Re: Cron - any advanced options?
On Thu,23.Apr.09, 03:39:44, Dave Sherohman wrote: Depending on the script, you may also be able to accomplish this with ps instead: ps ax | grep [m]y-script-name Shorter: pgrep my-script-name Regards, Andrei -- If you can't explain it simply, you don't understand it well enough. (Albert Einstein) signature.asc Description: Digital signature
Re: Cron - any advanced options?
Here's a little program that I picked up I don't remember where. It's what I use when I have this sort of problem. It atomically creates a lock file and tests for a previous lock file of the same name -- properly handling processes that quit without removing the lock, etc... Rick shlock.shar Description: Binary data
Re: Cron - any advanced options?
On 2009-04-23, Sjoerd Hardeman sjo...@lorentz.leidenuniv.nl wrote: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --enig96969A47323B843026EC6D74 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Kurian Thayil wrote: Hi All, =EF=BF=BD I have 3 cron jobs enabled and all are relating to RSYNC. Now, all of=20 these scripts are run once in every 7 minutes all day. The problem=20 occurs when the scripts doesn't finish to execute in 7 minutes. This=20 will result in starting execution of the same script again and this wil= l=20 malfunction the setup. =20 Is there an option in CRON, which always check if CRON has started the = process and is already running? Cron should execute the script only if = the the process isn't running already. Any hints on this? You could create a lockfile touch /var/lock/cronfiletest and the test if this lockfile exists, or else exit test -f /var/lock/cronfiletest || exit 0 Should it be this? test -f /var/lock/cronfiletest exit 0 if you want to exit when the lock file exist. You'll find similar tricks in many cron and init scripts. Sjoerd PS. Kurian, my apologies for the message sent to you. Hit the 'reply'=20 vs. 'reply to list' button accidentally. --enig96969A47323B843026EC6D74 Content-Type: application/pgp-signature; name=signature.asc Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename=signature.asc --enig96969A47323B843026EC6D74-- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Re: Cron - any advanced options?
Jeffrey Cao wrote: Is there an option in CRON, which always check if CRON has started the = process and is already running? Cron should execute the script only if = the the process isn't running already. Any hints on this? You could create a lockfile touch /var/lock/cronfiletest and the test if this lockfile exists, or else exit test -f /var/lock/cronfiletest || exit 0 Should it be this? test -f /var/lock/cronfiletest exit 0 if you want to exit when the lock file exist. Yes, of course. You're absolutely right. Sjoerd signature.asc Description: OpenPGP digital signature
Cron - any advanced options?
Hi All, I have 3 cron jobs enabled and all are relating to RSYNC. Now, all of these scripts are run once in every 7 minutes all day. The problem occurs when the scripts doesn't finish to execute in 7 minutes. This will result in starting execution of the same script again and this will malfunction the setup. Is there an option in CRON, which always check if CRON has started the process and is already running? Cron should execute the script only if the the process isn't running already. Any hints on this? Regards, Kurian Thayil.
Re: Cron - any advanced options?
On Thursday, 23.04.2009 at 13:42 +0530, Kurian Thayil wrote: I have 3 cron jobs enabled and all are relating to RSYNC. Now, all of these scripts are run once in every 7 minutes all day. The problem occurs when the scripts doesn't finish to execute in 7 minutes. This will result in starting execution of the same script again and this will malfunction the setup. Is there an option in CRON, which always check if CRON has started the process and is already running? Cron should execute the script only if the the process isn't running already. Any hints on this? Don't make it cron's responsibility to check whether the script is already running. Make it the *scripts's* responsibility. For example, the script should create a marker file (or similar) when it runs, deleting the marker file upon completion. The *first* thing the script should do is check for the existence of the marker file and, if it exists, then another instance of the script is already running; you can then terminate the script at that point. e.g. (partly bash, partly pseudo-code, completely untested) MARKER=/home/username/tmp/marker.txt if [ -e $MARKER ]; then echo Script already running exit touch $MARKER [...] [... real script here ...] [...] rm $MARKER Dave. -- Dave Ewart da...@ceu.ox.ac.uk Computing Manager, Cancer Epidemiology Unit University of Oxford / Cancer Research UK PGP: CC70 1883 BD92 E665 B840 118B 6E94 2CFD 694D E370 Get key from http://www.ceu.ox.ac.uk/~davee/davee-ceu-ox-ac-uk.asc N 51.7516, W 1.2152 signature.asc Description: Digital signature
Re: Cron - any advanced options?
Hi, Thats a pretty good idea. But I was thinking of an option like the one in Fcron. Fcron doesn't allow to start the process if it's already running (started by fcron). So I guess there should be a similar option in crontab too. Regards, Kurian Thayil On Thu, Apr 23, 2009 at 1:59 PM, Dave Ewart da...@ceu.ox.ac.uk wrote: On Thursday, 23.04.2009 at 13:42 +0530, Kurian Thayil wrote: I have 3 cron jobs enabled and all are relating to RSYNC. Now, all of these scripts are run once in every 7 minutes all day. The problem occurs when the scripts doesn't finish to execute in 7 minutes. This will result in starting execution of the same script again and this will malfunction the setup. Is there an option in CRON, which always check if CRON has started the process and is already running? Cron should execute the script only if the the process isn't running already. Any hints on this? Don't make it cron's responsibility to check whether the script is already running. Make it the *scripts's* responsibility. For example, the script should create a marker file (or similar) when it runs, deleting the marker file upon completion. The *first* thing the script should do is check for the existence of the marker file and, if it exists, then another instance of the script is already running; you can then terminate the script at that point. e.g. (partly bash, partly pseudo-code, completely untested) MARKER=/home/username/tmp/marker.txt if [ -e $MARKER ]; then echo Script already running exit touch $MARKER [...] [... real script here ...] [...] rm $MARKER Dave. -- Dave Ewart da...@ceu.ox.ac.uk Computing Manager, Cancer Epidemiology Unit University of Oxford / Cancer Research UK PGP: CC70 1883 BD92 E665 B840 118B 6E94 2CFD 694D E370 Get key from http://www.ceu.ox.ac.uk/~davee/davee-ceu-ox-ac-uk.asc N 51.7516, W 1.2152 -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) iD8DBQFJ8CbpbpQs/WlN43ARAkHRAJ9Jn+w/m3JpIPFn131OVVVkgmKYOACglczD MqzsbR6QH9Es1WsoUAZhTCk= =iHhR -END PGP SIGNATURE-
Re: Cron - any advanced options?
On Thu, Apr 23, 2009 at 09:29:29AM +0100, Dave Ewart wrote: Don't make it cron's responsibility to check whether the script is already running. Make it the *scripts's* responsibility. Agreed. If you make cron responsible for making sure it doesn't run twice, what happens when someone decides they should (for whatever reason) run it from the command line, a web-based tool, or anything other than cron? For example, the script should create a marker file (or similar) when it runs, deleting the marker file upon completion. Depending on the script, you may also be able to accomplish this with ps instead: ps ax | grep [m]y-script-name If it returns anything, then at least one process named my-script-name is already running, so abort. (The [brackets] around the first letter of my-script-name are to prevent grep my-script-name from appearing in the output and creating a false positive.) -- Dave Sherohman NomadNet, Inc. http://nomadnetinc.com/ -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Re: Cron - any advanced options?
Kurian Thayil wrote: Hi All, � I have 3 cron jobs enabled and all are relating to RSYNC. Now, all of these scripts are run once in every 7 minutes all day. The problem occurs when the scripts doesn't finish to execute in 7 minutes. This will result in starting execution of the same script again and this will malfunction the setup. Is there an option in CRON, which always check if CRON has started the process and is already running? Cron should execute the script only if the the process isn't running already. Any hints on this? You could create a lockfile touch /var/lock/cronfiletest and the test if this lockfile exists, or else exit test -f /var/lock/cronfiletest || exit 0 You'll find similar tricks in many cron and init scripts. Sjoerd PS. Kurian, my apologies for the message sent to you. Hit the 'reply' vs. 'reply to list' button accidentally. signature.asc Description: OpenPGP digital signature
