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Unscheduled crontab execution


 
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# 1  
Old 05-03-2009
Unscheduled crontab execution

Hi All,

Do apologise, for it has been a long while since I was last on the forum. I've been doing documentation and primiarily Windows efforts for some while now. Smilie

We are running a HP-UX 11.23 unit. This morning two separate crontab users executed shutdown scripts of their respective Oracle instance. The script worked (and so it should - I wrote it), however it was the crontab entries that has got me absolutely stumped as to why it ran. Sadly the boss is asking the very same question also.

The entries were as follows:
User#1: 45 2 25 05 0 nice ksh -c "/usr/local/bin/restart_md_v3.1.cron user1 MDAMER ORA stop" >> /usr1/log/user1/cronlog/restart_MDAMER.log 2>&1
..... which is 2:45am 25th May when a Sunday

User#2: 50 2 25 05 0 nice ksh -c "/usr/local/bin/restart_md_v3.1.cron user2 MDEMEA ORA stop" >> /usr1/log/user2/cronlog/restart_MDEMEA.log 2>&1
..... which is 2:50am 25th May when a Sunday

As you can see, neither of the two entries are for today, yet they ran !!

Would anyone have an idea on why these scripts executed or have seen something similar in their travels ???

Cheers,
Cameron
# 2  
Old 05-03-2009
Those crons fire on 25 May and every Sunday.
There is similar example in "man crontab".
Try replacing the day-of-week parameter with an "*" if you want the cron to execute annually on 25 May.
By the way 25 May 2009 is a Monday (it was a Sunday in 2008).
# 3  
Old 05-04-2009
Thanks for the reply methyl.
Yes I do know how to setup crontab entries, but cheers for the reminder.

The question was on the last line.
"Would anyone have an idea on why these scripts executed or have seen something similar in their travels ???"

Cheers,
Cameron
# 4  
Old 05-04-2009
It appears to me that the crontab entry is fine. Howver when it executes it in a wrong time then schedule, it makes me think that
1. the clock isn't right
2. the correct crontab entry is not used. Perhapes there are other crontab entries that was executed. Or do you really if it was initiatated by cron daemon ( or somebody ran the job explicitly).
3. You said two seperate crontab users ran it. Can you check at /var/spool/cron/crontabs and see if there are files created for those two users.


cheers,
Devaraj Takhellambam
# 5  
Old 05-04-2009
Hi Devaraj,
Thanks for the reply & interest.

Clock is ok - first thing I checked.
There are other similar crontab entries, however they run earlier in the evening.
These particular entries I setup last year for a purpose shutdown - I'd just left them there.
Both users have their respective file created in /var/spool/cron/crontabs .

This has me absolutely stumped as to how it even got executed.

Cheers,
Cameron
# 6  
Old 05-04-2009
I agree with methyls answer:
I understand run on may 25 and every sundays (in May...). Depending when you modified your cronfile last year (lets say the 22nd May) you would not have noticed any strange behaviour because the following sunday was ... the 25th... and the last sunday of May...
# 7  
Old 05-04-2009
I can't think of any other reason why it would have executed by itself at the wrong time. Even when the system clock is reset, cron is aborted and restarted. This issue seems to be a timing issue to me..

At this point, you may want to test it with echo commands to check if it is working correctly. test it with those two users.


cheers,
Devaraj Takhellambam
 

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