There appears to be different versions of the "Mac OS X for Unix Geeks" book.
The 4th edition of this book -- http://shop.oreilly.com/product/97805... -- appears to be the latest printed version. Apparently, it was published in 2008, with an ebook version available since 2009.
However, there also seems to be an alternate ebook version available, published in 2011 -- http://shop.oreilly.com/product/97805.... While this would at first seem to be related to an earlier printed version of the book, it also appears that this might be a newer version than the 4th edition.
Can you please tell me which is the latest version of this book, and what are the difference between these two ebooks?
Thanks for writing us about this, and I'm sorry for the confusion.
Mac OS X for Unix Geeks (Leopard), 4th Edition is the most current edition of this title. It was written for Mac OS X Leopard (10.5). Neither of the books had an ebook when it was first released, so ebooks were released later with the same content as the original print books. The 2011 ebook release does not have new content.
I hope that makes sense! Let us know if you have more questions.