Re: -man fails to use ANSI commands

[G. Branden Robinson]

Hi Anton,

At 2023-11-19T14:53:24+0300, Anton Shepelev wrote:
> `groff -man -Tutf8'  does  not  seem  to handle font
> styles on my terminal.  I have made sure that  plain
> `groff' works as expected:
> 
>                      This is
>                      .ft B
>                      strange
>                      .ft R
>                      indeed.
>                      .pl \n[nl]
> 
> The  word  `strange' above is typeset in bold, which
> on my terminal looks both bright and bold.   A  test
> man-page, however, is output all in the same default
> font style and color:
> 
>                     .TH 3 test
>                     .SH Section
>                     This is
>                     .B strange
>                     indeed.
> 
> whereas `man -l` renders the same source  correctly,
> with  the  words `Section' and `strange' highlighted
> and bold.
> 
> The incorrect output from -man shows that  it  tries
> to make characters bold by typing them over, e.g.:
> 
>             s^Hst^Htr^Hra^Han^Hng^Hge^He

Yes, that's the overstriking convention originally developed for
paper-based terminals.  People have clung to it like grim death.

By default, groff uses ECMA-48 SGR escape sequences to change the font
styles for terminals.  (Specifically, grotty(1) handles this, and its
man page has a discussion of the issues.)

However, this default has been unpopular in some quarters despite the
silliness of having nroff prepare output for a _paper_ terminal when
writing to a terminal emulator that is set up _specifically_ to emulate
a _video_ terminal (often, something like a DEC VT100, which supports
many ECMA-48 features).

The short version is that distributors sometimes modify groff to force
the overstriking convention, for a variety of (IMO, bad) reasons.

I hadn't heard of anyone making this change only for man pages, though.
Some new deviltry may be afoot on your system.

> instead of using ANSI control codes, and this has no
> intended effect.  How can I cause `-man  -Tutf8'  to
> use ANSI codes?

Check your environment for variables named "GROFF_SGR" (a Debianism) and
"GROFF_NO_SGR".  Unset them both and try "groff -man -Tutf8" again.

Regards,
Branden

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