Happy PI day

boing
29

You need to specify your time zone:

$  date -d '20 Jul 2069 16:37:33' +%s
3141589053
$ date -d '20 Jul 2069 16:37:33' -u +%s
3141563853
$ date -d @3141592653 -u
Sun Jul 21 00:37:33 UTC 2069
$ date -d @3141592653
Sat Jul 20 17:37:33 PDT 2069