Re: cron directory temporaries

On Sun, Nov 25, 2012 at 11:49:45AM +1000, Nick Edwards wrote:
> Does anyone know why /var/spool/cron is full of temporary 
> directories, shouldn't crontab remove them once it puts the
> new crontab in place?

Apparently it does not.

> The directories are actually empty, and the only user on the
> server is root, so surely it can't  be a permissions issue

FWIW I don't recommend this. Even if I am the only one logging in, 
I'll login to a non-root account and use su/sudo when higher 
privileges are needed.

> eg:
> 
> drwxr-xr-x  2 root root  4096 Jul 31 20:55 cron.AoUk2o/
> 
> Any suggestions muchly appreciated.

1. Look in the crond(8) manual.
2. Look in the crontab(1) manual.

I did both of those. I did not see mention of these directories. 
Maybe I missed it.

3. Experiment.

I did that also. I ran crontab -e (as a NON-root user of course) and 
found that a new mode 600 directory owned by that user was created 
under /var/spool/cron/ . When I saved the new crontab the directory 
was renamed (was crontab.AL6dpA and changed to cron.PnvHYt) and chown 
root:root mode 755.

Hmm, a mode 600 directory cannot be entered. I've never seen that. I 
didn't take the time to watch everything that happened in that 
directory during the crontab process. You might find strace(1) of 
interest if you want to do this.

My conclusion: it's sloppy and could be considered a bug. So the 
final suggestion, choose one of these:

4a. Report the issue to the project (I would not call it "bug" at 
first.)
4b. Dig in the code, find where and why this happens. Offer a patch 
to the project if you can and if appropriate.
4c. Make a simple cron.daily job to delete empty directories named 
/var/spool/cron/cron.* and root:root mode 755. See what breaks, if 
anything. :)
4d. Don't worry about it.

My choice: the last one.
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