The Unix operating system was first developed in 1969. The trademark is currently owned by The Open Group, an industry standards consortium. The operating system is currently well-know for running on servers even though it can run equally well on desktops and mobile devices. Its popularity on desktops grew when Apple rewrote and ported its PowerPC operating system to a Unix variant called Max OS X. On servers, Unix remains a very popular operating system and most hardware vendors support one or more Unix or Unix-like variations on it.
A lot of database administrators are either Unix administrators or Windows ones and not both. Finding an administrator skilled in both is quite rare. The reason is that to be an efficient administrator requires becoming well-versed and skilled in the underlying operating system. It's common to hear a Unix administrator make the comment that Oracle on Windows is small scale or use the colloquial term "mickey mouse". With recent...