Commands:

-n, --now

Display the current date/time

-d, --date=value

Parse an ISO 8601 date/time (for example, '2019-09-24 00:30:00 +01:00' or '2019-040')

-p, --period=value

Parse an ISO 8601 period (interval) with start time (for example, '2005-040/2005-043')

-D, --duration=value

Parse an ISO 8601 duration (for example, 'P1M')

-E, --expected=value

Exit with error status if result does not match this text. Requires: -n or -d

Output Modifiers:

-s, --seconds

Show result as a seconds since 0000-001 00:00:00Z

-S, --epoch

Show result as a seconds since EPOCH (1970-001 00:00:00Z)

-L, --local

Show result as a 'local' date/time

-O, --ordinal

Show result as an 'ordinal' date/time

-W, --week

Show result as an 'calendar week' date/time

For more information on the ISO 8601 standard, see https://en.wikipedia.org/wiki/ISO_8601