title: How to unpack and pack pkg file?
body: <p>I have a pkg file created by Install Maker for Mac.
  I want to replace one file in pkg. But I must do this under Linux system, because this is a part of download process. When user starts to download file server must replace one file in pkg.
  I have a solution how unpack pkg and replace a file but I dont know how pack again to pkg.
  <a href="http://emresaglam.com/blog/1035" rel="noreferrer">http://emresaglam.com/blog/1035</a>
  <a href="http://ilostmynotes.blogspot.com/2012/06/mac-os-x-pkg-bom-files-package.html" rel="noreferrer">http://ilostmynotes.blogspot.com/2012/06/mac-os-x-pkg-bom-files-package.html</a></p>