Ensuring Proper New DST Compliance

By now, if you haven’t heard about the change in daylight savings time (DST), then you need to break out from under your rock and update your servers. That’s where luckily, I come in. No, I won’t update your servers for you (unless you pay me and even then it’s iffy), but I will guide you along in updating them.

Before I jump headlong into helping you out, I feel as though (since it’s my blog anyway) that I just want to rant for a minute…

<rant>I heard that we tried this a while back and they had kids walking to school in the dark…which in and of itself isn’t good. So we figure, let’s try it again. If we can just save a little bit of money by everyone using 1 hour or so less power for 2 weeks, that everything would be dandy. I don’t think anyone took into account the man hours that it would take to update all the software and all the hardware and every little thing that uses dates and has relied on the system that we used for many years. And amusingly enough, if someone doesn’t get everything perfect with the updates for the power systems, then who knows, this may require people to use more power to make up for mistakes. Who’d have thought something like this has the possibility to backfire?</rant>

The first thing you need to do is to check to see if you are updated and ready to go. To do that, if you are in the EST/EDT timezone and your system isn’t updated, then it will look like this when you give it the following command:

# zdump -v /etc/localtime  | grep 2007
/etc/localtime  Sun Apr  1 06:59:59 2007 UTC = Sun Apr  1 01:59:59 2007 EST isdst=0 gmtoff=-18000
/etc/localtime  Sun Apr  1 07:00:00 2007 UTC = Sun Apr  1 03:00:00 2007 EDT isdst=1 gmtoff=-14400
/etc/localtime  Sun Oct 28 05:59:59 2007 UTC = Sun Oct 28 01:59:59 2007 EDT isdst=1 gmtoff=-14400
/etc/localtime  Sun Oct 28 06:00:00 2007 UTC = Sun Oct 28 01:00:00 2007 EST isdst=0 gmtoff=-18000

This is still on the old timezone setting since it says April 1. If that’s too confusing for you, here’s a handy dandy little one-liner that maybe a little more straightforward:

# zdump -v /etc/localtime  | grep 2007  | grep -q "Mar 11" && echo "New DST Compliant" || echo "Not New DST Compliant"
Not New DST Compliant

It will say “Not New DST Compliant” if your setup isn’t currently in compliance with the new DST setup.

To become DST compliant, all you really have to do is update your versions libc6 and locales. This update will ensure that your timezone data is up to date and your system will then respond to the time change accordingly. On a Debian, Ubuntu, or other apt based system, you will only have to do the following (note the ‘#’ means we are already root, if you are on Ubuntu, put a sudo in front of the command):

# apt-get update && apt-get install libc6 locales


# emerge --sync && emerge sys-libs/timezone-data

If all went well, then you should be able to execute the same command as above and it will look like this:

# zdump -v /etc/localtime  | grep 2007
/etc/localtime  Sun Mar 11 06:59:59 2007 UTC = Sun Mar 11 01:59:59 2007 EST isdst=0 gmtoff=-18000
/etc/localtime  Sun Mar 11 07:00:00 2007 UTC = Sun Mar 11 03:00:00 2007 EDT isdst=1 gmtoff=-14400
/etc/localtime  Sun Nov  4 05:59:59 2007 UTC = Sun Nov  4 01:59:59 2007 EDT isdst=1 gmtoff=-14400
/etc/localtime  Sun Nov  4 06:00:00 2007 UTC = Sun Nov  4 01:00:00 2007 EST isdst=0 gmtoff=-18000

And if you are still being lazy, here is the shorthand command again and the output that you should get:

# zdump -v /etc/localtime  | grep 2007  | grep -q "Mar 11" && echo "New DST Compliant" || echo "Not New DST Compliant"
New DST Compliant

That should be all you have to do. Remember that if you aren’t in MY timezone (Eastern Time, USA), then your output will be a little different.

Update: The error in the Gentoo update has been fixed. Thanks to Neo for pointing it out.

  • Neo

    Wrong for gentoo users… For gentoo users, simply do emerge sys-libs/timezone-data. Trying to do emerge libc6 locales will give a “package libc6/locales not found”.

    This is as described here:

    official gentoo website:

  • marco

    The Gentoo instructions did not work for me. I have two Gentoo machines. Both use ntp for setting the time. Machine ‘A’ shows the correct time, yet does not have sys-libs/timezone-data installed, and zdump shows it thinks DST doesn’t start until April (I’m in the PST zone). Machine ‘B’ does have sys-libs/timezone-data installed, yet zdump shows that it also thinks DST doesn’t start until April, and machine B’s clock is behind by one hour (i.e. it hasn’t applied DST yet).

  • http://eric.lubow.org/ eric

    The first thing I would say to do is to check your /etc/conf.d/clock file. Ensure that you have the proper timezone in there. I originally had America/New_York. That didn’t work so I changed it to EST5EDT and then reran ntpdate pool.ntp.org and it was sufficient. You may need to do something similar and make yours the equivilent (I’m not sure but I would assume its similar PST5PDT).