How will I introduce my son to Unixes and programming?
The same way I introduce him to any creative subject: By playing with him in an environment where we learn what we need to solve a problem we have, and where we apply what we learn and see results I hope make a positive impression.
The deeper part of the question: Do you mean teaching them GNU on Linux (or other UNIX based or -derived systems), or do you mean teaching them how to use a GUI on top of a Unix-like environment?
Thing is, my mother-in-law runs Mint/XFCE like a champ, because her only requirements from a computer are that she'll be able to use a web browser to pay her bills and to search for information, access her mail via an IMAP-capable mail client, and use (very basic features of) a word processor with the capability to print finished documents. I wouldn't call that "knowing" Unix, though.
What worked for me, back in the early nineties, was to only ever have access to computers where text input in a ROM-based BASIC interpreter or a DOS environment was the only way to start interacting with computers, and being social on a computer meant dialing a text-based BBS using an analog modem. If you were lucky, they had an ANSI color text environment.
Getting hold of the Debian base system after a few years of that was pure hacking joy, and once I bought a CD set containing RedHat 5.1 with the AfterStep window manager, I couldn't understand why anyone would want to be running Windows 95, NT 4 or Mac OS 7, with their various instabilities that could bring the entire computer down instead of just killing the single program which misbehaved.
This is an example to get to a point: Things have changed. A lot. Many kids' first interaction with a computer will be with an iPad or iPhone: a beautiful, intuitive touch interface with no reason - not even a possibility - to open a shell and fix what doesn't work the way you want in the system. The absolute majority of kids will never see the point in learning what makes the system tick underneath that gorgeous surface. And of those who do, the majority will never see the point in learning the underlying system beyond using Xcode and its existing libraries. That's what most people get wrong when they figure that "all kids should learn to code" or "all kids should learn proper computing": The lack of necessity also removes the motivation for all but those who would have learnt anyway, given a chance.
Since I am a hacker in the original sense of the word, my kid regularly sees me connecting to my own or my employer's servers using secure shell, for maintenance work or to improve something or other. I do have an old laptop running text-only FreeBSD for fun, and once he's old enough, he might appreciate the humor of it. But if he has no interest in the technology, I won't force him. Heck, he might even be required to run Microsoft products to be compatible with school requirements one day...
