How do I tell if an executable is a .NET application?
I prefer not to have to install Visual Studio. But if I have to I will. A commandline program is preferred.
An application is a .NET executable if it requires mscoree.dll to run. You can check for this using the Dependency Walker, but in general any tool that gives you the list of required DLL's to run will do.
If you want to know if a running process is a .NET process, I can only recommend Process Explorer. This tool will give you a lot of information about the process, including some .NET properties.