Cronjob running at wrong interval

Question

I have the following cron in my crontab:

0 5 * * * wget -q -O /dev/null http://www.mysite.com/crontask.php

From what I understand, this is to run at 5am every day and only once. However, I have noticed JUST today that it is running every 15 minutes from 5am. I did edit the crontab yesterday on a different cron job so i'm wondering if perhaps that has caused some sort of knock-on effect which make the system interpret the line above different when it 'installed'.

Running Centos.

As a responce to a query below. Here is a sample of the apache log (notice the incorrect time). I have masked the server IP address for security:

SERVERIPADDRESS - - [02/Mar/2011:05:15:04 +0000] "GET /crontask.php HTTP/1.0" 200 523 "-" "Wget/1.11.4 Red Hat modified" www.mysite.com

Here is the original:

SERVERIPADDRESS - - [02/Mar/2011:05:00:02 +0000] "GET /crontask.php HTTP/1.0" 200 523 "-" "Wget/1.11.4 Red Hat modified" www.mysite.com

Answer 1

Pablo's answer above makes great sense to me. It would also be helpful to check what cron is logging about this job. On an unmodified CentOS box, cron should log in /var/log/cron, so you should have some record of whether it's your job running at other intervals, or someone else's cron kicking this off.

If this file doesn't exist, your syslog.conf setup may be non-standard. Assuming it's not, you should see an entry like

Mar  2 05:00:01 servername crond[xxxxx]: (root) CMD (wget -q -O /dev/null http://www.mysite.com/crontask.php)

Do you see that, and what other comparable entries do you see?

In addition, and please forgive the comment, but I notice that in your time on SF, you've asked six questions and accepted the answers for none. Local etiquette is that you should accept the most-satisfactory answer for each question you ask, after a suitable period, by clicking on the tick outline next to the answer, and this helps drive the SF reputation system. It may be that none of your questions has a satisfactory answer, in which case I apologise for mentioning this; but we all see a red logo by your userID saying "0% accept rate", and this may discourage others from answering your questions in future. If you had a moment to revisit your earlier questions and review the answers, it would be helpful.

Answer 2

Your cron looks correct to me.

I would guess there is another cron on your system that might be calling this.

Check /etc/crontab and /var/spool/cron

It may be there is a cron running as another user account.

http://www.centos.org/docs/5/html/Deployment_Guide-en-US/ch-autotasks.html

Hope this helps you.