Manpages - roff.7

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 Electric to begin the

Multics system

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 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

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 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 typesetter as its only device.

nroff

produced text output suitable for terminals and line printers.

roff

was the reimplementation of the former runoff program with its limited features; this program was abandoned in later versions. Today, the name roff is used to refer to a troff/nroff 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 intermediate output format, and the postprocessor system. This completed the structure of a roff system as it is still in use today; see section “Using Roff” 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 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. Nowadays, it is accessible again (on-line) for non-commercial use; see SEE ALSO, below.

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. 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.

An alternative is

Gunnar Ritter’s Heirloom roff project

project, started in 2005, which provides enhanced versions of the various 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

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 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 syntactically obeys the rules of the roff formatting language. Each preprocessor defines a language of its own that is translated into roff code when run through the preprocessor program. Parts written in these languages may be 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 formatter just ignores all alien code. The preprocessor programs extract and transform only the document parts that are determined for them.

There are a lot of free and commercial roff preprocessors. Some of them aren’t available on each system, but there is a small set of preprocessors that are considered as an integral part of each roff system. The classical preprocessors are

tbl	for tables.
eqn	for mathematical formulae.
pic	for drawing diagrams.
refer	for bibliographic references.
soelim	for including macro files from standard locations.
chem	for drawing chemical formulæ.

Other known preprocessors that are not available on all systems include

grap	for constructing graphical elements.
grn	for including *gremlin*(1) pictures.

A roff formatter is a program that parses documents written in the roff formatting language or uses some of the roff macro packages. It generates intermediate output, which is intended to be fed into a single device postprocessor that must be specified by a command-line option to the formatter 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 language was first specified in [CSTR #97]; its GNU extension is documented in *groff_out*(5). The intermediate output language is a kind of assembly language compared to the high-level roff language. The generated intermediate output is optimized for a special 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 devices.

Often, the name troff is used as a general term to refer to both formatters.

Devices are hardware interfaces like printers, text or graphical terminals, etc., or software 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 imprecise 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.

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 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 manual pages; the macro sets for books, articles, and letters are me (probably from the first name of its creator Eric Allman), ms (from Manuscript Macros), and mm (from Memorandum Macros).

The classical roff formatting language is documented in the Troff User’s Manual [CSTR #54]. The roff language is a full programming language providing requests, definition of macros, escape sequences, string variables, number or size registers, and flow controls.

Requests are the predefined basic formatting commands similar to the commands at the shell prompt. The user can define request-like elements using predefined roff elements. These are then called macros. A document writer will not note any difference in usage for requests or macros; both are written on a line on their own starting with a dot.

Escape sequences are roff elements starting with a backslash

‘’$*

They can be inserted anywhere, 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

\*$

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.

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 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.

• The most general method is to include the following 3 comment lines at the end of the file.

      .\" Local Variables:
      .\" mode: nroff
      .\" End:
  

• There is a set of file name extensions, e.g. the man pages that trigger the automatic activation of the nroff mode.

• Theoretically, it is possible to write the sequence

      .\" -*- nroff -*-
  

  as 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.

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.

History of Unix Manpages

The history page of the mdocml project provides an overview of roff development up to date, with links to original documentation and comments of the original authors.

troff.org

The historical troff site provides an overview and pointers to the historical aspects of roff.

Multics

The Multics site contains a lot of information on the MIT projects, CTSS, Multics, early Unix, including runoff; especially useful are a glossary and the many links to ancient documents.

Unix Archive

The Ancient Unixes Archive provides the source code and some binaries of the ancient Unixes (including the source code of troff and its documentation) that were made public by Caldera since 2001, e.g. of the famous Unix version 7 for PDP-11 at the Unix V7 site.

Developers at AT&T Bell Labs

Bell Labs Computing and Mathematical Sciences Research provides a search facility for tracking information on the early developers.

Plan 9

The Plan 9 operating system by AT&T Bell Labs.

runoff

Jerry Saltzer’s home page stores some documents using the ancient RUNOFF formatting language.

(no term)

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

GNU roff

The groff web site provides the free roff implementation groff, the actual standard roff.

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

Bell Labs, 1976; revised by Brian Kernighan, 1992.

[CSTR #97]

Brian Kernighan,

A Typesetter-independent TROFF

Bell Labs, 1981, revised March 1982.

The “little language” roff papers are

[CSTR #114]

Jon L. Bentley and Brian W. Kernighan,

GRAP – A Language for Typesetting Graphs

Bell Labs, August 1984.

[CSTR #116]

Brian W. Kernighan,

PIC – A Graphics Language for Typesetting

Bell Labs, December 1984.

[CSTR #122]

J. L. Bentley, L. W. Jelinski, and B. W. Kernighan,

CHEM – A Program for Typesetting Chemical Structure Diagrams, Computers and Chemistry

Bell Labs, April 1986.

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

Due to its complex structure, a full roff system has many man pages, each describing a single aspect of roff. Unfortunately, there is no general naming scheme for the documentation among the different roff implementations.

In groff, the man page *groff*(1) contains a survey of all documentation available in groff.

On other systems, you are on your own, but *troff*(1) might be a good starting point.