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Re: Determining daylight savings changes on BSD



On Fri, Feb 02, 2007 at 10:36:37AM -0600, Dan Nelson wrote:

> In the last episode (Feb 02), Robert Fitzpatrick said:
> > I use the following command on our CentOS Linux servers to find out
> > if the system is ready for the daylight savings changes coming up,
> > but it does not seem to work the same on our FreeBSD 5.4 and 6.1
> > servers. How can I do this? I see the zdump command and the man page
> > seems to suggest the same usage, but...
> > 
> > esmtp# zdump -v US/Eastern | grep 2007
> > esmtp# zdump -v US/Eastern
> > US/Eastern  Fri Dec 13 20:45:52 1901 UTC = Fri Dec 13 20:45:52 1901 UTC isdst=0 gmtoff=0
> > US/Eastern  Sat Dec 14 20:45:52 1901 UTC = Sat Dec 14 20:45:52 1901 UTC isdst=0 gmtoff=0
> > US/Eastern  Mon Jan 18 03:14:07 2038 UTC = Mon Jan 18 03:14:07 2038 UTC isdst=0 gmtoff=0
> > US/Eastern  Tue Jan 19 03:14:07 2038 UTC = Tue Jan 19 03:14:07 2038 UTC isdst=0 gmtoff=0

I don't know how to read this.  There was another command I saw a while
back that gave similar looking information, but actually put out something
for 2007.   But, I can't find that mesage at the moment.

> That means you need to update your zoneinfo tables.  You can also use
> the date command to see if you need updating:
> 
> date -r 1173679260
> 
> If that prints "Mon Mar 12 02:01:00 EST 2007" you know you need to
> update.

Are you sure?   I see the EST where mine says EDT, but mine gives the
exact same date/time information as you show above outside of the EST.

If I subtract out exactly one day (86400 seconds) I get:
  Sun Mar 11 01:01:00 EST 2007    which is just 59 minutes before
the changeover.

Then, if I add an hour (3600 seconds) I get:
  Sun Mar 11 03:01:00 EDT 2007

So, I would expect the non-updated system to give:
  Mon Mar 12 01:01:00 EST 2007

Or is something else really messed up?
My system seems to be giving the correct current date/time.

////jerry

> 
> -- 
> 	Dan Nelson
> 	dnelson_(_at_)_allantgroup_(_dot_)_com
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