ request tells groff to center zero more
lines, in other words, stop centering.
All of these requests cause a break; that is, they always start a new
line. To start a new line without performing any other action, use
br.
Previous: Basics, Up: Tutorial for Macro Users [Contents][Index]
gtroff provides very low level operations for formatting a
document. There are many common routine operations which are done in
all documents. These common operations are written into macros
and collected into a macro package.
All macro packages provide certain common capabilities which fall into the following categories.
Next: Sections and Chapters, Previous: Common Features, Up: Common Features [Contents][Index]
One of the most common and most used capability is starting a paragraph. There are a number of different types of paragraphs, any of which can be initiated with macros supplied by the macro package. Normally, paragraphs start with a blank line and the first line indented, like the text in this manual. There are also block style paragraphs, which omit the indentation:
Some men look at constitutions with sanctimonious reverence, and deem them like the ark of the covenant, too sacred to be touched.
And there are also indented paragraphs which begin with a tag or label at the margin and the remaining text indented.
one This is the first paragraph. Notice how the first
line of the resulting paragraph lines up with the
other lines in the paragraph.
longlabel
This paragraph had a long label. The first
character of text on the first line will not line up
with the text on second and subsequent lines,
although they will line up with each other.
A variation of this is a bulleted list.
Next: Headers and Footers, Previous: Paragraphs, Up: Common Features [Contents][Index]
Most macro packages supply some form of section headers. The simplest kind is simply the heading on a line by itself in bold type. Others supply automatically numbered section heading or different heading styles at different levels. Some, more sophisticated, macro packages supply macros for starting chapters and appendices.
Next: Page Layout Adjustment, Previous: Sections and Chapters, Up: Common Features [Contents][Index]
Every macro package gives some way to manipulate the headers and footers (or titles) on each page. Some packages will allow for different ones on the even and odd pages (for material printed in a book form).
The titles are called three-part titles, that is, there is a left-justified part, a centered part, and a right-justified part. An automatically generated page number may be put in any of these fields with the ‘%’ character (see Page Layout for more details).
Next: Displays, Previous: Headers and Footers, Up: Common Features [Contents][Index]
Most macro packages let the user specify top and bottom margins and other details about the appearance of the printed pages.
Next: Footnotes and Annotations, Previous: Page Layout Adjustment, Up: Common Features [Contents][Index]
Displays are sections of text to be set off from the body of the paper. Major quotes, tables, and figures are types of displays, as are all the examples used in this document.
Major quotes are quotes which are several lines long, and hence are set in from the rest of the text without quote marks around them.
A list is an indented, single spaced, unfilled display. Lists should be used when the material to be printed should not be filled and justified like normal text, such as columns of figures or the examples used in this paper.
A keep is a display of lines which are kept on a single page if possible. An example for a keep might be a diagram. Keeps differ from lists in that lists may be broken over a page boundary whereas keeps will not.
Floating keeps move relative to the text. Hence, they are good for things which will be referred to by name, such as “See figure 3”. A floating keep will appear at the bottom of the current page if it will fit; otherwise, it will appear at the top of the next page. Meanwhile, the surrounding text will ‘flow’ around the keep, thus leaving now blank areas.
Next: Table of Contents, Previous: Displays, Up: Common Features [Contents][Index]
There are a number of requests to save text for later printing.
Footnotes are printed at the bottom of the current page.
Delayed text is very similar to a footnote except that it is printed when called for explicitly. This allows a list of references to appear (for example) at the end of each chapter, as is the convention in some disciplines.
Most macro packages which supply this functionality also supply a means of automatically numbering either type of annotation.
Next: Indices, Previous: Footnotes and Annotations, Up: Common Features [Contents][Index]
Tables of contents are a type of delayed text having a tag (usually the page number) attached to each entry after a row of dots. The table accumulates throughout the paper until printed, usually after the paper has ended. Many macro packages will provide the ability to have several tables of contents (i.e. one standard one, one for tables, etc).
Next: Paper Formats, Previous: Table of Contents, Up: Common Features [Contents][Index]
While some macro packages will use the term index, none actually provide that functionality. The facilities they call indices are actually more appropriate for tables of contents.
Next: Multiple Columns, Previous: Indices, Up: Common Features [Contents][Index]
Some macro packages provide stock formats for various kinds of documents. Many of them provide a common format for the title and opening pages of a technical paper. The mm macros in particular provide formats for letters and memoranda.
Next: Font and Size Changes, Previous: Paper Formats, Up: Common Features [Contents][Index]
Some macro packages (except man) provide the ability to have two or more columns on a page.
Next: Predefined Strings, Previous: Multiple Columns, Up: Common Features [Contents][Index]
The built-in font and size functions are not always intuitive, so all macro packages provide macros to make these operations simpler.
Next: Preprocessor Support, Previous: Font and Size Changes, Up: Common Features [Contents][Index]
Most macro packages provide various predefined strings for a variety of uses; examples are sub- and superscripts, printable dates, quotes and various special characters.
Next: Configuration and Customization, Previous: Predefined Strings, Up: Common Features [Contents][Index]
All macro packages provide support for the various preprocessors.
Previous: Preprocessor Support, Up: Common Features [Contents][Index]
Some macro packages provide means of customizing many of details of how the package behaves. This ranges from setting the default type size to changing the appearance of section headers.
Next: Programming Tutorial, Previous: Tutorial for Macro Users, Up: Top [Contents][Index]
This chapter documents the main macro packages that come with
groff.
| • man | ||
| • mdoc | ||
| • ms | ||
| • me | ||
| • mm |
Next: mdoc, Previous: Macro Packages, Up: Macro Packages [Contents][Index]
This is the most popular and probably the most important macro package
of groff. It is easy to use, and a vast majority of manual pages
are based on it.
| • Man options | ||
| • Man usage | ||
| • Man font macros | ||
| • Miscellaneous man stuff |
The command line format for using the man macros with
groff is:
groff -m man [ -rC1 ] [ -rD1 ] [ -rPnnn ] [ -rSxx ]
[ -rXnnn ] [ files… ]
It is possible to use ‘-man’ instead of ‘-m man’.
-rC1If more than one manual page is given on the command line, number the pages continuously, rather than starting each at 1.
-rD1Double-sided printing. Footers for even and odd pages are formatted differently.
-rPnnnEnumeration of pages will start with nnn rather than with 1.
-rSxxUse xx (which can be 10, 11, or 12pt) as the base document font size instead of the default value of 10pt.
-rXnnnAfter page nnn, number pages as nnna, nnnb, nnnc, etc. For example, the option -rX2 will produce the following page numbers: 1, 2, 2a, 2b, 2c, etc.
Next: Man font macros, Previous: Man options, Up: man [Contents][Index]
This section describes the available macros for manual pages. For further customization, put additional macros and requests into the file man.local which will be loaded immediately after tmac.an.
Sets the title of the man page to title and the section to section, which must take on a value between 1 and 8. The value section may also have a string appended, e.g. ‘.pm’, to indicate a specific subsection of the man pages.
Both title and section are positioned at the left and right in the header line (with section in parentheses immediately appended to title. extra1 will be positioned in the middle of the footer line. extra2 will be positioned at the left in the footer line (resp. at the left on even pages and at the right on odd pages if double-sided printing is active). extra3 is centered in the header line.
For HTML output, headers and footers are completely supressed.
Additionally, this macro starts a new page; the new line number is 1
again (except if the -rC1 option is given on the command line)
– this feature is intended only for formatting multiple man pages; a
single man page should contain exactly one TH macro at the
beginning of the file.
Sets up an unnumbered section heading sticking out to the left. Prints
out all the text following SH up to the end of the line (resp.
the text in the next line if there is no argument to SH) in bold
face, one size larger than the base document size. Additionally, the
left margin for the following text is reset to its default value.
Sets up an unnumbered section heading. Prints out all the text
following SS up to the end of the line (resp. the text in the
next line if there is no argument to SS) in bold face, at the sam
size as the base document size. Additionally, the left margin for the
following text is reset to its default value.
Sets up an indented paragraph with label. The indentation is set to nnn if that argument is supplied (the default unit is ‘n’ if omitted), otherwise it is set to the default indentation value.
The first line of text following this macro is interpreted as a string to be printed flush-left, as it is appropriate for a label. It is not interpreted as part of a paragraph, so there is no attempt to fill the first line with text from the following input lines. Nevertheless, if the label is not as wide as the indentation, then the paragraph starts at the same line (but indented), continuing on the following lines. If the label is wider than the indentation, then the descriptive part of the paragraph begins on the line following the label, entirely indented. Note that neither font shape nor font size of the label is set to a default value; on the other hand, the rest of the text will have default font settings.
These macros are mutual aliases. Any of them causes a line break at the
current position, followed by a vertical space downwards by the amount
specified by the PD macro. The font size and shape are reset to
the default value (10pt resp. Roman). Finally, the current left
margin is restored.
Sets up an indented paragraph, using designator as a tag to mark
its beginning. The indentation is set to nnn if that argument is
supplied (default unit is ‘n’), otherwise the default indentation
value is used. Font size and face of the paragraph (but not the
designator) are reset to its default values. To start an indented
paragraph with a particular indentation but without a designator, use
‘""’ (two doublequotes) as the first argument of IP.
For example, to start a paragraph with bullets as the designator and 4en indentation, write
.IP \(bu 4
Sets up a paragraph with hanging left indentation. The indentation is set to nnn if that argument is supplied (default unit is ‘n’), otherwise the default indentation value is used. Font size and face are reset to its default values.
This macro moves the left margin to the right by the value nnn if
specified (default unit is ‘n’); otherwise the default indentation
value is used. Calls to the RS macro can be nested.
This macro moves the left margin back to level nnn; if no argument
is given, it moves one level back. The first level (i.e., no call to
RS yet) has number 1, and each call to RS increases
the level by 1.
To summarize, the following macros cause a line break with the insertion
of vertical space (which amount can be changed with the PD
macro): SH, SS, TP, LP (PP,
P), IP, and HP.
The macros RS and RE also cause a break but no insertion
of vertical space.
Next: Miscellaneous man stuff, Previous: Man usage, Up: man [Contents][Index]
The standard font is Roman; the default text size is 10 point.
Causes the text on the same line or the text on the next line to appear in a font that is one point size smaller than the default font.
Causes the text on the same line or the text on the next line to appear in boldface font, one point size smaller than the default font.
Causes text on the same line to appear alternately in bold face and italic. The text must be on the same line as the macro call. Thus
.BI this "word and" that
would cause ‘this’ and ‘that’ to appear in bold face, while ‘word and’ appears in italics.
Causes text to appear alternately in italic and bold face. The text must be on the same line as the macro call.
Causes text on the same line to appear alternately in roman and italic. The text must be on the same line as the macro call.
Causes text on the same line to appear alternately in italic and roman. The text must be on the same line as the macro call.
Causes text on the same line to appear alternately in bold face and roman. The text must be on the same line as the macro call.
Causes text on the same line to appear alternately in roman and bold face. The text must be on the same line as the macro call.
Causes text to appear in roman font. If no text is present on the line where the macro is called, then the text of the next line appears in roman. This is the default font to which text is returned at the end of processing of the other macros.
Causes text to appear in bold face. If no text is present on the line where the macro is called, then the text of the next line appears in bold face.
Causes text to appear in italic. If no text is present on the line where the macro is called, then the text of the next line appears in italic.
Previous: Man font macros, Up: man [Contents][Index]
The default indentation is 7.2n for all output devices except for
grohtml which uses 1.2i instead.
Sets tabs every 0.5 inches. Since this macro is always called
during a TH request, it makes sense to call it only if the tab
positions have been changed.
Adjusts the empty space before a new paragraph (resp. section). The optional argument gives the amount of space (default units are ‘v’); without parameter, the value is reset to its default value (1 line for tty devices, 0.4v otherwise).
This affects the macros SH, SS, TP, LP
(resp. PP and P), IP, and HP.
The following strings are defined:
Switch back to the default font size.
The ‘registered’ sign.
The ‘trademark’ sign.
Left and right quote.
This is equal to \(lq and \(rq, respectively.
If a preprocessor like gtbl or geqn is needed, it has
become usage to make the first line of the man page look like this:
.\" word
Note the single space character after the double quote. word
consists of letters for the needed preprocessors: ‘e’ for
geqn, ‘r’ for grefer, ‘t’ for gtbl.
Modern implementations of the man program read this first line
and automatically call the right preprocessor(s).
Next: ms, Previous: man, Up: Macro Packages [Contents][Index]
Next: me, Previous: mdoc, Up: Macro Packages [Contents][Index]
Next: mm, Previous: ms, Up: Macro Packages [Contents][Index]
Previous: me, Up: Macro Packages [Contents][Index]
Next: Preprocessors, Previous: Macro Packages, Up: Top [Contents][Index]
This chapter covers all of the facilities of gtroff.
Users of macro packages may skip it if not interested in details.
Next: Input Conventions, Previous: Programming Tutorial, Up: Programming Tutorial [Contents][Index]
gtroff input files contain text with control commands
interspersed throughout. But, even without control codes, gtroff
will still do several things with the input text: filling and adjusting,
adding additional space after sentences, hyphenating and inserting
implicit line breaks.
| • Filling and Adjusting | ||
| • Hyphenation | ||
| • Sentences | ||
| • Tab Stops | ||
| • Implicit Line Breaks |
Next: Hyphenation, Previous: Text, Up: Text [Contents][Index]
When gtroff reads in text it collects words from input and fits
as many of them together on one output line as it can. This is known as
filling.
Once gtroff has a filled line it will try to adjust
it. Which means it will widen the spacing between words until the text
reaches the right margin (in the default adjustment mode). Extra spaces
between words are preserved, but spaces at the end of lines are ignored.
Spaces at the front of a line will cause a break (breaks will be
explained in Implicit Line Breaks)
See Manipulating Filling and Adjusting.
Next: Sentences, Previous: Filling and Adjusting, Up: Text [Contents][Index]
Since the odds of finding a set of words, for every output line, which
will fit nicely on a line without inserting excessive amounts of space
between words is not great, gtroff will hyphenate words so that
lines can be justified without there being too much space between words.
It uses an internal hyphenation algorithm (a simplified version of the
algorithm used within TeX) to indicate which words can be hyphenated
and how to do so. When a word is hyphenated the first part of the word
will be added to the current filled line being output (with an attached
hyphen), and the other portion will be added to the next line to be
filled.
Next: Tab Stops, Previous: Hyphenation, Up: Text [Contents][Index]
Although it is often debated, some typesetting rules say there should be different amounts of space after various punctuation marks. For example, the Chicago typsetting manual says that a period at the end of a sentence should have twice as much space following it as would a comma or a period as part of an abbreviation.
gtroff does this by flagging certain characters (normally
‘!’, ‘?’ and ‘.’) as end of sentence characters.
When gtroff encounters one of these characters at the end of a
line it will append two sentence spaces in the formatted output.
(Thus, one of the conventions mentioned in Input Conventions.)
In addition, the following characters resp. glyphs are treated
transparently while handling end of sentence characters: ‘"’,
‘'’, ‘)’, ‘]’, ‘*’, dg, and rq.
See the cflags request in Using Symbols, for more details.
To prevent the insertion of extra space after an end of sentence
character (at the end of a line), append \&.
Next: Implicit Line Breaks, Previous: Sentences, Up: Text [Contents][Index]
gtroff translates tabulator characters, also called
tabs (normally code point ASCII 0x09 resp.
EBCDIC 0x05), in the input into movements to the next
tabulator stop. These tab stops are initially located every half inch
across the page. Using this simple tables can easily be made. However,
it can often be deceptive as the appearance (and width) of the text on a
terminal and the results from gtroff can vary greatly.
Also, a possible sticking point is that lines beginning with tab characters will still be filled, again producing unexpected results. For example, the following input
| 1 | 2 | 3 | |
| 4 | 5 |
will produce
| 1 | 2 | 3 | 4 | 5 |
See Tabs and Fields.
An important concept in gtroff is the break. When a break
occurs, gtroff will output the partially filled line
(unjustified), and resume collecting and filling text on the next output
line.
There are several ways to cause a break in gtroff. A blank line
will not only cause a break, but it will also cause a one line vertical
space (effectively a blank line) to be output.
A line which begins with a space will cause a break and the space will be output at the beginning of the next line. Note that this space isn’t adjusted, even in fill mode.
The end of file will also cause a break – otherwise the last line of the document may vanish!
Certain requests also cause breaks, implicitly or explicitly. This will be discussed in Manipulating Filling and Adjusting.
Next: Measurements, Previous: Text, Up: Programming Tutorial [Contents][Index]
Since gtroff does filling automatically, it is traditional in
groff not to try and type things in as nicely formatted
paragraphs. These are some conventions commonly used when typing
gtroff text:
Next: Expressions, Previous: Input Conventions, Up: Programming Tutorial [Contents][Index]
gtroff (like any other programs) requires numeric parameters to
specify various measurements. Most numeric parameters4 may have a
measurement unit attached. These units are specified as a single
character which immediately follows the number or expression. Each of
these units are understood, by gtroff, to be a multiple of its
basic unit. So, whenever a different measurement unit is
specified gtroff converts this into its basic units. This
basic unit, represented by a ‘u’, is a device dependent measurement
which is quite small, ranging from 1/75th to 1/72000th of an inch. The
values may be given as fractional numbers – nevertheless, fractional
basic units are always rounded to integers.
Some of the measurement units are completely independent of any of the
current settings (e.g. type size) of gtroff.
iInches. An antiquated measurement unit still in use in certain backwards countries. One inch is equal to 2.54cm.
cCentimeters. One centimeter is equal to 0.3937in.
pPoints. This is a typesetter’s measurement used for measure type size. It is 72 points to an inch.
PPica. Another typesetting measurement. 6 Picas to an inch (and 12 points to a pica).
szSee Fractional Type Sizes, for a discussion of these units.
The other measurements understood by gtroff are dependent on
settings currently in effect in gtroff. These are very useful
for specifying measurements which should look proper with any size of
text.
mEms. This unit is equal to the current font size in points. So called because it is approximately the width of the letter ‘m’ in the current font.
nEns. This is half of an em.
vVertical space. This is equivalent to the current line spacing. See Sizes, for more information about this.
M100ths of an em.
| • Default Units |
Previous: Measurements, Up: Measurements [Contents][Index]
Many requests take a default unit. While this can be helpful at times, it can cause strange errors in some expressions. For example, the line length request expects em units. Here are several attempts to get a line length of 3.5 inches and the results:
3.5i ⇒ 3.5i 7/2 ⇒ 0i 7/2i ⇒ 0i 7i/2 ⇒ 0.1i 7i/2u ⇒ 3.5i
Everything will be converted to basic units first. In the above example it is assumed that 1i equals 240u, and 1m equals 10p (thus 1m equals 33u). The value 7i/2 will be first handled as 7i/2m, then converted to 1680u/66u which is 25u, and this is approximately 0.1i.
As a conclusion, the safest way to specify measurements is to always attach a scaling indicator. If you want to multiply or divide by a certain scalar value, use ‘u’ as the unit for that value.
Next: Identifiers, Previous: Measurements, Up: Programming Tutorial [Contents][Index]
gtroff has most of operators common to other languages:
gtroff only provides integer arithmetic. The internal type used
for computing results is ‘int’, which is usually a 32bit
signed integer.
if and while requests). See
below for the use of unary operators in motion requests.
(c;e). Evaluate e using c as
the default scaling indicator. If c is missing, ignore scaling
indicators in the evaluation of e.
Parentheses may be used as in any other language. However, in
gtroff they are necessary to ensure order of evaluation.
gtroff has no operator precedence; expressions are evaluated left
to right. This means that ‘3+5*4’ is evaluated as if it were
parenthesized like ‘(3+5)*4’, not as ‘3+(5*4)’, as expected.
For many requests which cause a motion on the page, the unary operators
work differently. The ‘+’ and ‘-’ operators then indicate a
motion relative to the current position (down or up, respectively), and
the ‘|’ operator indicates an absolute position on the page or
input line.
‘+’ and ‘-’ are also treated differently by the following
requests and escapes: bp, in, ll, lt,
nm, nr, pl, pn, po, ps,
rt, ti, \R, and \s. Here the plus and minus
signs indicate increments resp. decrements.
See Setting Registers.
Due to the way arguments are parsed, spaces are not allowed in expressions, unless the entire expression is surrounded by parentheses.
See Request Arguments, and Conditionals and Loops.
Next: Embedded Commands, Previous: Expressions, Up: Programming Tutorial [Contents][Index]
Like any other language, gtroff has rules for properly formed
identifiers. In gtroff, an identifier can be made up of
almost any printable character. The exception are the following
characters:
0x08 resp. EBCDIC 0x16) and character code 0x01.
groff runs on a machine based on ASCII, causing a
warning message of type ‘input’ (see Debugging, for more
details): 0x00, 0x0B, 0x0D-0x1F,
0x80-0x9F.
And here the illegal input characters if groff runs on an
EBCDIC host: 0x00, 0x08, 0x09,
0x0B, 0x0D-0x14, 0x17-0x1F,
0x30-0x3F.
Currently, some of these reserved codepoints are used internally, thus
making it non-trivial to extend gtroff to cover Unicode or other
character sets resp. encodings which use characters of these ranges.
Note that illegal characters will be removed before parsing; an identifier ‘foo’, followed by an illegal character, followed by ‘bar’ will be treated as ‘foobar’.
For example, any of the following is valid.
br PP (l end-list @_
Note that identifiers longer than two characters with a closing bracket (‘]’) in its name can’t be accessed with escape sequences which expect an identifier as a parameter. For example, ‘\[foo]]’ will access the glyph ‘foo’, followed by ‘]’, whereas ‘\C'foo]'’ really asks for glyph ‘foo]’.
Whether an identifier ident is valid in gtroff can be
tested with the \A escape. It expands to the character 1
or 0 according to whether its argument (delimited by quotes usually)
is or is not acceptable as the name of a string, macro, diversion,
number register, environment, or font. It will return 0 if no
argument is given. This is useful for looking up user input in some
sort of associative table.
\A'end-list'
⇒ 1
See Escapes, for details on parameter delimiting characters.
Identifiers in gtroff can be any length, but, in some contexts,
gtroff needs to be told where identifiers end and text begins
(and in different ways depending on their length).
gtroff only). Must be bracketed with ‘[’
and ‘]’ in some situations. Any length identifier can be put
in brackets.
Unlike many other programming languages, undefined identifiers are silently ignored or expanded to nothing.
See Interpolating Registers, and Strings.
Next: Registers, Previous: Identifiers, Up: Programming Tutorial [Contents][Index]
Most documents need more functionality beyond filling, adjusting and
implicit line breaking. In order to gain further functionality,
gtroff allows commands to be embedded into the text, in two ways.
The first is a request which takes up an entire line, and does some large scale operation (e.g. break lines, start new pages).
The other is an escape which can be embedded anywhere in the text, or even as an argument to a request. Escapes generally do more minor operations like sub- and superscripts, print a symbol, etc.
| • Requests | ||
| • Macros | ||
| • Escapes |
Next: Macros, Previous: Embedded Commands, Up: Embedded Commands [Contents][Index]
A request line begins with a control character, which is either a single quote (‘'’, the no-break control character) or a period (‘.’, the normal control character). These can be changed; see Character Translations, for details. After this there may be optional tabs or spaces followed by an identifier which is the name of the request. This may be followed by any number of space-separated arguments.
To begin a line with a control character without it being interpreted,
precede it with \&. This represents a zero width space, which
means it will not affect the output.
In most cases the period is used as a control character. Several requests will cause a break implicitly; using the single quote control character will prevent this.
| • Request Arguments |
Arguments to requests (and macros) are processed much like the shell: The line is split into arguments according to spaces. An argument which is intended to contain spaces can either be enclosed in quotes (single or double), or have the spaces escaped with backslashes.
.uh The Mouse Problem .uh "The Mouse Problem" .uh The\ Mouse\ Problem
The first line is the uh macro being called with 3 arguments,
‘The’, ‘Mouse’, and ‘Problem’. The latter two have the
same effect or calling the uh macro with one argument ‘The
Mouse Problem’.5
Note, however, that the ds request works differently.
See Strings, for more details.
Next: Escapes, Previous: Requests, Up: Embedded Commands [Contents][Index]
gtroff has a macro facility for defining a series of lines
which can be invoked by name. They are called in the same manner as
requests – arguments also may be passed in the same manner.
See Writing Macros, and Request Arguments.
Previous: Macros, Up: Embedded Commands [Contents][Index]
Escapes may occur anywhere in the input to gtroff. They begin
with a backslash usually and are followed by a single character which
indicates the function to be performed. The escape character can be
changed; see Character Translations.
Escape sequences which require an identifier as a parameter accept three possible syntax forms.
Examples:
\fB \n(XX \*[TeX]
Other escapes may require several arguments and/or some special format. In such cases the argument is traditionally enclosed in single quotes (and quotes are always used in this manual for the definitions of escape sequences). The enclosed text is then processed according to what that escape expects. Example:
\l'1.5i\(bu'
Note that the quote character can be replaced with any other character
which does not occur in the argument (even a newline or a space
character) in the following escapes: \o, \b, and
\X. This makes e.g.
A caf \o e\' in Paris ⇒ A café in Paris
possible, but it is better not to use this feature to avoid confusion.
The following escapes sequences (which are handled similarly to
characters since they don’t take a parameter) are also allowed as
delimiters: \%, ‘\ ’, \|, \^, \{,
\}, \', \`, \-, \_, \!,
\?, \@, \), \/, \,, \&,
\~, \0, \a, \c, \d, \e,
\E, \p, \r, \t, and \u. Again, don’t
use these if possible.
No newline characters as delimiters are allowed in the following
escapes: \A, \Z, \C, and \w.
Finally, the escapes \D, \h, \H, \l,
\L, \N, \R, \s, \S, \v, and
\x can’t use the following characters as delimiters:
0-9.
\%, \{, \},
\', \`, \-, \_, \!, \@,
\/, \c, \e, and \p.
To have a backslash (resp. the current escape character) appear in the
output several escapes are defined: \\, \e or \E.
These are very similar, and only differ with respect to being used in
macros or diversions. See Copy-in Mode, and Diversions, for
more information.
See Identifiers, and Character Translations.
| • Comments |
Probably one of the most6 common forms of escapes is the comment.
Start a comment. Everything to the end of the input line is ignored.
This may sound simple, but it can be tricky to keep the comments from interfering with the appearance of the final output.
If the escape is to the right of some text or a request, that portion of
the line will be ignored, but the space leading up to it will be noticed
by gtroff. This only affects the .ds request.
One possibly irritating idiosyncracy is that tabs must not be used to line up comments. Tabs are not treated as white space between the request and macro arguments.
A comment on a line by itself will be treated as a blank line, because after eliminating the comment, that is all that remains:
Test \" comment Test
will produce
Test Test
As a consequence, it is common to start the line with .\" which
will cause the line to be treated as an undefined request and thus
ignored completely.
Another commenting scheme seen sometimes is three consecutive single
quotes (''') at the beginning of a line. This works, but
gtroff will give a warning about an undefined macro (namely
''), which is harmless, but irritating.
Now to avoid all this gtroff has a new comment mechanism using
the \# escape. This escape works the same as \" except
that the newline is also ignored:
Test \# comment Test
will produce
Test Test
as expected.
For large blocks of text, the ig request may be useful.
See Strings.
Next: Manipulating Filling and Adjusting, Previous: Embedded Commands, Up: Programming Tutorial [Contents][Index]
Numeric variables in gtroff are called registers. There
are a number of built-in registers, supplying anything from the date to
details of formatting parameters.
See Identifiers, for details on register identifiers.
| • Setting Registers | ||
| • Interpolating Registers | ||
| • Auto-increment | ||
| • Assigning Formats | ||
| • Built-in Registers |
Next: Interpolating Registers, Previous: Registers, Up: Registers [Contents][Index]
Registers are defined resp. set via the nr request or the
\R escape.
Set number register ident to value. If ident doesn’t exist, it will be created.
The argument to \R has to be enclosed in quotes usually.
See Escapes, for details on parameter delimiting characters.
For example, the following two lines are equivalent:
.nr a 1 \R'a 1'
Both nr and \R have two additional special forms to
increment resp. decrement a register.
Increment (decrement) register ident by value.
.nr a 1
.nr a +1
\na
⇒ 2
To assign the negated value of a register to another register, some care must be taken to get the desired result:
.nr a 7
.nr b 3
.nr a -\nb
\na
⇒ 4
.nr a (-\nb)
\na
⇒ -3
The surrounding parentheses prevent the interpretation of the minus sign as a decrementing operator. An alternative is to start the assignment with a ‘0’:
.nr a 7
.nr b -3
.nr a \nb
\na
⇒ 4
.nr a 0\nb
\na
⇒ -3
Remove number register ident. If ident doesn’t exist, the request is ignored.
Rename number register ident1 to ident2. If either ident1 or ident2 doesn’t exist, the request is ignored.
This request creates an alias ident1 for a number register ident2. The new name and the old name will be exactly equivalent. If ident1 is undefined, a warning of type ‘reg’ will be generated, and the request will be ignored. See Debugging, for information about warnings.
Next: Auto-increment, Previous: Setting Registers, Up: Registers [Contents][Index]
Numeric registers can be accessed via the \n escape.
Interpolate number register ident. This means that the value of
the register is expanded in-place while gtroff is parsing the
input line.
.nr a 5
.nr as \na+\na
\n(as
⇒ 10
Next: Assigning Formats, Previous: Interpolating Registers, Up: Registers [Contents][Index]
Number registers can also be auto-incremented and auto-decremented. The
increment resp. decrement factor can be specified with a third
argument to the nr request or \R escape.
Set number register ident to value; the increment for
auto-incrementing is set to incr. Note that the \R escape
doesn’t support this notation.
To activate auto-incrementing, the escape \n has a special syntax
form.
Before interpolating, increment resp. decrement ident by the
auto-increment value as specified with the nr request (or the
\R escape). If no auto-increment value has been specified, both
syntax forms are identical to \n.
For example,
.nr a 0 1 .nr xx 0 5 .nr foo 0 -2 \n+a, \n+a, \n+a, \n+a, \n+a .br \n-(xx, \n-(xx, \n-(xx, \n-(xx, \n-(xx .br \n+[foo], \n+[foo], \n+[foo], \n+[foo], \n+[foo]
produces
1, 2, 3, 4, 5 -5, -10, -15, -20, -25 -2, -4, -6, -8, -10
To change the increment value without changing the value of a register, the following can be used.
.nr a \na 10
Next: Built-in Registers, Previous: Auto-increment, Up: Registers [Contents][Index]
When a register is used in the text of an input file (as opposed to part
of an expression) it is textually replaced (or interpolated) with a
representation of that number. This output format can be changed to a
variety of formats (numbers, Roman numerals, etc). This is done using
the af request.
Change the output format of a number register. The first argument ident is the name of the number register to be changed, and the second argument format is the output format. The following output formats are available:
1Decimal arabic numbers. This is the default format: 1, 2, 3, …
0…0Decimal numbers with as many digits as specified. So, ‘00’ would result in printing numbers as 01, 02, 03, …
In fact, any digit instead of zero will do; gtroff only counts
how many digits are specified. As a consequence, af’s default
format ‘1’ could be specified as ‘0’ also (and exactly this is
returned by the \g escape).
IUpper-case Roman numerals: 0, I, II, III, IV, …
iLower-case Roman numerals: 0, i, ii, iii, iv, …
AUpper-case letters: A, B, C, …, Z, AA, AB, …
aLower-case letters: a, b, c, …, z, aa, ab, …
Omitting the number register format will cause a warning of type ‘missing’. See Debugging, for more details. Specifying a nonexistent format causes an error.
The following example will produce ‘10, X, j, 010’:
.nr a 10 .af a 1 \" the default format \na, .af a I \na, .af a a \na, .af a 001 \na
The largest number representable for the ‘i’ and ‘I’ formats
is 39999 (resp. -39999); UNIX troff uses ‘z’ and
‘w’ to represent 10000 and 5000 in Roman numerals, and so does
gtroff. Currently, the correct glyphs (Unicode code points
U+2182 and U+2181, respectively) are not available.
If ident doesn’t exist, it will be created.
Changing the output format of a read-only register causes an error. It
is necessary to first copy the register’s value to a writeable register,
then apply the af request to this other register.
Return the current format of the specified register ident. For example, ‘\ga’ after the previous example would produce the string ‘000’. If the register hasn’t been defined yet, nothing is returned.
Previous: Assigning Formats, Up: Registers [Contents][Index]
The following lists some built-in registers which are not described elsewhere in this manual. Any register which begin with a ‘.’ is read-only. A complete listing of all built-in registers can be found in Register Index.
.HHorizontal resolution in basic units.
.VVertical resolution in basic units.
dwDay of the week (1-7).
dyDay of the month (1-31).
moCurrent month (1-12).
yearThe current year.
yrThe current year minus 1900. Unfortunately, the documentation of
UNIX Version 7’s troff had a year 2000 bug: It
incorrectly claimed that yr contains the last two digits of the
year. That claim has never been true of either traditional troff
or GNU troff. Old troff input that looks like this:
'\" The following line stopped working after 1999 This document was formatted in 19\n(yr.
can be corrected as follows:
This document was formatted in \n[year].
or, to be portable to older troff versions, as follows:
.nr y4 1900+\n(yr This document was formatted in \n(y4.
.cc.The current input line number. Register ‘.c’ is read-only,
whereas ‘c.’ (a gtroff extension) is writable also,
affecting both ‘.c’ and ‘c.’.
lnThe current output line number after a call to the nm
request to activate line numbering.
.xThe major version number. For example, if the version number is 1.03 then .x will contain ‘1’.
.yThe minor version number. For example, if the version number is 1.03 then .y will contain ‘03’.
.YThe revision number of groff.
.gAlways 1. Macros should use this to determine whether they are
running under GNU troff.
.AIf the command line option -a is used to produce an ASCII approximation of the output, this is set to 1, zero otherwise. See Groff Options.
.PThis register is set to 1 (and to 0 otherwise) if the current page is actually being printed, i.e., if the -o option is being used to only print selected pages. See Groff Options, for more information.
.TIf gtroff is called with the -T command line option, the
number register .T is set to 1, and zero otherwise.
See Groff Options.
Additionally, gtroff predefines a single (read/write) string
register .T which contains the current output device (for
example, ‘latin1’ or ‘ps’).
Next: Manipulating Hyphenation, Previous: Registers, Up: Programming Tutorial [Contents][Index]
Various ways of causing breaks were given in Implicit Line Breaks. The br request will likewise cause a break. Several
other requests will also cause breaks, but implicitly. These are
bp, ce, cf, fi, fl, in,
nf, rj, sp, ti, and trf.
Break the current line, i.e., the input collected so far will be emitted without adjustment.
If the no-break control character is used, no break will happen:
a
'br
b
⇒ a b
Initially, gtroff will fill and adjust text to both margins.
Filling can be disabled via the nf request and re-enabled with
the fi request.
Activate fill mode (which is the default). This request implicitly
enables adjusting; it will also cause a break in the text currently
being filled. The number register .u is set to 1.
The fill mode status is associated with the current environment (see Environments).
Activate no-fill mode. Input lines are output as-is, retaining line
breaks. The current line length will be ignored. This command
implicitly disables adjusting; it also causes a break. The number
register .u will be set to 0.
The fill mode status is associated with the current environment (see Environments).
Set adjusting mode.
Activation and deactivation of adjusting will be implicitly done with
calls to the fi resp. nf requests.
mode can have one of the following values:
lAdjust text to the left margin. This produces what is traditionally called ragged-right text.
rAdjust text to the right margin, producing ragged-left text.
cCenter filled text. This is different to the ce request which
only centers text without filling.
bnJustify to both margins. This is default of gtroff.
With no argument, gtroff will adjust lines the same way before
adjusting has been deactivated (with a call to na, for example).
text .ad r text .ad c text .na text .ad \" back to centering text
The current adjustment mode is available in the number register
.j; it can be stored and subsequently used to set adjustment.
The adjustment mode status is associated with the current environment (see Environments).
Disable adjusting. This request won’t change the current adjustment
mode: A call to ad afterwards will use the previous adjustment
setting.
The adjustment mode status is associated with the current environment (see Environments).
Adjust the current line and cause a break.
In most cases this will produce very ugly results, since gtroff
doesn’t have a sophisticated paragraph building algorithm (as TeX
have, for example); instead, gtroff fills and adjusts a paragraph
line by line:
This is an uninteresting sentence. This is an uninteresting sentence.\p This is an uninteresting sentence.
is formatted as
This is an uninteresting sentence. This is an uninteresting sentence. This is an uninteresting sentence.
Change the minimum size of a space between filled words. It takes its units as one twelfth of the space width parameter for the current font. Initially both the word_space_size and sentence_space_size are 12.
If two arguments are given to the ss request, the second argument
sets the sentence space size. If the second argument is not given,
sentence_space_size will be the same as word_space_size.
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, a
sentence should always be followed with either a newline or two spaces.
The number registers .ss and .sss are the values of the
parameters set by the first and second arguments of the ss
request.
The space and sentence space values are associated with the current environment (see Environments).
This request is ignored in nroff mode; it is also ignored if there is no parameter.
Center text. While the ‘ad c’ request will also center text,
it has the side effect of filling the text. ce will not fill the
text it affects. This request causes a break.
With no arguments, ce will center the next line of text.
nnn is a number indicating the number of lines to be centered. If
the argument is zero or negative, centering is disabled.
The basic length for centering text is the line length (as set with the
ll request) minus the indentation (as set with the in
request). Temporary indentation is ignored.
A common idiom is to turn on centering for a large number of lines, and to turn off centering after text to be centered. This is useful for any request which takes a number of lines as an argument.
.ce 1000 replace this with something more interesting … .ce 0
The .ce number register contains the number of lines remaining to
be centered, as set by the ce request.
Justify unfilled text to the right margin. Its arguments are identical
to the ce request. The .rj number register is the number
of lines to be right-justified as set by the rj request. This
request causes a line break.
Next: Manipulating Spacing, Previous: Manipulating Filling and Adjusting, Up: Programming Tutorial [Contents][Index]
As discussed in Hyphenation, gtroff will hyphenate words.
There are a number of ways to influence how hyphenation is done.
Enable hyphenation. The request has an optional numeric argument, mode, to restrict hyphenation if necessary:
1The default argument if mode is omitted. Hyphenate without
restrictions. This is also the start-up value of gtroff.
2Do not hyphenate the last word on a page or column.
4Do not hyphenate the last two characters of a word.
8Do not hyphenate the first two characters of a word.
Values in the previous table are additive. For example, the value 12 causes gtroff to neither hyphenate the last two nor the first
two characters of a word.
The current hyphenation restrictions can be found in the number register ‘.hy’.
The hyphenation mode is associated with the current environment (see Environments).
Disable hyphenation (i.e., set the hyphenation mode to zero). Note that
the hyphenation mode of the last call to hy is not remembered.
The hyphenation mode is associated with the current environment (see Environments).
Set the maximum number of consecutive hyphenated lines to nnn. If
this number is negative, there is no maximum. The default value is -1 if nnn is omitted. This value is associated with the current
environment (see Environments). Only lines output from a given
environment count towards the maximum associated with that environment.
Hyphens resulting from \% are counted; explicit hyphens are not.
The current setting of hlm is available in the .hlm
register. Also the number of immediately preceding consecutive
hyphenated lines are available in the number register ‘.hlc’.
Define how word1, word2, etc. are to be hyphenated. The words must be given with hyphens at the hyphenation points. For example:
.hw in-sa-lub-rious
Besides the space character, any character which hyphenation code value
is zero can be used to separate the arguments of hw (see the
documentation for the hcode request below for more information).
In addition, this request can be used more than once.
Hyphenation exceptions specified with the hw request are
associated with the current hyphenation language; it will cause an error
if there is no current hyphenation language.
This request is ignored if there is no parameter.
In old versions of troff there was a limited amount of space to
store such information; fortunately, with gtroff, this is no
longer a restriction.
To tell gtroff how to hyphenate words on the fly, the \%
escape, also known as the hyphenation character, can be used.
Preceding a word with this character will prevent it from being
hyphenated, putting it in a word will indicate to gtroff that the
word may be hyphenated at that point. Note that this mechanism will
only affect one word; to change the hyphenation of a word for the entire
document, use the hw request.
Change the hyphenation character to char. This character will
then work the same as the \% escape, and, thus, no longer appear
in the output. Without an argument, hc will reset the
hyphenation character to be \% (the default) only.
The hyphenation character is associated with the current environment (see Environments).
Read in a file of hyphenation patterns. This file will be searched for in the same way as tmac.name is searched for if the -mname option is specified.
It should have the same format as the argument to the \patterns
primitive in TeX (without using TeX’s macro expansion); 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.
If no hpf request is specified (either in the document or in a
macro package), gtroff won’t hyphenate at all.
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 or troffrc-end file; by default,
troffrc loads hyphenation patterns for American English (in file
hyphen.us).
It will cause an error if there is no current hyphenation language.
Sets the hyphenation code of character c1 to code1, that of c2 to code2, etc. 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.
This request will be ignored if it has no parameter.
Set the (right) hyphenation margin to length. If the current
adjustment mode is not ‘b’, the line will not be hyphenated if
it is shorter than length. Without argument, the hyphenation
margin will be reset to its default value, which is 0. The default
scaling indicator for this request is m. The hyphenation
margin is associated with the current environment
(see Environments).
A negative argument will reset the hyphenation margin to zero, emitting a warning of type ‘range’.
The current hyphenation margin is available in the .hym register.
Set the hyphenation space to hyphenation_space. If the current
adjustment mode is ‘b’, don’t hyphenate the line if the line
can be justified by adding no more than hyphenation_space extra
space to each word space. Without argument, the hyphenation space is
set to its default value, which is 0. The default scaling indicator
for this request is m. The hyphenation space is associated
with the current environment (see Environments).
A negative argument will reset the hyphenation space to zero, emitting a warning of type ‘range’.
The current hyphenation space is available in the .hys register.
Set the soft hyphen character to char. If the argument is
omitted, the soft hyphen character will be set to the default character
\(hy (this is the start-up value of gtroff also). 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.
Set the current hyphenation language to the string language.
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 or the
troffrc-end files; troffrc sets the default language to
‘us’.
The current hyphenation language is available as a string in the read-only number register ‘.hla’.
.ds curr_language \n[.hla]
\*[curr_language]
⇒ us
Next: Tabs and Fields, Previous: Manipulating Hyphenation, Up: Programming Tutorial [Contents][Index]
Space downwards distance. With no argument it will advance 1 line. A negative argument will cause gtroff to move up the page
the specified distance. If the argument is preceded by a ‘|’
gtroff will move that distance from the top of the page. This
request causes a line break. The default scaling indicator is v.
Output nnn-1 blank lines after each line of text. With no
argument gtroff will use the previous value before the last
ls call.
.ls 2 \" This causes double-spaced output .ls 3 \" This causes triple-spaced output .ls \" Again double spaced
The line spacing is associated with the current environment (see Environments).
The number register .L contains the current line spacing setting.
Sometimes, extra vertical spacing is only needed occasionally, e.g. to
allow space for a tall construct (like an equation). The \x
escape will do this. The escape is given a numerical argument, usually
enclosed in quotes (like ‘\x'3p'’); the default scaling indicator
is v. If this number is positive extra vertical space will
be inserted below the current line. A negative number will add space
above. If this escape is used multiple times on the same line, the
maximum of the values is used.
See Escapes, for details on parameter delimiting characters.
The .a number register contains the most recent (nonnegative)
extra vertical line space.
... example of inline equation ...
Enable no-space mode. In this mode, spacing (either via sp
or via blank lines) is disabled. The bp request to advance to
the next page is also disabled, except if it is accompanied by a page
number (see Page Control, for more information). This mode will end
when actual text is output or the rs request is encountered.
This request is useful for macros which want to avoid that subsequent macros inadvertently insert some vertical space before the text starts (for example, to set up the first paragraph after a section header). It is associated with the current diversion level.
Disable no-space mode. This request is associated with the current diversion level.
Next: Character Translations, Previous: Manipulating Spacing, Up: Programming Tutorial [Contents][Index]
A tab character (ASCII char 9, EBCDIC char 5) causes a horizontal movement to the next tab stop (which is much like that on a typewriter).
This escape is a non-interpreted tab character. In copy mode
(see Copy-in Mode), \t is the same as a real tab character.
Change tab stop positions. This request takes a series of tab specifiers as arguments (optionally divided into two groups with the letter ‘T’) which indicate where each tab stop is to be (overriding any previous settings).
Tab stops can be specified absolutely, i.e., as the distance from the left margin. For example, the following will set 6 tab stops every one inch.
.ta 1i 2i 3i 4i 5i 6i
Tab stops can also be specified relatively (using a leading ‘+’) which means that the specified tab stop will be set that distance from the previous tab stop. For example, the following is equivalent to the previous example.
.ta 1i +1i +1i +1i +1i +1i
gtroff supports an extended syntax to specify repeat values after
the ‘T’ mark (these values are always taken as relative) – this is
the usual way to specify tabs set at equal intervals. The following is,
yet again, the same as the previous examples. It does even more since
it defines an infinite number of tab stops separated by one inch.
.ta T 1i
Now we are ready to interpret the full syntax given at the beginning: 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.
Example: ‘4c +6c T 3c 5c 2c’ is equivalent to ‘4c 10c 13c 18c 20c 23c 28c 30c …’.
The material in each tab column (i.e., the column between two tab stops) may be justified to the right or left or centered in the column. This is specified by appending ‘R’, ‘L’, or ‘C’ to the tab specifier. The default justification is ‘L’. Example:
.ta 1i 2iC 2iR
Some notes:
ta request is ‘m’.
.ds foo a\tb\tc .ta T 5i \*[foo]
creates a single line which is a bit longer than 10 inches (a string is used to show exactly where the tab characters are). Now consider the following:
.ds bar a\tb b\tc .ta T 5i \*[bar]
gtroff first converts the tab stops of the line into unbreakable
horizontal movements, then splits the line after the second ‘b’
(assuming a sufficiently short line length). Usually, this isn’t what
the user wants.
.ds Z foo\tbar\tfoo .ds ZZ foo\tbar\tfoobar .ds ZZZ foo\tbar\tfoo\tbar .ta 2i 4iR \*[Z] .br \*[ZZ] .br \*[ZZZ] .br
which produces the following output:
foo bar foo foo bar foobar foo bar foobar
The first line right-justifies the second ‘foo’ relative to the tab stop. The second line right-justifies ‘foobar’. The third line finally right-justifies only ‘foo’ because of the additional tab character which marks the end of the string belonging to the last defined tab stop.
ta without an argument will unset all tab stops.
gtroff is ‘T 0.5i’. Even in nroff
mode this value is used (contrary to UNIX nroff which
has tab stops preset every 0.8i).
The number register .tabs contains a string representation of the
current tab settings suitable for use as an argument to the ta
request.
.ds tab-string \n[.tabs]
\*[tab-string]
⇒ T120u
Normally gtroff will fill the space to the next tab stop with
space. This can be changed with the tc request. With no
argument gtroff will revert to using space, which is the default.
The value of this tab repitition character is associated with the
current environment (see Environments).
| • Leaders | ||
| • Fields |
Next: Fields, Previous: Tabs and Fields, Up: Tabs and Fields [Contents][Index]
Sometimes it may may be desirable to use the tc request to fill a
particular tab stop with a given character (for example dots in a table
of contents), but also normal tab stops on the rest of the line. For
this gtroff provides an alternate tab mechanism, called
leaders which will do just that.
A leader character (character code 1) behaves similarly to a tab character: It moves to the next tab stop. The only difference is that for this movement, the fill character defaults to a period character and not to space.
This escape is a non-interpreted leader character. In copy mode
(see Copy-in Mode), \a is the same as a real leader
character.
The character that will be repeated can be declared with the lc
request. Without an argument, leaders will act the same as tabs (i.e.,
using space for filling). gtroff’s start-up value is ‘.’.
The value of this leader repitition character is associated with
the current environment (see Environments).
For a table of contents, to name an example, tab stops may be defined so that the section number is one tab stop, the title is the second with the remaining space being filled with a line of dots, and then the page number slightly separated from the dots.
.ds entry 1.1\tFoo\a\t12 .lc . .ta 1i 5i +.25i \*[entry]
This produces
1.1 Foo.......................................... 12
Previous: Leaders, Up: Tabs and Fields [Contents][Index]
Fields are a more general way of laying out tabular data. A field
is defined as the data between a pair of delimiting characters.
It contains substrings which are separated by padding characters.
The width of a field is the distance on the input line from the
position where the field starts to the next tab stop. A padding
character inserts stretchable space similar to TeX’s \hss
command (thus it can even be negative) to make the sum of all substring
lengths plus the stretchable space equal to the field width. If more
than one padding character is inserted, the available space is evenly
distributed among them.
Define a delimiting and a padding character for fields. If the latter is missing, the padding character defaults to a space character. If there is no argument at all, the field mechanism is disabled (which is the default). Note that contrary to e.g. the tab repitition character, delimiting and padding characters are not associated to the current environment (see Environments).
Example:
.fc # ^ .ta T 3i #foo^bar^smurf# .br #foo^^bar^smurf#
and here the result:
foo bar smurf foo bar smurf
Next: Troff and Nroff Mode, Previous: Tabs and Fields, Up: Programming Tutorial [Contents][Index]
The control character (‘.’) and the no-break control character
(‘'’) can be changed with the cc and c2 requests,
respectively.
Set the control character to c. With no argument the default control character ‘.’ is restored. The value of the control character is associated with the current environment (see Environments).
Set the no-break control character to c. With no argument the default control character ‘'’ is restored. The value of the no-break control character is associated with the current environment (see Environments).
Disable the escape mechanism completely. After executing this request, the backslash character ‘\’ no longer starts an escape sequence.
Set the escape character to c. With no argument the default
escape character ‘\’ is restored. It can be also used to re-enable
the escape mechanism after an eo request.
Note that changing the escape character globally will likely break macro
packages since gtroff has no mechanism (like TeX) to ‘intern’
macros, i.e., to convert a macro definition into an internal form which
is independent of its representation. If a macro is called, it will be
executed literally.
This escape sequence prints the current escape character (which is the backslash character ‘\’ by default).
A translation is a mapping of an input character to an output
character. The default mappings are given in the font definition files
for the specific output device (see Font Files); all mappings (both
with tr and in the font definition files) occur at output time,
i.e., the input character gets assigned the metric information of the
mapped output character.
Translate character a to b, character c to d, etc. If there is an odd number of arguments, the last one will be translated to the space character.
Some notes:
\(xx, \[xxx],
\C'xxx', \', \`, \-, \_),
characters defined with the char request, and numbered characters
(\N'xxx') can be translated also.
\e escape can be translated also.
\% escape (but \% can’t
be mapped onto another character).
\a), tab (and
\t).
shc request.
.tr a\&
foo bar
⇒ foo br
It is even possible to map the space character to nothing:
.tr aa \&
foo bar
⇒ foobar
As shown in the example, the space character can’t be the first
character pair as an argument of tr. Additionally, it is not
possible to map the space character to any other character; requests
like ‘.tr aa x’ will undo ‘.tr aa \&’ instead.
If justification is active, lines will be justified inspite of the ‘empty’ space character (but there is no minimal distance, i.e. the space character, between words).
tr.
tr request is ignored.
trnt is the same as the tr request except that the
translations do not apply to text that is transparently throughput into
a diversion with \!. See Diversions, for more information.
For example,
.tr ab .di x \!.tm a .di .x
will print ‘b’; if trnt is used instead of tr it will
print ‘a’.
Next: Line Layout, Previous: Character Translations, Up: Programming Tutorial [Contents][Index]
Originally, nroff and troff were two separate programs,
the former for tty output, the latter for everything else. With GNU
troff, both programs are merged into one executable.
Usually, a macro package can be used with both nroff and
troff. Nevertheless, it is sometimes necessary to make a
distinction between the two programs (resp. modes), and gtroff
provides two built-in conditions ‘n’ and ‘t’ for the
if, ie, and while requests to decide whether
gtroff shall behave like nroff or like troff.
Make the ‘t’ built-in condition true (and the ‘n’ built-in
condition false) for if, ie, and while conditional
requests. This is the default if gtroff (not
groff) is started with the -R switch to avoid loading of
the start-up files troffrc and troffrc-end. Without
-R, gtroff stays in troff mode if the output device is
not a tty (e.g. ‘ps’).
Make the ‘n’ built-in condition true (and the ‘t’ built-in
condition false) for if, ie, and while conditional
requests. This is the default if gtroff uses a tty output
device; the code for switching to nroff mode is in the file
tmac.tty which will be loaded by the start-up file
troffrc.
See Conditionals and Loops, for more details on built-in conditions.
Next: Page Layout, Previous: Troff and Nroff Mode, Up: Programming Tutorial [Contents][Index]
The following drawing shows the dimensions which gtroff uses for
placing a line of output onto the page. They are labeled with the
request which manipulates that dimension.
-->| in |<--
|<-----------ll------------>|
+----+----+----------------------+----+
| : : : |
+----+----+----------------------+----+
-->| po |<--
|<--------paper width---------------->|
These dimensions are:
po
Page offset – This is the leftmost position of text on the final output, defining the left margin.
in
Indentation – This is the distance from the left margin where text will be printed.
ll
Line length – This is the distance from the left margin to right margin.
.in +.5i .ll -.5i A bunch of really boring text which should be indented from both margins. Replace me with a better (and more) example! .in -.5i .ll +.5i
Set horizontal page offset to offset (resp. increment or
decrement the current value by offset). Note that this request
does not cause a break, so changing the page offset in the middle of
text being filled may not yield the expected result. The initial value
is 1i if in troff mode, and 0 if in nroff mode (see Troff and Nroff Mode); the default scaling indicator is m (and not v as incorrectly documented in the original UNIX troff
manual).
The current page offset can be found in the built-in number register ‘.o’.
If po is called without an argument, the page offset is reset to
the previous value before the last call to po.
.po 3i
\n[.o]
⇒ 720
.po -1i
\n[.o]
⇒ 480
.po
\n[.o]
⇒ 720
Set indentation to indent (resp. increment or decrement the current value by indent). This request causes a break. Initially, there is no indentation.
If in is called without an argument, the indentation is reset to
the previous value before the last call to in. The default
scaling indicator is m.
The indentation is associated with the current environment.
If a negative indentation value is specified (which is not allowed),
gtroff emits a warning of type ‘range’ and sets the
indentation to zero.
The effect of in is delayed until a partially collected line (if
it exists) is output.
The current indentation (as set by in) can be found in the
built-in number register ‘.i’.
Temporarily indent the next output line by offset. If an
increment or decrement value is specified, adjust the temporary
indentation relative to the value set by the in request.
This request causes a break; its value is associated with the current
environment. The default scaling indicator is m. A call of
ti without an argument is ignored.
If the total indentation value is negative (which is not allowed),
gtroff emits a warning of type ‘range’ and sets the
temporary indentation to zero. ‘Total indentation’ is either
offset if specified as an absolute value, or the temporary plus
normal indentation, if offset is given as a relative value.
The effect of ti is delayed until a partially collected line (if
it exists) is output.
The number register .in is the indentation that applies to the
current output line.
The difference between .i and .in is that the latter takes
into account whether a partially collected line still uses the old
indentation value resp. a temporary indentation value is active.
Set the line length to length (resp. increment or decrement the
current value by length). Initially, the line length is set to
6.5i. The effect of ll is delayed until a partially
collected line (if it exists) is output. The default scaling indicator
is m.
If ll is called without an argument, the line length is reset to
the previous value before the last call to ll. If a negative
line length is specified (which is not allowed), gtroff emits a
warning of type ‘range’ and sets the line length to zero.
The line length is associated with the current environment.
The current line length (as set by ll) can be found in the
built-in number register .l. The number register .ll is
the line length that applies to the current output line.
Similar to .i and .in, the difference between .l
and .ll is that the latter takes into account whether a partially
collected line still uses the old line length value.
Next: Page Control, Previous: Line Layout, Up: Programming Tutorial [Contents][Index]
gtroff provides some very primitive operations for controlling
page layout.
Set the page length to length (resp. increment or
decrement the current value by length). This is the length of the
physical output page. The default scaling indicator is v.
The current setting can be found in the built-in number register ‘.p’.
Note that this only specifies the size of the page, not the top and bottom margins. Those are not set by groff directly. See Traps, for further information on how to do this.
Negative pl values are possible also, but not very useful: No
trap is sprung, and each line is output on a single page (thus
suppressing all vertical spacing).
gtroff provides several operations which help in setting up top
and bottom titles (or headers and footers).
The tl request will print a title line, which consists of
three parts: a left justified portion, a centered portion and a right
justified portion. The argument to tl is specified as
'left'center'right'. The ‘%’ character is
replaced with the current page number. This character can be changed
with the pc request (see below).
The title line is printed using its own line length, which is specified
with the lt request. The current setting of this is available in
the .lt number register.
The pn request will change the page number of the next
page. The only argument is the page number.
The current page number is stored in the number register %. The
number register .pn contains the number of the next page: either
the value set by a pn request, or the number of the current page
plus 1.
The pc request will change the page number character (used by the
tl request) to a different character. With no argument, this
mechanism is disabled.
See Traps.
Next: Fonts, Previous: Page Layout, Up: Programming Tutorial [Contents][Index]
To stop processing the current page, and move to the next page, invoke
the bp request. This request will also cause a break. It can
also take an argument of what the next page should be numbered. The
only difference between bp and pn is that pn does
not cause a break or actually eject a page.
.de newpage 'bp 'sp .5i .tl 'left top'center top'right top' 'sp .3i ..
It is often necessary to force a certain amount of space before a new
page occurs. This is most useful to make sure that there is not a
single orphan line left at the bottom of a page. The ne
request will ensure that there is a certain distance, specified by the
first argument, before the next page is triggered (see Traps, for
further information). The default unit for ne is v and
the default argument is 1v.
For example, to make sure that no fewer than 2 lines get orphaned, do the following before each paragraph:
.ne 2 .ti +5n text
sv is similar to the ne request; it reserves the specified
amount of vertical space. If the desired amount of space exists before
the next trap (bottom page boundary), the space will be output
immediately. If there is not enough space, it is stored for later
output via the os request. The default argument is 1v
and the default unit is v.
Next: Sizes, Previous: Page Control, Up: Programming Tutorial [Contents][Index]
gtroff has the ability to switch fonts at any point in the text.
There are two ways to do this, via the ft request and the
\f escape.
Fonts are generally specified as upper-case strings, which are usually 1 to 4 characters representing an abbreviation or acronym of the font name.
The basic set of fonts are ‘R’, ‘I’, ‘B’, and ‘BI’. These are Times Roman, Italic, Bold, and Bold Italic. There is also at least one symbol font which contains various special symbols (Greek, mathematics). Such symbols fonts cannot be used directly, but should be used via an escape.
| • Changing Fonts | ||
| • Font Families | ||
| • Font Positions | ||
| • Using Symbols | ||
| • Artificial Fonts | ||
| • Ligatures and Kerning |
Next: Font Families, Previous: Fonts, Up: Fonts [Contents][Index]
Font changes can be done either with the ft request or the
\f request. With no arguments it will switch to the previous
font (also known as ‘P’).
eggs, bacon, .ft B spam .ft and sausage.
The \f escape is useful for changing fonts in the middle of
words:
eggs, bacon, \fBspam\fP and sausage.
Both of the above examples will produce the same output. Note the usage
of ‘P’ to indicate the previous font – using \f it is not
possible to omit this parameter.
Sometimes when putting letters of different fonts, more or less space at such boundaries are needed. There are two escapes to help with this.
The \/ escape 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. 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 small
amount of space is also called italic correction.
The \, escape modifies the spacing of the following character so
that the spacing between that character and the preceding character will
be correct if the preceding character is a Roman character. 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. In analogy to above, this space could be called left italic
correction, but this term isn’t used widely.
The ftr request will translate fonts; its syntax is
.ftr F G
which translates font F to font G. Whenever a font
named F is referred to in a \f escape sequence, or in the
ft, ul, bd, cs, tkf, special,
fspecial, fp, or code requests, font G will
be used. If G is missing, or equal to F then font F will not be translated.
Next: Font Positions, Previous: Changing Fonts, Up: Fonts [Contents][Index]
Due to the variety of fonts available, gtroff has added the
concept of font families. Each of these families has four styles
(‘R’, ‘I’, ‘B’ and ‘BI’).
The fonts are specified as the concatenation of the font family and
style. Specifying a font without the family part will cause
gtroff to use that style of the current family. By default,
gtroff uses the Times family.
This way, it is possible to use the basic four fonts and to select a different font family on the command line.
Font families can be switched with the fam request. The current
font family is available in the number register .fam. This is a
string-valued register.
spam, .fam H spam, .ft B spam, .fam T spam, .ft AR baked beans, .ft R and spam.
Next: Using Symbols, Previous: Font Families, Up: Fonts [Contents][Index]
For the sake of old phototypesetters and compatability with old versions
of troff, gtroff has the concept of font positions,
on which various fonts are mounted. The last one or two are reserved
for the symbol font(s).
New fonts can be mounted with the fp request. These numeric
positions can then be referred to with font changing commands. When
gtroff starts it is using font number one.
.fp 1 H .fp 2 HI .fp 3 HB wink, wink, .ft 2 nudge, nudge, .ft .ft 3 say no more! .ft
Note that after these font changes have taken place the original font is restored.
The current font in use, as a font position, is available in number
register .f. This can be useful to remember the current font,
for later recall.
.nr save-font \n(.f ... lots 'o text ... .ft \n[save-font]
The number of the next free font position is available in the number
register .fp. This is useful when mounting a new font, like so:
.fp \n[.fp] NEATOFONT
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 .fp register. Although gtroff 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.
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 gtroff after it has
been mounted. If there is no third argument then the internal name will
be used as the external name. This feature make it possible to use
fonts with long names in compatibility mode.
Next: Artificial Fonts, Previous: Font Positions, Up: Fonts [Contents][Index]
Symbols can be inserted by using a special escape sequence. This escape
is simply the escape character (usually a backslash) followed by an
identifier. The symbol identifiers have to be two or more characters,
since single characters conflict with all the other escapes. The
identifier can be either preceded by a parenthesis if it is two
characters long, or surrounded by square brackets. So, the symbol for
the mathematical Greek letter ‘pi’ can be produced either by \(*p
or \[*p].
area = \(*p\fIr\fP\u2\d
The escape \C'xxx' will typeset the character named
xxx. Normally it is more convenient to use \[xxx].
But \C has the advantage that it is compatible with recent
versions of ditroff and is available in compatibility mode.
The escape \N'n' will 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.
Each character has certain properties associated with it. These
properties can be modified with the cflags request. The first
argument is the the sum of the desired flags and the remaining arguments
are the characters to have those properties.
1the character ends sentences (initially characters ‘.?!’ have this property)
2lines can be broken before the character (initially no characters have this property)
4lines can be broken after the character (initially the characters ‘-\(hy\(em’ have this property)
8the character overlaps horizontally (initially the characters ‘\(ul\(rn\(ru’ have this property)
16the character overlaps vertically (initially character ‘\(br’ has this property)
32an 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).
New characters can be created with the char request. It is
called as
.char c string
This defines 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.
Its arguments are the characters to be removed. This undoes the effect
of a char request.
See Special Characters.
Next: Ligatures and Kerning, Previous: Using Symbols, Up: Fonts [Contents][Index]
There are a number of requests for artificially creating fonts. These
are largely vestigial remains from the days when output devices did not
have a wide variety of fonts, and when nroff and troff
were separate programs. These are no longer necessary in GNU
troff.
The ul request will print subsequent lines in italics on a device
capable of it, or underline the text on an character output device. The
single argument is the number of lines to be “underlined,” with no
argument, the next line will be underlined.
The cu request is similar to ul ...
The uf request will set the underline font used by ul and
cu.
The bd request artificially creates a bold font by printing each
character twice, slightly offset. The first argument specifies the font
to embolden, and the second is the number of basic units, minus one, by
which the two characters will be offset. If the second argument is
missing, emboldening will be turned off.
Previous: Artificial Fonts, Up: Fonts [Contents][Index]
What are ligatures?
The ligature mechanism can be switched on or off with the lg
request; if the parameter is non-zero or missing, ligatures are enabled,
otherwise disabled. Default is on. The current ligature mode can be
found in the number register .lg (set to 1 if ligatures are
enabled, 0 otherwise).
What is kerning?
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 \& between them.
Kerning can be activated with the kern request. If the parameter
is non-zero or missing, enable pairwise kerning, otherwise disable it.
The number register .kern is set to 1 if pairwise kerning is
enabled, 0 otherwise.
What is track kerning?
Track kerning must be used with great care since it is usually
considered bad typography if the reader notices the effect. The syntax
of the tkf request is
.tkf f s1 n1 s2 n2
Enable track kerning for font f. If the current font is f the width of every character will be increased by an amount between n1 and n2; if the current point size is less than or equal to s1 the width will be increased by n1; if it is greater than or equal to s2 the width will be increased by n2; if 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.
Next: Strings, Previous: Fonts, Up: Programming Tutorial [Contents][Index]
gtroff uses two dimensions with each line of text, type size and
vertical spacing. The type size is the height from the text
baseline to the top of the tallest character (descenders may drop
below this baseline). Vertical spacing is the amount of space
gtroff allows for a line of text; normally, this is about 20% larger than the current type size. Ratios smaller than this can result
in hard-to-read text; larger that this, it will spread the text out more
vertically (useful for term papers). By default, gtroff uses
10 point type on 12 point spacing.
The difference between type size and vertical spacing is known, by typesetters, as leading.
| • Changing Type Sizes | ||
| • Fractional Type Sizes |
Next: Fractional Type Sizes, Previous: Sizes, Up: Sizes [Contents][Index]
Using the ps request and the \s escape the type size can
be changed. The vs request will change the vertical spacing.
The default unit for the ps and vs requests are points.
The number registers .s and .v contain the current type
size and vertical spacing.
These requests take parameters in units of points. It is possible to specify sizes as an absolute size, or as a relative change from the current size. The size 0 means go back to the previous size. With no argument it will also revert to the previous size.
snap, snap, .ps +2 grin, grin, .ps +2 wink, wink, \s+2nudge, nudge,\s+8 say no more! .ps 10
The \s escape may be called in a variety of ways. Much like
other escapes there must be a way to determine where the argument ends
and the text begins. Any of the following forms are valid:
\snSet the point size to n points. n must be either 0 or in the range 4 to 39.
\s+n\s-nIncrease resp. decrease the point size by n points. n must be exactly one digit.
\s(nnSet the point size to nn points. nn must be exactly two digits.
\s+(nn\s-(nn\s(+nn\s(-nnIncrease resp. decrease the point size by nn points. nn must be exactly two digits.
See Fractional Type Sizes, for yet another syntactical form of using
the \s escape.
Some devices may only have certain permissible sizes, in which case
gtroff will round to the nearest permissible size.
... .sz macro example?? ...
Previous: Changing Type Sizes, Up: Sizes [Contents][Index]
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
gtroff interpret arguments that represent a point size 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 (see below).
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 thus sets the point size to 10250 scaled points, which is equal to 10.25 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 gtroff 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
gtroff 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.
The number register .s returns the point size in points as decimal
fraction. There is also a new number register .ps that returns
the point size in scaled points.
The last-requested point size in scaled points is contained in the
.psr number register. The last requested point size in points as
a decimal fraction can be found in .psr. This is a string-valued
register.
\s[n]\s'n'Set the point size to n scaled points; n is a numeric expression with a default scale indicator of ‘z’.
\s[+n]\s[-n]\s+[n]\s-[n]\s'+n'\s'-n'\s+'n'\s-'n'Increases resp. decreases the point size by n scaled points; n is a numeric expression with a default scale indicator of ‘z’.
See Font Files.
Next: Conditionals and Loops, Previous: Sizes, Up: Programming Tutorial [Contents][Index]
gtroff has string variables, which are entirely for user
convenience (i.e. there are no built-in strings). They are defined
via the ds request.
.ds UX \s-1UNIX\s0\u\s-3tm\s0\d
They are interpolated, or expanded in-place, via the \* escape:
The \*(UX Operating System
If the string named by the \* does not exist, the escape will be
replaced by nothing.
Caution: Unlike other requests, the second argument to the
ds request takes up the entire line including trailing spaces.
This means that comments on a line with such a request can introduce
unwanted space into a string.
.ds UX \s-1UNIX\s0\u\s-3tm\s0\d \" UNIX trademark
Instead the comment should be put on another line or have the comment escape adjacent with the end of the string.
.ds UX \s-1UNIX\s0\u\s-3tm\s0\d\" UNIX trademark
To produce leading space the string can be started with a double quote. No trailing quote is needed; in fact, any trailing quote is included in your string.
.ds sign " Yours in a white wine sauce,
The as request will append a string to another string. It works
similar to the ds request except that it appends the second
argument onto the string named by the first argument.
.as sign " with shallots, onions and garlic,
Strings are not limited to a single line of text. A string can span several lines by escaping the newlines with a backslash. The resulting string will be stored without the newlines.
.ds foo lots and lots \ of text are on these \ next several lines
Rudimentary string manipulation routines are given with the
substring and length requests. The former has the
following syntax:
.substring xx n1 [n2]
It replaces 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.
Here the syntax of the length request:
.length xx string
It computes the length of string and returns it in the number register xx (which is not necessarily defined before).
rn
rm
als
chop
See Identifiers, and Comments.
Next: Writing Macros, Previous: Strings, Up: Programming Tutorial [Contents][Index]
In if and while requests, there are several more operators
available:
eoTrue if the current page is even or odd numbered (respectively).
nTrue if the document is being processed in nroff mode.
tTrue if the document is being processed in troff mode.
'xxx'yyy'True if the string xxx is equal to the string yyy. Other characters can be used in place of the single quotes. The strings are ‘formatted’ before being compared.
rxxxTrue if there is a number register named xxx.
dxxxTrue if there is a string, macro, diversion, or request named xxx.
cchTrue if there is a character ch available; ch is either an
ASCII character or a special character (\(ch or
\[ch]); the condition will also be true if ch has
been defined by the char request.
| • if-else | ||
| • while |
Next: while, Previous: Conditionals and Loops, Up: Conditionals and Loops [Contents][Index]
gtroff has if-then-else constructs like other languages, although
the formatting can be painful.
The if request has the following syntax:
.if expr anything
where expr is the expression to be evaluated; anything (the remainder of the line) will be executed if expr evaluates to non-zero (true). anything will be interpreted as though it was on a line by itself. See Expressions, for more info.
Here are some examples:
.if t .ls 2 \" double spacing in troff .if 0 .ab how'd this happen?
An if-then-else is written using two requests ie and el.
The first request is the ‘if’ part and the latter is the ‘else’ part.
.ie .el
In many cases more than one request is to be executed as a result of any
of these requests. This can be done using the \{ and \}
escapes. The following example shows the possible ways to use these
escapes (note the position of the opening and closing braces).
.ie t \{\
. ds lq ``
. ds rq ''
.\}
.el \
.\{\
. ds lq "
. ds rq "\}
.ds qq "
See Expressions.
Previous: if-else, Up: Conditionals and Loops [Contents][Index]
gtroff provides a looping construct using the while
request, which is used much like the if (and related) requests.
The first argument is an expression which will be evaluated. The
while request will interpret the remainder of the line until the
expression evaluates to 0 or false.
.nr a 0 1 .while (\na<9) \&\n+a, \&\n+a
The preceding example produces:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
Note the usage of the \& escape to avoid a control character at
the beginning of a line.
The break request will break out of a while loop. Be sure
not to confuse this with the br request (causing a line break).
The continue request will finish the current iteration of a while
loop, immediately restarting the next iteration.
See Expressions.
Next: Page Motions, Previous: Conditionals and Loops, Up: Programming Tutorial [Contents][Index]
A macro is a collection of text and embedded commands which can be
invoked multiple times. Macros are used for defining common operations.
Macros are defined using the de request. This request takes a
name for the macro as the first argument. Subsequent lines are copied
into an internal buffer until the line .. is encountered. The
optional second argument to de can change this ending token.
Here a small example macro called ‘P’ which will cause a break and the insertion of some vertical space. It could be used to separate paragraphs.
.de P .br .sp .8v ..
The am request works similarly to de except it appends
onto the macro named by the first argument. So, to make the previously
defined ‘P’ macro actually do indented instead of block paragraphs,
is is possible to add the necessary code to the existing macro like
this:
.am P .ti +5n ..
Macros can be aliased with the als request.
| • Copy-in Mode | ||
| • Parameters |
Next: Parameters, Previous: Writing Macros, Up: Writing Macros [Contents][Index]
When gtroff reads in the text for a macro or diversion it copies
the text (including request lines, but excluding escapes) into an
internal buffer. Escapes will be converted into an internal form,
except for \n, \$, \*, \\ and
\RET which are evaluated and inserted into the text where
the escape was located. This is known as copy-in mode or
copy mode.
What this means is that you can specify when these escapes are to be
evaluated (either at copy-in time or at the time of use) by insulating
the escapes with an extra backslash. Compare this to the \def
and \edef commands in TeX.
For example, the following will result in the numbers 20 andbeing printed:
.nr x 20 .de y .nr x 10 \&\nx \&\\nx .. .y
Previous: Copy-in Mode, Up: Writing Macros [Contents][Index]
The arguments to a macro can be examined using a variety of escapes.
The number of arguments is available in the .$ number register.
Any individual argument can be retrieved with one of the following
escapes:
The escapes \$n, \$(nn and
\$[nnn] will result in the nth, nnth or
nnnth argument. As usual, the first form only accepts a single
number (larger than zero), the second only a two-digit number (larger or
equal to 10), and the third any positive integer value (larger than
zero). Macros can have an unlimited number of arguments. Note that due
to copy-in mode, two backslashes should be used on these in actual use
to prevent interpolation until the macro is actually invoked.
The request shift will shift the arguments 1 position, or as
many positions as specified by its argument. After executing this
request, argument i will become argument i-n;
arguments 1 to n will no longer be available. Shifting by
negative amounts is currently undefined.
In some cases it is convenient to use all of the arguments at once (for
example, to pass the arguments along to another macro). The \$*
escape is the concatenation of all the arguments separated by spaces. A
similar escape is \$@, which is the concatenation of all the
arguments with each surrounded by double quotes, and separated by
spaces.
The \$0 escape is the name by which the current macro was
invoked. The als request can make a macro have more than one
name.
.de vl .ie \\n(.$=1 .ds Vl Pre-Release Version .el .ds Vl Version \\$3, \\$4. ..
This would be called as
.vl $Id: groff.texinfo,v 1.38 2000/05/22 06:21:49 wlemb Exp $
See Request Arguments.
Next: Drawing Requests, Previous: Writing Macros, Up: Programming Tutorial [Contents][Index]
Motions up and down the page can be done with the sp request.
However, this causes a break so that the actual effect is to move to the
left margin and then to the specified location.
The request mk can be used to mark a location on a page, for
movement to later. This request takes a register name as an argument in
which to store the current page location. With no argument it will
store the location in an internal register. The results of this can be
used later by the rt or the sp request. The rt
request will return upwards to the location given in the register
name given as an argument, with no argument it will return to the
location marked with the mk request
... dual column example ...
The following escapes give fine control of movements about the page.
The \v'e' enables arbitrary vertical motion from the
current location on the page. The argument e specifies the
distance to move; positive is downwards and negative upwards. The
default unit for this escape is vertical spaces, v’s. Beware,
however, that gtroff will leave text processing to continue
wherever the motion ends, so to avoid interference with text processing,
motions should be balanced.
There are some special case escapes for vertical motion.
\r
move upwards 1v.
\u
move upwards .5v.
\d
move down .5v.
Horizontal motions can be done via the \h'e' escape. The
expression e indicates how far to move: positive is rightwards
and negative leftwards.
There are a number of special case escapes for horizontal motion:
\SP
an unbreakable and unpaddable (i.e. not expanded during filling) space. (Note: It is a backslash followed by a space.)
\~
an unbreakable space that stretches like a normal inter-word space when a line is adjusted.
\|
a 1/6th em space.
\^
a 1/12th em space.
\0
a space the size of a digit.
\&
A zero width 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.
... tex logo example ...
A frequent need is to do horizontal movement based on the width of some
arbitrary text (e.g. given as an argument to a macro). For that,
there is the escape \w'text' which will interpolate to the
width of the given text in basic units.
... strlen example ...
Font changes may occur in text which don’t affect current settings.
After use, \w sets several registers:
stsbThe highest and lowest point, respectively, in text.
rstrsbLike the st and sb registers, but takes account of the
heights and depths of characters.
ctis set according to what kinds of characters occur in text:
only short characters, no descenders or tall characters.
descender
tall character
both a descender and a tall character
sscThe amount of horizontal space (possibly negative) that should be added to the last character before a subscript.
skwHow 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.
\k
.k
Next: Traps, Previous: Page Motions, Up: Programming Tutorial [Contents][Index]
gtroff provides a number of ways to draw lines and other figures
on the page. Used in combination with the page motion commands
(see Page Motions, for more info), a wide variety of figures can be
drawn. However, for complex drawings these operations can be quite
cumbersome, and it may be wise to use graphic preprocessors like
gpic or ggrn. See gpic, and ggrn, for more
information.
All drawing is done via escapes.
The \l escape will draw a line rightwards from the current
location. The full syntax for this escape is
\l'lc'
where l is the length of the line to be drawn, starting at the current location; positive numbers will draw to the right, and negative will draw towards the left. This can also be specified absolutely (i.e. with a leading ‘|’) which will draw back to the beginning of the line.
The optional second parameter c is a character to draw the line
with. If this second argument is not specified, gtroff will use
the underscore character.
To separate the two arguments (to prevent gtroff from
interpreting a drawing character as a scaling indicator) use \&.
Here a small useful example:
.de box \(br\\$*\(br\l'|0\(rn'\l'|0\(ul' ..
Note that this works by outputting a box rule (a vertical line), then the text given as an argument and then another box rule. Then the line drawing escapes both draw from the current location to the beginning of the input line.
Vertical lines are drawn using the \L escape. Its parameters are
specified similar to the \l escape. If the length is positive,
the movement will be downwards, and upwards for negative values. The
default character is the box rule character. As with the vertical
motion escapes, text processing will blindly continue where the line
ends.
...box macro...
More flexible drawing functions are available via the \D escape.
While the previous escapes will work on a character device, these
escapes will not.
\D'l dx dy'Draw a line from the current location to the relative point specified by (dx,dy).
...revised box macro...
\D'c d'Draw a circle with a diameter of d with the leftmost point at the current position.
\D'C d'Draw a solid circle with the same parameters as an outlined circle.
\D'e dx dy'Draw an ellipse with a horizontal diameter of dx and a vertical diameter of dy with the leftmost point at the current position.
\D'E dx dy'Draw a solid ellipse with the same parameters as an outlined ellipse.
\D'a dx1 dy1 dx2 dy2'Draw an arc clockwise from the current location through the two specified locations (dx1,dy1) and (dx2,dy2).
\D'~ dx1 dy1 dx2 dy2 ...'Draw a spline from the current location to (dx1,dy1) and then to (dx2,dy2), and so on.
\D'f n'Set the shade of gray to be used for filling solid objects to n; n must be an integer between 0 and 1000, where 0 corresponds solid white and 1000 to solid black, and values in between correspond to intermediate shades of gray. This applies only to solid circles, solid ellipses and solid polygons. By default, a level of 1000 will be used.
\D'p dx1 dy1 dx2 dy2 ...'Draw a polygon from the current location to (dx1,dy1) and then to (dx2,dy2) and so on. When the specified data points are exhausted, a line is drawn back to the starting point.
... box example (yes, again)...
\D'P dx1 dy1 dx2 dy2 ...'Draw a solid polygon with the same parameters as an outlined polygon.
... shaded box example ...
\D't n'Set the current line thickness to n machine units. A value of
zero selects the smallest available line thickness. A negative value
makes the line thickness proportional to the current point size (this is
the default behaviour of ditroff).
The \b escape will pile a sequence of characters
vertically, and center it vertically on the current line. This can be
used to build large brackets and braces.
\b'\(lt\(bv\(lk\(bv\(lb'
See Drawing Functions.
Next: Diversions, Previous: Drawing Requests, Up: Programming Tutorial [Contents][Index]
Traps are locations, which, when reached, will call a specified macro. These traps can occur at a given location on the page, at a given location in the current diversion, after a certain number of input lines or at the end of input.
| • Page Location Traps | ||
| • Diversion Traps | ||
| • Input Line Traps | ||
| • End-of-input Traps |
Next: Diversion Traps, Previous: Traps, Up: Traps [Contents][Index]
Page location traps are frequently used for page headers and footers. The following is a simple example of this.
.de hd \" Page header 'sp .5i .tl 'Title''date' 'sp .3i .. .de fo \" Page footer 'sp 1v .tl ''%'' 'bp .. .wh 0 hd \" trap at top of the page .wh -1i fo \" trap one inch from bottom
The number register .t is the distance to the next trap.
The location of a trap can be changed later on with the ch
request. The first argument is the name of the macro to be invoked at
the trap, and the second argument is the new location for the trap.
This is useful for building up footnotes in a diversion to allow more
space at the bottom of the page for them.
... (simplified) footnote example ...
The vpt request will enable vertical position traps if the
argument 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. The current setting of
this is available in the number register .vpt.
The number register .trunc contains 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.
The number register .ne contains the amount of space that was
needed in the last ne request that caused a trap to be sprung.
Useful in conjunction with the .trunc register. See Page Control, for more information.
Next: Input Line Traps, Previous: Page Location Traps, Up: Traps [Contents][Index]
Traps can also be set within a diversion using the dt
request. Like wh the first argument is the location of the trap
and the second argument is the name of the macro to be invoked. The
number register .t will still work within diversions.
See Diversions, for more information.
Next: End-of-input Traps, Previous: Diversion Traps, Up: Traps [Contents][Index]
The it request will set an input line trap. The format for
calling this is
.it n name
where n is the number of lines of input which may be read before springing the trap, name is the macro to be invoked. Request lines are not counted as input lines.
For example, one possible use is to have a macro which will print the next n lines in a bold font.
.de B .it B-end \\$1 .ft B .. .de B-end .ft R ..
Previous: Input Line Traps, Up: Traps [Contents][Index]
The em request will set a trap at the end of input. The macro
specified as an argument will be executed after the last line of the
input file has been processed.
For example, if the document had to have a section at the bottom of the
last page for someone to approve it, the em request could be
used.
.de approval .ne 5v .sp |(\\n(.t-6v) .in +4i .lc _ .br Approved:\t\a .sp Date:\t\t\a .. .em approval
Next: Environments, Previous: Traps, Up: Programming Tutorial [Contents][Index]
In gtroff it is possible to divert text into a named
storage area. Due to the similarity to defining macros it is sometimes
said to be stored in a macro. This is used for saving text for output
at a later time, which is useful for keeping blocks of text on the same
page, footnotes, tables of contents and indices.
A diversion is initiated by the di request. Like the de
request, it takes an argument of a macro name to divert subsequent text
into. The da macro will append to an existing diversion.
di (resp. da) without an argument ends the diversion.
... end-note example ...
Diversions may be nested. The number register .z contains the
name of the current diversion. The number register .d contains
the current vertical place in the diversion. If not in a diversion it
is the same as the register nl.
.h
After completing a diversion, the built-in number registers dn
and dl contain the vertical and horizontal size of the diversion.
.\" Center text both horizontally & vertically .de (c .br .nf .di @c .. .de )c .br .di .nr @s (((\\n(.tu-\\n(dnu)/2u)-1v) .sp \\n(@su .ce 1000 .nf ..br .ce 0 .sp \\n(@su .br .fi .rr @s ..
Requests, macros and escapes are interpreted when read into a diversion.
There are two ways to prevent this; either way will take the given text
and transparently embed it into the diversion. The first method
is to prefix the line with \!. This will cause the entire line
to be transparently inserted into the diversion. This is useful for
macros which shouldn’t be invoked until the diverted text is actually
output.
The other way is to surround the text by the \? escape, i.e.
\?anything\?
anything may not contain newlines; use \! to embed
newlines in a diversion. The escape sequence \? is also
recognized in copy mode and turned into a single internal code; it is
this code that terminates anything. Thus the following example will
print 4.
.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
The asciify request only exists in order to make certain gross
hacks work with GNU troff. It unformats the diversion
specified as an argument in such a way that ASCII characters
that were formatted and diverted will be treated like ordinary input
characters when the diversion is reread. For example, the following
will set register n to 1.
.tr @. .di x @nr\ n\ 1 .br .di .tr @@ .asciify x .x
See Copy-in Mode.
Next: I/O, Previous: Diversions, Up: Programming Tutorial [Contents][Index]
It happens frequently that some text should be printed in a certain
format regardless of what may be in effect at the time, for example, in
a trap invoked macro to print headers and footers. To solve this
gtroff has environments in which text is processed. An
environment contains most of the parameters that control text
processing. It is possible to switch amongst these environments; by
default gtroff processes text in environment 0. The
following is the information kept in an environment.
These environments may be given arbitrary names (see Identifiers,
for more info). Old versions of troff only had environments
named ‘0’, ‘1’ and ‘2’.
The ev request will switch among environments. The single
argument is the name of the environment to switch to. With no argument
gtroff will switch back to the previous environment. There is no
limit on the number of named environments; they will be created the
first time that they are referenced. The .ev register contains
the name or number of the current environment. This is a string-valued
register.
Note that a call to ev (with argument) will push the previously
active environment onto a stack. If, say, environments ‘foo’,
‘bar’, and ‘zap’ are called (in that order), the first
ev request without parameter will switch back to environment
‘bar’ (which will be popped off the stack), and a second call will
switch back to environment ‘foo’.
... page break macro, revised ...
Here another example:
.ev footnote-env .fam N .ps 6 .vs 8 .ll -.5i .ev ... .ev footnote-env \(dg Note the large, friendly letters. .ev
To copy an environment into the current one, use the evc request,
which takes the name of the environment to copy from as an argument.
Next: Postprocessor Access, Previous: Environments, Up: Programming Tutorial [Contents][Index]
The so request will read in the file given as an argument and
include it in place of the so request. This is quite useful for
large documents, i.e. keeping each chapter in a separate file.
See gsoelim, for more information.
The mso request is the same as the so request except that
the file is searched for in the same directories as
tmac.name is searched for when the -mname
option is specified.
The cf and trf requests are to include a file. It will
transparently output the contents of file filename. Each line is output
as it were 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, to define a macro x
containing the contents of file f, use
.di x .trf f .di
The request .cf filename, when used in a diversion,
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. This request causes a line break.
With trf, unlike cf, the file cannot contain characters
such as NUL that are not legal gtroff input characters. This
request causes a line break.
The nx request will force gtroff to continue processing of
the file specified as an argument.
The rd request will read from standard input, and include what is
read as though it were part of the input file. Text is read until a
blank line is encountered.
Using these two requests it is easy to set up form letters. The form letter template is constructed like this:
.ce \*(td .sp 2 .nf .rd .sp .rd .fi Body of letter. .bp .nx repeat.let
When this is run, the following file should be redirected in. Note that
requests included in this file are executed as though they were part of
the form letter. The last block of input is the ex requests
which tells groff to stop processing. If this was not there, groff
would not know when to stop.
Trent A. Fisher 708 NW 19th Av., #202 Portland, OR 97209 Dear Trent, Len Adollar 4315 Sierra Vista San Diego, CA 92103 Dear Mr. Adollar, .ex
pi
The sy request will allow arbitrary system commands to be
executed from within a gtroff document. The output is not saved
anyplace, so it is up to the user to do so.
For example, the following example will introduce the current time into a document:
.sy perl -e 'printf ".nr H %d\\n.nr M %d\\n.nr S %d\\n",\ (localtime(time))[2,1,0]' > /tmp/x\n[$$] .so /tmp/x\n[$$] .sy rm /tmp/x\n[$$] \nH:\nM:\nS
Note that this works by having the perl script (run by sy)
print out the nr requests which will set the number registers
‘H’, ‘M’ and ‘S’, and then reads those commands in with
the so request.
The systat number register contains the return value of the
system() function executed by the last sy request.
The open request will open a file (specified as the second
argument) for writing and associate the stream (specified as the first
argument) with it.
The opena is like open, but if the file exists, append to
it instead of truncating it.
The write request will write to the file associated with the
stream specified by the first argument. The stream must previously have
been the subject of an open request. The remainder of the line is
interpreted as the ds request reads its second argument: A
leading ‘"’ will be stripped, and it will be read in copy-in mode.
The close request will close the stream specified by the first
argument; stream will no longer be an acceptable argument to the
write request.
... example of open write &c...
The \V escape will interpolate the contents of the specified
environment variable, as returned by getenv(). The argument to
\V is specified as an identifier, i.e. ‘\Vx’,
‘\V(xx’ or ‘\V[xxx]’. \V is interpreted in
copy-in mode.
Next: Miscellaneous, Previous: I/O, Up: Programming Tutorial [Contents][Index]
There are two escapes which will allow information to be directly given to the postprocessor. This is particularly useful for embedding POSTSCRIPT into the final document.
The \X escape will embed its argument into the gtroff
output preceded with ‘x X’.
The \Y escape is called with an identifier (i.e.
\Yx, \Y(xx or \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.
See Output Devices.
Next: Debugging, Previous: Postprocessor Access, Up: Programming Tutorial [Contents][Index]
This section contains parts of gtroff which cannot (yet) be
categorized elsewhere in this manual.
Line numbers can be printed in the left margin using the nm
request. The first argument is the line number of the next
output line; this defaults to 1. The second argument indicates on
which lines numbers will be printed, i.e. 5 means put line numbers on
every 5 lines; this defaults to 1. The third argument is the
space to be left between the number and the text; this defaults to 1. The fourth argument is the indentation of the line numbers.
Without arguments, line numbers are turned off.
The nn request will temporarily turn off line numbering. The
first argument is the number of lines not to be numbered; this defaults
to 1.
... line numbering example ...
Margin characters can be automatically printed to the right of the text
with the mc request. The first argument is the character to be
printed, and the second argument is the distance away from the main body
text. With no arguments the margin characters are turned off. If this
occurs before a break, no margin character will be printed.
This is quite useful for indicating text that has changed, and, in fact,
there are programs available for doing this (they are called
nrchbar and changebar and can be found in any
‘comp.sources.unix’ archive.
... margin char example ...
The primary reason for the existence of lf is to make debugging
documents which are split into many files, which are then put together
with soelim and other preprocessors. The first argument is the
name of the file and the second argument is the input line number in
that file. This way gtroff can produce error messages which are
intelligible to the user.
... example of soelim'ed doc ...
Next: Implementation Differences, Previous: Miscellaneous, Up: Programming Tutorial [Contents][Index]
gtroff is not easy to debug, but there are some useful features
and strategies for debugging.
tm request will send output to stderr; this is very useful
for printing debugging output.
.if \n(DB .tm debugging output
To activate these statements say
groff -rDB=1 file
ab request is similar to the tm request, except that
it will cause gtroff to stop processing. With no argument it
will print ‘User Abort’.
ex request will also cause gtroff to stop processing
(if encountered at the topmost level; see also I/O.
gtroff can be forced to suppress formatted output with
the -z flag.
pm request will dump out the entire symbol table.
pnr request will print the names and contents of all
currently defined number registers on stderr.
ptr request will 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.
fl request instructs gtroff to flush its output
immediately. The intention is that this be used when using
gtroff interactively. There is little other use for it. This
request causes a line break.
backtrace request will print a backtrace of the input stack
on stderr.
gtroff has command line options for printing out more warnings
(-w) and for printing backtraces (-b) when a warning
or an error occurs. The most verbose level of warnings is -ww.
warn request controls the level of warnings checked for. The
only argument 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 below. For example,
.warn 0 will disable all warnings, and .warn 1
will disable all warnings except that about missing characters. If an
argument is not given, all warnings will be enabled. The number
register .warn contains the current warning level.
| • Warnings |
The warnings that can be given to gtroff 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.
Non-existent characters. This is enabled by default.
Invalid numeric expressions. This is enabled by default. See Expressions.
In fill mode, lines which could not be broken so that their length was less than the line length. This is enabled by default.
Missing or mismatched closing delimiters.
Use of the el request with no matching ie request.
See if-else.
Meaningless scaling indicators.
Out of range arguments.
Dubious syntax in numeric expressions.
Use of di or da without an argument when there is no
current diversion.
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.
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.
Use of a tab character where a number was expected.
Use of \} where a number was expected.
Requests that are missing non-optional arguments.
Illegal input characters.
Unrecognized escape sequences. When an unrecognized escape sequence is encountered, the escape character is ignored.
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.
Non-existent fonts. This is enabled by default.
All warnings except ‘di’, ‘mac’ and ‘reg’. It is intended that this covers all warnings that are useful with traditional macro packages.
All warnings.
Next: Summary, Previous: Debugging, Up: Programming Tutorial [Contents][Index]
GNU troff has a number of features which cause incompatibilities
with documents written with old versions of troff.
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 recognized.
Compatibility mode can be turned on with the -C command line
option, and turned on or off with the cp request. The number
register .C is 1 if compatibility mode is on, 0 otherwise.
GNU troff does not allow the use of the escape sequences
\|, \^, \&, \}, \{,
\SP, \', \`, \-, \_, \!,
\%, and \c in names of strings, macros, diversions, number
registers, fonts or environments; UNIX troff does. The
\A escape sequence (see Identifiers) may be helpful in
avoiding use of these escape sequences in names.
Fractional point sizes cause one noteworthy incompatibility. In
UNIX troff the ps request ignores scale
indicators and thus
.ps 10u
will set the point size to 10 points, whereas in GNU troff it
will set the point size to 10 scaled points. See Fractional Type Sizes, for more information.
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 backslashes
is turned into one output backslash and the resulting output backslashes
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 backslash 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. To store, for some reason, an escape sequence in a
diversion that will be interpreted when the diversion is reread, either
use the traditional \! transparent output facility, or, if this
is unsuitable, the new \? escape sequence.
See Diversions, for more information.
Previous: Implementation Differences, Up: Programming Tutorial [Contents][Index]
Next: Output Devices, Previous: Programming Tutorial, Up: Top [Contents][Index]
This chapter describes all preprocessors that come with groff or
which are freely available.
| • geqn | ||
| • gtbl | ||
| • gpic | ||
| • ggrn | ||
| • grap | ||
| • grefer | ||
| • gsoelim |
Next: gtbl, Previous: Preprocessors, Up: Preprocessors [Contents][Index]
geqn| • Invoking geqn |
geqnNext: gpic, Previous: geqn, Up: Preprocessors [Contents][Index]
gtbl| • Invoking gtbl |
gtblNext: ggrn, Previous: gtbl, Up: Preprocessors [Contents][Index]
gpic| • Invoking gpic |
gpicNext: grap, Previous: gpic, Up: Preprocessors [Contents][Index]
ggrn| • Invoking ggrn |
ggrnNext: grefer, Previous: ggrn, Up: Preprocessors [Contents][Index]
grapA freely available implementation of grap, written by Ted Faber,
is available as an extra package from the following address:
Next: gsoelim, Previous: grap, Up: Preprocessors [Contents][Index]
grefer| • Invoking grefer |
greferPrevious: grefer, Up: Preprocessors [Contents][Index]
gsoelim| • Invoking gsoelim |
gsoelimNext: File formats, Previous: Preprocessors, Up: Top [Contents][Index]
| • Special Characters | ||
| • grotty | ||
| • grops | ||
| • grodvi | ||
| • grolj4 | ||
| • grolbp | ||
| • grohtml | ||
| • gxditview |
Next: grotty, Previous: Output Devices, Up: Output Devices [Contents][Index]
See Font Files.
Next: grops, Previous: Special Characters, Up: Output Devices [Contents][Index]
grotty| • Invoking grotty |
grottyNext: grodvi, Previous: grotty, Up: Output Devices [Contents][Index]
grops| • Invoking grops | ||
| • Embedding PostScript |
Next: Embedding PostScript, Previous: grops, Up: grops [Contents][Index]
gropsPrevious: Invoking grops, Up: grops [Contents][Index]
Next: grolj4, Previous: grops, Up: Output Devices [Contents][Index]
grodvi| • Invoking grodvi |
grodviNext: grolbp, Previous: grodvi, Up: Output Devices [Contents][Index]
grolj4| • Invoking grolj4 |
grolj4Next: grohtml, Previous: grolj4, Up: Output Devices [Contents][Index]
grolbp| • Invoking grolbp |
grolbpNext: gxditview, Previous: grolbp, Up: Output Devices [Contents][Index]
grohtml| • Invoking grohtml |
grohtmlPrevious: grohtml, Up: Output Devices [Contents][Index]
gxditview| • Invoking gxditview |
gxditviewNext: Installation, Previous: Output Devices, Up: Top [Contents][Index]
| • gtroff Output | ||
| • Font Files |
Next: Font Files, Previous: File formats, Up: File formats [Contents][Index]
gtroff OutputThis section describes the format output of GNU troff. The
output format used by GNU troff is very similar to that used by
UNIX device-independent troff (ditroff).
| • Output Format | ||
| • Device Control | ||
| • Drawing Functions | ||
| • Line Continuation |
Next: Device Control, Previous: gtroff Output, Up: gtroff Output [Contents][Index]
The output format is text based, as opposed to a binary format (like TeX DVI). The output format is 8-bit clean, thus single characters can have the eighth bit set, as can the names of fonts and special characters.
The output format consists of single command characters with attached parameters which are separated from subsequent text by whitespace or a newline.
The names of characters and fonts can be of arbitrary length; drivers
should not assume that they will be only two characters long (as
ditroff does).
When a character is to be printed, that character will always be in the
current font. Unlike ditroff, it is not necessary for drivers to
search special fonts to find a character.
HnVnhnvncnCnnnctxxxxxx is any sequence of characters terminated by a space or a newline; the first character should be printed at the current position, the the current horizontal position should be increased by the width of the first character, and so on for each character. The width of the character is that given in the font file, appropriately scaled for the current point size, and rounded so that it is a multiple of the horizontal resolution. Special characters cannot be printed using this command.
This command is only allowed if the ‘tcommand’ line is present in the DESC file.
un xxxThis is same as the ‘t’ command except that after printing each character, the current horizontal position is increased by the sum of the width of that character and n.
This command is only allowed if the ‘tcommand’ line is present in the DESC file.
nabpnsnThe argument to the ‘s’ command is in scaled points (units of points/n, where n is the argument to the ‘sizescale’ command in the DESC file).
fnx … \nDevice control.
Dc x…\nNext: Drawing Functions, Previous: Output Format, Up: gtroff Output [Contents][Index]
The ‘x’ command is normally followed by a letter or word indicating the function to perform, followed by white space separated arguments.
The first argument can be abbreviated to the first letter.
x initx Tx res n h vx HThe argument to the ‘x Height’ command is also in scaled points.
The first three output commands are guaranteed to be:
x T device x res n h v x init
For example, the input
crunchy \fH\s+2frog\s0\fP!?
will produce
... sample output here ...
Next: Line Continuation, Previous: Device Control, Up: gtroff Output [Contents][Index]
The ‘D’ drawing command has been extended. These extensions will
only be used by GNU pic if the -x option is given.
See Drawing Requests.
Df nSet the shade of gray to be used for filling solid objects to n; n must be an integer between 0 and 1000, where 0 corresponds solid white and 1000 to solid black, and values in between correspond to intermediate shades of gray. This applies only to solid circles, solid ellipses and solid polygons. By default, a level of 1000 will be used. Whatever color a solid object has, it should completely obscure everything beneath it. A value greater than 1000 or less than 0 can also be used: this means fill with the shade of gray that is currently being used for lines and text. Normally this will be black, but some drivers may provide a way of changing this.
DC dDraw a solid circle with a diameter of d with the leftmost point at the current position.
DE dx dyDraw a solid ellipse with a horizontal diameter of dx and a vertical diameter of dy with the leftmost point at the current position.
Dp dx1 dy1 dx2 dy2 … dxn dynDraw a polygon with. The first vertex is at the current position, the
second vertex at an offset (dx1,dy1) from the current
position, the second vertex at an offset (dx2,dy2) from the
first vertex, and so on up to the n-th vertex. At the moment, GNU
pic only uses this command to generate triangles and rectangles.
DP dx1 dy1 dx2 dy2 … dxn dynLike Dp but draw a solid rather than outlined polygon.
Dt nSet the current line thickness to n machine units.
Traditionally, UNIX troff drivers use a line thickness
proportional to the current point size; drivers should continue to do
this if no Dt command has been given, or if a Dt command
has been given with a negative value of n. A zero value of n selects the smallest available line thickness.
A difficulty arises in how the current position should be changed after
the execution of these commands. This is not of great importance since
the code generated by GNU pic does not depend on this. Given a
drawing command of the form
\D'c x1 y1 x2 y2 … xn yn'
where c is not one of ‘c’, ‘e’, ‘l’, ‘a’ or
‘~’, UNIX troff will treat each of the x value
as a horizontal quantity, and each of the y values as a vertical
quantity and will assume that the width of the drawn object is sum if
all x values, and that the height is the sum of all y values.
(The assumption about the height can be seen by examining the st
and sb registers after using such a D command in a
\w escape sequence.) This rule also holds for all the original
drawing commands with the exception of De. For the sake of
compatibility GNU troff also follows this rule, even though it
produces an ugly result in the case of the Df, Dt, and, to
a lesser extent, DE commands. Thus after executing a
D command of the form
Dc x1 y1 x2 y2 … xn yn
the current position should be increased horizontally by the sum of all x values and vertically by the sum of all y values.
Previous: Drawing Functions, Up: gtroff Output [Contents][Index]
There is a continuation convention which permits the argument to the
‘x X’ command to contain newlines: When outputting the argument
to the ‘x X’ command, GNU troff will follow each newline
in the argument with a ‘+’ character (as usual, it will terminate
the entire argument with a newline); thus if the line after the line
containing the ‘x X’ command starts with ‘+’, then the
newline ending the line containing the ‘x X’ command should be
treated as part of the argument to the ‘x X’ command, the
‘+’ should be ignored, and the part of the line following the
‘+’ should be treated like the part of the line following the
‘x X’ command.
Previous: gtroff Output, Up: File formats [Contents][Index]
The gtroff font format is roughly a superset of the
ditroff font format. Unlike the ditroff font format,
there is no associated binary format; all files are text files. The
font files for device name are stored in a directory
devname. There are two types of file: a device description
file called DESC and for each font ‘F’ a font file
called F.
| • DESC file format | ||
| • Font file format |
Next: Font file format, Previous: Font Files, Up: Font Files [Contents][Index]
The DESC file can contain the following types of line:
res nThere are n machine units per inch.
hor nThe horizontal resolution is n machine units.
vert nThe vertical resolution is n machine units.
sizescale nThe scale factor for point sizes. By default this has a value of 1.
One scaled point is equal to one point/n. The arguments to the
unitwidth and sizes commands are given in scaled points.
See Fractional Type Sizes, for more information.
unitwidth nQuantities in the font files are given in machine units for fonts whose point size is n scaled points.
tcommandThis means that the postprocessor can handle the ‘t’ and ‘u’ output commands.
sizes s1 s2 … sn 0This means that the device has fonts at s1, s2, … sn scaled points. The list of sizes must be terminated by a 0. Each si can also be a range of sizes m-n. The list can extend over more than one line.
styles S1 S2 … SmThe first m font positions will be associated with styles S1 … Sm.
fonts n F1 F2 F3 … FnFonts F1 … Fn will be mounted in the font positions m+1, …, m+n where m is the number of styles. This command may extend over more than one line. A font name of 0 will cause no font to be mounted on the corresponding font position.
family famThe default font family is fam.
charsetThis line and everything following in the file are ignored. It is allowed for the sake of backwards compatibility.
The res, unitwidth, fonts and sizes lines
are compulsory. Other commands are ignored by gtroff but may be
used by postprocessors to store arbitrary information about the device
in the DESC file.
Previous: DESC file format, Up: Font Files [Contents][Index]
A font file has two sections. The first section is a sequence of lines each containing a sequence of blank delimited words; the first word in the line is a key, and subsequent words give a value for that key.
name FThe name of the font is F.
spacewidth nThe normal width of a space is n.
slant nThe characters of the font have a slant of n degrees. (Positive means forward.)
ligatures lig1 lig2 … lign [0]Characters lig1, lig2, …, lign are ligatures; possible ligatures are ‘ff’, ‘fi’, ‘fl’, ‘ffi’ and ‘ffl’. For backwards compatibility, the list of ligatures may be terminated with a 0. The list of ligatures may not extend over more than one line.
specialThe font is special; this means that when a character is requested that is not present in the current font, it will be searched for in any special fonts that are mounted.
Other commands are ignored by gtroff but may be used by
postprocessors to store arbitrary information about the font in the font
file.
The first section can contain comments which start with the ‘#’ character and extend to the end of a line.
The second section contains one or two subsections. It must contain a
charset subsection and it may also contain a kernpairs
subsection. These subsections can appear in any order. Each
subsection starts with a word on a line by itself.
The word charset starts the character set subsection. The
charset line is followed by a sequence of lines. Each line gives
information for one character. A line comprises a number of fields
separated by blanks or tabs. The format is
name metrics type code comment
name identifies the character: If name is a single
character c then it corresponds to the gtroff input
character c; if it is of the form ‘\c’ where c is
a single character, then it corresponds to the gtroff input
character \c; otherwise it corresponds to the groff input
character ‘\[name]’. (If it is exactly two characters
xx it can be entered as ‘\(xx’.) gtroff
supports 8-bit characters; however some utilities have difficulties with
eight-bit characters. For this reason, there is a convention that the
name ‘charn’ is equivalent to the single character whose code
is n. For example, ‘char163’ would be equivalent to the
character with code 163 which is the pounds sterling sign in ISO Latin-1 character set. The name ‘---’ is special and indicates
that the character is unnamed; such characters can only be used by means
of the \N escape sequence in gtroff.
The type field gives the character type:
1the character has an descender, for example, ‘p’;
2the character has an ascender, for example, ‘b’;
3the character has both an ascender and a descender, for example, ‘(’.
The code field gives the code which the postprocessor uses to
print the character. The character can also be input to gtroff
using this code by means of the \N escape sequence. The code can
be any integer. If it starts with ‘0’ it will be interpreted as
octal; if it starts with ‘0x’ or ‘0X’ it will be interpreted as
hexadecimal.
Anything on the line after the code field will be ignored.
The metrics field has the form:
width[,height[,depth[,italic_correction [,left_italic_correction[,subscript_correction]]]]]
There must not be any spaces between these subfields (it has been split
here into two lines for better legibility only). Missing subfields are
assumed to be 0. The subfields are all decimal integers. Since
there is no associated binary format, these values are not required to
fit into a variable of type ‘char’ as they are in ditroff.
The width subfield gives the width of the character. The
height subfield gives the height of the character (upwards is
positive); if a character does not extend above the baseline, it should
be given a zero height, rather than a negative height. The depth
subfield gives the depth of the character, that is, the distance below
the lowest point below the baseline to which the character extends
(downwards is positive); if a character does not extend below above the
baseline, it should be given a zero depth, rather than a negative depth.
The italic_correction subfield gives the amount of space that
should be added after the character when it is immediately to be
followed by a character from a Roman font. The
left_italic_correction subfield gives the amount of space that
should be added before the character when it is immediately to be
preceded by a character from a Roman font. The
subscript_correction gives the amount of space that should be
added after a character before adding a subscript. This should be less
than the italic correction.
A line in the charset section can also have the format
name "
This indicates that name is just another name for the character mentioned in the preceding line.
The word kernpairs starts the kernpairs section. This contains a
sequence of lines of the form:
c1 c2 n
This means that when character c1 appears next to character c2 the space between them should be increased by n. Most entries in kernpairs section will have a negative value for n.
Next: Request and Escape Index, Previous: File formats, Up: Top [Contents][Index]
Next: Operator Index, Previous: Installation, Up: Top [Contents][Index]
In this index, escapes are listed with a leading backslash (‘\’) to distinguish them from requests which appear without the leading control character (normally either ‘.’ or ‘'’).
| Jump to: | '
(
.
[
\
]
A B C D E F H I K L M N O P R S T U V W |
|---|
| Jump to: | '
(
.
[
\
]
A B C D E F H I K L M N O P R S T U V W |
|---|
Next: Register Index, Previous: Request and Escape Index, Up: Top [Contents][Index]
| Jump to: | ! % & ( ) * + - . / : < = > | |
|---|
| Index Entry | Section | ||
|---|---|---|---|
| | |||
| ! | |||
!: | Expressions | ||
| | |||
| % | |||
%: | Expressions | ||
%: | Escapes | ||
| | |||
| & | |||
&: | Expressions | ||
&: | Escapes | ||
| | |||
| ( | |||
(: | Expressions | ||
(: | Escapes | ||
| | |||
| ) | |||
): | Expressions | ||
): | Escapes | ||
| | |||
| * | |||
*: | Expressions | ||
*: | Escapes | ||
| | |||
| + | |||
+: | Expressions | ||
+: | Expressions | ||
+: | Expressions | ||
+: | Escapes | ||
| | |||
| - | |||
-: | Expressions | ||
-: | Expressions | ||
-: | Expressions | ||
-: | Escapes | ||
| | |||
| . | |||
.: | Escapes | ||
| | |||
| / | |||
/: | Expressions | ||
/: | Escapes | ||
| | |||
| : | |||
:: | Expressions | ||
:: | Escapes | ||
| | |||
| < | |||
<: | Expressions | ||
<: | Escapes | ||
<=: | Expressions | ||
<?: | Expressions | ||
| | |||
| = | |||
=: | Expressions | ||
=: | Escapes | ||
==: | Expressions | ||
| | |||
| > | |||
>: | Expressions | ||
>: | Escapes | ||
>=: | Expressions | ||
>?: | Expressions | ||
| | |||
| | | |||
|: | Expressions | ||
|: | Drawing Requests | ||
| | |||
| Jump to: | ! % & ( ) * + - . / : < = > | |
|---|
Next: Macro and String Index, Previous: Operator Index, Up: Top [Contents][Index]
| Jump to: | %
.
C D L M N R S Y |
|---|
| Jump to: | %
.
C D L M N R S Y |
|---|
Next: Glyph Name Index, Previous: Register Index, Up: Top [Contents][Index]
In this index, strings are listed with the calling escape sequence (‘\*’) to distinguish them from macros which appear without the leading control character (normally either ‘.’ or ‘'’).
| Jump to: | \
B D H I L P R S T |
|---|
| Jump to: | \
B D H I L P R S T |
|---|
Next: Font File Keyword Index, Previous: Macro and String Index, Up: Top [Contents][Index]
A glyph name xx consisting of exactly two characters can be
accessed as ‘\(xx’. Glyph names xxx of any length can be
accessed as ‘\[xxx]’.
| Jump to: | B D E H L R U |
|---|
| Index Entry | Section | ||
|---|---|---|---|
| | |||
| B | |||
br: | Using Symbols | ||
| | |||
| D | |||
dg: | Sentences | ||
dg: | Using Symbols | ||
| | |||
| E | |||
em: | Using Symbols | ||
| | |||
| H | |||
hy: | Manipulating Hyphenation | ||
hy: | Using Symbols | ||
| | |||
| L | |||
lq: | Miscellaneous man stuff | ||
| | |||
| R | |||
rn: | Using Symbols | ||
rq: | Miscellaneous man stuff | ||
rq: | Sentences | ||
rq: | Using Symbols | ||
ru: | Using Symbols | ||
| | |||
| U | |||
ul: | Using Symbols | ||
| | |||
| Jump to: | B D E H L R U |
|---|
Next: Program and File Index, Previous: Glyph Name Index, Up: Top [Contents][Index]
| Jump to: | #
-
C F H K L N R S T U V |
|---|
| Jump to: | #
-
C F H K L N R S T U V |
|---|
Next: Concept Index, Previous: Font File Keyword Index, Up: Top [Contents][Index]
| Jump to: | C D G H M N P S T |
|---|
| Jump to: | C D G H M N P S T |
|---|
Previous: Program and File Index, Up: Top [Contents][Index]
| Jump to: | "
'
)
*
8
]
A B C D E F G H I J K L M N O P Q R S T U V W Y Z |
|---|
| Jump to: | "
'
)
*
8
]
A B C D E F G H I J K L M N O P Q R S T U V W Y Z |
|---|
groffgroff
What You See Is What You Get
The same is true for the other main macro
packages that come with groff: man, mdoc,
ms, mm, and mandoc. This won’t work in general;
for example, to load tmac.safer, either ‘-msafer’ or
‘-m safer’ must be used.
This section is derived from Writing Papers with nroff using -me by Eric P. Allman.
those that specify vertical or horizontal motion or a type size
The last solution, i.e., using escaped spaces,
is ‘classical’ in the sense that it can be found in most troff
documents. Nevertheless, it is not optimal in all situations since
‘\ ’ inserts a fixed-width, non-breaking space character which
can’t stretch. gtroff provides a different command \~ to
insert a stretchable, non-breaking space.
Unfortunately, this is a lie. But
hopefully future gtroff hackers will believe it :-)