Identifying UNIX versions

I work in an environment with numerous different versions of UNIX and Linux. Sometimes I'll be accessing multiple machines from my workstation. Occasionally, I need to confirm the OS for the current terminal. The way to determine which version of UNIX you are using is with:

uname -a

For Solaris you would get something like:

SunOS rd-r220-01 5.8 Generic_117350-26 sun4u sparc SUNW,Ultra-60

For HP-UX you would get something like:

HP-UX l2000-cs B.11.11 U 9000/800 158901567 unlimited-user license

or

HP-UX rdhpux04 B.11.23 U ia64 0216397005 unlimited-user license

For AIX you would get something like:

AIX rd-aix09 2 5 00017F8A4C00

From this it is a little harder to see the version. It is actually AIX 5.2. If you check the man page for uname it will help you decode the hexidecimal number at the end. This will tell you things like 4C is the model ID and the 00 is the submodel ID. Additionally, AIX uses other switches to tell you about things the -a normally gives you on other platforms. For example,

uname -p # the processor architecture
uname -M # the model

For Linux things are a little tricker. The uname -a will tell you it is Linux but it will not tell you if it is SuSE Linux Enterprise Server (SLES) 10.0, Redhat AS 5.0, et cetera. To figure this out, look for a text file in /etc/ which ends in 'release', i.e.

cat /etc/*release

This text file will tell you which distribution of Linux you are using.