Command Section
ROFF(7)								       ROFF(7)

       roff - concepts and history of roff typesetting

       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

       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.

       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 <>, 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

       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-

       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

       The most	important free roff project was	the GNU	port of	troff, created
       by James	Clark and put under the	GNU Public License <http://>.	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.

       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

   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.

       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

       Often, the name troff is	used as	a general term to refer	to  both  for-

   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.

       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  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

       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.

       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. for a document using the me macro	package,  for
       mm, for ms, file.pic for	pic files, etc.

       But  there  is  no  general  naming  scheme  for	roff documents,	though 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.

       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.

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

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

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

       heoretically,	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.

       ever 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.

       ever 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.

       tart 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 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

       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

       Besides	Emacs,	some other editors provide nroff style files too, e.g.
       vim(1), an extension of the vi(1) program.

       UNIX(R) is a registered trademark of the	Open Group.  But  things  have
       improved	considerably after Caldera had bought SCO UNIX in 2001.

       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
	      The  historical  troff  site  <> provides an
	      overview and pointers to all historical aspects of roff.

	      The Multics site <> 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 <> 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 <

       Developers at AT&T Bell Labs
	      Bell Labs	Computing and Mathematical Sciences Research <http://>  provides	 a search facility for
	      tracking information on the early	developers.

       Plan 9 The Plan 9 operating system <> by AT&T
	      Bell Labs.

       runoff Jerry Saltzer's home page	<
	      publications/pubs.html> stores some documents using the  ancient
	      runoff formatting	language.

       CSTR Papers
	      The Bell Labs CSTR site <
	      cstr.html> stores	the original troff  manuals  (CSTR  #54,  #97,
	      #114,  #116,  #122)  and famous historical documents on program-

       GNU roff
	      The groff	web site <>  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://>; Bell Labs,	1976; revised by Brian
	      Kernighan, 1992.

       [CSTR #97]
	      Brian Kernighan, A Typesetter-independent	TROFF <http://>,  Bell  Labs,  1981, revised March

       The "little language" roff papers are

       [CSTR #114]
	      Jon L. Bentley and Brian W. Kernighan, GRAP -- A Language	for
	      Typesetting  Graphs <>; Bell
	      Labs, August 1984.

       [CSTR #116]
	      Brian W. Kernighan, PIC -- A Graphics Language for Typesetting
	      <>;	Bell   Labs,  December

       [CSTR #122]
	      J. L. Bentley, L.	W. Jelinski, and B. W. Kernighan, CHEM -- A
	      Program for Typesetting Chemical Structure Diagrams, Computers
	      and Chemistry <>; 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

       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.

       Copyright (C) 2000, 2001, 2002, 2003, 2004  Free	 Software  Foundation,

       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 <>.

       This document is	part of	groff, the  GNU	 roff  distribution.   It  was
       written	by  Bernd Warken <[email protected]>; it is maintained by	Werner
       Lemberg <[email protected]>.

Groff Version 1.19.2	       4 September 2005			       ROFF(7)
Command Section