[root@ root]# date -d '2002-03-31 01:59:59 UTC' +%s
1017539999
[root@ root]# date -d '2002-03-31 02:00:00 UTC' +%s
1017536400
timestamp = prev_timestamp - 3599 ?? Back to the Future ??
[root@ root]# date -d '2002-03-31 03:00:00 UTC' +%s
1017543600
timestamp = prev_timestamp + 7200 ?? Hmmm...
------------------------
[root@ root]# date -u -d '1970-01-01 1017539999 sec'
Sun Mar 31 01:59:59 UTC 2002
[root@ root]# date -u -d '1970-01-01 1017540000 sec'
Sun Mar 31 02:00:00 UTC 2002
02:00:00 not exist time
[root@ root]# date -u -d '1970-01-01 1017543600 sec'
Sun Mar 31 03:00:00 UTC 2002
