[RndTbl] OS X tips

Adam Thompson athompso at athompso.net
Wed Dec 16 22:09:54 CST 2009


> Subject: [RndTbl] OS X tips
> 	Since OS X sort of qualifies as *NIX here goes...

Not sort of: Mac OS X *is* UNIX.

In fact, Mac OS X has a significantly better historical claim to that name
than any version of Linux that has ever existed.  For those who aren't
aware, Mac OS X consists of two pieces: the GUI, which is entirely
proprietary to Apple, and the underlying UNIX operating system, called
Darwin.

Darwin is the direct descendant of OpenStep (jointly developed by NeXT and
Sun), which is in turn the descendant of NextStep (developed by NeXT) which
was the combination of a CMU Mach micro-kernel, a complete implementation of
BSD UNIX on top of that, and the NextStep GUI on top of both.  (Yes, Display
PostScript was also an important part of the system architecture, if you
want to be *really* pedantic.)

Darwin apparently now also includes substantial amounts of code from the
FreeBSD project, which can also trace its ancestry directly back to the
original BSD UNIX operating system.

The name "UNIX" is specifically and legally reserved for operating systems
which pass the Single Unix Specification qualification tests, as
administered by the Open Group (and previously administered by OSF and
X/Open, at times), and whose vendors have also entered into a licensing
agreement with the Open Group to permit their use of the term UNIX(tm).
Note that POSIX-compliance by itself does NOT entitle an operating system to
call itself UNIX.

The Linux kernel is NOT UNIX.  It is *impossible* for the Linux kernel
itself to be called UNIX, because the UNIX requirements include vast amounts
of "user-land" software in addition to the kernel.  This means that each
distribution would have to independently undergo certification to qualify
for the UNIX trademark.

At least one Linux distribution ("LINUX-FT") has been certified as
POSIX.1-compliant, but not as UNIX(tm).
[http://www.ukuug.org/newsletter/linux-newsletter/linux@uk21/posix.shtml]
The vendor in question (Lasermoon) appears to be defunct, and the Linux-FT
development appears to have been taken over by Caldera (back when they were
pro-Linux).  Linux-FT, however, derived from a german distribution called
"Unifix Linux System".  Their website still exists (www.unifix.de) but
hasn't been updated since 2001.  The Unifix product page for v2.0
(http://www.unifix.de/products/unifix_2_0/index.html) claims that their
system is POSIX-certified... but it also proudly claims that it's based on
the 2.0 kernel.  I can't find any indication that the company is still
active.

Other currently-available operating systems that *are* "UNIX" include
Solaris, AIX, HP-UX, z/OS, and UnixWare (if SCO still answers their
phones!).  UNIXes that are no longer available (AFAIK) include SGI IRIX, NEC
UX/4800, NCR (TeraData) UNIX, SCO OpenServer, NEC FT-UX, and Stratus FTX.
The official list can be found at
http://www.opengroup.org/openbrand/register/.

Operating systems derived from BSD UNIX also have some legal basis to be
called "UNIX"; Apple's Mac OS X is in fact the only operating system that
has both the ancestral BSD claim *and* Open Group certification.  Sun
Solaris, IBM AIX, HP HP-UX, whatever NEC/TeraData ships now and SCO UnixWare
also have (at various versions) dual claims, but deriving from AT&T UNIX
licenses, not BSD.

So in terms of currently shipping product, the most UNIXy of UNIXes are:
MacOS X, Solaris, AIX, HP-UX and UnixWare.  Linux doesn't even make it to
the qualifying heats.


> 	When upgrading an Intel Mac from 10.4 to 10.6 I was able to
[...]
>
> 	They've finally implemented something like the pager. They
> call it Open Spaces. By default it gives the user four virtual
> screens.

Spaces, which closely mimics the "pager"-style behaviour that's been around
under UNIX since at least early versions of NCDwm (ca. 1991), has been
included since Mac OS X 10.5.
Exposé, which is a somewhat different feature that many people used to
obtain the same sort of productivity boost, has been included since Mac OS X
10.3.

FYI, the multiple-desktop feature has also been available under Microsoft
Windows to anyone running a Matrox video card (since about 1996) or ATI
video card (since about 1998, IIRC).

-Adam "Pedantic" Thompson
 <athompso at athompso.net>



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