Change in Daylight Savings Time Dates?

Has there been discussion of how to prepare for the upcoming change in the
start and end dates of Daylight Savings Time in the USA & Canada?

http://aa.usno.navy.mil/faq/docs/daylight_time.html

http://tf.nist.gov/general/history.htm

Starting this year, DST starts in March (instead of April) and ends in
November (instead of October).

How do we fix QNX to make it switch appropriately without sending someone to
each of our hundred customer sites to change the clock at the appropriate
date/times in March, April, October and November?

In article <eog93o$s6a$1@inn.qnx.com>, Jeff Maass <jmaass@layerzero.com> wrote:

Has there been discussion of how to prepare for the upcoming change in thmae
start and end dates of Daylight Savings Time in the USA & Canada?

http://aa.usno.navy.mil/faq/docs/daylight_time.html

http://tf.nist.gov/general/history.htm

Starting this year, DST starts in March (instead of April) and ends in
November (instead of October).

How do we fix QNX to make it switch appropriately without sending someone to
each of our hundred customer sites to change the clock at the appropriate
date/times in March, April, October and November?

You can use the TZ environment variable or the _CS_TIMEZONE sysconf variable
to set when daylight savings time starts or stops (the contents of
the /etc/TIMEZONE file are used to set them when the system boots).

The Users Guide has a “Setting the time zone” section in the “Configuring
your environment” chapter with a description of the string you use to
describe the rules.

What you can’t do currently is make the rules different for different
years. That is, once you’ve changed the TZ string to the new rules, the
system will apply those rules for all years, so if you ask to convert
a time in last year from UTC to local, it’s going to still use the new
rules. That’s the part we’re still working on. If you don’t care about this,
no problem. If you want a solution that works with the existing system,
as a very ugly hack you can write a program that uses setenv() to fiddle
the TZ environment string to the different rule sets before calling the
UTC=>local time conversion functions.


Brian Stecher (bstecher@qnx.com) QNX Software Systems
phone: +1 (613) 591-0931 (voice) 175 Terence Matthews Cr.
+1 (613) 591-3579 (fax) Kanata, Ontario, Canada K2M 1W8

“Brian Stecher” <bstecher@qnx.com> wrote in message
news:eoin4o$ign$1@inn.qnx.com

In article <eog93o$s6a$> 1@inn.qnx.com> >, Jeff Maass <> jmaass@layerzero.com
wrote:
Has there been discussion of how to prepare for the upcoming change in
thmae
start and end dates of Daylight Savings Time in the USA & Canada?

http://aa.usno.navy.mil/faq/docs/daylight_time.html

http://tf.nist.gov/general/history.htm

Starting this year, DST starts in March (instead of April) and ends in
November (instead of October).

How do we fix QNX to make it switch appropriately without sending someone
to
each of our hundred customer sites to change the clock at the appropriate
date/times in March, April, October and November?

You can use the TZ environment variable or the _CS_TIMEZONE sysconf
variable
to set when daylight savings time starts or stops (the contents of
the /etc/TIMEZONE file are used to set them when the system boots).

The Users Guide has a “Setting the time zone” section in the “Configuring
your environment” chapter with a description of the string you use to
describe the rules.

What you can’t do currently is make the rules different for different
years. That is, once you’ve changed the TZ string to the new rules, the
system will apply those rules for all years, so if you ask to convert
a time in last year from UTC to local, it’s going to still use the new
rules. That’s the part we’re still working on. If you don’t care about
this,
no problem. If you want a solution that works with the existing system,
as a very ugly hack you can write a program that uses setenv() to fiddle
the TZ environment string to the different rule sets before calling the
UTC=>local time conversion functions.


Brian Stecher (> bstecher@qnx.com> ) QNX Software Systems
phone: +1 (613) 591-0931 (voice) 175 Terence Matthews Cr.
+1 (613) 591-3579 (fax) Kanata, Ontario, Canada K2M 1W8

Brian:

Thanks!

I don’t care about conversion of times for previous years,
but I do care that the ‘phlocale’ Photon utility work to
allow our customers to change the date/time and timezone.

Doesn’t 'phlocale write to the TZ environment variable, and
does it know how to retain the proper (new) DST rules? I’d
guess not.

Jeff

phlocale reads the available rules from the file /etc/timezone/uc_tz_t. It
is this ASCII file that defines the various zones that are available for
users to choose through the GUI interface. When the user selects on of
these, phlocale sets the _CS_TIMEZONE sysconf variable (taking effect
immediately) and also writes the rule to the file /etc/TIMEZONE, which is
commonly used to initialize the the _CS_TIMEZONE when the system boots.

We intend to issue a patch containing a new uc_tz_t file that includes the
updated data for North American timezones. However, there is nothing
stopping you from making this change yourself in the meantime.

“Jeff Maass” <jmaass@layerzero.com> wrote in message
news:eoisnd$m0p$1@inn.qnx.com

“Brian Stecher” <> bstecher@qnx.com> > wrote in message
news:eoin4o$ign$> 1@inn.qnx.com> …
In article <eog93o$s6a$> 1@inn.qnx.com> >, Jeff Maass <> jmaass@layerzero.com
wrote:
Has there been discussion of how to prepare for the upcoming change in
thmae
start and end dates of Daylight Savings Time in the USA & Canada?

http://aa.usno.navy.mil/faq/docs/daylight_time.html

http://tf.nist.gov/general/history.htm

Starting this year, DST starts in March (instead of April) and ends in
November (instead of October).

How do we fix QNX to make it switch appropriately without sending
someone
to
each of our hundred customer sites to change the clock at the
appropriate
date/times in March, April, October and November?

You can use the TZ environment variable or the _CS_TIMEZONE sysconf
variable
to set when daylight savings time starts or stops (the contents of
the /etc/TIMEZONE file are used to set them when the system boots).

The Users Guide has a “Setting the time zone” section in the “Configuring
your environment” chapter with a description of the string you use to
describe the rules.

What you can’t do currently is make the rules different for different
years. That is, once you’ve changed the TZ string to the new rules, the
system will apply those rules for all years, so if you ask to convert
a time in last year from UTC to local, it’s going to still use the new
rules. That’s the part we’re still working on. If you don’t care about
this,
no problem. If you want a solution that works with the existing system,
as a very ugly hack you can write a program that uses setenv() to fiddle
the TZ environment string to the different rule sets before calling the
UTC=>local time conversion functions.


Brian Stecher (> bstecher@qnx.com> ) QNX Software Systems
phone: +1 (613) 591-0931 (voice) 175 Terence Matthews Cr.
+1 (613) 591-3579 (fax) Kanata, Ontario, Canada K2M 1W8


Brian:

Thanks!

I don’t care about conversion of times for previous years,
but I do care that the ‘phlocale’ Photon utility work to
allow our customers to change the date/time and timezone.

Doesn’t 'phlocale write to the TZ environment variable, and
does it know how to retain the proper (new) DST rules? I’d
guess not.

Jeff