I already took a look (quickly) at one OS Internals (http://newosxbook.com/index.php), but the books seem a bit old now, and very expensive for three old books (75$ each, 3 volumes).<p>Do you have any recommendation for books / blog posts / persons to follow... for techie stuff about *BSD / macOS, like OS internals, Darwin kernel internals, etc...<p>Thanks
Take a look at The Design And Implementation Of The Freebsd Operating System. It's a pretty good look at the history of FreeBSD and how it is put together.<p>Of course, if you're really after Darwin/macOS info, a lot of the book won't apply. Apple took FreeBSD userspace and FreeBSD network stack (in 2000ish), but I don't think they tool the scheduling or process management. And the current version of the book covers a lot of things that were added to FreeBSD after Apple took the stuff they did; maybe the earlier version of the book would be better, because Apple didn't do a lot of updates from upstream.
There’s a lot of documentation available at freebsd.org, openbsd.org and netbsd.org. Not like in the Linux world where documentation is scattered all over the WWW.<p>When it comes to books, you might want to have a look at <i>Absolute FreeBSD</i> by Michael W. Lucas. He’s also written books about OpenBSD, ZFS etc: <a href="https://mwl.io/nonfiction/os" rel="nofollow">https://mwl.io/nonfiction/os</a><p>Other web resources: <a href="https://www.unitedbsd.com/" rel="nofollow">https://www.unitedbsd.com/</a>
There was one really excellent book from a Google engineer about macOS. I forget the name. I have it myself somewhere.<p>But it's indeed very old, its relevance is minimal now. It's kinda time for a new one.