Shell Programming and Scripting

Hi Akash
What the experts are trying to tell you is to achieve this requirement in 2 steps, not with cron alone.

Step 1: Have a cron entry as shown below:

Code:

00 12 * * 4 abc.sh

The above cron entry will schedule your script(abc.sh) to run every thursday. However, your requirement is to run only on 1st and 3rd thursday.

Step 2: Changes in the script in order to block it from running other than 1st and 3rd thursday. You can add a small snippet like this at the beginning of your script abc.sh

Code:

dt=`date '+%d'`
$ if [ $dt -ge 8 -a $dt -le 14 ] || [ $dt -gt 21 ]
then
 exit
fi

This code will exit if the date range is within 2nd week or 4th week which in other words, helps your script to run only on 1st and 3rd thursdays (code not tested).

Guru.

Cron entry to run every thursday at midnight. Change min and hour to whatever is required.

Code:

0 0 * * 4 <command>

And an if-condition to check if it's the first or fourth thursday, try this bash code snippet: (untested)

Code:

if [ `date +%a` == "Thu" ]
then
    c=1
    dt=`date +%d`
    until [ $dt -gt 1 ]
    do
        dt=$(($dt - 7))
        c=$(($c + 1))
    done
    if [[ $c =~ [14] ]]
    then
        exit
    fi
fi

Thanks guys....
I can't change code in the script.
So it will be better to run this script through manually on Thursdays....

Thank you again guys...

I never said your script... I said your job!
And the job you are to write is a shell script containing all the above information.
Why a special job script?
Because compared to the script you might execute in command line and run. In batch mode cron has no idea of your environment and so you are to set it, and take out anything interactive wise like keyboard or terminal setting to not have cron errors... And since you are not aside when execution, I am quite sure you would like to know how the job executed? so you will in your job script output to log files I always use two one for normal execution and one for errors...
etc...

Thanks balajesuri....
Let assume I need to run a.sh on 12:00 AM.So just a simple doubt where I can use this if condition?

Hello Guys....

I found the solution at the time of sleeping....
We can schedule this by adding below line in cron.

00 12 1-7,14-21 * * 4 <Command>

I think it will work.(Not tested).
Please suggest on this.