1ROFF(7)                Miscellaneous Information Manual                ROFF(7)


6       roff - concepts and history of roff typesetting


9       roff  is  the general name for a set of text formatting programs, known
10       under names like troff, nroff, ditroff, groff, etc.  A roff system con‐
11       sists  of  an extensible text formatting language and a set of programs
12       for printing and converting to other text formats.  Unix-like operating
13       systems distribute a roff system as a core package.
15       The  most  common roff system today is the free software implementation
16       GNU roff, groff(1).  groff implements the look-and-feel and functional‐
17       ity of its ancestors, with many extensions.
19       The  ancestry  of  roff is described in section HISTORY.  In this docu‐
20       ment, the term roff always refers to the general  class  of  roff  pro‐
21       grams, not to the roff command provided in early UNIX systems.
23       In spite of its age, roff is in wide use today, for example, the manual
24       pages on UNIX systems (man pages), many software books, system documen‐
25       tation,  standards,  and  corporate documents are written in roff.  The
26       roff output for text devices is still unmatched, and its graphical out‐
27       put  has  the  same  quality as other free type-setting programs and is
28       better than some of the commercial systems.
30       roff is used to format UNIX manual pages, (or man pages), the  standard
31       documentation system on many UNIX-derived operating systems.
33       This document describes the history of the development of the roff sys‐
34       tem; some usage aspects common to all roff  versions,  details  on  the
35       roff pipeline, which is usually hidden behind front-ends like groff(1);
36       a general overview of the formatting language; some  tips  for  editing
37       roff files; and many pointers to further readings.


40       Document formatting by computer dates back to the 1960s.  The roff sys‐
41       tem itself is intimately connected to the Unix  operating  system,  but
42       its roots go back to the earlier operating systems CTSS and Multics.
44   The Predecessor RUNOFF
45       roff's ancestor RUNOFF was written in the MAD language by Jerry Saltzer
46       for the Compatible Time Sharing System (CTSS), a project of the  Massa‐
47       chusetts  Institute  of  Technology (MIT), in 1963 and 1964 – note that
48       CTSS commands were all uppercase.
50       In 1965, MIT's Project MAC  teamed  with  Bell  Telephone  Laboratories
51       (BTL)  and  General  Electric  to  begin  the  Multics  system ⟨http://
52       www.multicians.org⟩.  A command called runoff was written  for  Multics
53       in  the late 60s in the BCPL language, by Bob Morris, Doug McIlroy, and
54       other members of the Multics team.
56       Like its CTSS ancestor, Multics runoff formatted an input file consist‐
57       ing  of  text  and command lines; commands began with a period and were
58       two letters.  Output from these commands was to terminal  devices  such
59       as  IBM  Selectric  terminals.   Multics runoff had additional features
60       added, such as the ability to do two-pass  formatting;  it  became  the
61       main format for Multics documentation and text processing.
63       BCPL  and  runoff  were ported to the GCOS system at Bell Labs when BTL
64       left the development of Multics.
66       There is a free archive about historical RUNOFF documents.  You can get
67       it anonymously by the shell command
68              $git clone https://github.com/bwarken/RUNOFF_historical.git
70       As  well,  there  is  a new project for writing a program that can read
71       RUNOFF files , but it does not yet work so far.  You can get  an  early
72       version anonymously by the shell command
73              $git clone https://github.com/bwarken/runoff.git
75   The Classical nroff/troff System
76       At BTL, there was a need to drive the Graphic Systems CAT typesetter, a
77       graphical output device from a PDP-11 computer running Unix.  As runoff
78       was too limited for this task it was further developed into a more pow‐
79       erful text formatting system by Joseph F.  Ossanna,  who  already  pro‐
80       grammed several runoff ports.
82       The  name  runoff was shortened to roff.  The greatly enlarged language
83       of Ossanna's version already included all elements of a full roff  sys‐
84       tem.   All  modern  roff systems try to implement compatibility to this
85       system.  So Joe Ossanna can be called the father of all roff systems.
87       This first roff system had three formatter programs.
89       troff  (typesetter roff) generated a graphical output for the CAT type‐
90              setter as its only device.
92       nroff  produced text output suitable for terminals and line printers.
94       roff   was  the  reimplementation of the former runoff program with its
95              limited features; this program was abandoned in later  versions.
96              Today, the name roff is used to refer to a troff/nroff system as
97              a whole.
99       Ossanna's first version was written in the PDP-11 assembly language and
100       released  in  1973.   Brian  Kernighan  joined  the roff development by
101       rewriting it in the C programming language.  The C version was released
102       in 1975.
104       The  syntax  of the formatting language of the nroff/troff programs was
105       documented in the famous Troff User's Manual  [CSTR  #54],  first  pub‐
106       lished  in  1976, with further revisions up to 1992 by Brian Kernighan.
107       This document is the specification of the classical troff.   All  later
108       roff systems tried to establish compatibility with this specification.
110       After Ossanna's death in 1977, Kernighan went on with developing troff.
111       In the late 1970s, Kernighan equipped troff with a general interface to
112       support  more devices, the intermediate output format, and the postpro‐
113       cessor system.  This completed the structure of a roff system as it  is
114       still  in  use today; see section USING ROFF.  In 1979, these novelties
115       were described in the paper [CSTR #97].  This new troff version is  the
116       basis  for  all existing newer troff systems, including groff.  On some
117       systems, this device independent troff got a binary of its own,  called
118       ditroff(7).  All modern troff programs already provide the full ditroff
119       capabilities automatically.
121   Availability
122       The source code of both the ancient Unix and  classical  troff  weren't
123       available for two decades.  Meanwhile, it is accessible again (on-line)
124       for non-commercial use, cf. section SEE ALSO.
126   groff — free GNU roff
127       The most important free roff project  was  the  GNU  implementation  of
128       troff, written from scratch by James Clark and put under the GNU Public
129       License ⟨http://www.gnu.org/copyleft⟩.  It was called groff (GNU roff).
130       See groff(1) for an overview.
132       The  groff system is still actively developed.  It is compatible to the
133       classical troff, but many extensions were added.  It is the first  roff
134       system  that  is  available on almost all operating systems — and it is
135       free.  This makes groff the de-facto roff standard today.
137   Free Heirloom roff
138       An alternative is  Gunnar  Ritter's  Heirloom  roff  project  ⟨https://
139       github.com/n-t-roff/heirloom-doctools⟩  project, started in 2005, which
140       provides enhanced versions of the various roff tools found in the Open‐
141       Solaris  and  Plan  9  operating  systems,  now  available  under  free
142       licenses.  You can get this package with the shell command:
143              $ git clone https://github.com/n-t-roff/heirloom-doctools
145       Moreover, one finds there the Original Documenter's  Workbench  Release
146       3.3https://github.com/n-t-roff/DWB3.3⟩.


149       Most  people won't even notice that they are actually using roff.  When
150       you read a system manual page (man page) roff is working in  the  back‐
151       ground.   roff  documents  can  be  viewed  with a native viewer called
152       xditview(1x), a standard program of  the  X  window  distribution,  see
153       X(7x).  But using roff explicitly isn't difficult either.
155       Some roff implementations provide wrapper programs that make it easy to
156       use the roff system on the shell command line.  For  example,  the  GNU
157       roff implementation groff(1) provides command line options to avoid the
158       long command pipes of classical troff; a program grog(1) tries to guess
159       from  the  document  which arguments should be used for a run of groff;
160       people who do not like specifying command line options should  try  the
161       groffer(1)  program  for  graphically  displaying  groff  files and man
162       pages.
164   The roff Pipe
165       Each roff system consists of preprocessors,  roff  formatter  programs,
166       and  a  set  of device postprocessors.  This concept makes heavy use of
167       the piping mechanism, that is, a series of programs is called one after
168       the  other,  where  the output of each program in the queue is taken as
169       the input for the next program.
171              cat file | ... | preproc | ... | troff options | postproc
173       The preprocessors generate roff code that is fed into a roff  formatter
174       (e.g.  troff),  which in turn generates intermediate output that is fed
175       into a device postprocessor program for printing or final output.
177       All of these parts use programming languages of their  own;  each  lan‐
178       guage  is  totally  unrelated to the other parts.  Moreover, roff macro
179       packages that were tailored for special purposes can be included.
181       Most roff documents use the macros of  some  package,  intermixed  with
182       code  for one or more preprocessors, spiced with some elements from the
183       plain roff language.  The full power of the roff formatting language is
184       seldom needed by users; only programmers of macro packages need to know
185       about the gory details.
187   Preprocessors
188       A roff preprocessor is any program that generates output that syntacti‐
189       cally obeys the rules of the roff formatting language.  Each preproces‐
190       sor defines a language of its own that is  translated  into  roff  code
191       when run through the preprocessor program.  Parts written in these lan‐
192       guages may be included within a roff document; they are  identified  by
193       special  roff  requests  or  macros.  Each document that is enhanced by
194       preprocessor code must be run through all  corresponding  preprocessors
195       before  it  is fed into the actual roff formatter program, for the for‐
196       matter just ignores all alien code.  The preprocessor programs  extract
197       and transform only the document parts that are determined for them.
199       There  are  a  lot  of free and commercial roff preprocessors.  Some of
200       them aren't available on each system, but there is a small set of  pre‐
201       processors that are considered as an integral part of each roff system.
202       The classical preprocessors are
204              tbl      for tables.
205              eqn      for mathematical formulae.
206              pic      for drawing diagrams.
207              refer    for bibliographic references.
208              soelim   for including macro files from standard locations.
209              chem     for drawing chemical formulæ.
211       Other known preprocessors that are not available on all systems include
213              grap   for constructing graphical elements.
214              grn    for including gremlin(1) pictures.
216   Formatter Programs
217       A roff formatter is a program that parses documents written in the roff
218       formatting language or uses some of the roff macro packages.  It gener‐
219       ates intermediate output, which is intended to be  fed  into  a  single
220       device postprocessor that must be specified by a command-line option to
221       the formatter program.  The documents must have been  run  through  all
222       necessary preprocessors before.
224       The  output  produced by a roff formatter is represented in yet another
225       language, the intermediate output format or troff  output.   This  lan‐
226       guage  was  first  specified  in [CSTR #97]; its GNU extension is docu‐
227       mented in groff_out(5).  The intermediate output language is a kind  of
228       assembly language compared to the high-level roff language.  The gener‐
229       ated intermediate output is optimized for a  special  device,  but  the
230       language is the same for every device.
232       The  roff  formatter  is the heart of the roff system.  The traditional
233       roff had two formatters, nroff for text devices and troff for graphical
234       devices.
236       Often,  the  name troff is used as a general term to refer to both for‐
237       matters.
239   Devices and Postprocessors
240       Devices are hardware interfaces like printers, text or graphical termi‐
241       nals,  etc., or software interfaces such as a conversion into a differ‐
242       ent text or graphical format.
244       A roff postprocessor is a program that transforms troff output  into  a
245       form  suitable  for a special device.  The roff postprocessors are like
246       device drivers for the output target.
248       For each device there is a postprocessor program that fits  the  device
249       optimally.   The postprocessor parses the generated intermediate output
250       and generates device-specific code that is sent directly to the device.
252       The names of the devices and the postprocessor programs are  not  fixed
253       because  they  greatly depend on the software and hardware abilities of
254       the actual computer.  For example, the classical devices  mentioned  in
255       [CSTR  #54]  have  greatly  changed since the classical times.  The old
256       hardware doesn't exist any longer and  the  old  graphical  conversions
257       were quite imprecise when compared to their modern counterparts.
259       For  example, the Postscript device post in classical troff had a reso‐
260       lution of 720 units per inch, while groff's  ps  device  has  72000,  a
261       refinement of factor 100.
263       Today  the  operating  systems provide device drivers for most printer-
264       like hardware, so it isn't necessary to write a special hardware  post‐
265       processor for each printer.


268       Documents using roff are normal text files decorated by roff formatting
269       elements.  The roff formatting language is quite powerful; it is almost
270       a  full  programming language and provides elements to enlarge the lan‐
271       guage.  With these, it became possible to develop macro  packages  that
272       are  tailored  for  special applications.  Such macro packages are much
273       handier than plain roff.  So most people will choose  a  macro  package
274       without worrying about the internals of the roff language.
276   Macro Packages
277       Macro  packages are collections of macros that are suitable to format a
278       special kind of documents in a convenient way.  This greatly eases  the
279       usage  of  roff.  The macro definitions of a package are kept in a file
280       called name.tmac (classically tmac.name).  All tmac files are stored in
281       one or more directories at standardized positions.  Details on the nam‐
282       ing of macro packages and their placement is found in groff_tmac(5).
284       A macro package that is to be used in a document can  be  announced  to
285       the formatter by the command line option -m, see troff(1), or it can be
286       specified within a document using the file inclusion  requests  of  the
287       roff language, see groff(7).
289       Famous classical macro packages are man for traditional man pages, mdoc
290       for BSD-style manual pages; the macro sets  for  books,  articles,  and
291       letters  are  me (probably from the first name of its creator Eric All‐
292       man), ms (from Manuscript Macros), and mm (from Memorandum Macros).
294   The roff Formatting Language
295       The classical roff formatting  language  is  documented  in  the  Troff
296       User's Manual [CSTR #54].  The roff language is a full programming lan‐
297       guage providing  requests,  definition  of  macros,  escape  sequences,
298       string variables, number or size registers, and flow controls.
300       Requests  are  the  predefined basic formatting commands similar to the
301       commands at the shell prompt.  The user can  define  request-like  ele‐
302       ments using predefined roff elements.  These are then called macros.  A
303       document writer will not note any difference in usage for  requests  or
304       macros; both are written on a line on their own starting with a dot.
306       Escape sequences are roff elements starting with a backslash ‘\’.  They
307       can be inserted anywhere, also in the midst of text in  a  line.   They
308       are used to implement various features, including the insertion of non-
309       ASCII characters with \(, font changes with \f, in-line  comments  with
310       \",  the escaping of special control characters like \\, and many other
311       features.
313       Strings are variables that can store a string.  A string is  stored  by
314       the  .ds  request.   The stored string can be retrieved later by the \*
315       escape sequence.
317       Registers store numbers and sizes.  A register  can  be  set  with  the
318       request .nr and its value can be retrieved by the escape sequence \n.


321       Manual  pages (man pages) take the section number as a file name exten‐
322       sion, e.g., the filename for this document is roff.7, i.e., it is  kept
323       in section 7 of the man pages.
325       The  classical  macro  packages  take the package name as an extension,
326       e.g. file.me for a document using the me macro package, file.mm for mm,
327       file.ms for ms, file.pic for pic files, etc.
329       But  there  is  no  general  naming  scheme  for roff documents, though
330       file.tr for troff file is seen now and then.  Maybe there should  be  a
331       standardization for the filename extensions of roff files.
333       File  name extensions can be very handy in conjunction with the less(1)
334       pager.  It provides the possibility to feed all input into  a  command-
335       line pipe that is specified in the shell environment variable LESSOPEN.
336       This process is not well documented, so here an example:
338              LESSOPEN='|lesspipe %s'
340       where lesspipe is either a system supplied command or a shell script of
341       your own.
343       More  details  for  file  name  extensions  can be found at groff_file‐
344       names(7).


347       The best program for editing a roff document is Emacs (or Xemacs),  see
348       emacs(1).   It provides an nroff mode that is suitable for all kinds of
349       roff dialects.  This mode can be activated by the following methods.
351       When editing a file within Emacs the mode can be changed by typing ‘M-x
352       nroff-mode’,  where  M-x  means  to hold down the Meta key (or Alt) and
353       hitting the x key at the same time.
355       But it is also possible to have the mode  automatically  selected  when
356       the file is loaded into the editor.
358       ·      The  most  general  method is to include the following 3 comment
359              lines at the end of the file.
361                     .\" Local Variables:
362                     .\" mode: nroff
363                     .\" End:
365       ·      There is a set of file name extensions, e.g. the man pages  that
366              trigger the automatic activation of the nroff mode.
368       ·      Theoretically, it is possible to write the sequence
370                     .\" -*- nroff -*-
372              as  the  first  line  of a file to have it started in nroff mode
373              when loaded.  Unfortunately, some applications such as  the  man
374              program are confused by this; so this is deprecated.
376       All  roff  formatters  provide automated line breaks and horizontal and
377       vertical spacing.  In order to not disturb this, the following tips can
378       be helpful.
380       ·      Never include empty or blank lines in a roff document.  Instead,
381              use the empty request (a line consisting of a  dot  only)  or  a
382              line comment .\" if a structuring element is needed.
384       ·      Never  start  a  line  with  whitespace because this can lead to
385              unexpected behavior.  Indented paragraphs can be constructed  in
386              a controlled way by roff requests.
388       ·      Start  each sentence on a line of its own, for the spacing after
389              a dot is handled differently depending on whether it  terminates
390              an  abbreviation or a sentence.  To distinguish both cases, do a
391              line break after each sentence.
393       ·      To additionally use the auto-fill mode in Emacs, it is  best  to
394              insert  an  empty roff request (a line consisting of a dot only)
395              after each sentence.
397       The following example shows how optimal roff editing could look.
399              This is an example for a .I roff document.  .
400              This is the next sentence in the same paragraph.  .
401              This is a longer sentence stretching over several lines; abbreviations
402              like ‘cf.’ are easily identified because the dot is not
403              followed by a line break.  .  In the output, this will still go to
404              the same paragraph.
406       Besides Emacs, some other editors provide nroff style files  too,  e.g.
407       vim(1), an extension of the vi(1) program.


410       There  is a lot of documentation on roff.  The original papers on clas‐
411       sical troff are still available, and all aspects  of  groff  are  docu‐
412       mented in great detail.
414   Internet sites
415       troff.org
416              The  historical  troff  site  ⟨http://www.troff.org⟩ provides an
417              overview and pointers to all historical aspects of roff.
419       Multics
420              The Multics site ⟨http://www.multicians.org⟩ contains a  lot  of
421              information  on  the  MIT  projects,  CTSS, Multics, early Unix,
422              including runoff; especially useful are a glossary and the  many
423              links to ancient documents.
425       Unix Archive
426              The  Ancient  Unixes Archive ⟨http://www.tuhs.org/Archive/⟩ pro‐
427              vides the source code and some binaries of  the  ancient  Unixes
428              (including  the source code of troff and its documentation) that
429              were made public by Caldera since 2001, e.g. of the famous  Unix
430              version  7  for PDP-11 at the Unix V7 site ⟨http://www.tuhs.org/
431              Archive/PDP-11/Trees/V7⟩.
433       Developers at AT&T Bell Labs
434              Bell Labs Computing and Mathematical Sciences Research  ⟨http://
435              www.bell-labs.com/⟩  provides  a  search  facility  for tracking
436              information on the early developers.
438       Plan 9 The Plan 9 operating system ⟨http://plan9.bell-labs.com⟩ by AT&T
439              Bell Labs.
441       runoff Jerry   Saltzer's   home  page  ⟨http://web.mit.edu/Saltzer/www/
442              publications/pubs.html⟩ stores some documents using the  ancient
443              RUNOFF formatting language.
445       CSTR Papers
446              The   Bell   Labs   CSTR   site  ⟨http://cm.bell-labs.com/cm/cs/
447              cstr.html⟩ stores the original troff  manuals  (CSTR  #54,  #97,
448              #114,  #116,  #122)  and famous historical documents on program‐
449              ming.
451       GNU roff
452              The groff web site ⟨http://www.gnu.org/software/groff⟩  provides
453              the free roff implementation groff, the actual standard roff.
455   Historical roff Documentation
456       Many  classical  troff  documents are still available on-line.  The two
457       main manuals of the troff language are
459       [CSTR #54]
460              J.  F.  Ossanna,  Nroff/Troff  User's  Manualhttp://cm.bell-
461              labs.com/cm/cs/cstr/54.ps.gz⟩; Bell Labs, 1976; revised by Brian
462              Kernighan, 1992.
464       [CSTR #97]
465              Brian Kernighan, A Typesetter-independent TROFFhttp://cm.bell-
466              labs.com/cm/cs/cstr/97.ps.gz⟩,  Bell  Labs,  1981, revised March
467              1982.
469       The “little language” roff papers are
471       [CSTR #114]
472              Jon L. Bentley and Brian W. Kernighan, GRAP    A  Language  for
473              Typesetting      Graphshttp://cm.bell-labs.com/cm/cs/cstr/
474              114.ps.gz⟩; Bell Labs, August 1984.
476       [CSTR #116]
477              Brian W. Kernighan, PIC  A Graphics  Language  for  Typesetting
478http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz⟩;    Bell    Labs,
479              December 1984.
481       [CSTR #122]
482              J. L. Bentley, L. W. Jelinski, and B. W.  Kernighan,  CHEM    A
483              Program  for  Typesetting Chemical Structure Diagrams, Computers
484              and  Chemistryhttp://cm.bell-labs.com/cm/cs/cstr/122.ps.gz⟩;
485              Bell Labs, April 1986.
487       You  can  get an archive with most classical roff documentation as rea‐
488       sonable PDF files at github using the shell command
489              $ git clone https://github.com/bwarken/roff_classical.git
491   Manual Pages
492       Due to its complex structure, a full roff system has  many  man  pages,
493       each  describing  a  single aspect of roff.  Unfortunately, there is no
494       general naming scheme for the documentation among  the  different  roff
495       implementations.
497       In  groff, the man page groff(1) contains a survey of all documentation
498       available in groff.
500       On other systems, you are on your own, but troff(1)  might  be  a  good
501       starting point.


504       Copyright  ©  2000-2014                      Free  Software Foundation,
505       Inc.
507       Permission is granted to copy, distribute and/or modify  this  document
508       under the terms of the FDL (GNU Free Documentation License) Version 1.3
509       or any later version published by the Free Software  Foundation.   with
510       the Invariant Sections being the .au and .co macro definitions, with no
511       Front-Cover Texts, and with no Back-Cover Texts.
513       A copy of the Free Documentation License is included as a  file  called
514       FDL in the main directory of the groff source package.
516       The  license  text  is  also available on-line at the GNU copyleft site


520       This    man-page    was    written    by    Bernd    Warken     ⟨groff-
521       bernd.warken-72@web.de⟩   and   is   maintained   by   Werner   Lemberg
522       ⟨wl@gnu.org⟩.
526Groff Version 1.22.3            4 November 2014                        ROFF(7)