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Crontab: Set to run every hour but runs every 15 minutes. Why?

Posted on 2012-03-16
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Last Modified: 2012-06-27
I have the following set in /etc/crontab

40 * * * * root wget -q -O - 'http://www.mydomain.info/script.php' >/dev/null

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To me this command should run every hour at +40 minutes.

For some reason though it runs every 15 minutes.

Can anybody see why?
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Question by:AdrianSmithUK
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Expert Comment

by:woolmilkporc
ID: 37728976
Comment deleted.

wmp
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Author Comment

by:AdrianSmithUK
ID: 37728985
Dear woolmilkporc

That's not what you told me in this post - See accepted solution.

http://www.experts-exchange.com/OS/Linux/Q_26977577.html
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Expert Comment

by:woolmilkporc
ID: 37728991
That's why I deleted my comment - I was totally on the wrong track - don't have much time at this very moment.
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Expert Comment

by:woolmilkporc
ID: 37729016
Sorry again, I obviously confused root's crontab with the system crontab - I've been in a hurry.

Now that our meeting has been cancelled I'm back.

Your cron job should indeed run every 40 minutes. I don't see any obvious reason why it should do something else.

Maybe you should restart the cron daemon, just to be sure?
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Expert Comment

by:legolasthehansy
ID: 37729030
Check as root - "crontab -l"
See if the changes you made reflect on the Cron.
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Author Comment

by:AdrianSmithUK
ID: 37729031
Nice to have you back.

I had is set to:

0 * * * *

And it fired every 15 minutes from the hour. (10:00,  10:15 ...etc)

I changed it to

40 * * * *

Now it fires like this (11:40, 11:55 ...etc)
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Author Comment

by:AdrianSmithUK
ID: 37729045
Dear legolasthehansy

[root ~]# crontab -l
[root ~]# 

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I'm using Centos 6. When I run the command I get nothing.
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Assisted Solution

by:legolasthehansy
legolasthehansy earned 250 total points
ID: 37729049
Strange!

Check Cron logs.
Recreate the cron by deleting the entries and restarting CRON and then re-entering it.
Check if another user is running the same script using cron.
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Expert Comment

by:woolmilkporc
ID: 37729053
"crontab -l" would only work on root's crontab, not on /etc/crontab

Same confusion as mine before.

Did you recycle crond?
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Author Comment

by:AdrianSmithUK
ID: 37729088
Dear legolasthehansy

I looked in /var/log/cron

There is only a record for the hourly cron jobs.

I have Plesk installed. Do you think it could be to blame?
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Assisted Solution

by:woolmilkporc
woolmilkporc earned 250 total points
ID: 37729145
I once read a bug report saying that an empty line just above a job entry could inhbit the correct scheduling of the job.

Could this be the culprit here?
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Expert Comment

by:legolasthehansy
ID: 37729147
Not sure if Plesk has a utility to setup CRON's. But it should still show up on the files.

If you know the users allowed to access this server,
can you do this,

crontab -l <username1> (This would list the CRON's setup by username1)

You can get the list of users in the server by doing a cat on /etc/passwd and get the list of recent logged in users using the 'last' command.
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Accepted Solution

by:
AdrianSmithUK earned 0 total points
ID: 37729376
Chaps,

Thanks for your help.

I never found the solution to the original problem. I tried removing the spare lines, but still had the same problem.

I noticed that plesk runs a backup manager every 15 minutes which might be a clue.

Mar 16 13:16:01 sXXXXXXXX CROND[3453]: (root) CMD ([ -x /usr/local/psa/admin/sbin/backupmng ] && /usr/local/psa/admin/sbin/backupmng >/dev/null 2>&1)
Mar 16 13:31:01 sXXXXXXXX CROND[3453]: (root) CMD ([ -x /usr/local/psa/admin/sbin/backupmng ] && /usr/local/psa/admin/sbin/backupmng >/dev/null 2>&1)

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In the end I gave up and I used the built in plesk feature.

http://myhosting.com/kb/How_to_Set_Up_Scheduled_Tasks_(Cron_Jobs)_in_Plesk_10

I couldn't get it to work though.

In the end I found the problem was that SSH access was switched off for the domain.

Here is the solution:

http://drupal.org/node/1192934
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Author Closing Comment

by:AdrianSmithUK
ID: 37746272
Great Support!
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