Hello everyone. I'm new both to the forum and to unix scripting, and this website has been very useful in putting together a script I am working on. However, I have run into a bit of a snag, which is why I have come here seeking help. First I will say what I am trying to do, and then what I have done so far.

I am trying to download weather model data for a meteorological program called GEMPAK, and the models update ever so often and filenames are based on timestamp and model type. An example filename is 2011051800_nam242.gem
These files take up a LOT of space (this directory alone is 21 gig!), so as you can imagine, after downloading the files I want to delete the old ones. Even more so, I do not need the *entire* directory, just the last 2 day's worth at most.

So, here is what I have done so far.

Code:

cd / ;
wget -S -N -l1 -r -np -A.gem http://metfs1.agron.iastate.edu/data/gempak/model/nam ;
find /metfs1.agron.iastate.edu/data/gempak/model/nam2 -Btime +4 -exec rm {} \;

Now I have the entire directory downloaded in the proper hierarchy, an the script will remove items older than 4 days. However, when the script runs again, it downloads the files I just deleted all over again, and I am trying not to keep too much space with files I don't need. So, my question is, can anyone help me find a way to either download 'x' amount of files, or only after 'x' timestamp? Or maybe another way I do not know about? Thank you very much in advance.