def write
      begin
        buf = [ @flags, @length, @id, @crc].pack(FORMAT)
        crc = Zlib.crc32(buf, 0)
        @file.seek(@addr)
        @file.write(buf + [ crc ].pack('L'))
      rescue IOError => e
        PEROBS.log.fatal "Cannot write blob header into flat file DB: " +
          e.message
      end
    end
def write
      begin
        buf = [ @flags, @length, @id, @crc].pack(FORMAT)
        crc = Zlib.crc32(buf, 0)
        @file.seek(@addr)
        @file.write(buf + [ crc ].pack('L'))
      rescue IOError => e
        PEROBS.log.fatal "Cannot write blob header into flat file DB: " +
          e.message
      end
    end
Write the header to a given File.