Oracle runs on so many platforms, that essentially once you fire up a command line interface or otherwise give administration commands to it, it is its own OS.

Oracle runs on so many platforms, that essentially once you fire up a command line interface or otherwise give administration commands to it, it is its own OS. After installation (provided you don't run out of disk space), you can set it up and maintain it without (hardly) ever having to run an OS command. As a result, just about everything, including statistics to be gathered, users, etc. is just another table you can query via SQL or set using Oracle commands.