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From: Geoff Clare <geoff@clare.See-My-Signature.invalid>
Newsgroups: comp.unix.programmer
Subject: Re: Text based synchronous communication tool for Linux?
Date: Mon, 9 Dec 2024 15:02:23 +0000
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Richard Kettlewell wrote:

> Geoff Clare <geoff@clare.See-My-Signature.invalid> writes:
>> Muttley wrote:
>>
>>> talk is an age old unix util that allows people on the same machine to chat.
>>> Even MacOS has it installed.
>>
>> "Even" MacOS?  It's required for UNIX® conformance - if MacOS didn't
>> have talk, it wouldn't be able to be certified as UNIX.
> 
> I was surprised by that. Do you happen to know what motivated its
> inclusion?

The original decision to include talk goes back to POSIX.2-1992, where
the rationale begins with this paragraph:

    The write utility was included in POSIX.2 since it can be
    implemented on all terminal types. The talk utility, which cannot
    be implemented on certain terminals, was considered to be a
    ‘‘better’’ communications interface. Both of these programs are
    in widespread use on historical implementations. Therefore, both
    utilities have been specified.

> While this thread does show that there’s some demand for the
> application, it seems a surprising thing to include in a OS specification.

It's part of the "User Portability Utilities" option (which includes
things like ex and vi), so it's optional for POSIX conformance but
that option is mandated for UNIX conformance.

-- 
Geoff Clare <netnews@gclare.org.uk>