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 formulę
              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 formulę.
              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.

       · 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 trig-
         ger the automatic activation of the nroff mode.

       · 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.

       · 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.

       · 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.

       · 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.

       · 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

       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® is a registered trademark of the Open Group.  But things have im-
       proved 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 <>; it is maintained by Werner
       Lemberg <>.

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