cron usage

[David Henderson]

Thanks for the continued support Isaac.  So a bit after I wrote that
original email, I came back to the computer and saw that it had
started working.  After making some adjustments to the scripts to get
times, this is what I've come up with...

The difference between when the job was processed (e.g. showing in the
/var/spool/cron/crontabs/root file) vs when the script started
outputting to the target file:
processed: Sat Jan 9 21:46:32 America 2016
started: Sat Jan 9 22:15:00 UTC 2016

Tried with a second cron.d file:
processed: Sat Jan 9 22:28:24 America 2016
started: Sat Jan 9 22:45:00 UTC 2016

Time between removing a file (the first example above) from
/etc/cron.d and processed vs when the script stopped:
processed: Sat Jan 9 22:44:40 America 2016
stopped: Sat Jan 9 23:17:00 UTC 2016

To get the processed time: echo '* * * * * date >> target.txt' >
/etc/cron.d/test1 && date > target.txt
subsequent lines were from cron: * * * * * date >> target.txt

I'll play around with your info below to see if that helps any.

Thanks,
Dave



On 1/9/16, Isaac Dunham <ibid.ag at gmail.com> wrote:
> On Sat, Jan 09, 2016 at 02:40:21PM -0500, David Henderson wrote:
>> While this is simply just a proof of concept, I could not get this to
>> run correctly.  It had to be an obvious two-step approach, so I
>> created an initial root crontab and a small shell script to
>> dynamically create it there afterwards based on the contents of
>> /etc/cron.d.
>>
>> Initial /var/spool/cron/crontabs/root:
>> * * * * * /etc/cron.d/.cron.d
>>
>> /etc/cron.d/.cron.d:
>> #!/bin/sh
>> cat /etc/cron.d/* > /var/spool/cron/crontabs/root
>> echo "* * * * * $0" >> /var/spool/cron/crontabs/root
>>
>> I can see that the actual /var/spool/cron/crontabs/root file continues
>> to dynamically populate based on the contents of /etc/cron.d, however,
>> none of the jobs listed in those files actually runs.  Here's a sample
>> of what would be inside one of them:
>>
>> * * * * * date > /tmp/test1.txt
>>
>> I've also tried with and without usernames and is doesn't work either.
>> Any thoughts?
>
> Looking through the source code, I see:
> - cron will re-examine user crontabs every hour
> - cron will parse and delete cron.update every minute if it exists
> - cron.update is created by 'crontab', and is a simple list of users
> whose cron jobs need to be updated.
>
> In your example, .cron.d would need to have this line at the end:
> echo 'root' >> /var/spool/cron/crontabs/cron.update
>
> If that's not the problem, I've got no ideas.
>
> HTH,
> Isaac Dunham
>