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ROFF(7)		       Miscellaneous Information Manual		       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-set-
       ting  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 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	 stan-
       dard today.

       In  some	 ancient  Unix	systems,  there	 was a binary called roff that
       implemented the even more ancient runoff	of the Multics operating  sys-
       tem,  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 documen-
       tation, standards, and corporate	documents are written  in  roff.   The
       roff output for text devices is still unmatched,	and its	graphical out-
       put 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 sys-
       tems CTSS and Multics.

   The Predecessor runoff
       The evolution of	roff is	intimately related to the history of the oper-
       ating  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	Mul-
       tics <http://www.multicians.org>, the famous predecessor	of  Unix  from
       1963, runoff became the main format for documentation and text process-
       ing.  Both operating systems could only be run on very  expensive  com-
       puters at that time, so they were mostly	used in	research and for offi-
       cial 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 accord-
       ing 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, similar 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 Massachusetts Institute  of
       Technology),  there  was	 a  need to drive the Wang Graphic Systems CAT
       typesetter, 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 sys-
       tem.  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 type-
	      setter 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 pub-
       lished 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  developing 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 com-
       pleted 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 mod-
       ern  troff programs already provide the full ditroff capabilities auto-
       matically.

   Commercialization
       A major degradation occurred when the easily available Unix 7 operating
       system  was  commercialized.  A whole bunch of divergent	operating sys-
       tems emerged, fighting  each  other  with  incompatibilities  in	 their
       extensions.   Luckily, the incompatibilities did	not fight the original
       troff.  All of the different commercial roff systems made heavy use  of
       Osanna/Kernighan's open source code and documentation, 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.   Fortunately, Caldera bought SCO UNIX in
       2001.  In the following,	Caldera	made the ancient source	code  accessi-
       ble on-line for non-commercial use, cf. section SEE ALSO.

   Free	roff
       None  of	 the commercial	roff systems could attain the status of	a suc-
       cessor 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 outdated, 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 extensions, 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 back-
       ground.	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	document 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 postprocessors.  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 lan-
       guage 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 preprocessors, 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 syntacti-
       cally obeys the rules of	the roff formatting language.  Each preproces-
       sor  defines  a	language  of its own that is translated	into roff code
       when run	through	the preprocessor program.  Parts written in these lan-
       guages  may  be included	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  for-
       matter  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 pre-
       processors 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	gener-
       ates intermediate output, which is intended to be fed into a single de-
       vice postprocessor that must be specified by a command-line  option  to
       the  formatter  program.	  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  output format or troff output.  This lan-
       guage was first specified in [CSTR #97];	its GNU	extension is document-
       ed  in groff_out(5).  The intermediate output language is a kind	of as-
       sembly language compared	to the high-level roff language.  The generat-
       ed  intermediate	output is optimized for	a special device, but the lan-
       guage 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  for-
       matters.

   Devices and Postprocessors
       Devices are hardware interfaces like printers, text or graphical	termi-
       nals, etc., or software interfaces such as a conversion into a  differ-
       ent text	or graphical format.

       A  roff	postprocessor is a program that	transforms troff output	into a
       form suitable for a special device.  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 mentioned 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 counterparts.

       For example, the	Postscript device post in classical troff had a	 reso-
       lution  of 720, while groff's ps	device has 72000, a refinement of fac-
       tor 100.

       Today the operating systems provide device drivers  for	most  printer-
       like  hardware, so it isn't necessary to	write a	special	hardware post-
       processor for each printer.

ROFF PROGRAMMING
       Documents using roff are	normal text files decorated by roff formatting
       elements.  The roff formatting language is quite	powerful; it is	almost
       a full programming language and provides	elements to enlarge  the  lan-
       guage.	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 directories at standardized positions.  Details on the nam-
       ing 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 requests	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  All-
       man), ms	(from Manuscript Macros), and mm (from Memorandum Macros).

   The roff Formatting Language
       The  classical  roff formatting language	is documented in the Troff Us-
       er's Manual [CSTR #54].	The roff language is a full  programming  lan-
       guage  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 ele-
       ments 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, also in the	midst of text in a line.  They
       are used	to implement various features, including the insertion 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 re-
       quest .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	exten-
       sion,  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 using 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 possibility 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 following 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 editor.

       o The  most  general method is to include the following 3 comment lines
	 at the	end of the file.

	 .\" Local Variables:
	 .\" mode: nroff
	 .\" End:

       o There is a set	of file	name extensions, e.g. the man pages that trig-
	 ger the automatic activation of the nroff mode.

       o Theoretically,	it is possible to write	the sequence

	 .\" -*- nroff -*-

	 as  the  first	 line  of a file to have it started in nroff mode when
	 loaded.  Unfortunately, some applications 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.

       o Never	include	empty or blank lines in	a roff document.  Instead, use
	 the empty request (a line consisting of a dot only) or	a line comment
	 .\" if	a structuring element is needed.

       o Never start a line with whitespace because this can lead to unexpect-
	 ed behavior.  Indented	paragraphs can be constructed in a  controlled
	 way by	roff requests.

       o Start each sentence on	a line of its own, for the spacing after a dot
	 is handled differently	depending on whether it	terminates an abbrevi-
	 ation	or a sentence.	To distinguish both cases, do a	line break af-
	 ter each sentence.

       o 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	 clas-
       sical troff are still available,	and all	aspects	of groff are document-
       ed in great detail.

   Internet sites
       troff.org
	      The historical troff  site  <http://www.troff.org>  provides  an
	      overview and pointers to all historical aspects of roff.

       Multics
	      The  Multics  site <http://www.multicians.org> contains a	lot of
	      information on the MIT projects, CTSS, Multics, early Unix,  in-
	      cluding  runoff;	especially  useful are a glossary and the many
	      links to ancient documents.

       Unix Archive
	      The Ancient Unixes Archive  <http://www.tuhs.org/Archive/>  pro-
	      vides  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  program-
	      ming.

       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 language 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 Docu-
       mentation  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 2013			       ROFF(7)

NAME | DESCRIPTION | HISTORY | USING ROFF | ROFF PROGRAMMING | FILE NAME EXTENSIONS | EDITING ROFF | BUGS | SEE ALSO | AUTHORS

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