Troff
TROFF may also refer to a command in the BASIC programming language. It is short for 'TRACE OFF'. Some BASIC interpreter implementations used 'TROFF' in place of or in addition to 'TRACE OFF'
{{lowercase|title=troff}}
troff is a
document processing system developed by
AT&T for the
Unix operating system.
History
troff can trace its origins back to a
text formatting program called
RUNOFF, written by
Jerome H. Saltzer for
MIT's
CTSS operating system in the mid-1960s. (The name allegedly came from the phrase at the time,
I'll run off a document.)
Bob Morris ported it to the
GE 635 architecture and called the program
roff (an abbreviation of
runoff). It was rewritten as
rf for the
PDP-7, and at the same time (1969),
Doug McIlroy rewrote an extended and simplified version of
roff in the
BCPL programming language.The first version of
Unix was developed on a
PDP-7 which was sitting around
Bell Labs. In 1971 the developers wanted to get a
PDP-11 for further work on the operating system. In order to justify the cost for this system, they proposed that they would implement a document formatting system for the AT&T patents division. This first formatting program was a reimplementation of McIllroy's
roff, written by
Joe F. Ossanna.When they needed a more flexible language, a new version of
roff called
nroff (
Newer 'roff' ) was written. It had a much more complicated syntax, but provided the basis for all future versions. When they got a
Graphic Systems CAT Phototypesetter, Ossanna wrote a version of
nroff that would drive it. It was dubbed
troff, for
typesetter 'roff'. As such, the name
troff is pronounced
t-roff rather than
trough.With
troff came
nroff (they were actually almost the same program), which was for producing output for
line printers and character
terminals. It understood everything
troff did, and ignored the commands which were not applicable (e.g.
font changes).Unfortunately, Ossanna's
troff was written in
PDP-11 assembly language and produced output specifically for the CAT
phototypesetter. He rewrote it in
C, although it was now 7000 lines of uncommented code and still dependent on the CAT. As the CAT became less common, and was no longer supported by the manufacturer, the need to make it support other devices became a priority. However, before this could be done, Ossanna died.So,
Brian Kernighan took on the task of rewriting
troff. The newly rewritten version produced a device independent code which was very easy for postprocessors to read and translate to the appropriate printer codes. Also, this new version of
troff (called
ditroff for
device independent troff) had several extensions, which included drawing functions. It was described in a Bell Labs Computing Science Technical Report entitled "A Typesetter-independent TROFF"; it is available from the Computing Science Technology website in
gzipped
PostScript here. The document defines the output format of ditroff, which is used by many modern troff clones like
GNU groff.The
troff collection of tools was eventually called
Documenter's WorkBench (DWB), and was under continuous development in Bell Labs and later at the spin-off
Unix System Laboratories (USL) through 1994. At that time,
SoftQuad took over the maintenance, although Brian Kernighan continued to improve
troff on his own. There are thus currently four variants of the original Bell Labs
troff:
- An ancient variation from Bill Joy, still shipped by Sun Microsystems.
- The SoftQuad DWB, based on USL DWB 2.0 from 1994
- The DWB 3.4 from Lucent Software Solutions (USL)
- Troff, Plan 9 edition
Use of
troff and family was reduced somewhat in the 1990s, but it is still being used quite extensively. While
troff has been supplanted by other programs such as
Interleaf,
FrameMaker and
LaTeX, it is still the default format of the
UNIX documentation.The software was reimplemented as
groff for the
GNU system beginning in 1990. In addition, due to the
open sourcing of
Ancient UNIX Systems, as well as modern successors such as
OpenSolaris and
Plan 9 from Bell Labs, several versions of AT&T troff are available under various open source licenses.
Features
troff features commands to designate fonts, spacing, paragraphs, margins, footnotes and more. Unlike many other text formatters,
troff can position characters arbitrarily on a page, even overlapping them, and has a fully programmable input language. Separate preprocessors are used for more convenient production of tables, diagrams, and mathematics. Inputs to troff are plain text files that can be created by any text editor.Extensive
macro packages have been created for various document styles. A typical distribution of
troff includes the
me macros for formatting research papers,
man macros for creating Unix
man pages, and the
ms and
mm macros for letters, books, technical memoranda, and reports.As
troff evolved, since there are several things which cannot be done easily in
troff, several
preprocessors were developed. These programs transform certain parts of a document into
troff input, fitting naturally into the use of "pipelines" in Unix — sending the output of one program as the input to another (see
pipes and filters).The
eqn preprocessor allows mathematical formulae to be specified in a much simpler and more intuitive manner.
tbl is a preprocessor for formatting tables. The
refer preprocessor (and the similar program
bib) processes citations in a document according to a
bibliographic database. Later, several other preprocessors appeared. The
pic preprocessor provides a domain-specific programming language with a wide range of drawing functions. The
ideal preprocessor does much the same thing, although via a much different
paradigm. The
grap preprocessor takes specifications for graphs, but, unlike other preprocessors, produces
pic code.
Reimplementations
References
See also
External links
TroffTroffTroff
(...as imported from WP)
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