WHAT IS THE EFFECT OF DAYLIGHT SAVINGS ON CRON

ITEM: RTA000030571



QUESTION:                                                                       
When daylight savings time begins and we lose an hour, what happens to a        
cron job that is set to start at 2:00am? 2:30am?                                
                                                                                
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A:   We tested 'cron' and Daylight Savings Time on AIX version 3.2.  We         
found that a cron job set to start at the same time the time jumps an           
hour forward, or one that is to start within that hour, will not start.         
The two solutions that we offer are as follows:                                 
                                                                                
        *  Do not set a 'cron' job within that time frame.                      
                                                                                
        *  Change the time at which the change in time will occur.  You         
           can find more information about this in InfoExplorer.                
           Search on TZ or daylight.  Basically, your /etc/environment         
           file should have a line like the following:                          
                                                                                
              TZ=CST6CDT,M4.1.0/1:00:00,M10.1.0/1:00:00                         
                                                                                
           Which would change to Daylight Savings Time at 1:00 AM on            
           the first Sunday in April and change back at 1:00 AM on              
           the first Sunday in October.  The breakdown of the phrase            
           is CST6CDT=the time zone you are in; M4=the fourth month;            
           .1=the first occurrence of a day in the month; .0=Sunday;            
           /1:00:00= the time.  You may also use the Julian day of              
           of the year (i.e. March 19,1993 is the Julian day 78).               
                                                                                
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This item was created from library item Q625509      CDLNZ                      
                                                                                
Additional search words:                                                        
$$A APR93 CDLNZ CRON DAYLIGHT EFFECT IX JOBS MANAGEMENT OP RISCMGMT             
RISCSYSTEM SAVINGS SOFTWARE SYS SYSTEM 28                                       
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                                
                                                                               


WWQA: ITEM: RTA000030571 ITEM: RTA000030571
Dated: 03/1996 Category: RISCMGMT
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