That is, suppose you have some useful stuff in your project sources "root" directory, e.g. it looks like that:
frontend
backend
api
.metadata
some-makeshift-file-with-useful-content-you-do-not-want-to-be-removed
Now you want to use svn-clean script, which is a part of subversion-tools Debian package (see e.g. http://packages.debian.org/search?keywords=subversion-tools). If you invoke it like that:
svn-clean .
you'll lose your eclipse workspace and that useful file with a lenghty name. So:
find -maxdepth 1 -mindepth 1 -type d -name "[a-zA-Z]*" -exec svn-clean {} \;