Regarding pledge: I agree it's a good pragmatic design, but I wouldn't see it as an example of BSD vs. Linux broadly. To my mind it's a very specifically OpenBSD style design, a kind of ruthless reduction to a dozen or so hardcoded cases that cover 90% of the benefit, sane defaults, opposition to configurability if it can at all be avoided, and screw coming up with a clean "general" solution. Other BSDs have gone in different directions. FreeBSD's solution here is capsicum, which predates pledge and is more powerful in principle, but is more difficult to use, so not that many programs in FreeBSD actually use it.