The UNIX Programming Environment by Kernighan and Pike I have recently started reading "The UNIX Programming Environment" by Kernighan and Pike. My objective is to learn about the UNIX philosophy. My question is, Do I need to install UNIX on my desktop to make the most out of the book, or will any *NIX system work? I currently use Linux (ubuntu).

Your Ubuntu system will allow you to follow the exercises in _The Unix Programming Environment_ just fine, current versions of the commands used in the book still support the relevant options and features. There will be some minor variations, in particular you probably won’t be able to use the email-related commands to read your email.