Retrieve first hour in daylight savings change - GNU date

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Last weekend most of Western Europe shifted back one hour - there were two instances of 2017-10-29T02:00.



To translate the time into UTC I can use GNU date:



$ date -d 'TZ="Europe/Rome" 2017-10-29 02:00'
Sun Oct 29 01:00:00 UTC 2017


This returns the time in CET (ie the second 2am). How do I get date to return Sun Oct 29 00:00:00 UTC 2017 (the first 2am - CEST)?



Info:



$ date --version
date (GNU coreutils) 8.21



date coreutils




share|improve this question




















  • Actually, CEST ended on October 29, at 3:00 AM. So, 2 AM CET was 3 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 6:06










  • @kiamlaluno - I thought that’s what I said. At 3am the clocks went back an hour to 2am - ie two 2 AMs
    – DarkHeart
    Oct 30 '17 at 6:21











  • Did you try date -u ?
    – Serge
    Oct 30 '17 at 7:03










  • You are saying you get Sun Oct 29 01:00:00 UTC 2017 as output of date -d 'TZ="Europe/Rome" 2017-10-29 02:00' and you would want to get Sun Oct 29 00:00:00 UTC 2017, which is two hours earlier than the input. That is not just changing from CEST to CET or vice versa. On October 29, 2017, 2:00 AM CEST is 2:00 AM CEST, and 2:00 AM CET is 3:00 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 9:13










  • @kiamlaluno - Yes I want to change UTC to Europe time - having date translate both hours (2am CEST and 2am CET) not just the one.
    – DarkHeart
    Oct 31 '17 at 0:20














up vote
1
down vote

favorite












Last weekend most of Western Europe shifted back one hour - there were two instances of 2017-10-29T02:00.



To translate the time into UTC I can use GNU date:



$ date -d 'TZ="Europe/Rome" 2017-10-29 02:00'
Sun Oct 29 01:00:00 UTC 2017


This returns the time in CET (ie the second 2am). How do I get date to return Sun Oct 29 00:00:00 UTC 2017 (the first 2am - CEST)?



Info:



$ date --version
date (GNU coreutils) 8.21



date coreutils




share|improve this question




















  • Actually, CEST ended on October 29, at 3:00 AM. So, 2 AM CET was 3 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 6:06










  • @kiamlaluno - I thought that’s what I said. At 3am the clocks went back an hour to 2am - ie two 2 AMs
    – DarkHeart
    Oct 30 '17 at 6:21











  • Did you try date -u ?
    – Serge
    Oct 30 '17 at 7:03










  • You are saying you get Sun Oct 29 01:00:00 UTC 2017 as output of date -d 'TZ="Europe/Rome" 2017-10-29 02:00' and you would want to get Sun Oct 29 00:00:00 UTC 2017, which is two hours earlier than the input. That is not just changing from CEST to CET or vice versa. On October 29, 2017, 2:00 AM CEST is 2:00 AM CEST, and 2:00 AM CET is 3:00 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 9:13










  • @kiamlaluno - Yes I want to change UTC to Europe time - having date translate both hours (2am CEST and 2am CET) not just the one.
    – DarkHeart
    Oct 31 '17 at 0:20












up vote
1
down vote

favorite









up vote
1
down vote

favorite











Last weekend most of Western Europe shifted back one hour - there were two instances of 2017-10-29T02:00.



To translate the time into UTC I can use GNU date:



$ date -d 'TZ="Europe/Rome" 2017-10-29 02:00'
Sun Oct 29 01:00:00 UTC 2017


This returns the time in CET (ie the second 2am). How do I get date to return Sun Oct 29 00:00:00 UTC 2017 (the first 2am - CEST)?



Info:



$ date --version
date (GNU coreutils) 8.21



date coreutils




share|improve this question












Last weekend most of Western Europe shifted back one hour - there were two instances of 2017-10-29T02:00.



To translate the time into UTC I can use GNU date:



$ date -d 'TZ="Europe/Rome" 2017-10-29 02:00'
Sun Oct 29 01:00:00 UTC 2017


This returns the time in CET (ie the second 2am). How do I get date to return Sun Oct 29 00:00:00 UTC 2017 (the first 2am - CEST)?



Info:



$ date --version
date (GNU coreutils) 8.21




date coreutils





share|improve this question











share|improve this question




share|improve this question










asked Oct 30 '17 at 1:24









DarkHeart

3,38822136




3,38822136











  • Actually, CEST ended on October 29, at 3:00 AM. So, 2 AM CET was 3 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 6:06










  • @kiamlaluno - I thought that’s what I said. At 3am the clocks went back an hour to 2am - ie two 2 AMs
    – DarkHeart
    Oct 30 '17 at 6:21











  • Did you try date -u ?
    – Serge
    Oct 30 '17 at 7:03










  • You are saying you get Sun Oct 29 01:00:00 UTC 2017 as output of date -d 'TZ="Europe/Rome" 2017-10-29 02:00' and you would want to get Sun Oct 29 00:00:00 UTC 2017, which is two hours earlier than the input. That is not just changing from CEST to CET or vice versa. On October 29, 2017, 2:00 AM CEST is 2:00 AM CEST, and 2:00 AM CET is 3:00 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 9:13










  • @kiamlaluno - Yes I want to change UTC to Europe time - having date translate both hours (2am CEST and 2am CET) not just the one.
    – DarkHeart
    Oct 31 '17 at 0:20
















  • Actually, CEST ended on October 29, at 3:00 AM. So, 2 AM CET was 3 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 6:06










  • @kiamlaluno - I thought that’s what I said. At 3am the clocks went back an hour to 2am - ie two 2 AMs
    – DarkHeart
    Oct 30 '17 at 6:21











  • Did you try date -u ?
    – Serge
    Oct 30 '17 at 7:03










  • You are saying you get Sun Oct 29 01:00:00 UTC 2017 as output of date -d 'TZ="Europe/Rome" 2017-10-29 02:00' and you would want to get Sun Oct 29 00:00:00 UTC 2017, which is two hours earlier than the input. That is not just changing from CEST to CET or vice versa. On October 29, 2017, 2:00 AM CEST is 2:00 AM CEST, and 2:00 AM CET is 3:00 AM CEST.
    – kiamlaluno
    Oct 30 '17 at 9:13










  • @kiamlaluno - Yes I want to change UTC to Europe time - having date translate both hours (2am CEST and 2am CET) not just the one.
    – DarkHeart
    Oct 31 '17 at 0:20















Actually, CEST ended on October 29, at 3:00 AM. So, 2 AM CET was 3 AM CEST.
– kiamlaluno
Oct 30 '17 at 6:06




Actually, CEST ended on October 29, at 3:00 AM. So, 2 AM CET was 3 AM CEST.
– kiamlaluno
Oct 30 '17 at 6:06












@kiamlaluno - I thought that’s what I said. At 3am the clocks went back an hour to 2am - ie two 2 AMs
– DarkHeart
Oct 30 '17 at 6:21





@kiamlaluno - I thought that’s what I said. At 3am the clocks went back an hour to 2am - ie two 2 AMs
– DarkHeart
Oct 30 '17 at 6:21













Did you try date -u ?
– Serge
Oct 30 '17 at 7:03




Did you try date -u ?
– Serge
Oct 30 '17 at 7:03












You are saying you get Sun Oct 29 01:00:00 UTC 2017 as output of date -d 'TZ="Europe/Rome" 2017-10-29 02:00' and you would want to get Sun Oct 29 00:00:00 UTC 2017, which is two hours earlier than the input. That is not just changing from CEST to CET or vice versa. On October 29, 2017, 2:00 AM CEST is 2:00 AM CEST, and 2:00 AM CET is 3:00 AM CEST.
– kiamlaluno
Oct 30 '17 at 9:13




You are saying you get Sun Oct 29 01:00:00 UTC 2017 as output of date -d 'TZ="Europe/Rome" 2017-10-29 02:00' and you would want to get Sun Oct 29 00:00:00 UTC 2017, which is two hours earlier than the input. That is not just changing from CEST to CET or vice versa. On October 29, 2017, 2:00 AM CEST is 2:00 AM CEST, and 2:00 AM CET is 3:00 AM CEST.
– kiamlaluno
Oct 30 '17 at 9:13












@kiamlaluno - Yes I want to change UTC to Europe time - having date translate both hours (2am CEST and 2am CET) not just the one.
– DarkHeart
Oct 31 '17 at 0:20




@kiamlaluno - Yes I want to change UTC to Europe time - having date translate both hours (2am CEST and 2am CET) not just the one.
– DarkHeart
Oct 31 '17 at 0:20










2 Answers
2






active

oldest

votes

















up vote
1
down vote













The reference for timezone changes is zdump:



$ /usr/sbin/zdump -v -c 2017,2018 Europe/Rome
Europe/Rome -9223372036854775808 = NULL
Europe/Rome -9223372036854689408 = NULL
Europe/Rome Sun Mar 26 00:59:59 2017 UTC = Sun Mar 26 01:59:59 2017 CET isdst=0
Europe/Rome Sun Mar 26 01:00:00 2017 UTC = Sun Mar 26 03:00:00 2017 CEST isdst=1
Europe/Rome Sun Oct 29 00:59:59 2017 UTC = Sun Oct 29 02:59:59 2017 CEST isdst=1
Europe/Rome Sun Oct 29 01:00:00 2017 UTC = Sun Oct 29 02:00:00 2017 CET isdst=0
Europe/Rome 9223372036854689407 = NULL
Europe/Rome 9223372036854775807 = NULL





share|improve this answer



























    up vote
    1
    down vote



    accepted










    The time TZ="Europe/Rome" 2017-10-29 02:00 is ambiguous since this translates to two different UTC times, 00:00 and 01:00.



    How to make date return both is to specify the exact timezone itself, eg



    $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CEST'
    Sun Oct 29 00:00:00 UTC 2017
    $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CET'
    Sun Oct 29 01:00:00 UTC 2017


    However this means you have to work out the timezone outside the date command.






    share|improve this answer




















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      2 Answers
      2






      active

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      2 Answers
      2






      active

      oldest

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      active

      oldest

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      active

      oldest

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      up vote
      1
      down vote













      The reference for timezone changes is zdump:



      $ /usr/sbin/zdump -v -c 2017,2018 Europe/Rome
      Europe/Rome -9223372036854775808 = NULL
      Europe/Rome -9223372036854689408 = NULL
      Europe/Rome Sun Mar 26 00:59:59 2017 UTC = Sun Mar 26 01:59:59 2017 CET isdst=0
      Europe/Rome Sun Mar 26 01:00:00 2017 UTC = Sun Mar 26 03:00:00 2017 CEST isdst=1
      Europe/Rome Sun Oct 29 00:59:59 2017 UTC = Sun Oct 29 02:59:59 2017 CEST isdst=1
      Europe/Rome Sun Oct 29 01:00:00 2017 UTC = Sun Oct 29 02:00:00 2017 CET isdst=0
      Europe/Rome 9223372036854689407 = NULL
      Europe/Rome 9223372036854775807 = NULL





      share|improve this answer
























        up vote
        1
        down vote













        The reference for timezone changes is zdump:



        $ /usr/sbin/zdump -v -c 2017,2018 Europe/Rome
        Europe/Rome -9223372036854775808 = NULL
        Europe/Rome -9223372036854689408 = NULL
        Europe/Rome Sun Mar 26 00:59:59 2017 UTC = Sun Mar 26 01:59:59 2017 CET isdst=0
        Europe/Rome Sun Mar 26 01:00:00 2017 UTC = Sun Mar 26 03:00:00 2017 CEST isdst=1
        Europe/Rome Sun Oct 29 00:59:59 2017 UTC = Sun Oct 29 02:59:59 2017 CEST isdst=1
        Europe/Rome Sun Oct 29 01:00:00 2017 UTC = Sun Oct 29 02:00:00 2017 CET isdst=0
        Europe/Rome 9223372036854689407 = NULL
        Europe/Rome 9223372036854775807 = NULL





        share|improve this answer






















          up vote
          1
          down vote










          up vote
          1
          down vote









          The reference for timezone changes is zdump:



          $ /usr/sbin/zdump -v -c 2017,2018 Europe/Rome
          Europe/Rome -9223372036854775808 = NULL
          Europe/Rome -9223372036854689408 = NULL
          Europe/Rome Sun Mar 26 00:59:59 2017 UTC = Sun Mar 26 01:59:59 2017 CET isdst=0
          Europe/Rome Sun Mar 26 01:00:00 2017 UTC = Sun Mar 26 03:00:00 2017 CEST isdst=1
          Europe/Rome Sun Oct 29 00:59:59 2017 UTC = Sun Oct 29 02:59:59 2017 CEST isdst=1
          Europe/Rome Sun Oct 29 01:00:00 2017 UTC = Sun Oct 29 02:00:00 2017 CET isdst=0
          Europe/Rome 9223372036854689407 = NULL
          Europe/Rome 9223372036854775807 = NULL





          share|improve this answer












          The reference for timezone changes is zdump:



          $ /usr/sbin/zdump -v -c 2017,2018 Europe/Rome
          Europe/Rome -9223372036854775808 = NULL
          Europe/Rome -9223372036854689408 = NULL
          Europe/Rome Sun Mar 26 00:59:59 2017 UTC = Sun Mar 26 01:59:59 2017 CET isdst=0
          Europe/Rome Sun Mar 26 01:00:00 2017 UTC = Sun Mar 26 03:00:00 2017 CEST isdst=1
          Europe/Rome Sun Oct 29 00:59:59 2017 UTC = Sun Oct 29 02:59:59 2017 CEST isdst=1
          Europe/Rome Sun Oct 29 01:00:00 2017 UTC = Sun Oct 29 02:00:00 2017 CET isdst=0
          Europe/Rome 9223372036854689407 = NULL
          Europe/Rome 9223372036854775807 = NULL






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Oct 30 '17 at 7:20









          Satō Katsura

          10.7k11533




          10.7k11533






















              up vote
              1
              down vote



              accepted










              The time TZ="Europe/Rome" 2017-10-29 02:00 is ambiguous since this translates to two different UTC times, 00:00 and 01:00.



              How to make date return both is to specify the exact timezone itself, eg



              $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CEST'
              Sun Oct 29 00:00:00 UTC 2017
              $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CET'
              Sun Oct 29 01:00:00 UTC 2017


              However this means you have to work out the timezone outside the date command.






              share|improve this answer
























                up vote
                1
                down vote



                accepted










                The time TZ="Europe/Rome" 2017-10-29 02:00 is ambiguous since this translates to two different UTC times, 00:00 and 01:00.



                How to make date return both is to specify the exact timezone itself, eg



                $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CEST'
                Sun Oct 29 00:00:00 UTC 2017
                $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CET'
                Sun Oct 29 01:00:00 UTC 2017


                However this means you have to work out the timezone outside the date command.






                share|improve this answer






















                  up vote
                  1
                  down vote



                  accepted







                  up vote
                  1
                  down vote



                  accepted






                  The time TZ="Europe/Rome" 2017-10-29 02:00 is ambiguous since this translates to two different UTC times, 00:00 and 01:00.



                  How to make date return both is to specify the exact timezone itself, eg



                  $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CEST'
                  Sun Oct 29 00:00:00 UTC 2017
                  $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CET'
                  Sun Oct 29 01:00:00 UTC 2017


                  However this means you have to work out the timezone outside the date command.






                  share|improve this answer












                  The time TZ="Europe/Rome" 2017-10-29 02:00 is ambiguous since this translates to two different UTC times, 00:00 and 01:00.



                  How to make date return both is to specify the exact timezone itself, eg



                  $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CEST'
                  Sun Oct 29 00:00:00 UTC 2017
                  $ date -ud 'TZ="Europe/Rome" 02:00:00 10/29/2017 CET'
                  Sun Oct 29 01:00:00 UTC 2017


                  However this means you have to work out the timezone outside the date command.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Oct 31 '17 at 0:57









                  DarkHeart

                  3,38822136




                  3,38822136



























                       

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