python - 如何使用 os.environ 在 python 中设置时区

Question

例子:

os.environ['TZ'] = "CST+06CDT,M4.1.0,M10.5.0"

I can understand CST, 06 (offset from UTC ?? or GMT) , CDT == Central Daylight Saving Timebut

What do M4.1.0 and M10.5.0 mean ?

Here is what i found:

export TZ=EST05EDT

EST was taken from the chart below. Five hours has to be added to get UTC, hence the 05. And currently EDT, Eastern Daylight, is in effect.

TZ=.

DST timezones

  0      BST for British Summer.                                
  +400   ADT for Atlantic Daylight.                             
  +500   EDT for Eastern Daylight.                              
  +600   CDT for Central Daylight.                              
  +700   MDT for Mountain Daylight.                             
  +800   PDT for Pacific Daylight.                              
  +900   YDT for Yukon Daylight.                                
  +1000  HDT for Hawaii Daylight.                               
  -100   MEST for Middle European Summer,                       
             MESZ for Middle European Summer,                  
             SST for Swedish Summer and FST for French Summer. 
  -700   WADT for West Australian Daylight.                     
  -1000  EADT for Eastern Australian Daylight.                  
  -1200  NZDT for New Zealand Daylight.                         

有没有更简单的方法来回到我正确的时间？是的，只需取消设置 TZ 环境变量。

  $ unset TZ
  $ date
  Sun Aug 22 10:17:35 EDT 2004

请注意，即使 TZ 已针对夏令时进行了调整，您会在 5 个月后得到正确的时间吗？夏令时何时生效？下面显示的 TZ 值仅在正确的日期期间针对夏令时进行调整。例如，此条目从 4 月第一周凌晨 2 点开始生效，到 10 月第 5 周凌晨 2 点结束。注意 10.5.0 代表十月的第 5 周，而不是第 5 天。

  $ export TZ=EST+5EDT,M4.1.0/2,M10.5.0/2

Answer 1

来自python manual :

The standard format of the TZ environment variable is (whitespace added for clarity):

std offset [dst [offset [,start[/time], end[/time]]]]

Mm.n.d The d‘th day (0 <= d <= 6) or week n of month m of the year (1 <= n <= 5, 1 <= m <= 12, where week 5 means “the last d day in month m” which may occur in either the fourth or the fifth week). Week 1 is the first week in which the d‘th day occurs. Day zero is Sunday.