ちなみに、nfsfindを見ると下記のように書いてあったり # Check shared NFS filesystems for .nfs* files that # are more than a week old. # # These files are created by NFS clients when an open file # is removed. To preserve some semblance of Unix semantics # the client renames the file to a unique name so that the # file appears to have been removed from the directory, but # is still usable by the process that has the file open.