Unix Of Various FlavorsI mainly have used Linux these days. But in my past, there were many flavors of Unix to choose from. There was Solaris & SunOS for the Sun workstations. Then Ultrix for the DEC systems. HP UX for the HP workstations. Even IBM had its own version, AIX, for their RT systems.
There is also the differences between Berkley and AT&T Unix. Now Linux integrates both. One used "-" for command line options while the other did not. What is amazing is that after all these years, Unix is still around.