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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-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.

       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://>, 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.

       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 <>.  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 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

       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

       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

       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.

       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.

       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  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.

       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. for a document us-ing using
       ing 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 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.

       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.

        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

       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 classical troff are still available,
       and all aspects of groff are documented in great detail.

   Internet sites
              The historical troff site <> provides an overview and pointers to all his-torical historical
              torical aspects of roff.

              The  Multics  site  <>  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 <> 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 <>.

       Developers at AT&T Bell Labs
              Bell Labs Computing and Mathematical Sciences Research <>
              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 <> stores some
              documents using the ancient runoff formatting language.

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              manuals (CSTR #54, #97, #114, #116, #122) and famous historical documents on programming.

       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  lan-guage language
       guage are

       [CSTR #54]
              J.  F.  Osanna,  Nroff/Troff  User's  Manual <>; Bell Labs,
              1976; revised by Brian Kernighan, 1992.

       [CSTR #97]
              Brian Kernighan, A Typesetter-independent  TROFF  <>,  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://
    >; Bell Labs, August 1984.

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

       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 <>.

       This document is part of groff, the GNU roff distribution.  It was written by

       Bernd Warken <>; it is maintained by

       Werner Lemberg <>.

Groff Version 1.19.2                             2 June 2004                                         ROFF(7)

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