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ROFF(7)                          Miscellaneous Information Manual                         ROFF(7)

NAME
       roff - concepts and history of roff typesetting

DESCRIPTION
       roff  is  the  general  name for a set of text formatting programs, known under names like
       troff, nroff, ditroff, groff, etc.  A roff system consists of an extensible  text  format-
       ting  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 functionality of its ancestors, with many exten-
       sions.

       The ancestry of roff is described in section "History" below.  In this document, the  term
       roff always refers to the general class of roff programs, 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 sys-
       tems (man pages), many software books, system documentation, standards, and corporate doc-
       uments are written 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.

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

       This  document describes the history of the development of the roff system; some usage as-
       pects 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.

HISTORY
       Document formatting by computer dates back to the 1960s.  The roff system itself is  inti-
       mately  connected to the Unix operating system, but its roots go back to the earlier oper-
       ating 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 Massachusetts 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 Elec-
       tric 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 consisting of text and com-
       mand 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 powerful text formatting system by  Joseph  F.  Ossanna,
       who already programmed 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 system.  All modern roff systems try  to  im-
       plement 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 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  re-
              fer 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 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 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 in-
       termediate 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" below.  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 indepen-
       dent troff got a binary of its own, called ditroff(7).  All modern troff programs  already
       provide the full ditroff capabilities automatically.

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

   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 to-
       day.

   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 vari-
       ous roff tools found in the OpenSolaris 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>.

USING ROFF
       Most people won't even notice that they are actually using roff.  When you read  a  system
       manual page (man page) roff is working in the background.  But using roff explicitly isn't
       difficult either.

       Some roff implementations provide wrapper programs that make it easy to use the roff  sys-
       tem on the shell command line.  For example, the GNU roff implementation groff(1) provides
       command-line options to avoid the long command pipes of classical troff; a program grog(1)
       tries to guess from the document which arguments should be used for a run of groff; people
       who do not like specifying command-line options should  try  the  groffer(1)  program  for
       graphically displaying groff files and man pages.

   The roff Pipe
       Each  roff  system consists of preprocessors, roff formatter programs, and a set of device
       postprocessors.  This concept makes heavy use of the piping mechanism, that is,  a  series
       of  programs  is called one after the other, where the output of each program in the queue
       is taken as the input for the next program.

              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 language is totally  unre-
       lated  to  the  other parts.  Moreover, roff macro packages that were tailored for special
       purposes can be included.

       Most roff documents use the macros of some package, intermixed with code for one  or  more
       preprocessors,  spiced with some elements from the plain roff language.  The full power of
       the roff formatting language is seldom needed by users; only programmers of macro packages
       need to know about the gory details.

   Preprocessors
       A  roff  preprocessor  is  any  program that generates output that 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 writ-
       ten in these languages may be included within a roff document; they are identified by spe-
       cial 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  format-
       ter program, for the formatter just ignores all alien code.  The preprocessor programs ex-
       tract 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 inte-
       gral 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  lan-
       guage 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 program.  The documents must have been run through all neces-
       sary preprocessors before.

       The output produced by a roff formatter is represented in yet another language, the inter-
       mediate  output  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 inter-
       mediate 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 format-
       ters, 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 soft-
       ware interfaces 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 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 im-
       precise when compared to their modern counterparts.

       For example, the PostScript device post in classical troff had a resolution 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 postprocessor for each printer.

ROFF PROGRAMMING
       Documents using roff are normal text files decorated by  roff  formatting  elements.   The
       roff  formatting  language is quite powerful; it is almost a full programming language and
       provides elements to enlarge the 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  defini-
       tions  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
       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 requests of the roff language, see groff(7).

       Famous classical macro packages are man for traditional man pages, mdoc for BSD-style man-
       ual 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, defini-
       tion 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 re-
       quests 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 fea-
       tures, including the insertion of non-ASCII characters with \(, font changes with \f,  in-
       line  comments with \", the escaping of special control characters like \\, and many other
       features.

       Strings are variables that can store a string.  A string is stored  by  the  .ds  request.
       The stored string can be retrieved later by the \* escape sequence.

       Registers  store  numbers  and  sizes.  A register can be set with the request .nr and its
       value can be retrieved by the escape sequence \n.

FILE NAME EXTENSIONS
       Manual pages (man pages) take the section number as a file name extension, e.g., the file-
       name 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_filenames(5).

EDITING ROFF
       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  re-
              quest (a line consisting of a dot only) or a line comment .\" if a structuring ele-
              ment 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 judicious line breaking in a roff input file.

              This is an example of a
              .I roff
              document that you can type into your text editor.
              .
              This is the next sentence in the same paragraph.
              .
              This is a longer sentence stretching over several input lines;
              abbreviations like cf. are easily identified because the dot is
              not followed by a line break.
              .
              In the output, this sentence continues the same paragraph.

   Editing with Emacs
       The best program for editing a roff document is Emacs (or XEmacs); see emacs(1).  It  pro-
       vides an nroff mode that is suitable for all kinds of roff dialects.  This mode can be ac-
       tivated 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 press 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 auto-
              matic 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.  Unfortu-
              nately,  some applications such as the man program are confused by this; so this is
              deprecated.

   Editing with Vim
       Besides Emacs, some other editors provide nroff style files too, e.g. vim(1), an extension
       of  the  vi(1) program.  Vim's highlighting can be made to recognize roff files by setting
       the filetype option in a Vim modeline.  For this feature to work, your copy of vim must be
       built  with  support for, and configured to enable, several features; consult the editor's
       online help topics "auto-setting", "filetype", and "syntax".  Then put  the  following  at
       the end of your roff files, after any Emacs configuration:

                     .\" vim: set filetype=groff:

       Replace  "groff" in the above with "nroff" if you want highlighing that does not recognize
       many of the GNU extensions to roff, such as request, register,  and  string  names  longer
       than two characters.

AUTHORS
       This document was written by Bernd Warken <groff-bernd.warken-72 AT web.de>.

SEE ALSO
       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
       History of Unix Manpages
              The history page <http://manpages.bsd.lv/history.html> of the mdocml  project  pro-
              vides an overview of roff development up to date, with links to original documenta-
              tion and comments of the original authors.

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

       Multics
              The  Multics  site <http://www.multicians.org> contains a lot of information on the
              MIT projects, CTSS, Multics, early Unix, 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/> 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 <http://www.tuhs.org/Archive/PDP-11/Trees/
              V7>.

       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   (now   Alcatel)   CSTR   site  <https://www.alcatel-lucent.com/
              bell-labs-journals> stores the original troff manuals (CSTR #54, #97,  #114,  #116,
              #122) and famous historical documents on programming.

       GNU roff
              The  groff  web site <http://www.gnu.org/software/groff> provides the free roff im-
              plementation 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://www.troff.org/54.pdf>; 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 1982.

       The "little language" roff papers are

       [CSTR #114]
              Jon  L.  Bentley  and  Brian W. Kernighan, GRAP - A Language for Typesetting Graphs
              <http://cm.bell-labs.com/cm/cs/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 reasonable 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 documen-
       tation 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.

groff 1.22.4                              23 March 2022                                   ROFF(7)

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