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    The following form allows you to view linux man pages.

    Command:

    roff

    
    
    

    DESCRIPTION

           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
           package.
    
           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.
    
    
    

    HISTORY

           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  CTTS was further developed into the operating system Mul-
    
           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
           "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 empedes 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
           software.
    
           The most important free roff project was the GNU port of troff, created
           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.
    
    
    

    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  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
           pages.
           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.
    
       Preprocessors
           A roff preprocessor is any program that generates output that syntacti-
           cally obeys the rules of the roff formatting language.  Each preproces-
           sor defines a language of its own that is  translated  into  roff  code
           when run through the preprocessor program.  Parts written in these lan-
           guages may be included within a roff document; they are  identified  by
           special  roff  requests  or  macros.  Each document that is enhanced by
           preprocessor code must be run through all  corresponding  preprocessors
           before  it  is fed into the actual roff formatter program, for the for-
           matter just ignores all alien code.  The preprocessor programs  extract
           and transform only the document parts that are determined for them.
    
           There  are  a  lot  of free and commercial roff preprocessors.  Some of
           them aren't available on each system, but there is a small set of  pre-
           processors that are considered as an integral part of each roff system.
           The classical preprocessors are
    
                  tbl     for tables
                  eqn     for mathematical formulae
                  pic     for drawing diagrams
                  refer   for bibliographic references
                  soelim  for including macro files from standard locations
    
           Other known preprocessors that are not available on all systems include
    
                  chem    for drawing chemical formulae.
                  grap    for constructing graphical elements.
                  grn     for including gremlin(1) pictures.
    
       Formatter Programs
           A roff formatter is a program that parses documents written in the roff
           formatting language or uses some of the roff macro packages.  It gener-
           ates intermediate output, which is intended to be fed into a single de-
           vice postprocessor that must be specified by a command-line  option  to
           the  formatter  program.   The documents must have been run through all
           necessary preprocessors before.
    
           The output produced by a roff formatter is represented in  yet  another
           language,  the  intermediate  output format or troff output.  This lan-
           guage was first specified in [CSTR #97]; its GNU extension is document-
           ed  in groff_out(5).  The intermediate output language is a kind of as-
           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.
    
    
    

    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 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).
    
           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
           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  re-
           quest .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 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:
    
           sh# LESSOPEN='|lesspipe %s'
    
           where lesspipe is either a system supplied command or a shell script of
           your own.
    
    
    

    EDITING ROFF

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

    BUGS

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

    SEE ALSO

           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
           troff.org
                  The  historical  troff  site  <http://www.troff.org> provides an
                  overview and pointers to all historical aspects of  roff.   This
                  web  site  is  under  construction;  once,  it will be the major
                  source for roff history.
    
           Developers at AT&T Bell Labs
                  Bell Labs Computing and Mathematical Sciences Research  <http://
                  cm.bell-labs.com/cm/index.html>  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-
                  ming.
    
           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  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://
                  cm.bell-labs.com/cm/cs/54.ps>; Bell Labs, 1976; revised by Brian
                  Kernighan, 1992.
    
           [CSTR #97]
                  Brian  Kernighan,  A   Typesetter-independent   TROFF   <http://
                  cm.bell-labs.com/cm/cs/97.ps>,  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/114.ps>; Bell
                  Labs, August 1984.
    
           [CSTR #116]
                  Brian W. Kernighan, PIC -- A Graphics Language  for  Typesetting
                  <http://cm.bell-labs.com/cm/cs/116.ps>;   Bell   Labs,  December
                  1984.
    
           [CSTR #122]
                  J. L. Bentley, L. W. Jelinski, and B. W.  Kernighan,  CHEM  --  A
    
           starting point.
    
    
    

    AUTHORS

           Copyright (C) 2000, 2001, 2002 Free Software Foundation, Inc.
    
           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 <http://www.gnu.org/copyleft/fdl.html>.
    
           This  document  is  part  of  groff, the GNU roff distribution.  It was
           written by Bernd Warken <bwarken@mayn.de>; it is maintained  by  Werner
           Lemberg <wl@gnu.org>.
    
    
    

    Groff Version 1.18.1.4 23 April 2002 ROFF(7)

    
    
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