[rrd-users] Re: Local time zone

Robert Heber rheber at nawias.pl
Sat Nov 22 19:01:45 MET 2003


Hi,

this is exactly right:
local time:   Sat Nov 22 18:00:00 2003
UTC time:     Sat Nov 22 17:00:00 2003

but in fact I have a problem to correct the look of my graphs,
because they present data from some point in past to the "now".
This "now" is at the right edge of graph, and last presented
data is exactly one hour step aside to the left.

For example I had this situation at 18.00 local time,
(The big letters "DD" represent the data catched in
the "now" moment = 18.00):
ddddddddddddddddddddDD....
12  13  14  15  16  17  18

with help of trick with changing TZ variable in perl code:
$ENV{'TZ'} = "GMT-2"; or in rrdcgi: <RRD::SETENV TZ GMT-2>
I can "normalize" this graph to right time:
ddddddddddddddddddddDD....
13  14  15  16  17  18  19
but it is still not what I want.

I want this graph to look like before time change:
ddddddddddddddddddddddddDD
12  13  14  15  16  17  18
because "now" is 18.00 local time, and I do not need the
gap between 18.00 and 19.00 to be ploted in my graphs.

I do not know what is the reason of this gap and how to
get ride of it. And last but not least, if local=18,
UTC (or GMT)=17 why should I change TZ to GMT-2 to make
my graphs look normal ?

GMT-2 is Oscar Time Zone... I'm in the CET which is GMT+1,
and this does not make any sense.... ;)

http://www.timeanddate.com/library/abbreviations/timezones/eu/cet.html
http://www.timeanddate.com/library/abbreviations/timezones/military/o.html

Regards,
Robert


Użytkownik Alex van den Bogaerdt napisał:

> On Fri, Nov 21, 2003 at 11:52:03AM +0100, Robert Heber wrote:
> 
>>Hi,
>>
>>thank you for a hint, I think that this trace is good but
>>for now I can't make it work - I tried GMT or CET time zone,
>>and result is the same (my data is one hour late).
> 
> 
> Problems with time zones should be fixed right from the start.
> The first thing to do is to check the time on your computer.
> Is it running at the right time, and I don't mean the so called
> "wall clock time".
> 
> Try 
> 
> perl -e 'use POSIX;print asctime(localtime);print asctime(gmtime);'
> 
> It should display both "wall clock time" and UTC time.
> 
> For instance:
> 
> local time:   Sat Nov 22 11:47:39 2003
> UTC time:     Sat Nov 22 10:47:39 2003
> 
> This is correct, as (most of) Europe is one hour east of Greenwich
> and therefore the clock runs ahead of UTC.
> 
> If this is correct, only then worry about grapher scripts and such.
> 
> 
> UTC time *does*not*change* when daylight saving changes.
> 
> HTH
> Alex


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