[LRUG] Disrespectful cron

[Dominic Mitchell]

On Tue, Feb 13, 2007 at 04:06:01PM +0000, Andrew Stewart wrote:
> Hi Everyone,
> 
> I'm trying to set up cron on a server so that I can clear out old  
> sessions, rotate log files, etc.  I've used cron lots of times before  
> but for some reason can't get it working now.  Is anyone out there  
> good at this sort of thing?
> 
> I've simplified what I'm trying to do as far as I can but am still  
> stuck.  Here it is:
> 
> I have a Ruby script at /home/deploy/cron_test.rb:
> 
>    #!/usr/bin/ruby
>    puts 'Hello'
> 
> Its permissions are 777.  Running 'which ruby' gives /usr/bin/ruby.
> 
> crontab -l gives:
> 
> 35      *      *       *       *       /usr/bin/ruby /home/deploy/ 
> cron_test.rb > /home/deploy/cron.log

If that's a log file, you probably want to say:

  /usr/bin/ruby /home/deploy/cron_test.rb >> /home/deploy/cron.log

Otherwise each run will wipe out the previous file.

> (I update the minutes field every time I try to test cron.)
> 
> Now I would expect cron to fire at 35min past any hour and write  
> 'Hello' to the file /home/deploy/cron.log.  But nothing is written to  
> that file.  In fact the file is not created at all.  Creating it  
> myself and giving it 777 permissions doesn't help either.
> 
> So as far as I can tell cron is not executing my crontab.  cron  
> itself is running as proved by ps aux | grep cron:
> 
> root     32229  0.0  0.3  2480  960 ?        Ss   08:37   0:00 crond
> deploy     950  0.0  0.1  1672  448 pts/0    R+   11:04   0:00 grep cron
> 
> Does anyone have any ideas?

There's normally a log in /var/log/cron.log saying what cron is
attempting to do.  Have a look in there.

Another thing to try is inserting a line in your crontab like this one
so you get mailed any output.

  MAILTO=me at some.where

One last tip -- get rid of any blank lines in the crontab.  They've
caused me trouble in the past.

-Dom