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Brent L. Bates wrote:
>      I THOUGHT I had taken care of this, now I'm not so sure.  I downloaded
> and installed the lastest tzdata RPM.  `zdump -v' on the appropriate
> /usr/share/zoneinfo file showed the correct information.  I copied the
> zoneinfo file (/usr/share/zoneinfo/America/New_York) to /etc/localtime and
> thought that should fix everything.

This issue seems to be generating a lot of confusion for everyone in IT.
 It was actually a story on the news this morning.  We have done our
update, so I thought I would put together a small how-to.

Here are a few steps that you can follow on all your linux hosts,
whether they are SL or not (in our case, redhat, mandrake and SL).
These were the steps that I did on our small network.  On a larger
network, presumably you have other means of running commands across a
large number of hosts.


Note: 'hostlist' contains a list of all linux hosts on the network.  As
well, I use ssh keys to log into servers so that I'm not prompted for
passwords in these little scripts.


1 - Discover which timezone your servers are currently set to
- -------------------------------------------------------------
for host in `cat ~/hostlist`; do
  echo $host;
  ssh $host cat /etc/sysconfig/clock;
done

Your output should look like something like this.  As you can see the
timezone for this computer is "Canada/Pacific"
<host>
UTC=true
ARC=false
ZONE=Canada/Pacific


2 - Update timezone data on all hosts
- -----------------------------------
Each server can be updated by simply copying over know good timezone
files, symlinking /etc/localtime to the appropriate timezone file and
rebooting the machine.  In our case, I grabbed updated timezone files
from an SL4.4 box and copied them to all hosts.  The files I copied were:
/usr/share/zoneinfo/Canada/Pacific
and
/usr/share/zoneinfo/America/Vancouver.

If you have servers in several different timezones, you may want to
create a tarball with new zone info for all timezones listed in
/usr/share/zoneinfo/, copy that tarball to all hosts and overwrite the
old timezone data.  Then, based on the output from the script in section
one, you could automate the creation of a symlink from the appropriate
file in /usr/share/zoneinfo/ to /etc/localtime.


3 - Apply the changes
- ------------------------
The easiest way to ensure the changes are applied to all processes that
use the locale settings, is a reboot.  However, if you really want to be
sure everything is correct before rebooting, you can confirm the changes
by running a short little script something like this.

for host in `cat ~/hostlist`; do
  echo -n "$host  "
  ssh $host "date -d 'March 11 2007 02:30' | awk '{print \$5}'"
done

Note: I used the date command as it actually uses /etc/localtime and I
can be much more specific about which time I want to see, than if I were
to use zdump.

This script will spit out the timezone for each server.  All our servers
are in the Pacific timezone so I should expect to see PDT if all is
well.  If a change did not apply correctly then I would see PST.

Even if you have servers in multiple timezones, they should all indicate
they are in a daylight savings time timezone rather than a standard time
zone, so greping for 'D' may be sufficient to know whether the change is
correct or not.



Hopefully this is of use to someone and that no one has any issues as a
result of the changeover this Sunday.

- --
Mason Schmitt
Systems Administrator
Sunwave Cable Internet / Shuswap Internet Junction
ph: (250) 832-9711
www.sunwave.net
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