[johnklos]

Without going too far in to the politics of GNU/Linux, it's a bit messy. All the distros are different from each other, plus they're changing so rapidly that a book about one version is much less useful for managing another (think Ubuntu 14 -> 16, or Ubuntu 16 -> 18).

Also, while GNU/Linux is generally portable, many of the things you learn about Ubuntu will be different on what you'd run on a Raspberry Pi, or an UltraSPARC, or on a PowerPC.

NetBSD is the same OS on all the hardware it supports, so the system consistently does what it does regardless of where it's run. If you want to develop on a desktop and deploy on a Pi, for example, you'll have a much easier time with NetBSD :)

[dleslie]

Especially now that NetBSD can run on an RPi3. It was a bit embarassing that it could not.

[jmcneill]

RPi3 support was present in NetBSD 7.1 and 8.0. NetBSD 9.0 is the first release where you can run it in 64-bit mode.