How to convert a unix timestamp seconds since epoch to Ruby DateTime

Question

How do you convert a Unix timestamp  seconds since epoch  to Ruby DateTime

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Time Zone Handling  I just want to clarify  even though this has been commented so future people don t miss this very important distinction   DateTime strptime  1318996912    s       gt  Wed  19 Oct 2011 04 01 52  0000   displays a return value in UTC and requires the seconds to be a String and outputs a UTC Time object  whereas  Time at 1318996912      gt  2011-10-19 00 01 52 -0400   displays a return value in the LOCAL time zone  normally requires a FixNum argument  but the Time object itself is still in UTC even though the display is not    So even though I passed the same integer to both methods  I seemingly two different results because of how the class   to s method works  However  as  Eero had to remind me twice of   Time at 1318996912     DateTime strptime  1318996912    s       gt  true   An equality comparison between the two return values still returns true  Again  this is because the values are basically the same  although different classes  the     method takes care of this for you   but the  to s method prints drastically different strings  Although  if we look at the strings  we can see they are indeed the same time  just printed in different time zones   Method Argument Clarification  The docs also say  If a numeric argument is given  the result is in local time   which makes sense  but was a little confusing to me because they don t give any examples of non-integer arguments in the docs  So  for some non-integer argument examples   Time at  1318996912   TypeError  can t convert String into an exact number   you can t use a String argument  but you can use a Time argument into Time at and it will return the result in the time zone of the argument   Time at Time new 2007 11 1 15 25 0    09 00      gt  2007-11-01 15 25 00  0900   Benchmarks  After a discussion with  AdamEberlin on his answer  I decided to publish slightly changed benchmarks to make everything as equal as possible  Also  I never want to have to build these again so this is as good a place as any to save them   Time at int  to datetime   2 8x faster  09 10 58-watsw018    ruby -v ruby 2 3 7p456  2018-03-28 revision 63024   universal x86 64-darwin18  09 11 00-watsw018    irb irb main  001 0 gt  require  benchmark    gt  true irb main  002 0 gt  require  date    gt  true irb main  003 0 gt  irb main  004 0  format     s    gt    s  irb main  005 0 gt  times     1318996912    1318496913     gt    1318996912    1318496913   irb main  006 0 gt  int times   times map  amp  to i    gt   1318996912  1318496913  irb main  007 0 gt  irb main  008 0  datetime from strptime   DateTime strptime times first  format    gt    lt DateTime  2011-10-19T04 01 52 00 00   2455854j 14512s 0n   0s 2299161j  gt  irb main  009 0 gt  datetime from time   Time at int times first  to datetime   gt    lt DateTime  2011-10-19T00 01 52-04 00   2455854j 14512s 0n  -14400s 2299161j  gt  irb main  010 0 gt  irb main  011 0  datetime from strptime     datetime from time   gt  true irb main  012 0 gt  irb main  013 0  Benchmark measure do irb main  014 1    100 000 times   irb main  015 2      times each do  i  irb main  016 3        DateTime strptime i  format  irb main  017 3 gt      end irb main  018 2 gt      irb main  019 1 gt  end   gt    lt Benchmark  Tms 0x00007fbdc18f0d28  label      real 0 8680500000045868   cstime 0 0   cutime 0 0   stime 0 009999999999999998   utime 0 86   total 0 87 gt  irb main  020 0 gt  irb main  021 0  Benchmark measure do irb main  022 1    100 000 times   irb main  023 2      int times each do  i  irb main  024 3        Time at i  to datetime irb main  025 3 gt      end irb main  026 2 gt      irb main  027 1 gt  end   gt    lt Benchmark  Tms 0x00007fbdc3108be0  label      real 0 33059399999910966   cstime 0 0   cutime 0 0   stime 0 0   utime 0 32000000000000006   total 0 32000000000000006 gt        edited to not be completely and totally incorrect in every way          added benchmarks

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Sorry  brief moment of synapse failure  Here s the real answer   require  date   Time at seconds since epoch integer  to datetime   Brief example  this takes into account the current system timezone      date   s 1318996912    irb  ruby-1 9 2-p180  001  gt  require  date     gt  true   ruby-1 9 2-p180  002  gt  Time at 1318996912  to datetime    gt    lt DateTime  2011-10-18T23 01 52-05 00  13261609807 5400 -5 24 2299161  gt     Further update  for UTC    ruby-1 9 2-p180  003  gt  Time at 1318996912  utc to datetime    gt    lt DateTime  2011-10-19T04 01 52 00 00  13261609807 5400 0 1 2299161  gt    Recent Update  I benchmarked the top solutions in this thread while working on a HA service a week or two ago  and was surprised to find that Time at     outperforms DateTime strptime      update  added more benchmarks          ruby -v      gt  ruby 2 1 5p273  2014-11-13 revision 48405   x86 64-darwin13 0   irb main  038 0 gt  Benchmark measure do irb main  039 1      1318996912    1318496912   each do  s  irb main  040 2      DateTime strptime s    s   irb main  041 2 gt    end irb main  042 1 gt  end    gt    lt Benchmark      real 2 9e-05      total 0 0 gt   irb main  044 0 gt  Benchmark measure do irb main  045 1 gt     1318996912  1318496912  each do  i  irb main  046 2 gt      DateTime strptime i to s    s   irb main  047 2 gt    end irb main  048 1 gt  end    gt    lt Benchmark      real 2 0e-05      total 0 0 gt   irb main  050 0  Benchmark measure do irb main  051 1      1318996912    1318496912   each do  s  irb main  052 2      Time at s to i  to datetime irb main  053 2 gt    end irb main  054 1 gt  end    gt    lt Benchmark      real 1 5e-05      total 0 0 gt   irb main  056 0  Benchmark measure do irb main  057 1     1318996912  1318496912  each do  i  irb main  058 2      Time at i  to datetime irb main  059 2 gt    end irb main  060 1 gt  end    gt    lt Benchmark      real 2 0e-05      total 0 0 gt

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This tells you the date of the number of seconds in future from the moment you execute the code   time   Time new   1000000000  date in 1 billion seconds   puts time    according to the current time I am answering the question it prints 047-05-14 05 16 16  0000  1 billion seconds in future   or if you want to count billion seconds from a particular time  it s in format Time mktime year  month date hours minutes   time   Time mktime 1987 8 18 6 45    1000000000   puts  I would be 1 Billion seconds old on    time

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DateTime strptime can handle seconds since epoch  The number must be converted to a string   require  date  DateTime strptime  1318996912    s

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One command to convert date time to Unix format and then to string      DateTime strptime Time now utc to i to s   s   strftime   d  m  y        Time now utc to i  Converts time from Unix format     DateTime strptime Time now utc to i to s   s    Converts date and time from unix format to DateTime   finally strftime is used to format date  Example       irb main  034 0 gt  DateTime strptime  1410321600    s   strftime   d  m  y        10 09 14

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If you wanted just a Date  you can do Date strptime invoice date to s    s   where invoice date comes in the form of anFixnum and then converted to a String

[ruby] How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?

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