Daylight Savings Time settings in Linux
Notes on how to view or change the Daylight Savings Time settings on Linux.
Last updated: 8 June 2007
The conditions for the beginning and end of Daylight Savings Time (DST) in the United States have changed, starting in 2007. You can view the DST settings on your machine by opening up a command shell and giving the following command:This should produce something like:zdump -v /etc/localtime | grep 2007If you don't see DST starting on March 11 2007 then you need to update your settings. How you do this will depend on your Linux distribution./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
(Note that possibility of using a full-path filename on the zdump command line in place of a timezone name is not documented in the zdump man page.)
Fedora/Red HatUsing RPM I found that the file /etc/localtime is a file owned by the package glibc, rather than a soft link to a file for my particular timezone. Updating that package got me the proper settings. Simply updating the tzdata was not sufficient.
Other DistributionsI don't know the details for other distributions, but I'll post anything useful someone cares to send me if it's significantly different from Fedora/Red Hat.
Last modified: 08 June 2007 Copyright © 2007 by Spy Hill Research http://www.spy-hill.net /help/linux/DST.html