[gentoo-user] Sending console messages on Users

[gentoo-user] Sending console messages on Users

[Mick]

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Hi All,

What is the way to send a console warning to anyone logged on a machine before 
I reboot it?

If the user is logged on a console I will only need to send it to the console; 
in addition if the user is running webmin, or phpadmin, then I would really 
like a popup of sorts to alert them to log out (something like the net send 
command on MS Windows running with the messenger service).

Is there such a thing?
-- 
Regards,
Mick

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Re: [gentoo-user] Sending console messages on Users

[Albert Hopkins]

On Mon, 2007-05-28 at 18:52 +0100, Mick wrote:
> Hi All,
> 
> What is the way to send a console warning to anyone logged on a machine before 
> I reboot it?

shutdown(8) does this for you.  In addition there is wall(1).

> 
> If the user is logged on a console I will only need to send it to the console; 
> in addition if the user is running webmin, or phpadmin, then I would really 
> like a popup of sorts to alert them to log out (something like the net send 
> command on MS Windows running with the messenger service).
> 
> Is there such a thing?

I could give a long explanation on why in practice this never works
(even for wall msgs), but it's not interesting.  Instead I'll give you
some real-world examples of what I've seen.

      * Don't plan reboots during production or when production is at
        peak unless absolutely necessary.  In the latter case most
        people will be expecting a reboot because they are aware of a
        problem that is affecting production.
      * For small shops, it's just as easy, and more effective, to just
        go door-to-door letting everyone know there's going to be a
        reboot.
      * Nearly every medium-large place I've worked had an overhead
        speaker system (dunno why, call me lucky) where unexpected
        crashes and reboots were broadcast.
      * For planned reboots, one site I worked sent out broadcast emails
        periodically before a scheduled reboot.  There was a monthly
        schedule sent out as well as an email the week ans shortly
        before the reboot. This was a multi-platform, nation-wide
        operation and basically there was no universal way to let
        everyone know. Even for the single-platform shop I worked at,
        not everyone (that was affected) sat in front of a terminal. All
        relevant people or their supervisors were on the mailing list.
        If you didn't know, you didn't need to know.
      * Not even the Windows shop I worked at used net send to alert of
        reboots.  Maybe nice idea, but it doesn't work.  People are away
        from their computers, have the messenger service turned off,
        just click OK without reading the message, etc. etc.  All that
        net send every did in my experience is generate a lot of phone
        calls from people who didn't understand what it was or what it
        meant.
      * The most effective way I've seen was a recent job.  They simply
        announced on the loud speaker for everyone to log off and shut
        down until further notice.  There was no reboot announcement, no
        explanation.  Nothing.  Even if a person wasn't affected
        everyone was told to log out and turn off their machines.  This
        eliminated the phone calls from people asking "does this mean
        me?"  We just had everyone off.  For stragglers, VPN users, etc.
        They were manually disconnected.  Let them figure out what
        happened when they get back.

As for webmin and phpadmin users... well those people are
administrators... shouldn't they already know?  I wouldn't want a fellow
admin bouncing a server without tapping me on the shoulder or giving me
a call. Technology is rarely a good replacement for common sense.


--
Albert W. Hopkins

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Re: [gentoo-user] Sending console messages on Users

[Mick]

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On Monday 28 May 2007 20:14, Albert Hopkins wrote:
> On Mon, 2007-05-28 at 18:52 +0100, Mick wrote:

> > What is the way to send a console warning to anyone logged on a machine
> > before I reboot it?
>
> shutdown(8) does this for you.  In addition there is wall(1).

Of course wall! I had forgotten about that.  There's also talk to tap others 
on the shoulder.  I assume all these will work if logged onto a server via 
ssh?

> > If the user is logged on a console I will only need to send it to the
> > console; in addition if the user is running webmin, or phpadmin, then I
> > would really like a popup of sorts to alert them to log out (something
> > like the net send command on MS Windows running with the messenger
> > service).
>
> I could give a long explanation on why in practice this never works
> (even for wall msgs), but it's not interesting.  Instead I'll give you
> some real-world examples of what I've seen.
[snip...]

Thank you for a very informative insight.  :)
-- 
Regards,
Mick

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Re: [gentoo-user] Sending console messages on Users

[Dan Farrell]

On Mon, 28 May 2007 20:54:27 +0100
Mick <michaelkintzios@gmail.com> wrote:

> On Monday 28 May 2007 20:14, Albert Hopkins wrote:
> > On Mon, 2007-05-28 at 18:52 +0100, Mick wrote:
> 
> > > What is the way to send a console warning to anyone logged on a
> > > machine before I reboot it?
> >
> > shutdown(8) does this for you.  In addition there is wall(1).
> 
> Of course wall! I had forgotten about that.  There's also talk to tap
> others on the shoulder.  I assume all these will work if logged onto
> a server via ssh?
> 
> > > If the user is logged on a console I will only need to send it to
> > > the console; in addition if the user is running webmin, or
> > > phpadmin, then I would really like a popup of sorts to alert them
> > > to log out (something like the net send command on MS Windows
> > > running with the messenger service).
> >
> > I could give a long explanation on why in practice this never works
> > (even for wall msgs), but it's not interesting.  Instead I'll give
> > you some real-world examples of what I've seen.
> [snip...]
> 
> Thank you for a very informative insight.  :)

Yes, it should work at ssh terminals too.  My test verifies.  

A. Hopkins is right though; even if everyone _did_ work at the
terminal, and not say at the screen, people using ncurses or redrawing
the screen often at any rate could miss a wall message.  
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