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Can a Mac be used by different users at the same time?

I mean to say that we have a single Mac but 3 users. Can they access the same machine remotely at the same time for developing applications on iPhone or Mac?

Does Mac OS X server allow us to do this?

If so, how do I configure it for that?

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migrated from Mar 30 '10 at 9:20

This question came from our site for professional and enthusiast programmers.

Yes, but only one user can use the GUI at a time. You can have several people connected with SSH. – Dietrich Epp Mar 30 '10 at 9:07
See also Server Fault, "Mac OS X multi-user thin client server (terminal server)?" at… and "Something like “Terminal Services” for Mac OS X?" at… – Arjan Mar 30 '10 at 10:04
(From the Server Fault posts: iRAPP Terminal Server,, is sold at $298.00 -- not too bad, if the license for the iPhone development software allows for multiple sessions.) – Arjan Mar 30 '10 at 10:15
These comments are a bit out of date, more than one can use the GUI these days, with built-in sharing, etc. – rogerdpack Jan 5 at 23:09

This is supported by the built-in Screen Sharing as of OS X Lion, if you have set up multiple accounts:

Per-user screen sharing

You can remotely log in to a Mac with any user account on that computer and control it, without interrupting someone else who might be using the computer under a different login.

This works fine from Mac to Mac. To control from Windows, apparently one needs to "kickstart" ARD once. This can be done using the command line, by following Apple's Apple Remote Desktop: Configuring remotely via command line (kickstart). Or: in System Preferences disable Screen Sharing, Remote Login, Remote Management and Remote Apple Events, then enable all again, and finally disable all and just enable Screen Sharing.

But even when doing the above, my tests with an old XP machine and the latest version of UltraVNC were not very successful:

  • When the Mac was at the login window, using UltraVNC would really take over control of that Mac's screen, just like in the old days. Hence: both the Mac and the XP box would show exactly the same, and share a single session.
  • When the Mac user was logged in, starting VNC would show the background of the login window, but most often empty. Moving the mouse in Windows would make the Mac cursor change into a beach ball. Whenever the login window was not empty, it would still not respond to any clicks.
  • Using Remote Management rather than Screen Sharing made no difference.
  • As I do not need this myself, I did not test a lot though. A different OS, or another viewer, might yield different results. But the following quote from the most recent RealVNC's release notes are not very hopeful:

    Connections to Screen Sharing built-in to Mac OS X 10.7 (Lion) are not supported.
    Workaround: None.
    Status: Under consideration.

As an aside: beware not to test using a remote session from your Mac to some Windows box, back to the Mac, or using something like Parallels running Windows on the very same Mac. That yields an endless loop with a Droste Effect; reboot required...

For older versions of OS X, it is possible using Vine Server (OSXvnc). I never used it, but the creators claim:

[..] in Tiger (Mac OS 10.4) all those desktops can be accessed simultaneously using Vine Server (OSXvnc). This allows multiple users to be logged in, each using his or her own desktop on the same Mac.


All they need is a computer or PDA running a VNC viewer to access Vine Server (OSXvnc). Now you have a use for all those old PC's!


Each user MUST be logged in using Fast User Switching. If you reboot the computer you will need to go and log-in each user with Fast User Switching to enable access via VNC.

And using the very same software simultaneously might yield problems (like when temporary files are not stored in a user area), or might break the license agreements.

I don't know if this still works in Leopard and Snow Leopard. (But a recent post on Server Fault might indicate it's tested on a recent version of OS X, hence Snow Leopard?)

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apparently it "is possible, but painful" to connect from a windows box these days: – rogerdpack May 3 '12 at 3:48
Is it possible to connect from an older version of OS X to the latest version and user multi-user VNC? It doesn't seem to work... – Michael Apr 28 '13 at 18:11
I take that back - it works, but only if somebody else is logged in. If at the login screen, a remote session brings up the screen, allowing anybody at the console to see what I am typing. – Michael Apr 28 '13 at 18:46

As of Lion, yes. Here's the 9to5mac article on it. From Apple:

Per-user screen sharing

You can remotely log in to a Mac with any user account on that computer and control it, without interrupting someone else who might be using the computer under a different login.

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It's about time. – Daniel Beck Mar 24 '11 at 23:49

I was able to run 2 simultaneous and separate sessions from 2 windows laptops to a single mac mini, using Vines server. We had to have two users logged onto the Mac, with both sessions running separate vines server exe's. By using tightvnc configured to access the IP , port and pw combo for each vines servers, it worked.

Vines server settings were configured per the websites instructions.

Its not very robust, as the vines server instances assign a port number in startup sequence (first session 5900, second 5901, etc.), but it worked.

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plus I believe vine doesn't require OS X lion... – rogerdpack Apr 15 '13 at 5:46

We use Vine Server as well and log in to 1 mac with 3 different user accounts. It has its problems which we don't know how to solve. For example, when the mac user presses alt or capslock, it effects all the other accounts as well, which can be irritating.

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They would be able to access the same VNC session but that would only have one cursor (3 people would be fighting for it!).

I think what you're really after is source version control. Work on the project from your local machines, commit changes to your central server and pull back other people's changes.

I suggest you read up on the topic. Here's a nice gentle introduction:

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Not very helpful if as the questioner states, they have only one Mac. All the source control in the world won't help them to share one Mac between three. They need more Macs if they want to have more than one developer creating iPhone/Mac apps at the same time. – andynormancx Mar 30 '10 at 9:22
They only have one mac but they want other people to access it "remotely". A distributed version control system would allow each user to have their own core repository and recombine the code to a central location on request. Essential for lots of people hacking on the same codebase. – Oli Jun 3 '10 at 0:16
You don't need any macs or iphones to program for them. You only need one to build/test/deploy. If you only have one, it's pretty much a case of telling people to queue up, book slots, etc. Or get them to install their own "Hackintosh" installs as virtual machines. – Oli Jun 3 '10 at 0:18

In the past, I set up a single mac pro as follows (with the intention that other devs don't even need machines):

Multiple monitors
Multiple keyboards
Multiple mice

then I ran Parallels, which now allows you to virtualize OSX. I created a VM for each user.

I assigned specific keyboard and mice to each VM. The monitors all went with the main, it had the following limitations:

I had to log in, start up the VM's, move them to the correct monitor, and make that VM full-screen on that monitor.

If I accidentally (as the main user of the real machine) moved my mouse "off screen" then my mouse would appear over someone else's.

USB devices were easy enough to assign to specific VMs, but occasionally caused confusion at initial startup (e.g. same named keyboard...which one is it?).

We were doing both Android and iOS development, and this was workable. However, given the price of a mac mini vs a mac pro (and the need to buy OSX and parallels for each user), one is hard-pressed to not just buy a clump of minis. I guess if you wanted to "share" the horsepower of a beefy machine, it works out.

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I was also considering the solution using one very powerful machine for 2-4 users. But professionally I came away from that solution because of the following reasons:

1) If one user experiences problems and reboots, everyone will be affected - and wait for the reboot. Also those reboots will probably be more often required, when 4 users are working at the same time - compared with only 1 user.

2) If the machine breaks down I can send the programmers back home?

Therefore: Everyone gets his own machine and outsourcing source code management and build server seems to be the professional way.

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