DW_Hornet wrote:You can consider the mac os to be a derivative of linux.
Well, you can consider OSX to be a unix varient and you can consider a Linux system to be Unix like. But that is as close as they come.
OSX is based on a Mach kernel with a BSD subsystem. Now, you can run many GNU (GNU is Not Unix) tools on it to make it act very similar to a linux system from a user's standpoint.
In fact, when I did Solaris admin full time, usually one of the first steps was to install a GNU set of tools to make my life easier. For example, the Solaris version of tar does not support gzip compression whereas the GNU version does.
So, for me to unzip and uncompress a tar.gz file in one command required really two commands (this is from my head, so I may be a bit off):
gunzip -c filename.tar.gz|tar xvf -
With GNU tar, the example is:
tar zxvf filename.tar.gz
That was just one little example.
Now, Linux in its purest form, is really just the kernel. The anal people out there expect everyone to call, say RedHat or Ubuntu, a Linux/GNU system. This is because the GNU project really does most of the userland things such as commands and libraries, etc.
This is important to note because at this time NO ONE (I am talking to you SCO), has proven anything about any UNIX (copywrited) code being included in the Linux kernel or GNU tools.
This is different than the BSD derivatives of ATT's original UNIX code. And in fact, because of the BSD license, much of that code appears in other places. For example, the original TCP/IP code in windows (not sure if it has been replaced at this point) is copied from the BSD varients. In fact, if you do a "strings" on some of the Windows binaries, you will see the University of Berkley Reagents copywrite notice.
Anyways... Just a bit of Unix history. And it is a long and complex history.