When using the command line, your $PATH variable holds different paths to search when you enter a command. Today, I was using the Visual Studio 2008 command prompt, which has setup my $PATH variable to point at known locations relating to .Net and Visual Studio.
I could happily type in ‘sn’ in order to execute the program, however I had no idea where that exe lived and I needed the full path. I thought I would have to search using Windows, however I found that there is a ‘where’ command which will return you the full path for a command.
C:Program FilesMicrosoft Visual Studio 9.0VC>where sn
C:Program FilesMicrosoft SDKsWindowsv6.0ABinsn.exe