I got a notice today that my service provider needed to reboot my servers as there was a vulnerability that was exposed on the actual host that could cause problems and the only way to fix it was to reboot the entire host.  So I wanted to ensure that everybody was off the system and cleanly so that there was no  problems because this is rare that my entire server set would be going down at the same time.

On my windows machines I wanted to make sure that nobody was still connected via remote desktop connections.  To do this quickly, from a command prompt I issued the command:

qwinsta

Another option would be to use the SysInternals Suite of Tools which is available from Microsoft, there is one called PSLoggedOn that will give the information you are looking for.

On my RedHat 6.5 servers you can issue the command:

who -a

There is another one called “w”  that will give similar information but for a quick look the who command works great.