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This is version 1.0 of unroff.
Unroff is a Scheme-based, programmable, extensible troff translator
with a back-end for the Hypertext Markup Language. Unroff is free
software and is distributed both as source and as precompiled binaries.
* Overview
Unroff reads and parses UNIX troff documents and translates the embedded
markup into a different format. Neither the actual output format nor
any knowledge about particular troff macro sets (-man, -ms, etc.) are
hard-wired into unroff. Instead, the translation process is controlled
by a set of user-supplied procedures written in the Scheme programming
Translation rules for new output formats and troff macro packages can
be added easily by providing a corresponding set of Scheme procedures
(a `back-end'). Version 1.0 of unroff includes back-ends for translating
documents using the `man' and `ms' macros into the Hypertext Markup
Language (HTML) version 2.0. Additional requests facilitate use of
arbitrary hypertext links in troff documents.
* unroff and troff
In contrast to conventional troff `converters' (usually Perl scripts
some of which process nroff output) unroff includes a full troff parser
and closely mimics the troff processing engine.
This enables unroff to handle user-defined macros, strings, and
number registers, nested if-else requests, arbitrary fonts and font
positions, low-level formatting requests such as \l, \c, and \h, and
idiosyncrasies such as troff `copy mode' and the subtle differences
between request and macro invocations.
Unroff has adopted a number of groff extensions, among them long names
for macros, strings, number registers, and special characters, and the
escape sequences \$@ and \$*.
* unroff and Scheme
Unroff uses Elk, the Scheme-based Extension Language Kit, to achieve
programmability. It includes a full Scheme language implementation
with the usual amenities such as garbage collection, interactive
programming and testing, and dynamic loading. Standard Scheme has
been augmented by a set of new Scheme data types and primitives that
aid in writing new unroff back-ends.
A new troff request and an extension to the `.ig' request allow for
Scheme code to be embedded in troff documents; the code is then
evaluated on the fly as the documents are processed by unroff.
Unroff may be viewed as a prototype for hybrid applications that use
Scheme (in particular Elk) as their extension language. Approximately
half of its source consists of portable ANSI C code, and the other
half is written in Scheme and can be configured and tailored easily
without the need to recompile unroff. Authors of Elk-based applications
are encouraged to look into the source code or reuse parts of it for
their own projects.
As the time-critical Scheme primitives provided of unroff have been
coded in (efficient) C, its performance comes close to that of nroff
processing the same troff input.
* unroff and hypertext
troff documents that were originally written without intentions to
make them available in the World Wide Web (such as UNIX manual pages)
can easily be translated to the Hypertext Markup Language using the
predefined HTML back-ends.
As unroff closely simulates ordinary troff, even large or complex
documents (like technical reports or theses with many user-defined
macros) can be translated to HTML automatically without having to
add any structural cues to the documents.
The `-man' support has been tested with several hundred vendor- and
user-supplied manual pages and has produced good results in all but
less than a dozen cases (a few manual pages were found to make excessive
use of low-level troff constructs or to include tbl output verbatim).
* Managing hypertext documents with troff
Authors can benefit from unroff not only as a converter for existing
documents, but also when writing new documents that must exist both
in high-quality paper form and in the World Wide Web as hypertext.
Rather than writing hypertext documents directly in HTML (which is
cumbersome for long or complex texts), authors can continue using
ordinary troff together with the usual preprocessors and macro packages.
Unroff is then employed to produce the WWW form, while troff is used
in the normal way to typeset the same text, producing the printed
version (or, using nroff, an ASCII version if desired).
In this way authors of hypertext documents can take full advantage of
the usual troff facilities such as user-defined macros, conditional text,
tables, equations, and drawings, automatic table of contents generation,
footnotes/endnotes, indexes, etc., none of which are available when
composing documents directly in plain HTML.
Two new troff requests for embedding hypertext links in troff documents
are provided by the unroff HTML back-end. Arbitrary forward and backward
references using symbolic labels (rather than actual file names) among
groups of troff source files are supported. Another new request and
another extension to `.ig' allow for HTML code to be embedded directly
in troff documents. The hypertext capabilities are demonstrated by
the troff source of the Programmer's Manual that is part of the unroff
* Availability
The source distribution of unroff 1.0 as well as binary distributions
(with full Scheme source code and documentation) are available under:
You can obtain Elk 3.0 from the same WWW server at:
Elk 3.0 is also available from a number of FTP servers including these:
Oliver Laumann <net@cs.tu-berlin.de> # $Revision: 1.4 $