Shell Programming and Scripting

Hello everyone:

I am in the process of developing a shell script that will help me do the following:

1. I will backup to a mounted drive creating a folder for each day
2. After 45 days the first backup needs to be deleted, now, this has to happen everyday after I hit 45 days for the first time because after I hit 45 days for the first time the script will need to delete the oldest backup.
3. The script will execute using cronjob every night at 10 PM from Monday through Friday.

This is what I have so far:

date >> start
DT=`date "+%y%m%d"`
mkdir /nethdd/$DT
find /usr -print | cpio -pdmuv /nethdd/$DT
find /usr3 -print | cpio -pdmuv /nethdd/$DT
date >> end

As you can see I do not know how to start deleting the oldest every day after I hit 45 days for the first time.

Google is your friend. Try "shell delete older".