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roff (7)


roff - concepts and history of roff typesetting


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Miscellaneous Information Manual                                       ROFF(7)

       roff - concepts and history of roff typesetting

       roff  is  the general name for a set of text formatting programs, known
       under names like troff, nroff, ditroff, groff, etc.  A roff system con-
       sists  of  an extensible text formatting language and a set of programs
       for printing and converting to other text formats.  Unix-like operating
       systems distribute a roff system as a core package.

       The  most  common roff system today is the free software implementation
       GNU roff, groff(1).  groff implements the look-and-feel and functional-
       ity of its ancestors, with many extensions.

       The  ancestry  of  roff is described in section HISTORY.  In this docu-
       ment, the term roff always refers to the general  class  of  roff  pro-
       grams, not to the roff command provided in early UNIX systems.

       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.

       roff is used to format UNIX manual pages, (or man pages), the  standard
       documentation system on many UNIX-derived operating systems.

       This document describes the history of the development of the roff sys-
       tem; some usage aspects common to all roff  versions,  details  on  the
       roff pipeline, which is usually hidden behind front-ends like groff(1);
       a general overview of the formatting language; some  tips  for  editing
       roff files; and many pointers to further readings.

       Document formatting by computer dates back to the 1960s.  The roff sys-
       tem 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
       roff's ancestor RUNOFF was written in the MAD language by Jerry Saltzer
       for the Compatible Time Sharing System (CTSS), a project of the  Massa-
       chusetts  Institute  of  Technology (MIT), in 1963 and 1964 - note that
       CTSS commands were all uppercase.

       In 1965, MIT's Project MAC  teamed  with  Bell  Telephone  Laboratories
       (BTL)  and  General  Electric  to  begin  the  Multics  system <http://
       www.multicians.org>.  A command called runoff was written  for  Multics
       in  the late 60s in the BCPL language, by Bob Morris, Doug McIlroy, and
       other members of the Multics team.

       Like its CTSS ancestor, Multics runoff formatted an input file consist-
       ing  of  text  and command lines; commands began with a period and were
       two letters.  Output from these commands was to terminal  devices  such
       as  IBM  Selectric  terminals.   Multics runoff had additional features
       added, such as the ability to do two-pass  formatting;  it  became  the
       main format for Multics documentation and text processing.

       BCPL  and  runoff  were ported to the GCOS system at Bell Labs when BTL
       left the development of Multics.

       There is a free archive about historical RUNOFF documents.  You can get
       it anonymously by the shell command
              $git clone https://github.com/bwarken/RUNOFF_historical.git

       As  well,  there  is  a new project for writing a program that can read
       RUNOFF files , but it does not yet work so far.  You can get  an  early
       version anonymously by the shell command
              $git clone https://github.com/bwarken/runoff.git

   The Classical nroff/troff System
       At BTL, there was a need to drive the 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 pow-
       erful text formatting system by Joseph F.  Ossanna,  who  already  pro-
       grammed several runoff ports.

       The  name  runoff was shortened to roff.  The greatly enlarged language
       of Ossanna's version already included all elements of a full roff  sys-
       tem.   All  modern  roff systems try to implement compatibility to this
       system.  So Joe Ossanna 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 system as
              a whole.

       Ossanna's 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 Ossanna's death in 1977, Kernighan went on with developing troff.
       In the late 1970s, Kernighan equipped troff with a general interface to
       support  more devices, the intermediate output format, and the postpro-
       cessor 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.

       The source code of both the ancient Unix and  classical  troff  weren't
       available for two decades.  Meanwhile, it is accessible again (on-line)
       for non-commercial use, cf. section SEE ALSO.

   groff -- free GNU roff
       The most important free roff project  was  the  GNU  implementation  of
       troff, written from scratch 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.

   Free Heirloom roff
       An alternative is  Gunnar  Ritter's  Heirloom  roff  project  <https://
       github.com/n-t-roff/heirloom-doctools>  project, started in 2005, which
       provides enhanced versions of the various roff tools found in the Open-
       Solaris  and  Plan  9  operating  systems,  now  available  under  free
       licenses.  You can get this package with the shell command:
              $ git clone https://github.com/n-t-roff/heirloom-doctools

       Moreover, one finds there the Original Documenter's  Workbench  Release
       3.3 <https://github.com/n-t-roff/DWB3.3>.

       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.

              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.
              chem     for drawing chemical formulae.

       Other known preprocessors that are not available on all systems include

              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
       device 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 docu-
       mented in groff_out(5).  The intermediate output language is a kind  of
       assembly language compared to the high-level roff language.  The gener-
       ated intermediate output is optimized for a  special  device,  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

       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 units per inch, 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 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 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
       User'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
       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 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:

              LESSOPEN='|lesspipe %s'

       where lesspipe is either a system supplied command or a shell script of
       your own.

       More  details  for  file  name  extensions  can be found at groff_file-

       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
              trigger 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
              unexpected 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  abbreviation or a sentence.  To distinguish both cases, do a
              line break after 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 .I 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.

       See attributes(7) for descriptions of the following attributes:

       |Availability   | text/groff       |
       |Stability      | Uncommitted      |

       There  is a lot of documentation on roff.  The original papers on clas-
       sical troff are still available, and all aspects  of  groff  are  docu-
       mented in great detail.

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

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

       Unix Archive
              The  Ancient  Unixes Archive <http://www.tuhs.org/Archive/> 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/

       Developers at AT&T Bell Labs
              Bell Labs Computing and Mathematical Sciences Research  <http://
              www.bell-labs.com/>  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-

       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.  Ossanna,  Nroff/Troff  User's  Manual   <http://cm.bell-
              labs.com/cm/cs/cstr/54.ps.gz>; Bell Labs, 1976; revised by Brian
              Kernighan, 1992.

       [CSTR #97]
              Brian Kernighan, A Typesetter-independent TROFF <http://cm.bell-
              labs.com/cm/cs/cstr/97.ps.gz>,  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     <http://cm.bell-labs.com/cm/cs/cstr/
              114.ps.gz>; Bell Labs, August 1984.

       [CSTR #116]
              Brian W. Kernighan, PIC - A Graphics  Language  for  Typesetting
              <http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz>;    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/cstr/122.ps.gz>;
              Bell Labs, April 1986.

       You  can  get an archive with most classical roff documentation as rea-
       sonable PDF files at github using the shell command
              $ git clone https://github.com/bwarken/roff_classical.git

   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) 2000-2014           Free Software Foundation, Inc.

       Permission  is  granted to copy, distribute and/or modify this document
       under the terms of the FDL (GNU Free Documentation License) Version 1.3
       or  any  later version published by the Free Software Foundation.  with
       the Invariant Sections being the .au and .co macro definitions, with no
       Front-Cover Texts, and with no Back-Cover Texts.

       A  copy  of the Free Documentation License is included as a file called
       FDL in the main directory of the groff source package.

       The license text is also available on-line at  the  GNU  copyleft  site

       This     man-page    was    written    by    Bernd    Warken    <groff-
       bernd.warken-72@web.de>   and   is   maintained   by   Werner   Lemberg

       Source  code  for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source                was                downloaded                from

       Further information about this software can be found on the open source
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Groff Version 1.22.3            4 November 2014                        ROFF(7)