Determining the version of Solaris that you are running is important, especially when installing software packages and operating system patches. The uname command will help. The man page tells us about a variety of options, including:

Doing a uname -r will yield the operating system release level. For example, on an Ultra5 running Solaris 8, one sees an output of 5.8, while on a Netra 1125 running Solaris 2.6 one sees 5.6. The complete mappings are: