Offset between two time zones.

AsianFlu has asked for the wisdom of the Perl Monks concerning the following question:

In perl 5.6.0, on redhat 7, I used to do something like this:

$ENV{TZ}="US/Eastern";
# use locatime(time) to get the time
$ENV{TZ}="Other/Zone";
# use localtime(time) to get the time
# subtract the difference
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This doesn't work anymore on perl 5.8.0 on redhat 9. Although perl will start and localtime() obeys the current setting of TZ, using ENV{TZ} to change it, does nothing! so now I have to use this terrible thing:

my $rfc_offset = `TZ=US/Eastern; date +%s`;
my $rfc_offset2= `TZ=Other/Zone; date +%s`;
# code to work out difference in seconds.
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Which is highly upsetting! I do not want to load the huge Date::Time module in just do so such a simple thing. (current seconds difference between two time zones). What shall I do? I've tried POSIX strftime as well, and that doesnt help anymore either. Why was this (apparently) changed? or is it a bug?

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Re: Offset between two time zones. by sgifford (Prior) on Oct 24, 2003 at 23:15 UTC
I'm not sure there's a portable way to do what you want, apart from `Time::Date` or similar, or compiling a database of timezones and offsets and using that. That said, on my system `zdump(8)` looks helpful: sgifford@sglaptop sgifford$ /usr/sbin/zdump US/Michigan Zulu US/Michigan Fri Oct 24 03:16:56 2003 EDT Zulu Fri Oct 24 07:16:56 2003 UTC	[reply] [d/l]
Re: Offset between two time zones. by tachyon (Chancellor) on Oct 25, 2003 at 10:53 UTC
I know the internal handling of timezones changed significantly between RH6 and RH7.3 (Can't remember which version precisely). We always set server time to GMT (UTC) and have the offsets in a config file for apps where it matters. cheers tachyon s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print	[reply]