Red Hat Knowledgebase

Release Found: Tested on Red Hat Enterprise Linux 4

Solution:

The zdump utility which comes with glibc-common, can be used to output timezone data. For example, the following command will output all timezone data for Australia/Queensland:

# zdump -v Australia/Queensland

Some timezones contain large amounts of changes, in these cases, pipe the above command to less, for example:

# zdump -v Australia/Queensland | less

The following is an example of how to check for timezone changes between different versions of the tzdata package:

# rpm -Uvh --oldpackage tzdata-2005f-1.EL4.noarch.rpm
Preparing...                ########################################### [100%]
   1:tzdata                 ########################################### [100%]
# zdump -v America/Los_Angeles|grep 2007
America/Los_Angeles  Sun Apr  1 09:59:59 2007 UTC = Sun Apr  1 01:59:59 2007 PST isdst=0 gmtoff=-28800
America/Los_Angeles  Sun Apr  1 10:00:00 2007 UTC = Sun Apr  1 03:00:00 2007 PDT isdst=1 gmtoff=-25200
America/Los_Angeles  Sun Oct 28 08:59:59 2007 UTC = Sun Oct 28 01:59:59 2007 PDT isdst=1 gmtoff=-25200
America/Los_Angeles  Sun Oct 28 09:00:00 2007 UTC = Sun Oct 28 01:00:00 2007 PST isdst=0 gmtoff=-28800

# rpm -Uvh tzdata-2005m-1.EL4.noarch.rpm
Preparing...                ########################################### [100%]
   1:tzdata                 ########################################### [100%]
# zdump -v America/Los_Angeles|grep 2007
America/Los_Angeles  Sun Mar 11 09:59:59 2007 UTC = Sun Mar 11 01:59:59 2007 PST isdst=0 gmtoff=-28800
America/Los_Angeles  Sun Mar 11 10:00:00 2007 UTC = Sun Mar 11 03:00:00 2007 PDT isdst=1 gmtoff=-25200
America/Los_Angeles  Sun Nov  4 08:59:59 2007 UTC = Sun Nov  4 01:59:59 2007 PDT isdst=1 gmtoff=-25200
America/Los_Angeles  Sun Nov  4 09:00:00 2007 UTC = Sun Nov  4 01:00:00 2007 PST isdst=0 gmtoff=-28800

The output above indicates daylight savings changes with the string isdst.

Note: For a list of timezones refer to the files under /usr/share/zoneinfo/.