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I will not ask why a timestamp is 1 January 1970 at 00:00 but in several cases in my computer they are 1 January 1970 at 01:00, how did the 01:00 coincidentally get set with a number of apps? enter image description here

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    The 01:00 is unlikely to be set but shown to you due to your local timezone setting.
    – Paul Pazderski
    Commented Jul 30, 2023 at 14:29
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    Timezone? echo "$TZ".
    – waltinator
    Commented Jul 30, 2023 at 14:30
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    Oh I'd expect the epoch time to be midnight local time fore Bell Labs. So if the government in Bourdara removes 14 days from the calendar then epoch time would be not 1 January even...?
    – Niklas Rosencrantz
    Commented Jul 31, 2023 at 6:02
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    Re "I'd expect the epoch time to be midnight local time fore Bell Labs", It's 1970-01-01T00:00:00Z, the "Z" meaning UTC
    – ikegami
    Commented Jul 31, 2023 at 16:34
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    Re "So if the government in Bourdara removes 14 days from the calendar", Then they wouldn't be following the Gregorian calendar like basically the rest of the world, and you have have to figure out how to translate 1970-01-01 into their calendar. Exactly how you have to translate 00:00:00Z into your local time zone if you want to know what the epoch was in your time zone.
    – ikegami
    Commented Jul 31, 2023 at 16:58

1 Answer 1

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The UK government (in its infinite wisdom) decided to experiment with Daylight Saving Time.

It shifted to DST on Sunday, 18 February, 1968, and omitted the shift back that Autumn.

It observed DST all through 1969 and 1970, did nothing in the Spring of 1971, and shifted back to GMT on Sunday, 31 October, 1971.

Therefore, the Unix base time of 0 is correctly shown as 01:00:00 for the UK timezone.

See https://www.timeanddate.com/time/change/uk/london?year=1970

$ date -d @0
Thu  1 Jan 01:00:00 BST 1970
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    I got indirectly caught by this one myself, several years ago — took me ages to track down, as it's so counterintuitive! (British Summer Time, in January???) (BTW, the term ‘daylight saving time’ isn't used in the UK.)
    – gidds
    Commented Jul 31, 2023 at 20:18
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    @gidds I have lived in the UK for 74 years, and I am still mildly surprised that UTC and GMT are the same (in spite of standing on the Prime Meridian at Greenwich). Agreed that BST is British Summer Time (although Summer itself is elusive). But New York has Eastern Time (EST/EDT Standard and Daylight). I understand DST to be the generic term for any seasonal adjustment to local wall clock time. I am also pleased that most of India runs at UTC+5:30, and delighted that Assam uses "Tea Garden Time" at UTC+6:30.
    – Paul_Pedant
    Commented Jul 31, 2023 at 22:51
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    Epoch time 0 (1970-01-01Z00:00:00) was also at 1970-01-01T01:00:00 in many European countries (France, Germany, Poland, Italy...) as they were and still are UTC+01:00 in Winter.
    – Stéphane Chazelas
    Commented Aug 1, 2023 at 9:16
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    ksh93 actually gets the time wrong for epoch 0 in the Europe/London timezone
    – Stéphane Chazelas
    Commented Aug 1, 2023 at 9:24
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    @MikeScott I refer you to Wikipedia articles "Daylight saving time" and "Daylight saving time by country". Even in the USA, DST is a generic term: there are nine US time zones (4 for the 48 states, 3 for territories, plus Alaska and Hawaii). Each has its own acronym (e.g. MDT is Mountain Daylight Time), so DST means nine different offsets from UTC in the US alone. It is not summer time in the UK: it is BST -- British Summer Time.
    – Paul_Pedant
    Commented Aug 2, 2023 at 7:38

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