Title here
Summary here
Epoch in Erlang
A common requirement in programs is getting the number of seconds, milliseconds, or nanoseconds since the Unix epoch. Here’s how to do it in Erlang.
-module(epoch).
-export([main/0]).
main() ->
% Use erlang:system_time/1 to get elapsed time since the Unix epoch
% in seconds, milliseconds or nanoseconds.
Now = erlang:system_time(second),
io:format("~p~n", [calendar:system_time_to_universal_time(Now)]),
io:format("~p~n", [erlang:system_time(second)]),
io:format("~p~n", [erlang:system_time(millisecond)]),
io:format("~p~n", [erlang:system_time(nanosecond)]),
% You can also convert integer seconds or nanoseconds
% since the epoch into the corresponding datetime.
SecondsSinceEpoch = erlang:system_time(second),
NanosSinceEpoch = erlang:system_time(nanosecond),
io:format("~p~n", [calendar:system_time_to_universal_time(SecondsSinceEpoch)]),
io:format("~p~n", [calendar:system_time_to_universal_time(NanosSinceEpoch, nanosecond)]).To run the program:
$ erlc epoch.erl
$ erl -noshell -s epoch main -s init stop
{{2023,5,15},{12,34,56}}
1684154096
1684154096123
1684154096123456789
{{2023,5,15},{12,34,56}}
{{2023,5,15},{12,34,56}}In Erlang, we use erlang:system_time/1 to get the current system time in various units. The calendar:system_time_to_universal_time/1 and calendar:system_time_to_universal_time/2 functions are used to convert system time to datetime tuples.
Next, we’ll look at another time-related task: time parsing and formatting.