crond problem

branden_burger · 03-24-2005, 03:44 PM

what happens if I put in a */100 in the minutes field of /etc/crontab for a certain command to be run? I mean, my intention was to run it every 100 minutes, but it turns out that you can only have integers from 0-59 in that field.

thanks

acid_kewpie · 03-25-2005, 03:57 AM

well it never runs, as there's no hundredth minute... maybe run it every 120 minutes? so for hours it's */2

homey · 03-25-2005, 11:15 AM

The results may suprise you.

I made a little script and ran it as root user ( su - ) in my crontab.
First, I ran it every minute
* * * * * /home/test

This also ran every minute
*/1 * * * * /home/test

Then I ran it every ten minutes
*/10 * * * * /home/test

Then I put in the */100

*/100 * * * * /home/test

The first thing I noticed was this message...

# crontab -e
crontab: installing new crontab
You have new mail in /var/spool/mail/root

I checked the mail and it's not an error message,
but the fact that it sends an email when I used the bogus input
indicates that the crontab may be confused.

As this partial ls -al shows, the new cron job now ran at every hour

I guess that the minutes field is ignored because it is invalid. That field needs to be a value between zero and 59 .

Code:

-rw-r--r--   1 root   root   3177714 Mar 25 10:30 1030.tar.gz
-rw-r--r--   1 root   root   3177714 Mar 25 10:40 1040.tar.gz
-rw-r--r--   1 root   root   3177714 Mar 25 11:00 1100.tar.gz
-rw-r--r--   1 root   root   3177714 Mar 25 12:00 1200.tar.gz

Code:

 
#!/bin/bash
filename=`date '+%H%M'`
cd /home/images

/bin/tar -cvzf /home/${filename}.tar.gz .

branden_burger · 03-25-2005, 05:03 PM

Well, what do you know, that's what I found out too! Nice - in case you do have a job which is critical to have done, it doesn't not do it at all.

Thanks!