Cron cleared after every 5 days

dushyantg · 04-06-2020, 02:39 AM

Hi

I have created a cron job which executes every 3 mins. its working fine after starting for 5 days than it automatically got stopped. when I checked crontab it was blank.

my crontab is like below

*/3 * * * * /home/test.sh

It is working continuous 5 days and that got stopped automatically and line which I have added in crontab
"*/3 * * * * /home/test.sh" is not there.

there is no error in cron logs too.

Please suggest/guide me what should I do?

Thanks.

berndbausch · 04-06-2020, 03:50 AM

I see two interesting paragraphs in the manual page.

Quote:

There are two ways how changes in crontables are checked. The first
method is checking the modtime of a file. The second method is using
the inotify support. Using of inotify is logged in the /var/log/cron
log after the daemon is started. The inotify support checks for
changes in all crontables and accesses the hard disk only when a
change is detected.

If cron can be notified with inotify, so can you.

And the debug flags:

Quote:

crond -x [ext,sch,proc,pars,load,misc,test,bit]

I am not sure what they mean, but perhaps you can find out?

TB0ne · 04-06-2020, 08:36 AM

Quote:

Originally Posted by dushyantg

Hi
I have created a cron job which executes every 3 mins. its working fine after starting for 5 days than it automatically got stopped. when I checked crontab it was blank.

my crontab is like below

*/3 * * * * /home/test.sh

It is working continuous 5 days and that got stopped automatically and line which I have added in crontab
"*/3 * * * * /home/test.sh" is not there.

there is no error in cron logs too. Please suggest/guide me what should I do?

First, you are not providing any details that would clarify things. What version/distro of Linux? What is actually IN that test.sh file? And does this have anything to do with your other cron thread?
https://www.linuxquestions.org/quest...on-4175669153/

Messing with permissions/attributes on system-level things (like cron), isn't a good idea. And just reading your question tells you the answer...you say yourself that the line you added **WAS MISSING FROM CRON**. That would certainly explain why the job isn't running, wouldn't it??

dushyantg · 04-08-2020, 04:50 AM

Quote:

Originally Posted by TB0ne

First, you are not providing any details that would clarify things. What version/distro of Linux? What is actually IN that test.sh file? And does this have anything to do with your other cron thread?
https://www.linuxquestions.org/quest...on-4175669153/

Messing with permissions/attributes on system-level things (like cron), isn't a good idea. And just reading your question tells you the answer...you say yourself that the line you added **WAS MISSING FROM CRON**. That would certainly explain why the job isn't running, wouldn't it??

I am using CentOS 7. yes lines were automatically get wiped after every 5 days. when my DB was down and I have check the status of crontab it was not having the lines which I have added there. after that I have checked cron logs but it was not having any details or error related to that.

TB0ne · 04-08-2020, 07:46 AM

Quote:

Originally Posted by dushyantg

I am using CentOS 7. yes lines were automatically get wiped after every 5 days. when my DB was down and I have check the status of crontab it was not having the lines which I have added there. after that I have checked cron logs but it was not having any details or error related to that.

So we're back to the obvious answer to your initial question: the cron job didn't run because **IT WAS NOT THERE**. And the only way that can happen is if someone deleted the jobs. Even doing a system update won't erase a crontab file.

You haven't said whether this relates to your other cron related thread or not (mentioned previously), or why you were messing with attributes/permissions on a system level thing like cron. You also haven't said what's in that shell script you're running either. Is this CentOS machine real or virtual? Hosted? Updated recently? Restating your question doesn't provide new information.