The Example Scripts for maintenace here:
http://wiki.splitbrain.org/wiki:tips:maintenance#keeping_playground_clean
dont seem to make much sense to me, since the example path do not really lead to the wanted data.
Plus its not mentioned that you first have to create a backup of what you want to be restored periodicaly.
cp -rpf /path/to/savedwiki/data/playground/playground.txt /path/to/dokuwiki/data/playground/
cp -rpf /path/to/savedwiki/data/wiki/ /path/to/dokuwiki/data/wiki/
plus data/wiki is wrong anyway -> must be data/pages/wiki since this is the structure of the wiki ;)
I'm not 100% sure so i'd rather ask here then editing it.