synchronize time

[jdow]

On 2012/03/04 22:45, Tim wrote:
> On Sun, 2012-03-04 at 15:57 -0600, Aaron Konstam wrote:
>> Well your point is incorrect. Cups browsing did not work if UTC was
>> not set. TThe clocks were set correctly. The hardware clock was
>> operating on UTC time and the system clock was running on local time.
>
> You just don't get it, do you?!  You've even said it above:
>
>      Your hardware clock is running on UTC
>
> Therefore, you ***MUST*** set your clock configuration to say that UTC
> is set.  If you do not, then your time is set wrong.

I explained why and why your terminology is possibly confusing. If your
HARDWARE clock, the one on the motehrboard, is set to UTC you must tell
the OS so it knows to adjust its internal clock on boot to match by
simply reading it. If it said LOCAL and you HW clock was set to local
time the OS can use the TZ setting to translate the motherboard clock's
local time to UTC. Then your OS's clock is set to UTC, which fact is
invisible to you except that "things work."

> Correct setting of your time is dependent on the hardware clock, setting
> the UTC/not-UTC flag, and setting the correct timezone.  The combination
> of them all allows the computer to work out what localtime is.

Exactly. And for all directory listings and routine purposes the time
displayed to the user is the system's UTC corrected to local time. So
you really never see what time the OS thinks it is. It "feels like" it
is local time.

> Again, I repeat, it's not a CUPS fault that it doesn't like UTC set.
> It's your fault that you're running your clock on UTC but saying that it
> is not.

Fastening on CUPS is probably obscuring the matter, Tim. Concentrate on
the fact that ntp was not working for him. Since it has a limited adjustment
range, by design, it is quite obvious he had his motherboard clock either
set to UTC and he'd told his OS it was local time, or his motherboard clock
was set to local time and he'd told the OS it was UTC. Either way ntp will
not startup correctly and will drop out. The check box for telling the OS
that the hardware clock is UTC or local time is rather easy to overlook
during setup.

> The UTC/not-UTC setting is for the hardware clock, not the software
> clock.

Well, the check box is as is the value it changes, the third line in
/etc/adjtime. {^_-} That is quite distinct from the TZ setting even if
it appears on the same panel.

> If you run the hardware clock on UTC, then you set the UTC flag for UTC.
>
> If you run the hardware clock on local time, then set the UTC flag for
> local time.

Exactly. And maybe the above and my last posting helps send some understanding
on the problem. {o.o}

> CUPS will work either way.  It doesn't care whether one clock is set to
> UTC, or not.  What it cares about is the correct time.
>
> But if you set your hardware clock on UTC, but say it's running
> localtime; or, if you set your clock on localtime, but say it's running
> on UTC; you ARE going to have problems, because doing so is just plain
> wrong.
>
>     *** THE UTC FLAG IS FOR THE HARDWARE CLOCK ***
>                                 ^^^^^^^^
> I've said this about three times, in three emails, what's so hard to
> understand about it?

Calm down, step back, and try to alter vocabulary and expand descriptions so
it is easier for people to understand what is really taking place. That's what
I've tried to do now. I hope it works.

And to be sure, Tim, I am not disagreeing with you. You are 100% correct and
still, not perhaps, "correct enough." More detail of what is really taking
place is probably needed, detail you and I know so well we forget it when
explaining to people.

{^_-}