SUMMARY: Setting Date/Time

From: bgille - Bill Gillespie <bgille_at_acxiom.com>
Date: Thu, 08 Oct 1998 10:14:23 -0500

Original question:

> What is the correct process for setting the date and time on a DEC Alpha 4100 running Unix 4.0b?
>
> Is it as simple as using the Unix date command?
> Do you have to reboot after doing this, and what happens if you don't?
>

A lot of responses indicating that yes, use the date -nu command, and no reboot is necessary. However, you should set the box to single user mode (this is actually mentioned in the man page for date as well).

A very nice response by Peter, pchapin_at_twilight.vtc.vsc.edu:

It can be that simple. No reboot is necessary. The kernel will immediately
accept the new time. However, jumping the time abruptly -- especially by a
large step -- can sometimes cause certain applications to get confused.
For example, cron jobs might be missed (or run twice "in a row"), etc.

Another approach is to use something like xntpd to sychronize the time to
time servers on the 'net. The xntpd daemon will "nudge" the time in small
steps to bring it up to date and then insure that it never drifts too far
from the correct time. That solution might be overkill for what you're
doing.

I have a machine running Linux that has a screwed up clock. it falls
behind by many minutes per day. I've used the date command to reset the
time on that machine by as much as two hours at once. It worked okay. But
then that machine wasn't running any time sensitive applications. I'm
running xntpd on it now just so that I don't have to bother resetting the
time regularly. The log file makes for amusing reading (if a log file can
be said to be amusing). The xntpd daemon is constantly compensating for
the screwed up clock. However, the time on the box is now never more than
a second or two off.
Received on Thu Oct 08 1998 - 15:11:48 NZDT

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