bug#19090: date bug?

[Bob Proulx]

Plato wrote:
> After I set the date
>       sudo date 11172042
>       mo nov 17 20:42:00 CET 2014
> The screen blanks.

I am sure by now you have figured out that the screen blanker software
is looking at the time as it passes by.  If you set the date then the
system time jumps from one time to another.  If the screen blanker is
configured to blank after, say, five minutes then setting the time
ahead more than five minutes will cause it to think that five minutes
has passed and that it should blank the screen.

This is unlikely to be a real problem.  The time should not routinely
be set forward.  Setting the system time is something that really
should happen exactly once at early boot time before anyone has logged
into the system.  After that the time should tick along at the rate of
one second per second and never be jumped again.

>       Is this a bug or is something else going on?

It is a self-inflicted problem if you are manually jumping the system
time around.  Having the system time jump around creates invalid time
sequences.

>       The man page does not mention screenblanking.

The documentation mentions things directly related to date.  It has no
way of knowing if you are running screen blanking software.  Or any
other software that is using the clock.  It can't.

> Also seen it on an other computer
> Running Debian Wheezy

Sure.  The computers are operating correctly.  Don't jump the clock! :-)

If you are needing to set the clock you should investigate NTP
(network time protocol) to use it to keep the system time in sync with
the outside world.  The best known is ntpd (my preferred and
recommended software) but there are other alternatives too.

Bob