I have always found it difficult to find information about the system itself in Unix, whether it be
Which OS I am using (version number and all, to compare it with the latest available builds)?
Which Desktop Environment am I using? If I am using KDE, most of the programs begin with a K and I can say I am using KDE, but there should be some way to query this, say from a script.
Which kernel version am I using? (For example, I am using Fedora, and I want to know what Linux kernel version I am using)
Basically, what I miss is a single point/utility that can get all this information for me. Most of the times the solutions to the above would themselves be OS specific. Then, you are stuck.