Re: Tilde (~) in bash(1) is typeset incorrectly as Unicode character

[Chet Ramey]

On 7/26/23 11:35 AM, G. Branden Robinson wrote:

> I know a little about groff.  Your advice is fine for man pages that
> target only groff[1] and/or mandoc[2], but not Heirloom Doctools
> troff,[3] neatroff[4] or Plan 9 troff (in its original form or as
> maintained in Plan 9 from User Space[5]), and not legacy implementations
> descended from AT&T troff that are, as far as I can tell, unmaintained
> by the few Unix System V vendors that still exist.[6][7]
>
> Many projects don't need to worry about such extreme portability in
> their man pages, but GNU Bash arguably does.  (I'm open to correction.)

It's an ongoing struggle. There are projects (e.g., a 4.3BSD preservation
effort) that request such accommodations, but it's becoming more difficult
to support them.

> Furthermore, in the *roff language itself, as originally implemented by
> Joe Ossanna (and re-implemented by Brian Kernighan) there is no good
> way to test for the existence of a special character.[8]
>
> As a first stab at it, I'd divide the world into two camps: (a) groff
> and mandoc(1), and (b) everything else, and not worry about (b).

I'd consider that, but, as you point out, there are some legacy Unix
systems that still ship old versions of troff and associated tools.

> The bash(1) man page has an extensive preamble already that still
> includes a workaround for 4.3BSD(!), so adding a little bit to it to
> accommodate systems developed since 1990 might not be too disruptive.
>
> I'm attaching a straw man diff to the bash(1) page.  If Chet likes it,
> I'm happy to prepare one against the bash devel branch.

Thanks. I'll probably apply some variant of this to the set of man pages
that need it.

> bash(1) also attempts to select a font named "CW" in places, which is
> another portability problem (it's a Unix System III [and later] troff
> font name that was available on _some_ output devices).  But I'd like to
> see how we get over this bridge before I try to cross that one.  :)

(For others reading, it's the constant width font, usually Courier.) I
haven't received any bug reports about that, and groff and mandoc both
support it, so I'm inclined to leave it alone.

Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/