|
|
Эта страница руководства для версии 10.9 Mac OS XЕсли Вы выполняете различную версию Mac OS X, просматриваете документацию локально:
Читать страницы руководстваСтраницы руководства предназначаются как справочник для людей, уже понимающих технологию.
|
ROFF(7) ROFF(7)
NAME
roff - concepts and history of roff typesetting
DESCRIPTION
roff is the general name for a set of type-setting programs, known under names like troff, nroff,
ditroff, groff, etc. A roff type-setting system consists of an extensible text formatting language
and a set of programs for printing and converting to other text formats. Traditionally, it is the
main text processing system of Unix; every Unix-like operating system still distributes a roff system
as a core package.
The most common roff system today is the free software implementation GNU roff, groff(1). The pre-groff pregroff
groff implementations are referred to as classical (dating back as long as 1973). groff implements
the look-and-feel and functionality of its classical ancestors, but has many extensions. As groff is
the only roff system that is available for every (or almost every) computer system it is the de-facto
roff standard today.
In some ancient Unix systems, there was a binary called roff that implemented the even more ancient
runoff of the Multics operating system, cf. section HISTORY. The functionality of this program was
very restricted even in comparison to ancient troff; it is not supported any longer. Consequently,
in this document, the term roff always refers to the general meaning of roff system, not to the
ancient roff binary.
In spite of its age, roff is in wide use today, for example, the manual pages on UNIX systems
(man pages), many software books, system documentation, standards, and corporate documents are writ-ten written
ten in roff. The roff output for text devices is still unmatched, and its graphical output has the
same quality as other free type-setting programs and is better than some of the commercial systems.
The most popular application of roff is the concept of manual pages or shortly man pages; this is the
standard documentation system on many operating systems.
This document describes the historical facts around the development of the roff system; some usage
aspects common to all roff versions, details on the roff pipeline, which is usually hidden behind
front-ends like groff(1); an general overview of the formatting language; some tips for editing roff
files; and many pointers to further readings.
HISTORY
The roff text processing system has a very long history, dating back to the 1960s. The roff system
itself is intimately connected to the Unix operating system, but its roots go back to the earlier
operating systems CTSS and Multics.
The Predecessor runoff
The evolution of roff is intimately related to the history of the operating systems. Its predecessor
runoff was written by Jerry Saltzer on the CTSS operating system (Compatible Time Sharing System) as
early as 1961. When CTSS was further developed into the operating system Multics <http://
www.multicians.org>, the famous predecessor of Unix from 1963, runoff became the main format for doc-umentation documentation
umentation and text processing. Both operating systems could only be run on very expensive computers
at that time, so they were mostly used in research and for official and military tasks.
The possibilities of the runoff language were quite limited as compared to modern roff. Only text
output was possible in the 1960s. This could be implemented by a set of requests of length 2, many
of which are still identically used in roff. The language was modelled according to the habits of
typesetting in the pre-computer age, where lines starting with a dot were used in manuscripts to
denote formatting requests to the person who would perform the typesetting manually later on.
The runoff program was written in the PL/1 language first, later on in BCPL, the grandmother of the
C programming language. In the Multics operating system, the help system was handled by runoff, sim-ilar similar
ilar to roff's task to manage the Unix manual pages. There are still documents written in the runoff
language; for examples see Saltzer's home page, cf. section SEE ALSO.
The Classical nroff/troff System
In the 1970s, the Multics off-spring Unix became more and more popular because it could be run on
affordable machines and was easily available for universities at that time. At MIT (the Mas-sachusetts Massachusetts
sachusetts Institute of Technology), there was a need to drive the Wang Graphic Systems CAT typeset-ter, typesetter,
ter, a graphical output device from a PDP-11 computer running Unix. As runoff was too limited for
this task it was further developed into a more powerful text formatting system by Josef F. Osanna, a
main developer of the Multics operating system and programmer of several runoff ports.
The name runoff was shortened to roff. The greatly enlarged language of Osanna's concept included
already all elements of a full roff system. All modern roff systems try to implement compatibility
to this system. So Joe Osanna can be called the father of all roff systems.
This first roff system had three formatter programs.
troff (typesetter roff) generated a graphical output for the CAT typesetter as its only device.
nroff produced text output suitable for terminals and line printers.
roff was the reimplementation of the former runoff program with its limited features; this program
was abandoned in later versions. Today, the name roff is used to refer to a troff/nroff sytem
as a whole.
Osanna first version was written in the PDP-11 assembly language and released in 1973. Brian
Kernighan joined the roff development by rewriting it in the C programming language. The C version
was released in 1975.
The syntax of the formatting language of the nroff/troff programs was documented in the famous Troff
User's Manual [CSTR #54], first published in 1976, with further revisions up to 1992 by Brian
Kernighan. This document is the specification of the classical troff. All later roff systems tried
to establish compatibility with this specification.
After Osanna had died in 1977 by a heart-attack at the age of about 50, Kernighan went on with devel-oping developing
oping troff. The next milestone was to equip troff with a general interface to support more devices,
the intermediate output format and the postprocessor system. This completed the structure of a roff
system as it is still in use today; see section USING ROFF. In 1979, these novelties were described
in the paper [CSTR #97]. This new troff version is the basis for all existing newer troff systems,
including groff. On some systems, this device independent troff got a binary of its own, called
ditroff(7). All modern troff programs already provide the full ditroff capabilities automatically.
Commercialization
A major degradation occurred when the easily available Unix 7 operating system was commercialized. A
whole bunch of divergent operating systems emerged, fighting each other with incompatibilities in
their extensions. Luckily, the incompatibilities did not fight the original troff. All of the dif-ferent different
ferent commercial roff systems made heavy use of Osanna/Kernighan's open source code and documenta-tion, documentation,
tion, but sold them as "their" system -- with only minor additions.
The source code of both the ancient Unix and classical troff weren't available for two decades. For-tunately, Fortunately,
tunately, Caldera bought SCO UNIX in 2001. In the following, Caldera made the ancient source code
accessible on-line for non-commercial use, cf. section SEE ALSO.
Free roff
None of the commercial roff systems could attain the status of a successor for the general roff
development. Everyone was only interested in their own stuff. This led to a steep downfall of the
once excellent Unix operating system during the 1980s.
As a counter-measure to the galopping commercialization, AT&T Bell Labs tried to launch a rescue
project with their Plan 9 operating system. It is freely available for non-commercial use, even the
source code, but has a proprietary license that impedes the free development. This concept is out-dated, outdated,
dated, so Plan 9 was not accepted as a platform to bundle the main-stream development.
The only remedy came from the emerging free operatings systems (386BSD, GNU/Linux, etc.) and software
projects during the 1980s and 1990s. These implemented the ancient Unix features and many exten-sions, extensions,
sions, such that the old experience is not lost. In the 21st century, Unix-like systems are again a
major factor in computer industry -- thanks to free software.
The most important free roff project was the GNU port of troff, created by James Clark and put under
the GNU Public License <http://www.gnu.org/copyleft>. It was called groff (GNU roff). See groff(1)
for an overview.
The groff system is still actively developed. It is compatible to the classical troff, but many
extensions were added. It is the first roff system that is available on almost all operating systems
-- and it is free. This makes groff the de-facto roff standard today.
USING ROFF
Most people won't even notice that they are actually using roff. When you read a system manual page
(man page) roff is working in the background. Roff documents can be viewed with a native viewer
called xditview(1x), a standard program of the X window distribution, see X(7x). But using roff
explicitly isn't difficult either.
Some roff implementations provide wrapper programs that make it easy to use the roff system on the
shell command line. For example, the GNU roff implementation groff(1) provides command line options
to avoid the long command pipes of classical troff; a program grog(1) tries to guess from the docu-ment document
ment which arguments should be used for a run of groff; people who do not like specifying command
line options should try the groffer(1) program for graphically displaying groff files and man pages.
The roff Pipe
Each roff system consists of preprocessors, roff formatter programs, and a set of device postproces-sors. postprocessors.
sors. This concept makes heavy use of the piping mechanism, that is, a series of programs is called
one after the other, where the output of each program in the queue is taken as the input for the next
program.
sh# cat file | ... | preproc | ... | troff options | postproc
The preprocessors generate roff code that is fed into a roff formatter (e.g. troff), which in turn
generates intermediate output that is fed into a device postprocessor program for printing or final
output.
All of these parts use programming languages of their own; each language is totally unrelated to the
other parts. Moreover, roff macro packages that were tailored for special purposes can be included.
Most roff documents use the macros of some package, intermixed with code for one or more preproces-sors, preprocessors,
sors, spiced with some elements from the plain roff language. The full power of the roff formatting
language is seldom needed by users; only programmers of macro packages need to know about the gory
details.
Preprocessors
A roff preprocessor is any program that generates output that syntactically obeys the rules of the
roff formatting language. Each preprocessor defines a language of its own that is translated into
roff code when run through the preprocessor program. Parts written in these languages may be includ-ed included
ed within a roff document; they are identified by special roff requests or macros. Each document
that is enhanced by preprocessor code must be run through all corresponding preprocessors before it
is fed into the actual roff formatter program, for the formatter just ignores all alien code. The
preprocessor programs extract and transform only the document parts that are determined for them.
There are a lot of free and commercial roff preprocessors. Some of them aren't available on each
system, but there is a small set of preprocessors that are considered as an integral part of each
roff system. The classical preprocessors are
tbl for tables
eqn for mathematical formulae
pic for drawing diagrams
refer for bibliographic references
soelim for including macro files from standard locations
Other known preprocessors that are not available on all systems include
chem for drawing chemical formulae.
grap for constructing graphical elements.
grn for including gremlin(1) pictures.
Formatter Programs
A roff formatter is a program that parses documents written in the roff formatting language or uses
some of the roff macro packages. It generates intermediate output, which is intended to be fed into
a single device postprocessor that must be specified by a command-line option to the formatter pro-gram. program.
gram. The documents must have been run through all necessary preprocessors before.
The output produced by a roff formatter is represented in yet another language, the intermediate out-put output
put format or troff output. This language was first specified in [CSTR #97]; its GNU extension is
documented in groff_out(5). The intermediate output language is a kind of assembly language compared
to the high-level roff language. The generated intermediate output is optimized for a special de-vice, device,
vice, but the language is the same for every device.
The roff formatter is the heart of the roff system. The traditional roff had two formatters, nroff
for text devices and troff for graphical devices.
Often, the name troff is used as a general term to refer to both formatters.
Devices and Postprocessors
Devices are hardware interfaces like printers, text or graphical terminals, etc., or software inter-faces interfaces
faces such as a conversion into a different text or graphical format.
A roff postprocessor is a program that transforms troff output into a form suitable for a special de-vice. device.
vice. The roff postprocessors are like device drivers for the output target.
For each device there is a postprocessor program that fits the device optimally. The postprocessor
parses the generated intermediate output and generates device-specific code that is sent directly to
the device.
The names of the devices and the postprocessor programs are not fixed because they greatly depend on
the software and hardware abilities of the actual computer. For example, the classical devices men-tioned mentioned
tioned in [CSTR #54] have greatly changed since the classical times. The old hardware doesn't exist
any longer and the old graphical conversions were quite imprecise when compared to their modern coun-terparts. counterparts.
terparts.
For example, the Postscript device post in classical troff had a resolution of 720, while groff's ps
device has 72000, a refinement of factor 100.
Today the operating systems provide device drivers for most printer-like hardware, so it isn't neces-sary necessary
sary to write a special hardware postprocessor for each printer.
ROFF PROGRAMMING
Documents using roff are normal text files decorated by roff formatting elements. The roff format-ting formatting
ting language is quite powerful; it is almost a full programming language and provides elements to
enlarge the language. With these, it became possible to develop macro packages that are tailored for
special applications. Such macro packages are much handier than plain roff. So most people will
choose a macro package without worrying about the internals of the roff language.
Macro Packages
Macro packages are collections of macros that are suitable to format a special kind of documents in a
convenient way. This greatly eases the usage of roff. The macro definitions of a package are kept
in a file called name.tmac (classically tmac.name). All tmac files are stored in one or more direc-tories directories
tories at standardized positions. Details on the naming of macro packages and their placement is
found in groff_tmac(5).
A macro package that is to be used in a document can be announced to the formatter by the command
line option -m, see troff(1), or it can be specified within a document using the file inclusion re-quests requests
quests of the roff language, see groff(7).
Famous classical macro packages are man for traditional man pages, mdoc for BSD-style manual pages;
the macro sets for books, articles, and letters are me (probably from the first name of its creator
Eric Allman), ms (from Manuscript Macros), and mm (from Memorandum Macros).
The roff Formatting Language
The classical roff formatting language is documented in the Troff User's Manual [CSTR #54]. The roff
language is a full programming language providing requests, definition of macros, escape sequences,
string variables, number or size registers, and flow controls.
Requests are the predefined basic formatting commands similar to the commands at the shell prompt.
The user can define request-like elements using predefined roff elements. These are then called
macros. A document writer will not note any difference in usage for requests or macros; both are
written on a line on their own starting with a dot.
Escape sequences are roff elements starting with a backslash `\'. They can be inserted anywhere, al-so also
so in the midst of text in a line. They are used to implement various features, including the inser-tion insertion
tion of non-ASCII characters with \(, font changes with \f, in-line comments with \", the escaping of
special control characters like \\, and many other features.
Strings are variables that can store a string. A string is stored by the .ds request. The stored
string can be retrieved later by the \* escape sequence.
Registers store numbers and sizes. A register can be set with the request .nr and its value can be
retrieved by the escape sequence \n.
FILE NAME EXTENSIONS
Manual pages (man pages) take the section number as a file name extension, e.g., the filename for
this document is roff.7, i.e., it is kept in section 7 of the man pages.
The classical macro packages take the package name as an extension, e.g. file.me for a document us-ing using
ing the me macro package, file.mm for mm, file.ms for ms, file.pic for pic files, etc.
But there is no general naming scheme for roff documents, though file.tr for troff file is seen now
and then. Maybe there should be a standardization for the filename extensions of roff files.
File name extensions can be very handy in conjunction with the less(1) pager. It provides the possi-bility possibility
bility to feed all input into a command-line pipe that is specified in the shell environment variable
LESSOPEN. This process is not well documented, so here an example:
sh# LESSOPEN='|lesspipe %s'
where lesspipe is either a system supplied command or a shell script of your own.
EDITING ROFF
The best program for editing a roff document is Emacs (or Xemacs), see emacs(1). It provides an
nroff mode that is suitable for all kinds of roff dialects. This mode can be activated by the fol-lowing following
lowing methods.
When editing a file within Emacs the mode can be changed by typing `M-x nroff-mode', where M-x means
to hold down the Meta key (or Alt) and hitting the x key at the same time.
But it is also possible to have the mode automatically selected when the file is loaded into the edi-tor. editor.
tor.
• The most general method is to include the following 3 comment lines at the end of the file.
.\" Local Variables:
.\" mode: nroff
.\" End:
• There is a set of file name extensions, e.g. the man pages that trigger the automatic activation of
the nroff mode.
• Theoretically, it is possible to write the sequence
.\" -*- nroff -*-as -*as
as the first line of a file to have it started in nroff mode when loaded. Unfortunately, some ap-plications applications
plications such as the man program are confused by this; so this is deprecated.
All roff formatters provide automated line breaks and horizontal and vertical spacing. In order to
not disturb this, the following tips can be helpful.
• Never include empty or blank lines in a roff document. Instead, use the empty request (a line con-sisting consisting
sisting of a dot only) or a line comment .\" if a structuring element is needed.
• Never start a line with whitespace because this can lead to unexpected behavior. Indented para-graphs paragraphs
graphs can be constructed in a controlled way by roff requests.
• Start each sentence on a line of its own, for the spacing after a dot is handled differently de-pending depending
pending on whether it terminates an abbreviation or a sentence. To distinguish both cases, do a
line break after each sentence.
• To additionally use the auto-fill mode in Emacs, it is best to insert an empty roff request (a line
consisting of a dot only) after each sentence.
The following example shows how optimal roff editing could look.
This is an example for a roff document.
.
This is the next sentence in the same paragraph.
.
This is a longer sentence stretching over several
lines; abbreviations like `cf.' are easily
identified because the dot is not followed by a
line break.
.
In the output, this will still go to the same
paragraph.
Besides Emacs, some other editors provide nroff style files too, e.g. vim(1), an extension of the
vi(1) program.
BUGS
UNIX(R) is a registered trademark of the Open Group. But things have improved considerably after
Caldera had bought SCO UNIX in 2001.
SEE ALSO
There is a lot of documentation on roff. The original papers on classical troff are still available,
and all aspects of groff are documented in great detail.
Internet sites
troff.org
The historical troff site <http://www.troff.org> provides an overview and pointers to all his-torical historical
torical aspects of roff.
Multics
The Multics site <http://www.multicians.org> contains a lot of information on the MIT
projects, CTSS, Multics, early Unix, including runoff; especially useful are a glossary and
the many links to ancient documents.
Unix Archive
The Ancient Unixes Archive <http://www.tuhs.org/Archive/> provides the source code and some
binaries of the ancient Unixes (including the source code of troff and its documentation) that
were made public by Caldera since 2001, e.g. of the famous Unix version 7 for PDP-11 at the
Unix V7 site <http://www.tuhs.org/Archive/PDP-11/Trees/V7>.
Developers at AT&T Bell Labs
Bell Labs Computing and Mathematical Sciences Research <http://cm.bell-labs.com/cm/index.html>
provides a search facility for tracking information on the early developers.
Plan 9 The Plan 9 operating system <http://plan9.bell-labs.com> by AT&T Bell Labs.
runoff Jerry Saltzer's home page <http://web.mit.edu/Saltzer/www/publications/pubs.html> stores some
documents using the ancient runoff formatting language.
CSTR Papers
The Bell Labs CSTR site <http://cm.bell-labs.com/cm/cs/cstr.html> stores the original troff
manuals (CSTR #54, #97, #114, #116, #122) and famous historical documents on programming.
GNU roff
The groff web site <http://www.gnu.org/software/groff> provides the free roff implementation
groff, the actual standard roff.
Historical roff Documentation
Many classical troff documents are still available on-line. The two main manuals of the troff lan-guage language
guage are
[CSTR #54]
J. F. Osanna, Nroff/Troff User's Manual <http://cm.bell-labs.com/cm/cs/54.ps>; Bell Labs,
1976; revised by Brian Kernighan, 1992.
[CSTR #97]
Brian Kernighan, A Typesetter-independent TROFF <http://cm.bell-labs.com/cm/cs/97.ps>, Bell
Labs, 1981, revised March 1982.
The "little language" roff papers are
[CSTR #114]
Jon L. Bentley and Brian W. Kernighan, GRAP -- A Language for Typesetting Graphs <http://
cm.bell-labs.com/cm/cs/114.ps>; Bell Labs, August 1984.
[CSTR #116]
Brian W. Kernighan, PIC -- A Graphics Language for Typesetting <http://cm.bell-labs.com/cm/cs/
116.ps>; Bell Labs, December 1984.
[CSTR #122]
J. L. Bentley, L. W. Jelinski, and B. W. Kernighan, CHEM -- A Program for Typesetting Chemical
Structure Diagrams, Computers and Chemistry <http://cm.bell-labs.com/cm/cs/122.ps>; Bell Labs,
April 1986.
Manual Pages
Due to its complex structure, a full roff system has many man pages, each describing a single aspect
of roff. Unfortunately, there is no general naming scheme for the documentation among the different
roff implementations.
In groff, the man page groff(1) contains a survey of all documentation available in groff.
On other systems, you are on your own, but troff(1) might be a good starting point.
AUTHORS
Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
This document is distributed under the terms of the FDL (GNU Free Documentation License) version 1.1
or later. You should have received a copy of the FDL on your system, it is also available on-line at
the GNU copyleft site <http://www.gnu.org/copyleft/fdl.html>.
This document is part of groff, the GNU roff distribution. It was written by
Bernd Warken <bwarken@mayn.de>; it is maintained by
Werner Lemberg <wl@gnu.org>.
Groff Version 1.19.2 2 June 2004 ROFF(7)
|
Сообщение о проблемах
Способ сообщить о проблеме с этой страницей руководства зависит от типа проблемы:
- Ошибки содержания
- Ошибки отчета в содержании этой документации со ссылками на отзыв ниже.
- Отчеты об ошибках
- Сообщите об ошибках в функциональности описанного инструмента или API через Генератор отчетов Ошибки.
- Форматирование проблем
- Отчет, форматирующий ошибки в интерактивной версии этих страниц со ссылками на отзыв ниже.