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It's complicated. Original UNIX by AT&T was newer open-sourced. BSD (Berkley Software Distribution) was opensource distribution of user programs for UNIX (like

by lisivka 10y ago

It's complicated. Original UNIX by AT&T was newer open-sourced. BSD (Berkley Software Distribution) was opensource distribution of user programs for UNIX (like TCP/IP stack, vi editor, etc.), used by original UNIX, with proportions 20% of AT&T code and 80% of BSD code. So technically, BSD is(0.8) not(0.2) UNIX. FreeBSD is branched from BSD code, so it is(0.8) not(0.2) UNIX too. Apple MacOS X is based on FreeBSD code (and lot of other code), and it certified as UNIX compatible, so MacOS X can be named as UNIX. iOS is based on MacOS X, so iOS is UNIX too.

JonathonW 10y ago
If you want to get technical about it, the Mac kernel itself isn't a traditional UNIX or BSD kernel; XNU (which, conveniently enough, stands for "X is not UNIX") is a hybrid composed of the Mach microkernel, some FreeBSD components, and Apple's own driver model. The system as a whole is able to brand itself as UNIX compliant, though, because it complies with the Single UNIX Specification. That spec is concerned about userspace behavior, not kernel or implementation, and you don't have to include any actual UNIX source code to be able to brand your OS as a "UNIX" according to the spec and trademark guidelines.
- lisivka 10y ago
  Yep, XNU is Mach microkernel + FreeBSD kernel. Some features of XNU are even ported back to FreeBSD kernel. IMHO, that is enough to draw direct connection from XNU to original UNIX (without ™), unlike Linux kernel.
  - TickleSteve 10y ago
    Mach microkernel + FreeBSD userland.... not kernel. BSD is a 'personality' layer.
deaddodo 10y ago
He asked about the Kernel. The Kernel is XNU / Mach, modified to act like a monolithic/hybrid kernel. The BSD code in Mac OS X is all user space, much of which probably isn't in iOS at all.
- Udo_Schmitz 10y ago
  Nope. Part of kernel as well: https://en.wikipedia.org/wiki/XNU#BSD https://en.wikipedia.org/wiki/XNU#BSD
  - deleted 10y ago
    [deleted]
bitwize 10y ago
Original Unix by AT&T was open sourced under BSD terms, but long after Linux and macOS came into being.

by lisivka 10y ago

JonathonW 10y ago

If you want to get technical about it, the Mac kernel itself isn't a traditional UNIX or BSD kernel; XNU (which, conveniently enough, stands for "X is not UNIX") is a hybrid composed of the Mach microkernel, some FreeBSD components, and Apple's own driver model. The system as a whole is able to brand itself as UNIX compliant, though, because it complies with the Single UNIX Specification. That spec is concerned about userspace behavior, not kernel or implementation, and you don't have to include any actual UNIX source code to be able to brand your OS as a "UNIX" according to the spec and trademark guidelines.

lisivka 10y ago
Yep, XNU is Mach microkernel + FreeBSD kernel. Some features of XNU are even ported back to FreeBSD kernel. IMHO, that is enough to draw direct connection from XNU to original UNIX (without ™), unlike Linux kernel.
- TickleSteve 10y ago
  Mach microkernel + FreeBSD userland.... not kernel. BSD is a 'personality' layer.

deaddodo 10y ago

He asked about the Kernel. The Kernel is XNU / Mach, modified to act like a monolithic/hybrid kernel. The BSD code in Mac OS X is all user space, much of which probably isn't in iOS at all.

Udo_Schmitz 10y ago
Nope. Part of kernel as well: https://en.wikipedia.org/wiki/XNU#BSD https://en.wikipedia.org/wiki/XNU#BSD
- deleted 10y ago
  [deleted]

bitwize 10y ago

Original Unix by AT&T was open sourced under BSD terms, but long after Linux and macOS came into being.