For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems, as reported in /var/log/cron: ------------------------- Mar 16 14:01:01 helen crond[27833]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 helen crond[27834]: (root) CMD (run-parts /etc/cron.hourly) ------------------------- On the other it just runs once, as expected. ------------------------- Mar 16 13:01:01 althea crond[23373]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 althea crond[23553]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 15:01:01 althea crond[23695]: (root) CMD (run-parts /etc/cron.hourly) -------------------------
This doesn't have any bad effect, but it does run the scripts in /etc/cron.hourly twice.
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
On Tue, Mar 16, 2010 at 9:15 AM, Timothy Murphy gayleard@eircom.net wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems, as reported in /var/log/cron:
Mar 16 14:01:01 helen crond[27833]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 helen crond[27834]: (root) CMD (run-parts /etc/cron.hourly)
On the other it just runs once, as expected.
Mar 16 13:01:01 althea crond[23373]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 althea crond[23553]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 15:01:01 althea crond[23695]: (root) CMD (run-parts /etc/cron.hourly)
This doesn't have any bad effect, but it does run the scripts in /etc/cron.hourly twice.
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
hourly, daily, weekly and monthly jobs are configured in /etc/crontab. What's your /etc/crontab look like? Are you seeing the same behavior for daily/weekly jobs? Have you simply tried restarting the cron service?
Jeff
On 03/16/2010 10:11 AM, Jeff wrote:
On Tue, Mar 16, 2010 at 9:15 AM, Timothy Murphygayleard@eircom.net wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems, as reported in /var/log/cron:
Mar 16 14:01:01 helen crond[27833]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 helen crond[27834]: (root) CMD (run-parts /etc/cron.hourly)
On the other it just runs once, as expected.
Mar 16 13:01:01 althea crond[23373]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 althea crond[23553]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 15:01:01 althea crond[23695]: (root) CMD (run-parts /etc/cron.hourly)
This doesn't have any bad effect, but it does run the scripts in /etc/cron.hourly twice.
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
hourly, daily, weekly and monthly jobs are configured in /etc/crontab. What's your /etc/crontab look like? Are you seeing the same behavior for daily/weekly jobs? Have you simply tried restarting the cron service?
Also, make sure that cron.hourly is _not_ run from /etc/anacrontab or from any of the crontabs in /var/spool/cron.
Jeff wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems,
hourly, daily, weekly and monthly jobs are configured in /etc/crontab. What's your /etc/crontab look like? Are you seeing the same behavior for daily/weekly jobs? Have you simply tried restarting the cron service?
I have indeed - several times, as well as re-booting the system. My crontab is the original, I think: --------------------------------- [root@helen tim]# cat /etc/crontab SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root HOME=/
# run-parts 01 * * * * root run-parts /etc/cron.hourly 02 4 * * * root run-parts /etc/cron.daily 22 4 * * 0 root run-parts /etc/cron.weekly 42 4 1 * * root run-parts /etc/cron.monthly --------------------------------- /etc/anacrontab reads: --------------------------------- [root@helen tim]# cat /etc/anacrontab # /etc/anacrontab: configuration file for anacron
# See anacron(8) and anacrontab(5) for details.
SHELL=/bin/sh PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root
1 65 cron.daily run-parts /etc/cron.daily 7 70 cron.weekly run-parts /etc/cron.weekly 30 75 cron.monthly run-parts /etc/cron.monthly --------------------------------- I see now that /etc/cron.daily also runs twice: --------------------------------- Mar 16 04:01:02 helen crond[22696]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 04:01:02 helen crond[22699]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 04:02:01 helen crond[22723]: (root) CMD (run-parts /etc/cron.daily) Mar 16 04:02:01 helen crond[22724]: (root) CMD (run-parts /etc/cron.daily) Mar 16 04:02:01 helen anacron[22742]: Updated timestamp for job `cron.daily' to 2010-03-16 Mar 16 04:02:11 helen anacron[23204]: Updated timestamp for job `cron.daily' to 2010-03-16 --------------------------------- crond is only running once: --------------------------------- [root@helen tim]# ps aux | grep cron root 5978 0.0 0.0 61152 732 pts/1 S+ 12:15 0:00 grep cron root 16700 0.0 0.0 74816 1236 ? Ss Mar15 0:01 crond --------------------------------- I remain mystified ...
Timothy,
On Wednesday, March 17, 2010 you wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems,
Here comes a very weird idea. I don't know the internals of the cron-daemon good enough to know if this can actually happen. If you have a NTP-job every hour started by cron that corrects the internal time and if your internal clock runs too fast, the system time may be reset every hour so that the cron-job will start twice. As I said, I don't know if cron-daemon has a mechanism that would avoid that problem.
best regards --- Michael Schumacher PAMAS Partikelmess- und Analysesysteme GmbH Dieselstr.10, D-71277 Rutesheim Tel +49-7152-99630 Fax +49-7152-996333 Geschäftsführer: Gerhard Schreck Handelsregister B Stuttgart HRB 252024
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Michael Schumacher Sent: Wednesday, March 17, 2010 9:00 To: CentOS mailing list Subject: Re: [CentOS] cron.hourly runs twice
Timothy,
On Wednesday, March 17, 2010 you wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems,
Need to get a look into the runtime environment:
Add this to the cron.hourly
#!/bin/sh pstree -up >> /tmp/foo.log
Next hour look at the parents (and their pids).
Here comes a very weird idea. I don't know the internals of the cron-daemon good enough to know if this can actually happen. If you have a NTP-job every hour started by cron that corrects the internal time and if your internal clock runs too fast, the system time may be reset every hour so that the cron-job will start twice. As I said, I don't know if cron-daemon has a mechanism that would avoid that problem.
best regards
Michael Schumacher PAMAS Partikelmess- und Analysesysteme GmbH Dieselstr.10, D-71277 Rutesheim Tel +49-7152-99630 Fax +49-7152-996333 Geschäftsführer: Gerhard Schreck Handelsregister B Stuttgart HRB 252024
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
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Jason Pyeron wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems,
Add this to the cron.hourly
#!/bin/sh pstree -up >> /tmp/foo.log
I tried this; the relevant lines on the first machine are: ----------------------------------------- |-crond(9167)-+-crond(9439)---run-parts(9441)-+-awk(9452) | | `-foo(9450)--- pstree(9451) | `-crond(9440)---run-parts(9442)-+-awk(9455) | `-foo(9454)--- pstree(9456) |-cupsd(5301)---{cupsd}(17775) ----------------------------------------- and on the other CentOS machine: ----------------------------------------- |-crond(2824)---crond(28255)---run-parts(28256)---foo(28257)--- pstree(28258) -----------------------------------------
I've checked that /etc/rc.d/init.d/crond on the two machines are the same. So too is /etc/sysconfig/crond .
I'm not clear why crond starts another copy of crond, even on the second machine?
-- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- - - - Jason Pyeron PD Inc. http://www.pdinc.us - - Principal Consultant 10 West 24th Street #100 - - +1 (443) 269-1555 x333 Baltimore, Maryland 21218 - - - -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- This message is copyright PD Inc, subject to license 20080407P00.
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Timothy Murphy Sent: Wednesday, March 17, 2010 18:05 To: centos@centos.org Subject: Re: [CentOS] cron.hourly runs twice
Jason Pyeron wrote:
For some reason I cannot fathom, cron.hourly runs twice each hour on one of my two CentOS-5.4 systems,
Add this to the cron.hourly
#!/bin/sh pstree -up >> /tmp/foo.log
I tried this; the relevant lines on the first machine are:
|-crond(9167)-+-crond(9439)---run-parts(9441)-+-awk(9452) | | `-foo(9450)---pstree(9451) | `-crond(9440)---run-parts(9442)-+-awk(9455) | `-foo(9454)--- pstree(9456) |-cupsd(5301)---{cupsd}(17775)
and on the other CentOS machine:
Good, what I thought
|-crond(2824)---crond(28255)---run-parts(28256)---foo(28257)--- pstree(28258)
I've checked that /etc/rc.d/init.d/crond on the two machines are the same. So too is /etc/sysconfig/crond .
I'm not clear why crond starts another copy of crond, even on the second machine?
Please send output of:
for i in /etc/crontab /var/spool/cron/*; do echo $i && cat $i; done
-- Timothy Murphy e-mail: gayleard /at/ eircom.net tel: +353-86-2336090, +353-1-2842366 s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On a side note clock changes are not the issue:
Daylight Saving Time and other time changes
Local time changes of less than three hours, such as those caused by the start or end of Daylight Saving Time, are handled specially. This only applies to jobs that run at a specific time and jobs that are run with a granularity greater than one hour. Jobs that run more frequently are scheduled normally.
If time has moved forward, those jobs that would have run in the interval that has been skipped will be run immediately. Conversely, if time has moved backward, care is taken to avoid running jobs twice.
Time changes of more than 3 hours are considered to be corrections to the clock or timezone, and the new time is used immediately.
Jason Pyeron wrote:
Please send output of:
for i in /etc/crontab /var/spool/cron/*; do echo $i && cat $i; done
Thank you very much. That seems indeed to be the solution. On the first machine I have: ------------------------------------------- [root@helen tmp]# for i in /etc/crontab /var/spool/cron/*; do echo $i && cat $i; done /etc/crontab SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root HOME=/
# run-parts 01 * * * * root run-parts /etc/cron.hourly 02 4 * * * root run-parts /etc/cron.daily 22 4 * * 0 root run-parts /etc/cron.weekly 42 4 1 * * root run-parts /etc/cron.monthly
/var/spool/cron/root
SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root HOME=/
# run-parts 01 * * * * run-parts /etc/cron.hourly 02 4 * * * run-parts /etc/cron.daily 22 4 * * 0 run-parts /etc/cron.weekly 42 4 1 * * run-parts /etc/cron.monthly ------------------------------------------- On the second machine I have ------------------------------------------- [root@althea tmp]# for i in /etc/crontab /var/spool/cron/*; do echo $i && cat $i; done /etc/crontab SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root HOME=/
# run-parts 01 * * * * root run-parts /etc/cron.hourly 02 4 * * * root run-parts /etc/cron.daily 22 4 * * 0 root run-parts /etc/cron.weekly 42 4 1 * * root run-parts /etc/cron.monthly /var/spool/cron/* cat: /var/spool/cron/*: No such file or directory -------------------------------------------
So it seems that entry at /var/spool/cron/root is the cause of the problem. I've no idea where it came from; I guess I must have copied at some time - I see the file is dated 1 March.
Timothy,
On Tuesday, March 16, 2010 you wrote:
Mar 16 14:01:01 helen crond[27833]: (root) CMD (run-parts /etc/cron.hourly) Mar 16 14:01:01 helen crond[27834]: (root) CMD (run-parts /etc/cron.hourly)
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
Did you edit one of the jobs? Some Editors (joe) create a file with an "~" at the end as a backup. If you edit one of your cronjob-scripts in /etc/cron.hourly/ , you may create a second file that will be run by cron too. This happened here some time ago and it took some time to figure out the reason.
best regards --- Michael Schumacher PAMAS Partikelmess- und Analysesysteme GmbH Dieselstr.10, D-71277 Rutesheim Tel +49-7152-99630 Fax +49-7152-996333 Geschäftsführer: Gerhard Schreck Handelsregister B Stuttgart HRB 252024
Michael Schumacher wrote:
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
Did you edit one of the jobs? Some Editors (joe) create a file with an "~" at the end as a backup. If you edit one of your cronjob-scripts in /etc/cron.hourly/ , you may create a second file that will be run by cron too. This happened here some time ago and it took some time to figure out the reason.
Thanks for the suggestion. I haven't edited any of the scripts in /etc/cron.hourly . Also, I checked and found that cron.hourly starts twice before any of the scripts starts. Each of the scripts then runs twice.
Timothy wrote:
Michael Schumacher wrote:
I just wonder if anyone has come across this curiosity? Or can suggest any possible cause.
Did you edit one of the jobs? Some Editors (joe) create a file with an "~" at the end as a backup. If you edit one of your cronjob-scripts in /etc/cron.hourly/ , you may create a second file that will be run by cron too. This happened here some time ago and it took some time to figure out the reason.
Thanks for the suggestion. I haven't edited any of the scripts in /etc/cron.hourly . Also, I checked and found that cron.hourly starts twice before any of the scripts starts. Each of the scripts then runs twice.
This finally hit: under no circumstances should you be editing your crontab with vi in the directory. ALWAYS use crontab -e.
Another thing, and this constantly irritates me: ll, in CentOS, seems to be ls -l,*not* ls -la, and so doesn't show .files; have you looked for those?
mark
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Jason Pyeron -
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m.roth＠5-cent.us -
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Timothy Murphy