(PHP >= 5.3.0, PECL phar >= 2.0.0)
Compresses the entire tar/zip archive using Gzip or Bzip2 compression
object PharData::compress ( int $compression [, string $extension ] )
For tar archives, this method compresses the entire archive using gzip compression or bzip2 compression. The resulting file can be processed with the gunzip command/bunzip command, or accessed directly and transparently with the Phar extension.