set cron to run job every 30hours

sandy_linux · 09-02-2011, 06:06 AM

I was wondering how to set the cron to run every x hours, where x is greater than 23 ? I have a script that runs for 28hours and hence I want to schedule this every 28hours. How can I do it?

Thanks

colucix · 09-02-2011, 06:48 AM

Please, take a look at this: http://www.linuxquestions.org/questi...7/#post3772149.

sandy_linux · 09-02-2011, 07:21 AM

Thanks for pointing me to this thread. But, I wonder about the statement:

"at now +4 days" means "at now +30 hours". really? What will I then write when I want to execute the script after 4 days? I guess, same?

smoker · 09-02-2011, 07:25 AM

You could do it without cron.
Modify your main script so that the last thing it does is call the at command.
i.e. if your script is called main.sh ...

Code:

at now + 1 minute < ./main.sh

Of course you will have to make sure that any log files that your script creates will be moved or renamed before the script is repeated.

Here is a sample script, just check on main.txt to see what happens. Comment out the at command to stop the script repeating.

Code:

#!/bin/bash
############
## main.sh #
############

echo `date` >> main.txt
for a in `seq 10`
do
echo "hello $a" >> main.txt
done
echo "---------------------" >> main.txt
at now + 1 minute < ./main.sh

colucix · 09-02-2011, 07:32 AM

Quote:

Originally Posted by sandy_linux

Thanks for pointing me to this thread. But, I wonder about the statement:

"at now +4 days" means "at now +30 hours". really? What will I then write when I want to execute the script after 4 days? I guess, same?

Well.. that was not the post at which I've redirected you. Anyway, yes... you can use at instead of cron as pointed out by smoker above.

Reuti · 09-02-2011, 08:38 AM

There is also gnubatch, which is not a full blown resource manager (aka queuing system) but meant as a replacement for cron:

Code:

$ gbch-r -A - -r hours:30 foobar.sh
$ gbch-jlist -H -F "%N %U %H %I %p %L %T %c %P %r"
Jobno User  Title     Cmd Interp Pri Loadlev Date/time        Cond Progress Repeat
31849 reuti foobar.sh sh         150    1000 02/09/2011 15:30               Hours:30
$
$ gbch-jlist -H -F "%N %U %H %I %p %L %T %c %P %r"
Jobno User  Title     Cmd Interp Pri Loadlev Date/time        Cond Progress Repeat
31849 reuti foobar.sh sh         150    1000 03/09/2011 21:30               Hours:30

will repeat the job every 30 hours from now (unless you give a different time for the first start). I added -A - as the default is to skip the weekend.

Depending on the return code of the job you can increase/decrease variables inside gnubatch to start/stop other jobs at certain conditions. You can also shift the next execution if necessary or limit it to 15 runs or so.