void initializeFileHeader() throws IOException {
      if (useNewMagic) {
        out.write(MAGIC);
        out.write(CURRENT_VERSION);
      } else {
        out.write(ORIGINAL_MAGIC_VERSION);
      }
    }
Write the initial part of file header.
ql/src/java/org/apache/hadoop/hive/ql/io/RCFile.java