Thanks! Although a monthly backup may take place on say the 1st. It's not necessarily the last Friday of the month. I'm not really sure how I can write this down clearly. There is an example in post 3 ^

If I understand your code that will run it the first, second and third Friday, but not the fourth of each month, whereas we require it to run on every fourth week.

I was thinking along the lines of using an initial date, then +28 days (multiple). Since there is no set date as such the monthly backups take place, its every four weeks. So we could start the cycle in the script on whatever date. For example, I know our next monthly backups begin on Friday 30th April 2010. Here is a few dates after this to try and give more of an idea of the cycle -

30th April (Just happens to be the last Friday)
28th May (Just happens to be the last Friday)
25th June (Just happens to be the last Friday)
23rd July (Not the last Friday, it's in fact the 4th out of 5 Fridays in July)
20th August (Not the last Friday either, it's the 3rd out of 4)

The reason it is set a little odd like this is because it's the weekend after our pay (we get paid 4 weekly, not monthly).

Hope this makes sense.

Thanks for the replies!
Rab



Edit - Poor attempt at pseudo like code below

Cron Entry - 00 21 * * 5 /backupscript

backupscript -

Code:

if todays date is +28 (multiple) 30th April 
then run monthly backup
else run normal backup
fi

There is probably a better way to do it, I don't know enough about scripting to get my head around it



Edit 2 - This is AIX v5.3 if it makes any difference.