How to get UTC timestamp in Ruby?

How to get UTC timestamp in Ruby?

You could use: Time.now.to_i.

time = Time.now.getutc

Rationale: In my eyes a timestamp is exactly that: A point in time. This can be accurately represented with an object. If you need anything else, a scalar value, e.g. seconds since the Unix epoch, 100-ns intervals since 1601 or maybe a string for display purposes or storing the timestamp in a database, you can readily get that from the object. But that depends very much on your intended use.

Saying that »a true timestamp is the number of seconds since the Unix epoch« is a little missing the point, as that is one way of representing a point in time, but it also needs additional information to even know that you're dealing with a time and not a number. A Time object solves this problem nicely by representing a point in time and also being explicit about what it is.

The default formatting is not very useful, in my opinion. I prefer ISO8601 as it's sortable, relatively compact and widely recognized:

>> require 'time'
=> true
>> Time.now.utc.iso8601
=> "2011-07-28T23:14:04Z"

if you need a human-readable timestamp (like rails migration has) ex. "20190527141340"

Time.now.utc.to_formatted_s(:number)  # using Rails

Time.now.utc.strftime("%Y%m%d%H%M%S") # using Ruby

Usually timestamp has no timezone.

% irb
> Time.now.to_i == Time.now.getutc.to_i
=> true

What good is a timestamp with its granularity given in seconds? I find it much more practical working with Time.now.to_f. Heck, you may even throw a to_s.sub('.','') to get rid of the decimal point, or perform a typecast like this: Integer(1e6*Time.now.to_f).

Time.utc(2010, 05, 17)

time = Time.zone.now()

It will work as

irb> Time.zone.now
=> 2017-12-02 12:06:41 UTC

The proper way is to do a Time.now.getutc.to_i to get the proper timestamp amount as simply displaying the integer need not always be same as the utc timestamp due to time zone differences.