How do you convert a Unix timestamp (seconds since epoch) to Ruby DateTime?
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 > require 'date'
=> true
ruby-1.9.2-p180 :002 > Time.at(1318996912).to_datetime
=> #<DateTime: 2011-10-18T23:01:52-05:00 (13261609807/5400,-5/24,2299161)>
Further update (for UTC):
ruby-1.9.2-p180 :003 > Time.at(1318996912).utc.to_datetime
=> #<DateTime: 2011-10-19T04:01:52+00:00 (13261609807/5400,0/1,2299161)>
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
# => ruby 2.1.5p273 (2014-11-13 revision 48405) [x86_64-darwin13.0]
irb(main):038:0> Benchmark.measure do
irb(main):039:1* ["1318996912", "1318496912"].each do |s|
irb(main):040:2* DateTime.strptime(s, '%s')
irb(main):041:2> end
irb(main):042:1> end
=> #<Benchmark ... @real=2.9e-05 ... @total=0.0>
irb(main):044:0> Benchmark.measure do
irb(main):045:1> [1318996912, 1318496912].each do |i|
irb(main):046:2> DateTime.strptime(i.to_s, '%s')
irb(main):047:2> end
irb(main):048:1> end
=> #<Benchmark ... @real=2.0e-05 ... @total=0.0>
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> end
irb(main):054:1> end
=> #<Benchmark ... @real=1.5e-05 ... @total=0.0>
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> end
irb(main):060:1> end
=> #<Benchmark ... @real=2.0e-05 ... @total=0.0>