Signed-off-by: Leslie Lamport <yangkunlin7@huawei.com> (cherry picked from commit d353a8906c1f025d499faa833ecd7d44a2e5ad2d)
In usage(),"--du" and "--prune" options are supported, but the description of them is not given. Signed-off-by: xueyamao <xueyamao@kylinos.cn> (cherry picked from commit bffdefafb79edb984742902c46b0dc17b28be113)