RE: [Groff] ditroff

[Ted Harding]

On 17-Nov-01 Bernd Warken wrote:
> xditview(1) speaks about a ditroff program.  What is it? Should there
> be a ditroff link/script in groff?

"ditroff" is simply troff.

Once Upon A Time, the old troff (that was written
to drive a CAT typesetter, as well as nroff that
was written to display to a terminal) was generalised.

A new output format was created, which was not
device-specific; and the task of rendering this
output to a display was relegated to whatever
postprocessor was specific to the device. The
task of the post-processor was to interpret the
device-independent commands produced by troff.

This new troff was called "ditroff" (device-independent
troff), though as a program it was still invoked
with the command "troff".

GNU troff is a somehat extended version of ditroff
(i.e. gtroff's output includes everything which works
with ditroff plus a bit): see man groff_out.

So, as far as xditview and groff are concerned, "ditroff
output" means "troff output" (i.e. as described in
man groff_out).

The best device ("-T<device>") to use with xditview
is ps: ... | troff -Tps .... | xditview

You can also (and probably better) invoke xditview
using groff's "-X" option:

   groff -Tps -X ....

Note: Paradoxically, TeX's output format (DVI) is
also device-independent; it is converted to a particular
device rendition by a suitable program (e.g. dvi2ps
for conversion to PostScript). However, DVI is also
a device as far as gtroff is concerned ("-Tdvi"),
troff's output being converted to .dvi by grodvi.

Ted.

--------------------------------------------------------------------
E-Mail: (Ted Harding) <address@hidden>
Fax-to-email: +44 (0)870 167 1972
Date: 17-Nov-01                                       Time: 22:39:28
------------------------------ XFMail ------------------------------