Re: Proposal: Add option to add dates to write(1)

["James K. Lowden" <jklowden%schemamania.org@localhost>]

On Fri, 25 May 2012 02:05:32 -0400 (EDT)
Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:

> I think it's a very sane thing to want.  I'm not convinced
> it's infeasible; I just haven't come up with a way of doing it that I
> consider reasonably sane

Fair enough.  Your primary concern seems to be how to decide which among
zero or more users "associated" with the terminal should write(1) pay
attention to.  

> >> Part of the reason I mentioned (a) is that write is writing to a
> >> tty, whereas environments are attached to processes;
> 
> What if multiple processes are associated with the tty 
...
> What if the user logged in on that tty does not own any processes on
> the tty?  

I might have gotten us sidetracked by introducing processes into the
discussion.  Processes are irrelevant because, as you pointed out,
we're not notifying processes with write.  We're notifying human
beings via the terminal.  The only things that matter ISTM are the
person and the terminal.  

I see no problem using the preferences of the logged-in user to
determine the date format of its message notice. It is both technically
unambiguous and meets the POLA test.  

That policy can be expressed unambiguously: write(1) consults the
preference expressed by the same user as reported by who(1) for the
terminal.  If no user is so indicated, or no preference found, write
behaves as it does today.  

It's furthermore reasonable for the user to expect that "as I log in,
so shall write format my date".  There are innumerable technical
reasons to invoke a process as another user, having (as you know)
mostly to do with privilege.  When it comes to aesthetics, the nearest
proxy we have to the human being is the login account.  

--jkl