[CentOS] the at command

Tue Jan 22 06:20:56 UTC 2013
Chris Geldenhuis <chris.gelden at iafrica.com>

On 01/21/2013 11:46 PM, Jerry Geis wrote:
>> @Jerry:
>> You might explain what it is you are attempting to do or why it is you need
>> to schedule a job down to the second.
> I am looking for a way to "sync" up running a command on 10 boxes at the
> same time.
> So I thought - hey in my program "I can send a command out that I want
> to run - this command is also another program of mine, get the current
> time, add 5 seconds to it, send this time HH:MM:SS
> to all 10 boxes and "schedule" an "at" command to run at that time.
> So all 10 boxes are running NTP and I thought it would be fine then if
> one box got it slightly faster
> than the last it would not matter as the "at" command would schedule the
> command to run
> all at the same time.
> So what mechanizim exists to run command down to the second?
> I'd rather not wait an entire 59 seconds to run the command.
> Thanks,
> Jerry
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Hi Jerry,

AFAIK the at and cron command do a "best effort" to run during the 
minute that you have specified. There is no guarantee that the process 
will kick off at 00 seconds. This all depends on load etc. etc. so that 
scheduling a job to start on an exact second is always going to be a