code: def write_conf(cluster, conf, overwrite):
      
      import os
  
      path = '/etc/ceph/{cluster}.conf'.format(cluster=cluster)
      tmp = '{path}.{pid}.tmp'.format(path=path, pid=os.getpid())
  
      if os.path.exists(path):
          with open(path) as f:
              old = f.read()
              if old != conf and not overwrite:
                  raise RuntimeError('config file %s exists with different content; use --overwrite-conf to overwrite' % path)
      with open(tmp, 'w') as f:
          f.write(conf)
          f.flush()
          os.fsync(f)
      os.rename(tmp, path)
docs: write cluster configuration to /etc/ceph/{cluster}.conf