Hi,

Help please!

I have to schedule some job on every Monday and alternate Thursday with Cron. I am not sure as if I pass 1 and 5 on the day filed, the job will be scheduled for every Monday and Thursday. How to schedule in job in above case.

Thanks in anticipation.

Have a read of this link regarding this stuff:

cron and crontab

Regards

Hi Frank

Thanks for the link!

However my problem is still open.

From the given link
---------------------------
0 0 1-7 * 5 /some/script
You might hope that will run /some/script during the first minute of the first Friday of the month. Unfortunately, it will run the script on each day of the first week of the month and on every Friday.
----------------------

In my case I have to schedule the job on every Monday and every alternate Thursday. If the write the below code

0 0 1-7 * 1,4 <path to script>

Then above will run every Monday and Thursday, however I have to skip one week and then run the script in case of Thursday.

Please help !

Regards

A simple, though not particularly elegant, solution, is to write a wrapper script that executes your target script on the specified days, and call the wrapper script from cron.

eg (of the top of my head, not tested):
set the cron entry to call the wrapper every monday and thursday.
The wrapper will only run the script on a thursday if the flagfile doesn't exist (and create the flagfile, once it has run). The next time it gets called on a thursday the flagfile will exist, so it doesn't run the script, just deletes the flagfile.

You may want to be careful where you store the flagfile, as on your system /tmp and /var/tmp may be 'cleaned' if the system is rebooted. You also have to ensure that the flagfile is uniquely named, so that nothing else can interfere with it.

Thanks Wempy

Are we saying without having a wrapper script it’s not possible to schedule the script on alternate days of the week?

well, it is possible, but your crontab lines get awfully long. Cron will only execute EVERY set day, there is no explicit way to tell it every Other set day, so you have to test whether it should run today or not, and in the simple, binary, case like this, the easiest (maybe quickest) solution is to keep track of things with a flagfile.
You can put the logic in the wrapper script above into the cron entry, but, as I said, it makes the entry very long, and difficult to read.

I appreciate you help!

Please can you let me know what will be the entry in crontab evne though its big I would like to test it.

Thanks again