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need a cron job that runs every wednesday at noon

Posted on 2012-04-11
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Last Modified: 2012-04-17
I need a Linux cron job that runs every Wednesday at noon.
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Question by:cschene
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by:woolmilkporc
woolmilkporc earned 300 total points
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0 12 * * 3 /path/to/command

Add it to your crontab by means of "crontab -e"

wmp
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by:cschene
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I tried it and got this error message:

[root@localhost Carefx]# 0 12 * * 3 /opt/Carefx/crontabtest.sh
bash: 0: command not found
[root@localhost Carefx]# crontab -e
no crontab for root - using an empty one
crontab: no changes made to crontab

[root@localhost Carefx]# 0 12 * * 3 /opt/Carefx/crontabtest.sh <---- this is what I was trying to add
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by:woolmilkporc
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1) Type crontab -e  to open an editor (probably vi) for the crontab.

2) Type i to go to input mode

3) Type the line I gave you

4) Hit the ESC key, then type :wq!

5) Done
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by:cschene
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I did what you suggested but my cron command  never ran. Is there something else I need to configure?
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by:woolmilkporc
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Check your entry with

crontab -l

All corrrect?

Did you receive any emails from cron?

Does the script run successfully from the command line?

There is also a cron log, but its location is OS dependent. Which is your OS ("uname -a")?
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by:cschene
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Here is the output


uname -a
Linux localhost.localdomain 2.6.18-194.el5 #1 SMP Fri Apr 2 14:58:14 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux


 crontab -l
0 17 * * 3 /opt/Carefx/crontabtest.sh
0 12 * * 3 /opt/Carefx/crontabtest.sh

no email, yes the script runs correctly from the command line

I looked for a cron.log...but did not find one


[root@localhost ~]# find / -name 'cron*.log' -print
[root@localhost ~]# find / -name 'cron.log' -print
[root@localhost ~]#

The crond service is running:


[root@localhost init.d]# ./crond
Usage: ./crond {start|stop|status|reload|restart|condrestart}
[root@localhost init.d]# ./crond status
crond (pid  3864) is running...
[root@localhost init.d]#
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Expert Comment

by:woolmilkporc
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What is the script supposed to do? Are you really sure that it didn't run?

Please be aware that under cron the user's environment is not fully initialized (no initialization scripts like .profile etc. are run).

PATH is just /bin and /usr/bin and there are only a few variables set, like $HOME.

So if your script relies on the usual environment you must initialize it explicitly, and you'll have to call all executables which reside outside of /bin or /usr/bin by their full path.

And yes, finding the location of the cron log is always a problem under Linux.
Please search just for *cron*, without any suffix:

find / -name "*cron*"
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by:nmitev
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Probably a permissions issue, if cron is not running as root.

Try modifying the command to
0 12 * * 3  root  /opt/Carefx/crontabtest.sh

Open in new window

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Accepted Solution

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MikeOM_DBA earned 200 total points
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Or, add a trace file to figure out if the script generate an error:
0 12 * * 3 /opt/Carefx/crontabtest.sh >/opt/Carefx/crontabtest.trc 2>&1

Open in new window

:p
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by:cschene
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What does cron do if the machine is not running at the time the job is supposed to run?
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by:woolmilkporc
woolmilkporc earned 300 total points
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Nothing. Cron doesn't account for the past, only for the future.
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Author Comment

by:cschene
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Ok, I think I have idea as to what is happening: It seems that one of my commands errors out  and when that happens, it seems that the cron job aborts...is there a way I can tell it to continue even if there are errors?
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Expert Comment

by:woolmilkporc
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Rather correct the error.

And take care not to start your script with "#!/bin/bash -e" or "#!/bin/bash -u"
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Author Comment

by:cschene
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Thanks experts.....If you don't mind i would like to divide up the points since I was helped by more than one comment.
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Expert Comment

by:woolmilkporc
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No problem, go ahead!

wmp
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Author Comment

by:cschene
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Increase points
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