[SOLVED] Convert list of timestamps to UTC

jlinkels · 03-06-2009, 02:12 PM

Code:

jlinkels@jlinkels-lt:~$ date --utc -d "2007-02-04 13:30:00 GMT-10 hours"
Sun Feb  4 03:30:00 UTC 2007
jlinkels@jlinkels-lt:~$ date --utc -d "2007-02-04 13:30:00 CET"
Sun Feb  4 12:30:00 UTC 2007

I am not sure what date does when you enter the TLA for GMT+10, but if you take the effort to enter GMT-10 hours in the date string it gives the correct UTC time.

Using the TLA for CET (GMT-1) does work.

jlinkels

wje_lq · 03-06-2009, 02:53 PM

Quote:

Originally Posted by jlinkels

Code:

jlinkels@jlinkels-lt:~$ date --utc -d "2007-02-04 13:30:00 GMT-10 hours"
Sun Feb  4 03:30:00 UTC 2007
jlinkels@jlinkels-lt:~$ date --utc -d "2007-02-04 13:30:00 CET"
Sun Feb  4 12:30:00 UTC 2007

I am not sure what date does when you enter the TLA for GMT+10, but if you take the effort to enter GMT-10 hours in the date string it gives the correct UTC time.

Using the TLA for CET (GMT-1) does work.
jlinkels

Inspired by this, I came up with a one-line bash script that will entirely replace my Perl script.

Code:

date --utc -d "$* GMT-10 hours" +'%F %T'

I know, it says GMT-10 instead of GMT+10, but it does work for translating GMT+10 to UTC.

If, say, you store that one-line shell script as xxx in a directory in your $PATH, you'll see output like this:

Code:

wally:~/thursday/2$ xxx 2009-01-25 20:57:22
2009-01-25 10:57:22
wally:~/thursday/2$ xxx 2009-01-25 10:57:22
2009-01-25 00:57:22
wally:~/thursday/2$ xxx 2009-01-25 00:57:22
2009-01-24 14:57:22
wally:~/thursday/2$

jlinkels · 03-06-2009, 03:15 PM

Quote:

Originally Posted by wje_lq

I know, it says GMT-10 instead of GMT+10, but it does work for translating GMT+10 to UTC.

I never understood why that is. I live in an unnamed time zone where it is 4 hours earlier than GMT. Still I have to enter GMT+4 as my time zone.

jlinkels

wje_lq · 03-06-2009, 05:01 PM

Quote:

I never understood why that is. I live in an unnamed time zone where it is 4 hours earlier than GMT. Still I have to enter GMT+4 as my time zone.

This is indeed puzzling. I tried a similar experiment. I'm in California, whose time is (at this time of year) eight hours earlier than UTC. But:

Code:

wally:~$ echo $TZ

wally:~$ date
Fri Mar  6 14:58:20 PST 2009
wally:~$ export TZ=GMT+8
wally:~$ date
Fri Mar  6 14:58:33 GMT 2009
wally:~$ export TZ=GMT-8
wally:~$ date
Sat Mar  7 06:58:40 GMT 2009
wally:~$ export TZ=GMT+10
wally:~$ date
Fri Mar  6 12:58:49 GMT 2009
wally:~$ export TZ=GMT-10
wally:~$ date
Sat Mar  7 08:58:55 GMT 2009
wally:~$ export TZ=UTC
wally:~$ date
Fri Mar  6 22:59:07 UTC 2009
wally:~$

So, hattori.hanzo, you think that just because you're in Australia, you're at GMT+10? I would have thought so, too, but our computer overlords know different! Look at the above output, look at the final few lines, and you'll see you're really at GMT-10!

hattori.hanzo · 06-02-2013, 09:28 PM

Quote:

Originally Posted by wje_lq

Inspired by this, I came up with a one-line bash script that will entirely replace my Perl script.

Code:

date --utc -d "$* GMT-10 hours" +'%F %T'

I know, it says GMT-10 instead of GMT+10, but it does work for translating GMT+10 to UTC.

If, say, you store that one-line shell script as xxx in a directory in your $PATH, you'll see output like this:

Code:

wally:~/thursday/2$ xxx 2009-01-25 20:57:22
2009-01-25 10:57:22
wally:~/thursday/2$ xxx 2009-01-25 10:57:22
2009-01-25 00:57:22
wally:~/thursday/2$ xxx 2009-01-25 00:57:22
2009-01-24 14:57:22
wally:~/thursday/2$

I had been using your perl code in my script since my last post in this thread. :-) Just researching on how to speed things up. The time conversion process from local time to UTC is taking too long for the amount of lines I am processing.

I might look into testing:

Code:

date --utc -d "$* GMT0-10 hours" +'%F %T'

Cheers