Re: [PATCH] minor fixes to Texinfo manual (and AT&T troff behavior)

"G. Branden Robinson" <[email protected]> Thu, 6 Aug 2026 08:57:43 -0500

Newsgroups	gmane.comp.printing.groff.general
Message-ID	<20260806135743.nlekxam2vjwyclg3@illithid>

Hi Dave,

At 2026-08-04T23:45:50-0500, Dave Kemper wrote:
> On Sun, Aug 2, 2026 at 7:42 PM G. Branden Robinson
> <[email protected]> wrote:
> > GNU troff, the formatter, _doesn't_ emit output in such cases.
> >
> > But any file that the formatter loads, from a macro package to the
> > troffrc to the input, can cause output to start.
> 
> True, and if the sentence in the manual read "GNU 'troff' does not
> emit output if its input does not cause output to start," I'd have no
> quibble.
> 
> But the sentence says "GNU 'troff' does not emit output if it has
> nothing to format."  The command "echo . | groff -mom" has nothing to
> format, but it emits output.  So this sentence in the manual is not
> true as an absolute.
> 
> But this counterexample is a corner case.  A modified phrasing like
> "typically does not emit output" allows for such corner cases while
> making a useful point about normal behavior, and not getting bogged
> down in the esoterica of what "causes output to start" means.

To further/over- qualify this point, mom(7) is giving the formatter
something to format by generating some embedded PostScript.

It's possible for a stray blank line in a troffrc or a macro file to do
the same thing.  This is such a difficult hazard to track down that for
groff 1.24.0 I added logic to detect it.  (This required no changes to
the formatter; it was a simple matter of macro programming.)

$ echo >> ./tmac/troffrc
$ echo foobar | ./build/test-groff -a
troffrc:/home/branden/src/GIT/groff/build/../tmac/troffrc:86: text line in startup file
<beginning of page>
foobar

Regards,
Branden

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