Cron job 的day saving问题

Changing the effective date to switch to DST

 If you wish to change the date or time at which the system switches to DST and back to Standard Time from the defaults for your zone, edit the TZ line in /etc/environment. Change the line to read something like the following: TZ=CST6CDT,M3.2.0/2:00:00,M11.1.0/2:00:00The above example would effect a change to Daylight Savings Time at 2:00 AM on the second Sunday in March and change back at 2:00 AM on the first Sunday in November, and keep the US Central Time Zone time offset from GMT. The breakdown of the string is: CST6CDT is the time zone you are in; M3 is the third month; .2 is the second occurrence of the day in the month; .0 is Sunday; /1:00:00 is the time. In more detail, the format is TZ = local_timezone,date/time,date/time. Here date is in the form of Mm.n.d, day d(0-6) of week n (1-5, where week 5 means "the last d day in month m" and which may occur in either the fourth or the fifth week) of month m of the year. Week 1 is the first week in which the day d occurs. Day zero is Sunday. This format is compliant with POSIX 1003.1 standards for Extensions to Time Functions. NOTE: This can be changed in the smit chtz panel as well.