If you want to keep a folder in a standard state (for whatever reason) then the following is one way of doing it (I'm sure there are others). Making the folder read only is another way, but this may not be what you want to do.
(MAKE SURE YOU USE THE CORRECT " ' ` SYMBOLS IN THESE STEPS!)
Create a list of the files in the directory that you want to keep standard e.g. the root level of your hard drive ( '%>' represents the prompt):
%> cd /This creates a file at the top level of your hard drive called 'filelist', which we'll use to compare contents to. If you are using this to keep the top level of your hard drive clean then run 'ls >/filelist' twice so the 'filelist' file does not get deleted or moved!).
%> ls >/filelist
%> cd /it will delete all files and folders in root except those listed in the file called "filelist".
>%> rm -r "`ls | grep -v -x --file=/filelist`"
%> cd /which will move all files and folders not listed in the filelist from root to the current logged in users 'Documents' folder (or any other path you care to specify).
%> mv "`ls | grep -v -x --file=/filelist`" ~/Documents/
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