Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations IamaSherpa on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
Daylight Savings, fall back, coming
- Thread starter dwcasey
- Start date
AIX doesn't modify the system clock in any way at DST changeover dates (nor should any other self-respecting OS do). The system clock runs on GMT or CUT and internally it is just a number of seconds since 1/1/1970 00:00:00.
It is only the way time is displayed that is changed:
Your timezone parameter adds or deducts an amount of seconds to/from the CUT time before converting and displaying the time in human readable form. It is the timezone amount that is changed at DST changeover times.
Please note, cron operates in a system-defined timezone and if that timezone is one that observes DST then yes, at DST to ST changeover it hits times 01:00 to 01:59 twice. At ST to DST changeover it will not hit times 02:00 to 02:59.
It is best not to have any cron schedules between 01:00 and 2:59 or if you do, expect strange stuff to happen at the changeover dates.
Note, for Europe and other continents DST, the changeover dates and times are different than for USA. See this link:
HTH,
p5wizard
It is only the way time is displayed that is changed:
Your timezone parameter adds or deducts an amount of seconds to/from the CUT time before converting and displaying the time in human readable form. It is the timezone amount that is changed at DST changeover times.
Please note, cron operates in a system-defined timezone and if that timezone is one that observes DST then yes, at DST to ST changeover it hits times 01:00 to 01:59 twice. At ST to DST changeover it will not hit times 02:00 to 02:59.
It is best not to have any cron schedules between 01:00 and 2:59 or if you do, expect strange stuff to happen at the changeover dates.
Note, for Europe and other continents DST, the changeover dates and times are different than for USA. See this link:
HTH,
p5wizard
The cron man page is very clear on what happens to cron jobs on the night in question.
In brief:-
In the autumnal change any job between 01:00 and 02:00 inclusive will run twice
In the vernal change jobs between 02:01 and 02:59 inclusive will be missed.
On the internet no one knows you're a dog
Columb Healy
In brief:-
In the autumnal change any job between 01:00 and 02:00 inclusive will run twice
In the vernal change jobs between 02:01 and 02:59 inclusive will be missed.
On the internet no one knows you're a dog
Columb Healy
- Thread starter
- #4
- Status