Need some CRON help

davidstvz · 05-21-2010, 11:34 AM

I've done some reading about CRON and I can't seem to find a good resource that explains it. In particular, there seems to be a system level CRON and then individual user CRON, and also ways to run things as root from the individual user CRON. I haven't seen a page that explains both together and suggests the most appropriate way to use it.

I wouldn't have thought this would be all that confusing.

So, how should I be using CRON and can anyone recommend a page with a good explanation of it?

I'm using Debian (Lenny) btw.

fruttenboel · 05-21-2010, 12:08 PM

Quote:

Originally Posted by davidstvz

I've done some reading about CRON and I can't seem to find a good resource that explains it. In particular, there seems to be a system level CRON and then individual user CRON, and also ways to run things as root from the individual user CRON. I haven't seen a page that explains both together and suggests the most appropriate way to use it.

I wouldn't have thought this would be all that confusing.

So, how should I be using CRON and can anyone recommend a page with a good explanation of it?

I'm using Debian (Lenny) btw.

Visit my website http://fruttenboel.verhoeven272.nl/linux/index.html and click on the two entries for 'Crontab' in the navigator frame.

http://fruttenboel.verhoeven272.nl/linux/crontab.html
http://seerofsouls.com/wiki/How-Tos/Crontab

That explains more than I can tell here in a short message.

Never edit the crontab files manually. Always use the vi front end.

davidstvz · 06-02-2010, 01:07 PM

I looked at those pages now that I have some time, and it's pretty straightforward.

However, is there some system level crontab that isn't tied to a specific user?

If I want to run things as root, should I just switch to root and edit root's crontab?

As an example, these files are in etc but I have trouble finding documentation of them:

Code:

drwxr-xr-x 2 root root 4.0K 2009-10-29 16:58 cron.d
drwxr-xr-x 2 root root 4.0K 2010-04-30 13:13 cron.daily
drwxr-xr-x 2 root root 4.0K 2007-12-25 13:20 cron.hourly
drwxr-xr-x 2 root root 4.0K 2007-12-25 13:20 cron.monthly
-rw-r--r-- 1 root root  724 2008-09-28 06:07 crontab
drwxr-xr-x 2 root root 4.0K 2009-11-12 17:04 cron.weekly

HasC · 06-02-2010, 01:29 PM

Quote:

Originally Posted by davidstvz

However, is there some system level crontab that isn't tied to a specific user?

/etc/crontab

Quote:

Originally Posted by davidstvz

If I want to run things as root, should I just switch to root and edit root's crontab?

How's "run as root"? As user root? or you want to run system-wide programs? For the latter, just edit /etc/crontab, or add entries in /etc/cron.d

Quote:

Originally Posted by davidstvz

As an example, these files are in etc but I have trouble finding documentation of them:

Code:

drwxr-xr-x 2 root root 4.0K 2009-10-29 16:58 cron.d
drwxr-xr-x 2 root root 4.0K 2010-04-30 13:13 cron.daily
drwxr-xr-x 2 root root 4.0K 2007-12-25 13:20 cron.hourly
drwxr-xr-x 2 root root 4.0K 2007-12-25 13:20 cron.monthly
-rw-r--r-- 1 root root  724 2008-09-28 06:07 crontab
drwxr-xr-x 2 root root 4.0K 2009-11-12 17:04 cron.weekly

The dirs cron.{hourly,daily,weekly,monthly} contains scripts meant to be run at certain moments (the directory names says it all

.
crontab and cron.d are the "system-wide" crontabs

davidstvz · 06-02-2010, 01:47 PM

I guess that's relatively straightforward then. Now I'm not even sure what trouble I was having in the past.