'Finds the old files in cache.'

def _find_old_cache_files(self, share):

    mount_fs = self._get_mount_point_for_share(share)
    threshold_minutes = self.configuration.expiry_thres_minutes
    cmd = ['find', mount_fs, '-maxdepth', '1', '-name', 'img-cache*', '-amin', ('+%s' % threshold_minutes)]
    (res, _err) = self._execute(run_as_root=self._execute_as_root, *cmd)
    if res:
        old_file_paths = res.strip('\n').split('\n')
        mount_fs_len = len(mount_fs)
        old_files = [x[(mount_fs_len + 1):] for x in old_file_paths]
        eligible_files = self._shortlist_del_eligible_files(share, old_files)
        return eligible_files
    return []
