In userspace the Unix way is about disconnected utilities connected by pipes, but that hasn't been uniformly true at more of the "system" level (well, GNU did o

In userspace the Unix way is about disconnected utilities connected by pipes, but that hasn't been uniformly true at more of the "system" level (well, GNU did originally have that philosophy all the way through, even down to the kernel, but most Unixen haven't). The BSDs, for example, generally pride themselves on tighter coupling in the core OS than Linux has traditionally had. You can swap out some components from a default FreeBSD install, mostly more application-level ones (sendmail->postfix, clang->gcc), but the base system is integrated and does things one way, supporting some customization but not every kind of wholesale surgery you might want to do on it. You certainly can't swap out the init system for another one in any kind of supported way. The same is pretty much true of most other Unixen, such as Solaris (which has a pretty integrated init system, too). I generally like the utilities+pipes model, but for system stuff it's seemed like false advertising to me for a long time anyway: the Linux kernel is monolithic, and many of its features (like cgroups) don't make much sense unless you have some userspace counterpart configuring/arbitrating them and a uniform way of making sure everything gets set up consistently. Traditionally this is handled by a tangle of shell scripts with distribution-specific conventions to make sure they don't step on each other's feet (Debian has piles of this in Debian policy). That's a unified system in practice, because you can't really arbitrarily rewrite the init/configure/reconfigure scripts or swap things out and still have a working system that is Debian-integrated. The scripts are literally separate files on disk, but in practice they're a spaghetti-code implementation of Debian Configuration, a monolithic system that handles initialization and services and package configuration and can't be modified without extreme care if you want things to keep working in the way all the other packages (and apt, dpkg-reconfigure, the diversions system, etc.) expect.