Re: [9fans] 'wall' messages

[rog@vitanuova.com]

> Exactly! So if a write to the structures on the cpu would work locally they
> will work with drawterm, since the processes are running on the cpu server
> side and that is the box that wants to send the shutdown warning. The fact
> that I'm accessing those resources via drawterm is really moot.

you're assuming, i believe, that connections to the cpu server are
uniform: i.e.  that each connection to the cpu server imports a
namespace from the remote side that contains a draw device, etc.

in fact that's not necessarily the case: if i distrust the cpu server,
i might export to it a namespace containing only my /dev/cons.
in fact, if i telnet to the cpu server, there's no namespace
(and who's to say that i'm not running some odd protocol
over the telnet link?)

to get back to the original request (how do we inform all users that
the machine is going down?): while mail is an option, it doesn't
necessarily work well, particularly if there are many cpu servers,
going up and down frequently: users would be likely to get many
irrelevant messages.

surely all one needs is a per-machine service that provides such
information to whoever asks for it?  something simple in /srv should
do the job.  that way, users can choose to display the info however
their GUI preferences might indicate; moreover, the information is
potentially available to non-interactive programs that might wish to
take evasive action in the fact in imminent shutdown.

  rog.

PS. of course, "wall" in unix-like systems doesn't necessarily help
much in these GUI-oriented days: who's to say a user is displaying the
output from any ptys?