Summary: Problems with daylight savings change
Kevin Beauchamp <[email protected]>
| Newsgroups | gmane.os.tru64.managers |
|---|---|
| Organization | University of Alberta |
| Message-ID | <[email protected]> |
On Mon, 29 Jan 2007, I wrote:
> Regarding the upcoming changes to the beginning and ending dates of daylight
> savings time, we've looked at the patches HP released and seen that they
> start at version 4.0E: since we're still on 4.0D it doesn't look like that
> is an option for us.
>
> I downloaded the new timezone data file tzdata2007a.tar.gz from
> ftp://elsie.nci.hi.gov/pub and tried to compile it with our old version of
> zic, but it failed.
>
> I then tried compiling both the new timezone code and data, but the new code
> will not compile on our system with the default Makefile.
>
> Has anyone still on a version of Digital Unix too old to use the patches
> found a way to upgrade their timezone information?
Thanks to all who replied:
"Stacks, David W" <[email protected]>
James Sainsbury <[email protected]>
Franz Fischer <[email protected]>
The solution was to use the version of zic we already had and modify our
existing timezone data. The HP DST file (contents quoted below: thanks David)
helped.
Two minor issues:
1) our zdump choked on the leading colon when specifying the timezone but
worked when it was omitted.
2) "zic backward" failed.
Note: We have not tried rolling the clock ahead to test how the system acts
during the new daylight savings period as yet. Caveat emptor.
Thanks again.
Contents of the HP DST file:
__________
The following steps will implement the 2007 changes to U.S. Daylight Saving
Time (DST) rules on Tru64 UNIX version 5 systems for which an Early Release
Patch (ERP) is not available. An ERP to implement these changes is available
for V5.1A with patch kit 6, for V5.1B with patch kit 4 (aka V5.1B-2), and
V5.1B with patch kit 5 (aka V5.1B-3). For all other V5 version/patch kit
combinations, the changes must be implemented manually. This is a reasonably
quick and straightforward process and does not require a system reboot.
Step 1: For comparison purposes, display the times for DST changes for 2006
and 2007 under the current rules. This can be done using any of the United
States time zones; for this example, we will use America/New_York. To verify
the time zone in use on your system, display the symbolic link
/etc/zoneinfo/localtime:
# ls -l /etc/zoneinfo/localtime
lrwxrwxrwx 1 root system 18 Feb 8 2004 /etc/zoneinfo/localtime
-> ./America/New_York
Now use zdump to show the DST transitions for this time zone in 2006-2007:
# zdump -v :America/New_York | grep ‘200[67]’
:America/New_York Fri Oct 20 14:59:45 2006 EDT
:America/New_York Sun Apr 2 06:59:59 2006 GMT = Sun Apr 2 01:59:59 2006 EST
isdst=0 gmtoff=-18000
:America/New_York Sun Apr 2 07:00:00 2006 GMT = Sun Apr 2 03:00:00 2006 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Oct 29 05:59:59 2006 GMT = Sun Oct 29 01:59:59 2006 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Oct 29 06:00:00 2006 GMT = Sun Oct 29 01:00:00 2006 EST
isdst=0 gmtoff=-18000
:America/New_York Sun Apr 1 06:59:59 2007 GMT = Sun Apr 1 01:59:59 2007 EST
isdst=0 gmtoff=-18000
:America/New_York Sun Apr 1 07:00:00 2007 GMT = Sun Apr 1 03:00:00 2007 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Oct 28 05:59:59 2007 GMT = Sun Oct 28 01:59:59 2007 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Oct 28 06:00:00 2007 GMT = Sun Oct 28 01:00:00 2007 EST
isdst=0 gmtoff=-18000
The first line of output shows the current system time. Each subsequent pair
of lines shows the time just before and just after a DST transition. The
first pair shows the spring transition to DST on the first Sunday in April,
while the second pair shows the fall transition to Standard time on the last
Sunday in October. This shows that the current DST rules are in effect for
both 2006 and 2007. Save this output for later comparison.
Step 2: Modify the time zone source file that contains the US time zone rules.
First, save a backup copy of this file:
# cd /etc/zoneinfo/sources
# cp northamerica northamerica.bak
Now edit file “northamerica” with an editor of your choice and find the
section of lines that begin with “Rule US”. This section should look
like this:
# Rule NAME FROM TO TYPE IN ON AT SAVE
LETTER/S
Rule US 1918 1919 - Mar lastSun 2:00 1:00 W #
War
Rule US 1918 1919 - Oct lastSun 2:00 0 S
Rule US 1942 only - Feb 9 2:00 1:00 W #
War
Rule US 1945 only - Aug 14 23:00u 1:00 P #
Peace
Rule US 1945 only - Sep 30 2:00 0 S
Rule US 1967 max - Oct lastSun 2:00 0 S
Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
Rule US 1974 only - Jan 6 2:00 1:00 D
Rule US 1975 only - Feb 23 2:00 1:00 D
Rule US 1976 1986 - Apr lastSun 2:00 1:00 D
Rule US 1987 max - Apr Sun>=1 2:00 1:00 D
You will need to modify two of the above lines (highlighted in bold text) and
add two new lines at the end of the list. In each of the bold lines, change
“max” to “2006”. Then add the following two lines at the end of the section:
Rule US 2007 max - Mar Sun>=8 2:00 1:00 D
Rule US 2007 max - Nov Sun>=1 2:00 0 S
The modified section should now look like this:
# Rule NAME FROM TO TYPE IN ON AT SAVE
LETTER/S
Rule US 1918 1919 - Mar lastSun 2:00 1:00 W #
War
Rule US 1918 1919 - Oct lastSun 2:00 0 S
Rule US 1942 only - Feb 9 2:00 1:00 W #
War
Rule US 1945 only - Aug 14 23:00u 1:00 P #
Peace
Rule US 1945 only - Sep 30 2:00 0 S
Rule US 1967 2006 - Oct lastSun 2:00 0 S
Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
Rule US 1974 only - Jan 6 2:00 1:00 D
Rule US 1975 only - Feb 23 2:00 1:00 D
Rule US 1976 1986 - Apr lastSun 2:00 1:00 D
Rule US 1987 2006 - Apr Sun>=1 2:00 1:00 D
Rule US 2007 max - Mar Sun>=8 2:00 1:00 D
Rule US 2007 max - Nov Sun>=1 2:00 0 S
Save the file and exit the editor.
Step 3: Compile the new timezone definitions. Your current working directory
should be /etc/zoneinfo/sources.
# zic northamerica
# zic backward
The second “zic” command is needed to restore some hard links for old-style
timezones that still exist for backward compatibility.
Step 4: Verify the changes. Use zdump to display the DST transition times
for 2006-7 under the new rules:
# zdump -v :America/New_York | grep ‘200[67]’
:America/New_York Fri Oct 20 15:03:35 2006 EDT
:America/New_York Sun Apr 2 06:59:59 2006 GMT = Sun Apr 2 01:59:59 2006 EST
isdst=0 gmtoff=-18000
:America/New_York Sun Apr 2 07:00:00 2006 GMT = Sun Apr 2 03:00:00 2006 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Oct 29 05:59:59 2006 GMT = Sun Oct 29 01:59:59 2006 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Oct 29 06:00:00 2006 GMT = Sun Oct 29 01:00:00 2006 EST
isdst=0 gmtoff=-18000
:America/New_York Sun Mar 11 06:59:59 2007 GMT = Sun Mar 11 01:59:59 2007 EST
isdst=0 gmtoff=-18000
:America/New_York Sun Mar 11 07:00:00 2007 GMT = Sun Mar 11 03:00:00 2007 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Nov 4 05:59:59 2007 GMT = Sun Nov 4 01:59:59 2007 EDT
isdst=1 gmtoff=-14400
:America/New_York Sun Nov 4 06:00:00 2007 GMT = Sun Nov 4 01:00:00 2007 EST
isdst=0 gmtoff=-18000
This output shows that the transition times for 2006 are still under the old
rules: first Sunday in April and last Sunday in October. But starting in
2007 (you can verify this for any other year with zdump) the transitions
follow the new rules. They occur on the second Sunday in March and the first
Sunday in November.
__________
--
Kevin Beauchamp
Specialist Technician
University of Alberta (main campus)
Facilities and Operations
mailstop: RCMS, Room 100A
Edmonton AB
T6G 2H1 Canada
Tel: (780) 492-2074
Fax: (780) 492-5945
email: [email protected]