With Lion this is possible, but I think there is a limit of 2 sessions, and you don't need to be running the server tools. When you screen share a Mac that has it enabled, you can choose to either just take over the screen as per the scenario you are used to, or move to the "virtual display", where you can log in as a 2nd user.
Many (particularly PC/Windows) VNC clients are getting tripped up by this new behaviour and do not connect at at all at present, so you might need to careful with your choice of client.
Edit: I think the 2 session limit is to provide the ability to allow an administrator to login on the 2nd session to work without interupting the normal user, I would test whether more than 2 sessions are available, but I can only get it to work from a Mac client using screen share via the finder rather than a specific VNC client app, and I only have 2 Macs...
Q: "How can I force airport to die?"
You can disable Wi-Fi (aka "AirPort") by using the networksetup
command.
In order to do this, you have to know which "en" port AirPort is using. Usually it is either en0 or en1. You can find out for sure by using this command:
networksetup -listnetworkserviceorder
and looking at the output.
For example, here is the output of that command on my MacBook Air:
An asterisk (*) denotes that a network service is disabled.
(1) Bluetooth DUN
(Hardware Port: Bluetooth DUN, Device: Bluetooth-Modem)
(2) USB Ethernet
(Hardware Port: USB Ethernet, Device: en2)
(3) Wi-Fi
(Hardware Port: Wi-Fi, Device: en0)
(4) Bluetooth PAN
(Hardware Port: Bluetooth PAN, Device: en1)
As you can see in the third entry, mine is 'en0'. Therefore, to turn off Wi-Fi on my Mac, I use the command:
sudo networksetup -setairportpower en0 off
turning it back on again, as you might expect:
sudo networksetup -setairportpower en0 on
Note that I am on 10.9 and so things may be slightly different, but I do not think they will be significant. At one point Mac OS X's networksetup
command may have referred to this as "AirPort" instead of "Wi-Fi" but I think that was back in Snow Leopard (10.6).
Best Answer
Assuming there are no passwords, you can have each user session open another one when starting, using CGSession. I did not try it with Yosemite, but it does work for me with El Capitan.
chmod 777
(with the trailing space); drag the file’s icon in the Terminal window; press Return).Set the file’s contents to the following, and save:
Repeat for each user except user1. Set user1 to log in automatically on startup (System Preferences/Users and Groups/Options/Automatic login/user1).