Date Command Gives Wrong Week Number for Dec 31











up vote
18
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When I try to get the week number for Dec 31, it returns 1. When I get the week number for Dec 30, I get 52 --- which is what I would expect. The day Monday is correct. This is on a RPI running Ubuntu.



$ date -d "2018-12-30T1:58:55" +"%V%a"

52Sun

$ date -d "2018-12-31T1:58:55" +"%V%a"

01Mon


Same issue without time string



$ date -d "2018-12-31" +"%V%a"

01Mon









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  • 7




    "Date Command Gives Wrong Week Number for Dec 31" – "Wrong" according to which specification? Is the specification you are using the same one that the manual for date says it is using?
    – Jörg W Mittag
    yesterday






  • 2




    Excel week number inconsistent results, Excel weeknum function returns wrong week, UI calendar shows wrong week number
    – phuclv
    yesterday






  • 2




    You might be interested in Why does the MonthCalendar control show the wrong week numbers in Romania? The blog post is about Windows, but the issue being discussed is general (and seems to be the same as what you are encountering).
    – a CVn
    21 hours ago












  • "The computer must be wrong, because I obviously didn't make a mistake!" reminds me of when I complained that the FORTRAN IV compiler must have a bug, because my first simple program couldn't have any errors...
    – RonJohn
    2 hours ago















up vote
18
down vote

favorite












When I try to get the week number for Dec 31, it returns 1. When I get the week number for Dec 30, I get 52 --- which is what I would expect. The day Monday is correct. This is on a RPI running Ubuntu.



$ date -d "2018-12-30T1:58:55" +"%V%a"

52Sun

$ date -d "2018-12-31T1:58:55" +"%V%a"

01Mon


Same issue without time string



$ date -d "2018-12-31" +"%V%a"

01Mon









share|improve this question









New contributor




George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
















  • 7




    "Date Command Gives Wrong Week Number for Dec 31" – "Wrong" according to which specification? Is the specification you are using the same one that the manual for date says it is using?
    – Jörg W Mittag
    yesterday






  • 2




    Excel week number inconsistent results, Excel weeknum function returns wrong week, UI calendar shows wrong week number
    – phuclv
    yesterday






  • 2




    You might be interested in Why does the MonthCalendar control show the wrong week numbers in Romania? The blog post is about Windows, but the issue being discussed is general (and seems to be the same as what you are encountering).
    – a CVn
    21 hours ago












  • "The computer must be wrong, because I obviously didn't make a mistake!" reminds me of when I complained that the FORTRAN IV compiler must have a bug, because my first simple program couldn't have any errors...
    – RonJohn
    2 hours ago













up vote
18
down vote

favorite









up vote
18
down vote

favorite











When I try to get the week number for Dec 31, it returns 1. When I get the week number for Dec 30, I get 52 --- which is what I would expect. The day Monday is correct. This is on a RPI running Ubuntu.



$ date -d "2018-12-30T1:58:55" +"%V%a"

52Sun

$ date -d "2018-12-31T1:58:55" +"%V%a"

01Mon


Same issue without time string



$ date -d "2018-12-31" +"%V%a"

01Mon









share|improve this question









New contributor




George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











When I try to get the week number for Dec 31, it returns 1. When I get the week number for Dec 30, I get 52 --- which is what I would expect. The day Monday is correct. This is on a RPI running Ubuntu.



$ date -d "2018-12-30T1:58:55" +"%V%a"

52Sun

$ date -d "2018-12-31T1:58:55" +"%V%a"

01Mon


Same issue without time string



$ date -d "2018-12-31" +"%V%a"

01Mon






linux command-line date






share|improve this question









New contributor




George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited yesterday









Jesse_b

11.1k22962




11.1k22962






New contributor




George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked yesterday









George Shafer

1024




1024




New contributor




George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






George Shafer is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 7




    "Date Command Gives Wrong Week Number for Dec 31" – "Wrong" according to which specification? Is the specification you are using the same one that the manual for date says it is using?
    – Jörg W Mittag
    yesterday






  • 2




    Excel week number inconsistent results, Excel weeknum function returns wrong week, UI calendar shows wrong week number
    – phuclv
    yesterday






  • 2




    You might be interested in Why does the MonthCalendar control show the wrong week numbers in Romania? The blog post is about Windows, but the issue being discussed is general (and seems to be the same as what you are encountering).
    – a CVn
    21 hours ago












  • "The computer must be wrong, because I obviously didn't make a mistake!" reminds me of when I complained that the FORTRAN IV compiler must have a bug, because my first simple program couldn't have any errors...
    – RonJohn
    2 hours ago














  • 7




    "Date Command Gives Wrong Week Number for Dec 31" – "Wrong" according to which specification? Is the specification you are using the same one that the manual for date says it is using?
    – Jörg W Mittag
    yesterday






  • 2




    Excel week number inconsistent results, Excel weeknum function returns wrong week, UI calendar shows wrong week number
    – phuclv
    yesterday






  • 2




    You might be interested in Why does the MonthCalendar control show the wrong week numbers in Romania? The blog post is about Windows, but the issue being discussed is general (and seems to be the same as what you are encountering).
    – a CVn
    21 hours ago












  • "The computer must be wrong, because I obviously didn't make a mistake!" reminds me of when I complained that the FORTRAN IV compiler must have a bug, because my first simple program couldn't have any errors...
    – RonJohn
    2 hours ago








7




7




"Date Command Gives Wrong Week Number for Dec 31" – "Wrong" according to which specification? Is the specification you are using the same one that the manual for date says it is using?
– Jörg W Mittag
yesterday




"Date Command Gives Wrong Week Number for Dec 31" – "Wrong" according to which specification? Is the specification you are using the same one that the manual for date says it is using?
– Jörg W Mittag
yesterday




2




2




Excel week number inconsistent results, Excel weeknum function returns wrong week, UI calendar shows wrong week number
– phuclv
yesterday




Excel week number inconsistent results, Excel weeknum function returns wrong week, UI calendar shows wrong week number
– phuclv
yesterday




2




2




You might be interested in Why does the MonthCalendar control show the wrong week numbers in Romania? The blog post is about Windows, but the issue being discussed is general (and seems to be the same as what you are encountering).
– a CVn
21 hours ago






You might be interested in Why does the MonthCalendar control show the wrong week numbers in Romania? The blog post is about Windows, but the issue being discussed is general (and seems to be the same as what you are encountering).
– a CVn
21 hours ago














"The computer must be wrong, because I obviously didn't make a mistake!" reminds me of when I complained that the FORTRAN IV compiler must have a bug, because my first simple program couldn't have any errors...
– RonJohn
2 hours ago




"The computer must be wrong, because I obviously didn't make a mistake!" reminds me of when I complained that the FORTRAN IV compiler must have a bug, because my first simple program couldn't have any errors...
– RonJohn
2 hours ago










2 Answers
2






active

oldest

votes

















up vote
42
down vote



accepted










This is giving you the ISO week which starts on Monday's




The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2004) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.








An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days. The extra week is sometimes referred to as a leap week, although ISO 8601 does not use this term.



Weeks start with Monday. Each week's year is the Gregorian year in which the Thursday falls. The first week of the year, hence, always contains 4 January. ISO week year numbering therefore slightly deviates from the Gregorian for some days close to 1 January.






If you want to show 12/31 as week 52 you should use %U which does not use the ISO standard:



$ date -d "2018-12-31T1:58:55" +"%V%a"
01Mon
$ date -d "2018-12-31T1:58:55" +"%U%a"
52Mon





share|improve this answer





















  • Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
    – George Shafer
    10 hours ago


















up vote
2
down vote













The definition of the week number is different between Europe and the USA, probably ISO versus ANSI standards. This may be related to a week being Sunday--Saturday or Monday--Sunday, and this again may be related to the Jewish versus Christian definition of the Lord's Day (Sabbath vs Sunday).



For Europe, week number 1 contains the first Thursday in January, and thus it contains a minimum of 4 days (i.e. a majority) belonging to the new year (Thu-Fri-Sat-Sun).



Anyway, in such years when ALL (!!) week numbers are +/- 1 different between Europe and the USA this gives great fun with setting schedules in multi-national companies. :-)






share|improve this answer








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StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    42
    down vote



    accepted










    This is giving you the ISO week which starts on Monday's




    The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2004) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.








    An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days. The extra week is sometimes referred to as a leap week, although ISO 8601 does not use this term.



    Weeks start with Monday. Each week's year is the Gregorian year in which the Thursday falls. The first week of the year, hence, always contains 4 January. ISO week year numbering therefore slightly deviates from the Gregorian for some days close to 1 January.






    If you want to show 12/31 as week 52 you should use %U which does not use the ISO standard:



    $ date -d "2018-12-31T1:58:55" +"%V%a"
    01Mon
    $ date -d "2018-12-31T1:58:55" +"%U%a"
    52Mon





    share|improve this answer





















    • Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
      – George Shafer
      10 hours ago















    up vote
    42
    down vote



    accepted










    This is giving you the ISO week which starts on Monday's




    The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2004) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.








    An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days. The extra week is sometimes referred to as a leap week, although ISO 8601 does not use this term.



    Weeks start with Monday. Each week's year is the Gregorian year in which the Thursday falls. The first week of the year, hence, always contains 4 January. ISO week year numbering therefore slightly deviates from the Gregorian for some days close to 1 January.






    If you want to show 12/31 as week 52 you should use %U which does not use the ISO standard:



    $ date -d "2018-12-31T1:58:55" +"%V%a"
    01Mon
    $ date -d "2018-12-31T1:58:55" +"%U%a"
    52Mon





    share|improve this answer





















    • Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
      – George Shafer
      10 hours ago













    up vote
    42
    down vote



    accepted







    up vote
    42
    down vote



    accepted






    This is giving you the ISO week which starts on Monday's




    The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2004) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.








    An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days. The extra week is sometimes referred to as a leap week, although ISO 8601 does not use this term.



    Weeks start with Monday. Each week's year is the Gregorian year in which the Thursday falls. The first week of the year, hence, always contains 4 January. ISO week year numbering therefore slightly deviates from the Gregorian for some days close to 1 January.






    If you want to show 12/31 as week 52 you should use %U which does not use the ISO standard:



    $ date -d "2018-12-31T1:58:55" +"%V%a"
    01Mon
    $ date -d "2018-12-31T1:58:55" +"%U%a"
    52Mon





    share|improve this answer












    This is giving you the ISO week which starts on Monday's




    The ISO week date system is effectively a leap week calendar system that is part of the ISO 8601 date and time standard issued by the International Organization for Standardization (ISO) since 1988 (last revised in 2004) and, before that, it was defined in ISO (R) 2015 since 1971. It is used (mainly) in government and business for fiscal years, as well as in timekeeping. This was previously known as "Industrial date coding". The system specifies a week year atop the Gregorian calendar by defining a notation for ordinal weeks of the year.








    An ISO week-numbering year (also called ISO year informally) has 52 or 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366 days. The extra week is sometimes referred to as a leap week, although ISO 8601 does not use this term.



    Weeks start with Monday. Each week's year is the Gregorian year in which the Thursday falls. The first week of the year, hence, always contains 4 January. ISO week year numbering therefore slightly deviates from the Gregorian for some days close to 1 January.






    If you want to show 12/31 as week 52 you should use %U which does not use the ISO standard:



    $ date -d "2018-12-31T1:58:55" +"%V%a"
    01Mon
    $ date -d "2018-12-31T1:58:55" +"%U%a"
    52Mon






    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered yesterday









    Jesse_b

    11.1k22962




    11.1k22962












    • Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
      – George Shafer
      10 hours ago


















    • Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
      – George Shafer
      10 hours ago
















    Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
    – George Shafer
    10 hours ago




    Thanks. That is what I was looking for. I used a much more convoluted method with the cal command.
    – George Shafer
    10 hours ago












    up vote
    2
    down vote













    The definition of the week number is different between Europe and the USA, probably ISO versus ANSI standards. This may be related to a week being Sunday--Saturday or Monday--Sunday, and this again may be related to the Jewish versus Christian definition of the Lord's Day (Sabbath vs Sunday).



    For Europe, week number 1 contains the first Thursday in January, and thus it contains a minimum of 4 days (i.e. a majority) belonging to the new year (Thu-Fri-Sat-Sun).



    Anyway, in such years when ALL (!!) week numbers are +/- 1 different between Europe and the USA this gives great fun with setting schedules in multi-national companies. :-)






    share|improve this answer








    New contributor




    StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






















      up vote
      2
      down vote













      The definition of the week number is different between Europe and the USA, probably ISO versus ANSI standards. This may be related to a week being Sunday--Saturday or Monday--Sunday, and this again may be related to the Jewish versus Christian definition of the Lord's Day (Sabbath vs Sunday).



      For Europe, week number 1 contains the first Thursday in January, and thus it contains a minimum of 4 days (i.e. a majority) belonging to the new year (Thu-Fri-Sat-Sun).



      Anyway, in such years when ALL (!!) week numbers are +/- 1 different between Europe and the USA this gives great fun with setting schedules in multi-national companies. :-)






      share|improve this answer








      New contributor




      StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.




















        up vote
        2
        down vote










        up vote
        2
        down vote









        The definition of the week number is different between Europe and the USA, probably ISO versus ANSI standards. This may be related to a week being Sunday--Saturday or Monday--Sunday, and this again may be related to the Jewish versus Christian definition of the Lord's Day (Sabbath vs Sunday).



        For Europe, week number 1 contains the first Thursday in January, and thus it contains a minimum of 4 days (i.e. a majority) belonging to the new year (Thu-Fri-Sat-Sun).



        Anyway, in such years when ALL (!!) week numbers are +/- 1 different between Europe and the USA this gives great fun with setting schedules in multi-national companies. :-)






        share|improve this answer








        New contributor




        StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.









        The definition of the week number is different between Europe and the USA, probably ISO versus ANSI standards. This may be related to a week being Sunday--Saturday or Monday--Sunday, and this again may be related to the Jewish versus Christian definition of the Lord's Day (Sabbath vs Sunday).



        For Europe, week number 1 contains the first Thursday in January, and thus it contains a minimum of 4 days (i.e. a majority) belonging to the new year (Thu-Fri-Sat-Sun).



        Anyway, in such years when ALL (!!) week numbers are +/- 1 different between Europe and the USA this gives great fun with setting schedules in multi-national companies. :-)







        share|improve this answer








        New contributor




        StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.









        share|improve this answer



        share|improve this answer






        New contributor




        StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.









        answered 19 hours ago









        StessenJ

        1291




        1291




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        New contributor





        StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.






        StessenJ is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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